The Official AVS Antenna Topic! [Text View] - Page 40

holl_ands

07-10-09, 11:50 AM

Do you have some recommendations for such FM antenna (i.e. yielding low noise FM stereo)?
TV stations tend to be clumped together on one (or several) mountain tops.
However, FM towers seem to be randomly scattered...so you are likely to have
one or more within a dozen miles of you....which can cause intermods within
the FM band if passed through a Preamp. Intermod noise can prevent reception
of some weak stations. Hence preference for a direct FM antenna connection.

You can enter your location to determine FM station distance/direction/signal levels
as well as download a *.kmz file (unzip and double click) which installs FM station
icon locations for display in GoogleEarth at www.fmfool.com

=======================================
Fol. website summarizes most hi-gain (and other) FM antennas...click on
"Antenna Performance Curves": http://ham-radio.com/k6sti/
It also includes some DIY, esp indoor, antenna designs....

Omnidirectional antennas, such as the "Turnstile" are frequently used for
FM since the towers are usually not from a single direction. For distant reception,
you'll need a high gain, directional antenna...and perhaps a rotator...

Digital Rules

07-10-09, 02:29 PM

Intermod noise can prevent reception
of some weak stations. Hence preference for a direct FM antenna connection.More importantly, amplification can add a lot of unecessary noise(hiss) when listening to FM "stereo". Line loss is extremely low on FM, so amplification generally does more harm than good with a cable run of 200' or less.

JimP

07-10-09, 04:32 PM

Regarding television reception.

I now have a combination UHF/VHF antenna pointing due south and a UHF only antenna pointing to the west.

I found that my channel master 7775 preamp is UHF only. Any suggestions as to preamps and connections that would be effective and minimize any signal losses.

Digital Rules

07-10-09, 05:30 PM

I found that my channel master 7775 preamp is UHF only. Any suggestions as to preamps and connections that would be effective and minimize any signal losses.Are you planning on receiving UHF off both antennas; or will one antenna be exclusively for VHF, & one just for UHF?

JimP

07-10-09, 05:34 PM

UHF off of both and VHF off of one of those.

Satcom15

07-10-09, 08:12 PM

holl_ands,
Just thought you might like to see what I think is a unique Cable TV OTA receive site in northern California. Its located northeast of Chico along SR 32. See the picture below. I noticed this site years ago (early 80s) one time when driving up the highway. Some of the reflector screen supports are visible from the highway and being a radio geek I had to check it out. I can't recall how tall they are, but it seems there is a section of a parabolic reflector aimed at a building where there was a high gain VHF/UHF antenna (the focal point). I was surprised to see the structures still standing in the Googel Earth image, particularly since there are a lot of satellite antennas. When I drove through there back in the 80s, I don't recall seeing the antennas then. I'm thinking that that the system was aimed at the SF Bay area and had much more gain than ganging multiple antennas. Also, the site elevation is about 1350 ft. So all in all there is a good view of transmitters located in the SF Bay Area about 140 miles away. It also probably can see Sacramento stations too about 80 miles south. Wonder if it is still in use. Interesting, eh? :D

Cheers.
Satcom

http://i275.photobucket.com/albums/jj319/com30sptr2/Slide1.jpg

300ohm

07-10-09, 11:04 PM

if i remember correctly i think home depot has makita.
Yeah both Lowes and Home Depot (I think I got the jig saw there) carry Makita. But darn it, they dont stock the unique blades, heh.

EscapeVelocity

07-11-09, 01:43 AM

Thought this crowd might be interested...

Antenna Comparison

Winegard 9032
xg91
HD7698P
Antenna Craft YA10-7-13

http://www.hdtvtruckee.com/AntennaComparison.htm

systems2000

07-11-09, 09:09 AM

How can you compare a XG91 to an Antenna Craft YA10-7-13?

Tower Guy

07-11-09, 09:42 AM

Just thought you might like to see what I think is a unique Cable TV OTA receive site in northern California.

The cable system in Kingston, NY also had such an antenna in Port Ewen, NY. It was aimed at the Empire State Building.

The towers were 40' tall. The reflector was made with stainless steel wires 2" apart running horizontally. It worked on VHF, but not for UHF. The feed was a conventional TV antenna 20' off the ground. Channel 13 in Albany made reception of New York's WNET 13 troublesome, especially after Albany installed a CP antenna.

The site engineer referred to the antenna as a DEW line antenna. I've never seen such an antenna on any of the DEW line pictures that I've found.

Here's the tvfool report for the California location.
http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3db09ac296716a05

ProjectSHO89

07-11-09, 10:13 AM

How can you compare a XG91 to an Antenna Craft YA10-7-13?

You should probably READ THE ARTICLE before commenting with no knowledge....

Satcom15

07-11-09, 11:57 AM

The cable system in Kingston, NY also had such an antenna in Port Ewen, NY. It was aimed at the Empire State Building.

The towers were 40' tall. The reflector was made with stainless steel wires 2" apart running horizontally. It worked on VHF, but not for UHF. The feed was a conventional TV antenna 20' off the ground. Channel 13 in Albany made reception of New York's WNET 13 troublesome, especially after Albany installed a CP antenna.

The site engineer referred to the antenna as a DEW line antenna. I've never seen such an antenna on any of the DEW line pictures that I've found.

Here's the tvfool report for the California location.
http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3db09ac296716a05

Tower Guy,
Thanks for the info. Your note confirmed my thought that similar installations must have existed elsewhere around the nation. Your description agrees with what I recall seeing. Wonder what kind of gain these antenna systems had. That reflector had to scoop up a lot of RF.

As for the Dew Line antenna comment, perhaps that's a because it resembled the White Alice troposcatter communication systems. At some locations they had very large "Bill Board" reflectors that looked similar to the antenna here.

Cheers.
Satcom

kinemax

07-11-09, 07:03 PM

More importantly, amplification can add a lot of unecessary noise(hiss) when listening to FM "stereo". Line loss is extremely low on FM, so amplification generally does more harm than good with a cable run of 200' or less.
So, does this mean that, if I were to use the VHF/UHF antenna for FM, I would be better of splitting off the FM signal near the antenna prior to amplification?

EscapeVelocity

07-11-09, 08:35 PM

Lonely antenna spotted....

Can you name it?

http://i302.photobucket.com/albums/nn88/EscapeVelo/IMG_0943.jpg

http://i302.photobucket.com/albums/nn88/EscapeVelo/IMG_0942.jpg

http://i302.photobucket.com/albums/nn88/EscapeVelo/IMG_0939.jpg

http://i302.photobucket.com/albums/nn88/EscapeVelo/IMG_0940.jpg

Digital Rules

07-12-09, 08:32 AM

So, does this mean that, if I were to use the VHF/UHF antenna for FM, I would be better of splitting off the FM signal near the antenna prior to amplification?You will be OK as long as you don't use too much amplification. I was referring to a dedicated FM only antenna, where there is really no need to amplify.

Digital Rules

07-12-09, 08:35 AM

Lonely antenna spotted....

Can you name it?

http://i302.photobucket.com/albums/nn88/EscapeVelo/IMG_0940.jpg
Looks like a Channel Master 3016. http://www.solidsignal.com/prod_display.asp?PROD=ANC3016

systems2000

07-12-09, 11:23 AM

You should probably READ THE ARTICLE before commenting with no knowledge....
I did read the article. My comment was directed towards this:
Antenna Comparison

Winegard 9032
xg91
HD7698P
Antenna Craft YA10-7-13

300ohm

07-12-09, 12:51 PM

Looks like a Channel Master 3016.
Yep, the directors give it away. Its mounted upside down for some reason, heh. No real harm on dry days, but rain would puddle and remain longer on the element standoffs. Not quite the safest place to mount an antenna either.

johnpost

07-12-09, 01:41 PM

Lonely antenna spotted....

Can you name it?

http://i302.photobucket.com/albums/nn88/EscapeVelo/IMG_0939.jpg

sometimes people want to mount their antennas to an electrical service entrance (where the electrical wires come to a building) because it seems a convenient antenna mast support. it is a very bad idea for two reasons.

1) it is a very noisy electrical environment so the antenna won't work well.

2) you might die or your house catch on fire. whenever you need to do antenna work you come dangerously close to live electric wires, even skilled professionals only do so with lots of precautions. the antenna might fall and bring electricity into your house via the antenna which is a shock and fire hazard.

The only thing safe on a service entrance is lights and then only if well below the drip loop going into the weather head (the lowest point of the wires near the pole). the ladder should not have to go high enough where it might touch the wires and with you on the ladder you should not be able to touch the wires with you arms extended.

This system seems to be abandoned now and the antenna may have been placed before the wires were live. Neither matter; an antenna within falling distance of wires or an antenna or a light within contact distance of wires is a serious hazard.

Don't do like or similar to this photo.

EscapeVelocity

07-12-09, 01:41 PM

I might give it a new home. Its just out there on a the electric pole of presumably a trailer that burned down or was towed away or something. Ill go have another look at the wiring. I dont think its hooked up to the power grid anymore, except maybe the night light.

Great advice johnpost. I dont think the brightest bunch in the berry patch lived there. :)

nordloewelabs

07-12-09, 01:42 PM

Lonely antenna spotted.... Can you name it?

http://i302.photobucket.com/albums/nn88/EscapeVelo/IMG_0940.jpg

not so lonely.... some birdie seems to have befriended it.

Rick313

07-12-09, 02:16 PM

Does anyone here have experience with DigiTenna (http://www.digitenna.com)brand antennas? As I understand it, the company has only been around for about a year. I had not heard of them until EV mentioned them last week on his thread EV's Best Top Rated DTV Indoor Antenna Review Test Round-Up Guide (http://www.avsforum.com/avs-vb/showthread.php?p=16780952#post16780952). Their specs look good, but I haven't been able to find any objective reviews. Does anyone here have experience with them?

300ohm

07-12-09, 08:16 PM

not so lonely.... some birdie seems to have befriended it.
(Looking all over for a bird in that picture, heh) Thats not a nest on the line, its spanish moss.

systems2000

07-13-09, 11:29 PM

Over the weekend, I finally mounted the Zig-Zag antenna. I didn't get a chance to test it with a pre-amp. It did work without isolating it from the tower. Unfortunately, I wasn't able to acquire any stations from Baltimore, D.C., WLYH, or WPMT (I didn't try for WTAJ).

I finally aligned it for W08EE-D (215°M) to check for VHF capabilities. It acquired WVPY, WWPB, WHAG, WWPX, & WJAL. I'm getting 100% quality and no signs of degradation, drop-outs, interference, or fading.

WVPY (209°M), WWPX (215°M), WWPB (226°M), WHAG (227°M), & WJAL (279°M).

Tschmidt

07-14-09, 12:19 PM

I'm in southern NH 42 miles away from Boston stations. Currently have separate VHF (YA-1713) and UHF (CM 4228 old style) roof mounted antennas. I offset them by 105 degrees to minimize need to use rotator. VHF picks up NH channel 9 and 11 and UHF Boston stations. WHDH (Boston) was schedule to move back to VHF but due to technical problems appear they will be staying on UHF. Use CM 7777 mast mounted preamp and 8-way splitter.

This is my only my second post so not able to embed URLs.
Have posted setup details on my site: tschmidt-dot-com/writings

Here is TVfool info, FCC site data is pretty similar.
/?option=com_wrapper&Itemid=29&q=id%3d74fa1d6ecdfd6f

We are having problems receiving WSBK and WGBX. WGBX is a high priority for us. I emailed station and they replied they are transmitting at full power and final antenna. I realize modeling is only a rough approximation but we are able to receive stations that model weaker reliably (WHDH (UHF) and WFXT). WLVI and WBPX also model weaker and we receive them occasionally. Almost never able to receive WGBX. Hoped termination of Nightlight broadcast would help but had no effect.

All Boston stations are in the same heading so terrain differences are not an issue. WLVI in on RF channel 41, WHDH 42 and WGBX 43 so system frequency response does not seem to be a factor.

Terrain here in NH is a problem and even though antenna is 30 ft above grade it is below tree level and in shadow of distance hill.

Any comments or ideas are appreciated. Is the 91-XG a better choice? I hate to randomly try different combinations.

fixed typo meant 91XG not 43

Tower Guy

07-14-09, 12:34 PM

Any comments or ideas are appreciated. Is the 43-XG a better choice?

No, the 43 XG has similar or even less gain as the 4228. The 91XG may help, but I'd say that you need more than 1-2 db.

So, what's wrong? Have you tried your 4228 without tilt? Does the other end of the house miss the big tree better?

Tschmidt

07-14-09, 12:59 PM

I'd say that you need more than 1-2 db.

So, what's wrong? Have you tried your 4228 without tilt? Does the other end of the house miss the big tree better?
Thanks for the quick response. Receive signal level of WGBX is so low it does not even sync most of the time. Agree I need more then a couple of dB. BTW meant 91XG, not 43XG. This is snow and ice country. The 4228 survived last December's ice storm without a hitch. By comparison 91XG looks pretty fragile with lot more surface area.

Have not tried comparing tilt and vertical mount of the 4228. It is a pain to take the mast done and play. Other end of house is blocked even worse. It is not just a single tree but a tree line. Plus aesthetically mounting antenna on Western side, away from driveway is better.

Tschmidt

07-14-09, 03:31 PM

Added links now that I have hit the magic number:

TVfool data:
http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3d74fa1d6ecdfd6f

Outdoor antenna setup:
http://www.tschmidt.com/writings/Design%20and%20install%20outdoor%20TV%20antenna.htm

/tom

systems2000

07-14-09, 03:47 PM

Plus aesthetically mounting antenna on Western side, away from driveway is better.
Do you want reception or aesthetics? Unfortunately, they don't always work out together.

serndipity

07-14-09, 06:48 PM

We are having problems receiving WSBK and WGBX. WGBX is a high priority for us.

The Boston MA (includes Southern NH) OTA thread is here:

http://www.avsforum.com/avs-vb/showthread.php?t=453241

WBZ, WSBK, WGBH and WGBX antennas are all at the same height and tower in Needham (generally well received in even in SE NH).

BTW. I lived in Amherst NH before moving to Marblehead MA. Using a DIY indoor antenna, I have no problems receiving NH channels 9, 11 and 50 here (although at sea level, having the ocean in my frontyard makes a big difference).

Tschmidt

07-15-09, 01:14 AM

http://www.avsforum.com/avs-vb/showthread.php?t=453241
I've posted there also. But this is more about antenna performance in general rather then then specific region.

WBZ, WSBK, WGBH and WGBX antennas are all at the same height and tower in Needham
They are not quite the same height but pretty close. That is why significant difference in receive level is so confusing given the relatively small difference in transmit power between WGBH and WGBX.
According to Necrat: WBZ, WCVB, WGBH, WGBX, WSBK, WYDN are all on the Needham tower, other stations have their own towers.

Using a DIY indoor antenna, I have no problems receiving NH channels 9, 11 and 50 here
9 and 11 come in fine. 50 is a no show even though analog was fine. Looking at TVfool info there is terrain obstruction but receive level still models pretty high. It is not a big deal since it requires rotating the antenna.

300ohm

07-15-09, 02:20 PM

WGBX is a high priority for us. hat is why significant difference in receive level is so confusing given the relatively small difference in transmit power between WGBH and WGBX.
6db of NM difference can be quite significant on a two edge station. Have you tried moving the antenna up and down in say 6 inch increments ? You may find a hot spot for it that way.

gerty112

07-15-09, 03:16 PM

Clearstream C4 works great for all UHF stations in Los Angeles. I sent back the Clearstream C5 today because it did not work for the Hi VHF like it stated.

Where did you get a Clearstream C5 in LA to be returning it in early July?

The manufacturer is taking pre-orders now, and says it won't be released until late July. The on-line web-sites selling it also say "not in stock" are taking back/pre-orders only.

rbarbier

07-15-09, 03:57 PM

Where did you get a Clearstream C5 in LA to be returning it in early July?

The manufacturer is taking pre-orders now, and says it won't be released until late July. The on-line web-sites selling it also say "not in stock" are taking back/pre-orders only.

I ordred it directly from the manufacturer (even though it said pre-order). They actually shipped it out a few days later. It did work pretty good but not the same stable reception that I get with the C4 for UHF. I am 57 miles away also.

I sent it back a few days later and picked up the AntennaCraft Y5-7-13 and get 0 signal with that one (looks like the C5 might be better then the Y5-7-13).

I just hate High VHF. That is all I have to say. UHF at 57 miles away with a small C4 antenna and I get perfect UHF reception. High VHF with a 5' antenna and still no signal.

JimP

07-15-09, 05:01 PM

I'm looking at the bottom of a Winegard AP-4800 UHF antenna preamplifier.

It says on the bottom (with VHF BY-PASS). Does that mean that VHF is allowed to go through the preamp without amplification or does it mean that VHF is filtered out and doesn't go through the device.

holl_ands

07-15-09, 05:23 PM

ProjectSHO89

07-15-09, 07:29 PM

Where did you get a Clearstream C5 in LA to be returning it in early July?

The manufacturer is taking pre-orders now, and says it won't be released until late July. The on-line web-sites selling it also say "not in stock" are taking back/pre-orders only.

See http://www.avsforum.com/avs-vb/showthread.php?p=16642463&highlight=birdie#post16642463

A small shipment was airlifted in mid-June to fill a specific need and about 100or so pre-orders were filled at that time. I heard they should have a large shipment in within a week or so that will clear out all existing pre-orders.

You might contact them as they might have a couple of "open box" specials available from mis-orders available. I heard that two which were received back were never even assembled and the other was from rbarbier.... Sounds like a pretty good rate of acceptance...

rbarbier

07-15-09, 08:34 PM

See http://www.avsforum.com/avs-vb/showthread.php?p=16642463&highlight=birdie#post16642463

A small shipment was airlifted in mid-June to fill a specific need and about 100or so pre-orders were filled at that time. I heard they should have a large shipment in within a week or so that will clear out all existing pre-orders.

You might contact them as they might have a couple of "open box" specials available from mis-orders available. I heard that two which were received back were never even assembled and the other was from rbarbier.... Sounds like a pretty good rate of acceptance...

And mine was only installed for about 5 days on my patio and I took good care of it. I still would recommend it. I think if I was a little closer (or the stations were operating at more power), it would have worked better. The C4 with the C5 looked good together though. My C4 is lonely again.

ngarrang

07-15-09, 09:10 PM

I am thinking of ganging a second DB4 to my existing DB4. What is the proper distance apart their center points should be for best results centered on channel 30?

Davird_Jr

07-15-09, 10:27 PM

I am 57 miles away also.

I sent it back a few days later and picked up the AntennaCraft Y5-7-13 and get 0 signal with that one (looks like the C5 might be better then the Y5-7-13).

I just hate High VHF. That is all I have to say. UHF at 57 miles away with a small C4 antenna and I get perfect UHF reception. High VHF with a 5' antenna and still no signal.

You might think about a deep fringe antenna at your distance out. I get rock solid VHF from 50 miles over mountainous terrain with a Winegard HD8200. Signal levels 90 - 100 %.

ProjectSHO89

07-15-09, 10:31 PM

You might think about a deep fringe antenna at your distance out. I get rock solid VHF from 50 miles over mountainous terrain with a Winegard HD8200. Signal levels 90 - 100 %.

Unfortunately, he has to keep it on his balcony. The 8200 is probably bigger than the whole balcony.

rbarbier

07-15-09, 10:39 PM

Unfortunately, he has to keep it on his balcony. The 8200 is probably bigger than the whole balcony.

Yeah. Even the current 5' antenna is taking up a good amount of my space. I want something like the C5 for High VHF with a little more gain or something.

EscapeVelocity

07-15-09, 10:51 PM

How about make your own 16" loop with 1" or 1/2" copper tubing and put a screen behind it about 15" back?

rbarbier

07-15-09, 11:24 PM

How about make your own 16" loop with 1" or 1/2" copper tubing and put a screen behind it about 15" back?

PLEASE explain this. Would this work for 7-13 in my area?

Thanks in advance.

(I really only care about 7 (ABC) and 11 (FOX)) if that helps.

EscapeVelocity

07-15-09, 11:36 PM

Well, people make 16" loops for the ham band 144Mhz. I was just thinking out loud.

Maybe a 15" loop and 15" Reflector Screen.

JimP

07-16-09, 07:03 AM

Yesterday, I attempted to increase my signal strength by reaiming my Yagi antenna to point directly at the station that I'd like to peak. It was a few degrees different. I wound up loosing a couple of points of signal strength versus aiming it to peak out the signal. Is it possible that I was getting a higher number before due to some cumulative reflection effect where I'm still better off aiming it dead on at their tower? I haven't watched enough since then to know how it affected the signal.

Digital Rules

07-16-09, 07:24 AM

Yesterday, I attempted to increase my signal strength by reaiming my Yagi antenna to point directly at the station that I'd like to peak . . . . . . I wound up loosing a couple of points of signal strength versus aiming it to peak out the signal. Is it possible that I was getting a higher number before due to some cumulative reflection effect where I'm still better off aiming it dead on at their tower?Yes, it could be many things(trees, buildings, hills, system overload). It may only affect certain channels even though they are coming from the same direction. I have 17 channels coming from the same direction. All come in fine except 2, which both require re-aiming 30 degrees off axis.

ProjectSHO89

07-16-09, 08:39 AM

How about make your own 16" loop with 1" or 1/2" copper tubing and put a screen behind it about 15" back?

That would be even lower gain than either antenna already tried out....

arxaw

07-16-09, 09:12 AM

...I just hate High VHF. That is all I have to say. UHF at 57 miles away with a small C4 antenna and I get perfect UHF reception. High VHF with a 5' antenna and still no signal.Same scenario for many many people in certain parts of the country.

rbarbier

07-16-09, 11:03 AM

That would be even lower gain than either antenna already tried out....

Is there something similar to the V21 without channels 2-6 and without the UHF channel? Would this antenna work in my situation? Or if I just cut off the Low VHF part and use this as a UHF/High VHF antenna?

Or...how about paying somebody to make me a custom antenna for 7-13 with the highest gain and small form factor. I am willing to do this also.

Thanks.

ctdish

07-16-09, 11:36 AM

Same scenario for many many people in certain parts of the country.
Not here. AT 50 miles VHF near perfect. On UHF half the stations come in intermittently on a single UHF antenna, the rest not at all.
John

rbarbier

07-16-09, 11:38 AM

Not here. AT 50 miles VHF near perfect. On UHF half the stations come in intermittently on a single UHF antenna, the rest not at all.
John

What antennas are you using for UHF/VHF?

rbarbier

07-16-09, 12:22 PM

arxaw

07-16-09, 12:47 PM

One way to tell. Bypass the 7777 and see if your signal quality improves.

You can't just unplug the power supply, you have to temporarily bypass the preamp.

But if your tvfool results are correct, overload is not likely. The 7777 might be defective, though.

JimP

07-16-09, 12:55 PM

Is the power supply warm or cool to the touch? It should be warm.

rbarbier

07-16-09, 01:11 PM

Is the power supply warm or cool to the touch? It should be warm.

Not sure. Not at home right now. I know the 7777 works for the UHF because I do get a higher signal with UHF through the 7777. I never really had to use the 7777 for VHF until now. I know the switch inside the Amp is correct (seperate instead of combined) and FM Trap is on.

I will try running VHF antenna directly to my TV (about 15' cable run) and see if I get any signal.

ProjectSHO89

07-16-09, 02:45 PM

Could I be overloading my TV? According to TVfool, my High VHF signals are 18.5, 16.6, 15.5 and 12.7 NM(dB). My UHF signals start at 7.0 dB down to 1.7 dB.

I am using the CM7777 with a short cable run (like 10 feet split to 4 tuners). What is weird is that my strongest UHF channel (43..CBS 2.1) is actually one of my lowest dB signal on TVfool.

http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3d74fa52fb44c917

Pretty much zero chance of overload from the actual signals. Usually don't have to worry about that until the TVFool Rx level is more positive than -20 dBm or so. You might try an FM trap (check FMfool.com for any nearby FM stations.)

Try also running straight from the VHF > 7777> to a single set.

holl_ands

07-16-09, 04:08 PM

Well, people make 16" loops for the ham band 144Mhz. I was just thinking out loud.

Maybe a 15" loop and 15" Reflector Screen.
Optimum Circular Loop diameter for the Hi-VHF Band is 24-inches using 1/2-in pipe,
23-inches for QuarterInchCopperTubing, 21.5-inches for AWG12 and 21-inches for
AWG26 (tiny wire taped to window):
http://imageevent.com/holl_ands/loops/vhfloop
So Loop Reflector would probably be about 5-percent larger....next on my list...

Other antenna analyzes can also be found here:
http://imageevent.com/holl_ands/

EscapeVelocity

07-16-09, 04:25 PM

Thanks Holl_ands!

Neil L

07-16-09, 05:29 PM

So Loop Reflector would probably be about 5-percent larger....next on my list......optimal spacing between the loop and reflector?

rbarbier

07-16-09, 06:43 PM

Pretty much zero chance of overload from the actual signals. Usually don't have to worry about that until the TVFool Rx level is more positive than -20 dBm or so. You might try an FM trap (check FMfool.com for any nearby FM stations.)

Try also running straight from the VHF > 7777> to a single set.

Tried both ways (directly to my TV and directly from my 7777), same thing. No signal. Tried scanning without antenna then rescanning. UHF still 80% on my TV. Guess I am in a dead zone for VHF.

Guess I will dream about the days I got all my local channels in HD when they were all UHF. Maybe if I move, I will get the biggest High VHF antenna I can find. That might work.

Davird_Jr

07-16-09, 09:30 PM

Tried both ways (directly to my TV and directly from my 7777), same thing. No signal. Tried scanning without antenna then rescanning. UHF still 80% on my TV. Guess I am in a dead zone for VHF.

Guess I will dream about the days I got all my local channels in HD when they were all UHF. Maybe if I move, I will get the biggest High VHF antenna I can find. That might work.

I did not realize you only had a balcony to mount the antenna. You might try looking around your neighborhood to see what antennas other people are using.

rbarbier

07-16-09, 10:07 PM

I did not realize you only had a balcony to mount the antenna. You might try looking around your neighborhood to see what antennas other people are using.

Not too many people have antennas around here and the ones that I do see are old. I really don't see huge antennas out here but I don't know what kind of reception they have either. The balcony worked/works perfect for me with my C4 UHF antenna. I even had perfect UHF digital with my Squareshooter 1000 at 57 miles away. I think my location might be optimized for UHF signals or something. Just can't get the High VHF stations at my location.

Rick313

07-16-09, 10:20 PM

Just can't get the High VHF stations at my location.

Your TVFool results show almost all of your VHF signals as 1Edge which indicates that there is some sort of obstruction between you and the transmitters. That probably explains why you're having such a hard time finding an antenna that works well for VHF.

I assume that your balcony faces toward the transmitters. Have you tried aiming the antenna at various angles? Sometimes aiming the antenna in a slightly different direction will allow you to pickup a reflected signal.

rbarbier

07-16-09, 10:37 PM

Your TVFool results show almost all of your VHF signals as 1Edge which indicates that there is some sort of obstruction between you and the transmitters. That probably explains why you're having such a hard time finding an antenna that works well for VHF.

I assume that your balcony faces toward the transmitters. Have you tried aiming the antenna at various angles? Sometimes aiming the antenna in a slightly different direction will allow you to pickup a reflected signal.

Yeah. My balcony faces the correct direction. I tried all directions but still nothing.

I thought VHF was supposed to be better with obstructions. All my UHF stations are 1Edge and from the same degrees and I don't have any issues. I can even have my C4 antenna inside my apartment and I still get a usable signal for most of my UHF stations. I can even lay my C4 on the floor of the balcony and I still get a reception (I live on the second floor).

I will keep playing around with the VHF antenna and see what happens. I might just get a second UHF antenna and face it towards San Diego and at least have Fox5 from San Diego (about 77 miles away). I am able to get that station most of the time even though my antenna is facing the LA towers.

Rick313

07-16-09, 11:00 PM

I thought VHF was supposed to be better with obstructions.

I know it's supposed to propagate better through trees, but I'm not sure about other obstructions.

I will keep playing around with the VHF antenna and see what happens.

You might try angling it up a just a bit if you can. Sometimes that helps too. Good luck.

JimP

07-16-09, 11:22 PM

Yeah. My balcony faces the correct direction. I tried all directions but still nothing.

I thought VHF was supposed to be better with obstructions. All my UHF stations are 1Edge and from the same degrees and I don't have any issues. I can even have my C4 antenna inside my apartment and I still get a usable signal for most of my UHF stations. I can even lay my C4 on the floor of the balcony and I still get a reception (I live on the second floor).

I will keep playing around with the VHF antenna and see what happens. I might just get a second UHF antenna and face it towards San Diego and at least have Fox5 from San Diego (about 77 miles away). I am able to get that station most of the time even though my antenna is facing the LA towers.

I'm new at this, so I'm throwing this out there for others to comment on.

The AntennaCraft Y5-7-13 VHF antenna you used specifications read "Mileage VHF:60 Miles" which I believe presumes that you have perfect conditions and no line loss. Even with an amplifier, you don't have enough signal at 57 miles to amplify for it to matter.

If you're looking for a dual antenna solution, then the VHF antenna should be something like the Antennacraft Y10-7-13 rated up to 100 miles for high band VHF. Note that its 10' long. Here's a comparison of antennacraft's 3 Yagi style antennas. http://www.antennacraft.net/Yagi.html

rbarbier

07-16-09, 11:33 PM

I'm new at this, so I'm throwing this out there for others to comment on.

The AntennaCraft Y5-7-13 VHF antenna you used specifications read "Mileage VHF:60 Miles" which I believe presumes that you have perfect conditions and no line loss. Even with an amplifier, you don't have enough signal at 57 miles to amplify for it to matter.

If you're looking for a dual antenna solution, then the VHF antenna should be something like the Antennacraft Y10-7-13 rated up to 100 miles for high band VHF. Note that its 10' long. Here's a comparison of antennacraft's 3 Yagi style antennas. http://www.antennacraft.net/Yagi.html

Yeah. That might work but I find it ridiculous that i need a 10' long antenna for the same signal as my 28" long antenna. 10' might be too long for my balcony.

finlay648

07-17-09, 02:49 AM

Yeah. That might work but I find it ridiculous that i need a 10' long antenna for the same signal as my 28" long antenna. 10' might be too long for my balcony.

Is it possible that you are getting a lot of multipath reception on VHF? When my local stations switched to VHF digital I had problems in spite of having lots of signal strength. I have a Zenith CECB that showed lots of signal but I couldn't get reliable digital reception because the multipath reception increased a lot with VHF. I had to move that antenna around until I found a sweet spot.

JimP

07-17-09, 03:56 AM

Yeah. That might work but I find it ridiculous that i need a 10' long antenna for the same signal as my 28" long antenna. 10' might be too long for my balcony.

Therein lies the problem. It isn't the same signal.

But as you said, you can get another UHF antenna and point it in the opposite direction and pick up the same networks with other stations. If you can do so reliably with a second 28" long antenna, why not do that?

Another option that is out there but gets away from free TV is to go satellite and pick up distant locals. Just be sure that you've got line of sight for the satellites that do locals.

johnpost

07-17-09, 08:26 AM

All my UHF stations are 1Edge and from the same degrees and I don't have any issues.

You might try angling it up a just a bit if you can. Sometimes that helps too. Good luck.

try that it makes a big difference for 1edge

Yeah. That might work but I find it ridiculous that i need a 10' long antenna for the same signal as my 28" long antenna. 10' might be too long for my balcony.

not ridiculous just the laws of nature.

Is it possible that you are getting a lot of multipath reception on VHF?

if you have multipath overload then eliminating some of that may help. people have placed antennas in wire cages to cut down paths other than from the front. maybe cumbersome and not nice to look at but it does work.

rbarbier

07-17-09, 08:42 AM

Therein lies the problem. It isn't the same signal.

But as you said, you can get another UHF antenna and point it in the opposite direction and pick up the same networks with other stations. If you can do so reliably with a second 28" long antenna, why not do that?

Another option that is out there but gets away from free TV is to go satellite and pick up distant locals. Just be sure that you've got line of sight for the satellites that do locals.

I already have DirecTV. I like using my antenna for local TV because I have it running into my Media Center PC with 3 digital tuners and one analog tuner. This allows me to record multiple shows at one time for free plus unlimited space on my PC. Plus, the quality of the OTA channels are much better than the DirecTV channels.

rbarbier

07-17-09, 08:44 AM

[QUOTE=johnpost;16839826]

not ridiculous just the laws of nature.

QUOTE]

Yeah. I understandy WHY VHF needs a bigger antenna. I just think that if UHF requires smaller antennas, why not just go with UHF? Not everyone can put up 15' antennas for free TV.

JimP

07-17-09, 08:58 AM

rgharrin

07-17-09, 08:59 AM

Tried both ways (directly to my TV and directly from my 7777), same thing. No signal. Tried scanning without antenna then rescanning. UHF still 80% on my TV. Guess I am in a dead zone for VHF.

Guess I will dream about the days I got all my local channels in HD when they were all UHF. Maybe if I move, I will get the biggest High VHF antenna I can find. That might work.

I feel your pain. Exactly the same problem. Got all the stations from 65 mi.
Then FOX decided to be the only VHF station (15kW). Can't get it at all.
Even those with VHF antennas have failed.

rbarbier

07-17-09, 09:01 AM

rbarbier

07-17-09, 09:05 AM

Then the next guy wants to get VHF from a 100 miles out and doesn't want to put up an even larger antenna. When do you say that due to your choice of where to live that you have the consequences of poorer OTA reception.

I don't live 100 miles out. I live 57 miles out. Also, I get perfect reception with UHF and did for over 4 years. I can understand if I didn't get any reception for either UHF or VHF but if I am able to get perfect UHF then I don't see the problem. I don't think 57 miles away is asking for too much for reliable reception without drastic measures.

Like I said, I even had perfect UHF reception with a small Square Shooter 1000 that is only 16" square. Now, I am using a "larger" C4 for UHF (if you call 28" large).

Plus, I know other people that are closer then me (and further then me), that also lost reception with High VHF and they have bigger High VHF antenna then I do.

rbarbier

07-17-09, 09:07 AM

I feel your pain. Exactly the same problem. Got all the stations from 65 mi.
Then FOX decided to be the only VHF station (15kW). Can't get it at all.
Even those with VHF antennas have failed.

Exactly. That is the point I am trying to make. People have their "theories" about VHF traveling further then UHF, or that VHF will penetrate structures more, but from first hand expierence, this is not true.

Davird_Jr

07-17-09, 10:49 AM

Exactly. That is the point I am trying to make. People have their "theories" about VHF traveling further then UHF, or that VHF will penetrate structures more, but from first hand expierence, this is not true.

On the other hand here at my location the exact opposite is true. VHF reliable, UHF unreliable. Wish all my stations were on VHF. I guess we all just have to make the best of our particular location. If you could swing the 10 foot antenna I would try that. I would bet much better than what you were trying. OTA is important to you so it may be your only choice. Here a 14 foot antenna is the norm if you want good OTA. And a lot of people here refuse to get sat and there is no cable. But it is very rural here and lots of mountains so people don't mind getting monster antennas. Problem for UHF is there is no monster antenna to improve reception. Best UHF antennas here are marginal. I might try stacking antennas to try and improve my UHF. Now you want to talk about a monster!:D

johnpost

07-17-09, 10:59 AM

rbarbier

07-17-09, 11:00 AM

On the other hand here at my location the exact opposite is true. VHF reliable, UHF unreliable. Wish all my stations were on VHF. I guess we all just have to make the best of our particular location. If you could swing the 10 foot antenna I would try that. I would bet much better than what you were trying. OTA is important to you so it may be your only choice. Here a 14 foot antenna is the norm if you want good OTA. And a lot of people here refuse to get sat and there is no cable. But it is very rural here and lots of mountains so people don't mind getting monster antennas. Problem for UHF is there is no monster antenna to improve reception. Best UHF antennas here are marginal. I might try stacking antennas to try and improve my UHF. Now you want to talk about a monster!:D

I would say have the stations broadcast on UHF and VHF. I think there are 4 free UHF frequencies they can use in the Los Angeles area for 7, 9, 11 and 13. Keep them on High VHF for the people that like VHF and put them on UHF for all the other people.

rbarbier

07-17-09, 11:03 AM

Satcom15

07-17-09, 11:22 AM

Tried up/down/left/right/sideways/upside down/kids holding it/wife holding it/dog holding it/on the floor/high in the air/without pre-amp/with pre-amp/with splitter/without splitter/C4 antenna/C5 antenna/y5-713 antenna/different cables/double scan.

Sometimes I think we need better test equipment to isolate problems. A spectrum analyzer and/or frequency selectable power meter would probably be very helpful in solving your problems. The spectrum analyzer would give a picture of the RF spectrum and power as received by your antenna to verify there is or is not a signal to be had at the frequency expected as well as show adjacent emissions, noise, etc. There are probably other TV related test equipment devices that would be useful too, but I'm not sure what (hey, I'm an analog RF guy living in a digital world :D ).

Unfortunately, most test equipment is too expensive for individuals to own. Wonder if there is any sort of inexpensive panadaptor/spectrum analyzer software that could be installed on a computer rather than a stand alone hardware appliance? Alternatively, perhaps there is an opportunity to create test equipment coops where members pool fees to buy equipment they can borrow when needed. Don't know what the best solution is but the comments I see here sure point to the need for better test equipment in the hands of consumers to isolate problems and save people time and money.

johnpost

07-17-09, 11:40 AM

have you tried tilting your antenna up as was suggested. sometimes necessary for 1 edge.

Tried up/down/left/right/sideways/upside down/kids holding it/wife holding it/dog holding it/on the floor/high in the air/without pre-amp/with pre-amp/with splitter/without splitter/C4 antenna/C5 antenna/y5-713 antenna/different cables/double scan.

not saying in your case but aiming digital is far different than analog.

just a couple degrees different makes a big difference.

if you are using a tv or converter box as your indicator you need to wait half a minute or more after every increment of movement to detect it. what would probably be a 6 beer project if you have a hard reception situation.

nordloewelabs

07-17-09, 12:41 PM

rbarbier

07-17-09, 01:01 PM

you said you use an PC to watch TV. right? if so, then try this: place the antenna far from the computer. I have two Desktop PCs in the living room where my antenna is. the first PC is about 8 feet away from the antenna and causes heavy interference. the second one is farther away and causes no interference. i have analog Hauppauge TV cards in each PC.

the place where I get the best VHF reception is the kitchen, with the antenna 6 inches (not feet!) off the floor.... (!)

Thanks for the suggestion but when I test my antenna, I have my computer off (I use my TV to check the signal because it has a better meter than Media Center).

Does VHF get more interference than UHF because I don't have any interference with UHF when I use my computer and the antenna is close to my PC?

Rick313

07-17-09, 01:15 PM

johnpost

07-17-09, 01:18 PM

the place where I get the best VHF reception is the kitchen, with the antenna 6 inches (not feet!) off the floor.... (!)

is that with your VHF-LO antenna?

rbarbier

07-17-09, 01:20 PM

Have you checked the Los Angeles, CA - OTA (http://www.avsforum.com/avs-vb/showthread.php?t=191672) thread to see what works for other people in the area? Seems like I've read a lot of complaints on other threads about reception issues in the Los Angeles area. People on the local thread might have a little more insight into your situation.

Yup. Same issues. A lot of people are having issues with the High VHF but there are some that are having better signal with High VHF than with UHF. The answer is to get the biggest VHF antenna.

nordloewelabs

07-17-09, 01:35 PM

Does VHF get more interference than UHF because I don't have any interference with UHF when I use my computer and the antenna is close to my PC?

My UHF channels are marginally affected by the PCs. the VHF charnels, on the other hand, become unwatchable.

is that with your VHF-LO antenna?

currently, my antenna is a home-made folded dipole made of 12 AWG wire specifically built For Hi-VHF. I'm waiting for a CM2016 to be shipped by Solid Signal.

nordloewelabs

07-17-09, 02:26 PM

the problem with Hi-VHF, from what i have been able to gather so far, is that -- even though the FCC is well acquainted with this particular band -- their experience is mostly founded on its use to broadcast NTSC signals. people behind the ATSC format seem to have worried too little about reception in the following scenarios:

a) in the cities.
b) with indoor antennas.
c) on Hi-VHF.

to make things worse, the FCC seems to also have performed too little tests in the 3 scenarios above. in other words, both the creation of ATSC and its deployment have been done in a rather sloppy fashion. a few days ago, I was reading about other over-the-air DTV technologies (http://en.wikipedia.org/wiki/Digital_television) such as the ones employed in Europe (DVB-T), Japan (ISDB-T) and Brazil (ISDB-Tb).... the latter 2 are basically the same and were designed from the ground up with indoors and city reception in mind.

obviously, we all stand on the shoulders of Giants. all DTV formats used nowadays have sipped heavily from the ATSC Fountain (which started it all) and learnt the Good, the Bad and the Ugly. the question is, will the FCC fix ATSC someday? the use of VHF seems to be its biggest blunder....

all my personal opinion of course... :cool:

Tower Guy

07-17-09, 04:30 PM

people behind the ATSC format seem to have worried too little about reception in the following scenarios:

a) in the cities.
b) with indoor antennas.
c) on Hi-VHF.

The ATSC committee knew the DTV limitations of VHF. Unfortunately, the close packing of analog VHF stations prevented the FCC from assigning the transmitter powers that were suggested by the ATSC folks. The FCC did all that they could given the facts at hand.

Now we have some VHF stations asking for enough power to fix VHF, and others who changed their mind because they know now that UHF is the sweet spot for mobile video.

With sufficient power, VHF is still better than UHF for DTV in the fringes. The question now is what's the market? Is it conventional at home off-air viewing or Watchman type cell phones? The former favors VHF, the latter UHF. I believe that both are equally valuable.

systems2000

07-17-09, 06:26 PM

nordloewelabs

07-17-09, 06:50 PM

I've been wondering lately if the manufacturers of antennas need to rethink their designs.

What is need is for their VHF antennas to be made more directional since multipath and ATSC don't go well together. maybe they don't need to do anything new. they merely need to remove omni-directional VHF antennas from their catalog.

nordloewelabs

07-17-09, 07:27 PM

by the way, is it possible to build the converter boxes so that they can handle multipath better?

ProjectSHO89

07-17-09, 07:36 PM

by the way, is it possible to build the converter boxes so that they can handle multipath better?

That improvement has been taking place with each successive generation of tuner chip-sets.

EscapeVelocity

07-17-09, 07:40 PM

There is a rumor going around that Wade is discontinuing their Delhi consumer antenna line. Can anybody confirm that?

nordloewelabs

07-17-09, 07:52 PM

That improvement has been taking place with each successive generation of tuner chip-sets.

so in all likelihood, the FCC won't change a thing about how DTV gets deployed. the industry, on the other hard, will adapt its tuners and antennas to compensate for the bad decisions made so far.

serndipity

07-17-09, 08:04 PM

I've been wondering lately if the manufacturers of antennas need to rethink their designs. Which is truely best for DTV reception ¼-wave, ½-wave, or full-wave designs?

Those that I know who get solid VHF reception are using antennas that are much larger than needed for NTSC reception in the same location.

I could not agree more.

Quite frankly, they're still designing and making antennas like it is still 1950., .

Now that many DTV stations have returned to their VHF channel assignments, much of what you will find available (both in DIY or commercial antennas), may no longer be well suited (e.g. monstrous).

I believe that there is a better solution and am working on a DIY design that is very unique (out of the box thinking) that is:

Simple and easy to build (e.g. only requires 6th grade math, has no critical dimensions, phasing lines, reflector etc.).

Scalable (e.g. compact size for VHF/UHF coverage, much smaller than current VHF/UHF combination antennas).

Wide-band (e.g. near flat SWR over the VHF/UHF bandwidth which eliminates SWR losses).

Has high gain and directionality.

At this time, I have built a UHF version which compares to my DIY C2 type wide-band double loop, 4 bay bow tie, as well as a 13 element LPDA (exceeds all on VHF high band reception).

Although I am quite certain of the design scalability, I have yet to build a VHF/UHF version for verification.

Stay tuned.

nordloewelabs

07-18-09, 10:40 AM

according to TVFool, the 3 Hi-VHF channels in my area have Power of at least -38dBm. however, as many others here, i cant receive them well. probably due to ATSC's heavy susceptibility to multipath interference in the VHF band. 3 weeks ago i ordered a CM2016 (http://www.solidsignal.com/prod_display.asp?prod=CM2016) from SolidSignal but havent received it yet (still out-of-stock) and this wait has given me time to ponder.... now i'm thinking about changing my order to get something more directional. on Hi-VHF, the CM2016 is omni-directional and has a gain of only 2dB.

the antennas i'm contemplating (for use indoors) are:

RCA ANT751 (http://www.solidsignal.com/prod_display.asp?PROD=ANT751&xzoom=Large#xview) (cant find specs anywhere)
AntennaCraft Y5-7-13 (http://www.solidsignal.com/prod_display.asp?PROD=Y5-7-13&xzoom=Large#xview)
AntennaCraft HBU22 (http://www.solidsignal.com/prod_display.asp?PROD=HBU22&xzoom=Large#xview)

i know some of them are Hi-VHF only but since UHF channels come so easy in my apartment (i get all of them with my home-made 12 AWG Folded Dipole), i'll probably be able to receive UHF stations with a VHF-only antenna (right??? :confused:). i certainly dont like their sizes for use indoors but i've become rather pessimistic about improvements in the Hi-VHF band. does anyone want to opine on the antennas listed above? please, feel free to do so.

nordloewelabs

07-18-09, 10:44 AM

kedirekin

07-18-09, 11:16 AM

It does indeed mean its gain is less than one-tenth the gain of a dipole, at least on channel 7. Performance on higher VHF is much better.

They advertise it as a VHF-HI/UHF antenna because they can get away with it, and despite the low gain it probably works fairly well for near-suburban use.

ctdish

07-18-09, 11:18 AM

I don't know if the channel 7 gain is correct but the front to back numbers make no sense and have to be wrong and the VHF beawidths are suspect.
John

Digital Rules

07-18-09, 11:54 AM

nordloewelabs

07-18-09, 12:09 PM

They advertise it as a VHF-HI/UHF antenna because they can get away with it, and despite the low gain it probably works fairly well for near-suburban use.

It does in my area. It actually works better on VHF 8 than the Clearstream C-4.
frankly, this doesnt say much as the ClearStream antennas are a major piece of false advertisement VHF-wise. :)

serndipity

07-18-09, 12:14 PM

i noticed a thing about the Winegard HD-1080 (http://www.solidsignal.com/prod_display.asp?PROD=HD-1080&xzoom=Large#xview).... its gain on ch-7 is -11dB! what does that mean? does it give only 10% of the gain of a reference dipole?!?! if so, why would anyone use it instead of a dipole? worse yet, why would Winegard advertise it as a Hi-VHF/UHF antenna? what am i missing?

The field strength produced by an antenna is proportional to the current flowing in it. The ratio of power required to produce a given field strength with a 'comparison' antenna to the power required to produce the same field strength with a specified type of antenna is called the power gain, or loss, of the latter antenna.

The number of decibels corresponding to a given power ratio is:

dB = 10 log P2/P1

The power ratio for -11 dB is .07943, which comparatively, means that less than 8% of the of the signal is available.

BTW, the ratio for -3 dB is .5 or a loss of one half the power.

rabbit73

07-18-09, 12:56 PM

Quite frankly, they're still designing and making antennas like it is still 1950., .

I believe that there is a better solution and am working on a DIY design that is very unique (out of the box thinking) that is:

Simple and easy to build (e.g. only requires 6th grade math, has no critical dimensions, phasing lines, reflector etc.).

Scalable (e.g. compact size for VHF/UHF coverage, much smaller than current VHF/UHF combination antennas).

Wide-band (e.g. near flat SWR over the VHF/UHF bandwidth which eliminates SWR losses).

Has high gain and directionality.

At this time, I have built a UHF version which compares to my DIY C2 type wide-band double loop, 4 bay bow tie, as well as a 13 element LPDA (exceeds all on VHF high band reception).

Although I am quite certain of the design scalability, I have yet to build a VHF/UHF version for verification.

Stay tuned.

Looking forward to your DIY design.

holl_ands

07-18-09, 01:23 PM

I don't know if the channel 7 gain is correct but the front to back numbers make no sense and have to be wrong and the VHF beawidths are suspect.
John
F/B and BW numbers make perfect sense, once you understand at VHF
there are no reflectors or directors, hence it is bi-directional, like a dipole.

For example fol. Folded Dipole has 2.06 dBi Gain, 80-deg BW and 0 dB F/B on Ch7.
[It eventually reaches 2.15 dBi (0 dBd) Gain on Ch9 and climbs to 2.24 dBi on Ch13.]

ctdish

07-18-09, 03:17 PM

I was looking at the small negative F/B for UHF. Should be larger and positive and the 0 deg. BW for channels 13 and 14.

Dan Kolton

07-18-09, 05:16 PM

I have significant pixilation and dropouts between 6 and 7 pm on one channel. Great picture much earlier or later. This channel is 4.9 miles away at 65 degrees and is at -17.5dbm per tvfool. At 61 degrees and 2.5 miles (-17.6dbm) is another channel with which I never have problems. Both are LOS, but my attic mounted CM4221 looks through trees. This, however, is equally true for both channels. My Tivo "signal strength" is close to the same for both channels, and hardly shows the problem. The same comparison pretty much holds using a CM7000 CECB and a set-top dipole.

Any ideas?

holl_ands

07-18-09, 06:21 PM

I was looking at the small negative F/B for UHF. Should be larger and positive and the 0 deg. BW for channels 13 and 14.
I'm not surprised by the magnitude of the UHF F/B, after all it's just a 2-Bay.
Although I suspect the supporting azimuthal plots must be some funny,
stretched scale that greatly exaggerates the F/B numbers....and you're right,
F/B numbers should be POSITIVE.

The Winegard Spec Sheet is the source of these typos (/fantasies?):
http://www.winegard.com/kbase/upload/HD-1080.pdf

300ohm

07-18-09, 10:15 PM

Although I suspect the supporting azimuthal plots must be some funny,
stretched scale that greatly exaggerates the F/B numbers....and you're right,
F/B numbers should be POSITIVE.

The Winegard Spec Sheet is the source of these typos (/fantasies?):
http://www.winegard.com/kbase/upload/HD-1080.pdf
Those are some ugly patterns. I cant see the detailed numbers, but it does look like uhf gain is flipped in the opposite direction of vhf gain, and both are skewed to some degree.

flcs3

07-18-09, 10:25 PM

nordloewelabs, I have skimmed though some of your previous messages,
but have not exhaustively read through them all. Apologies if what
follows has been suggested previously.

according to TVFool, the 3 Hi-VHF channels in my area have Power of at least -38dBm. however, as many others here, i cant receive them well. probably due to ATSC's heavy susceptibility to multipath interference in the VHF band.

Another possibility is interference induced by strong FM stations.
fmfool suggests that most of the NYC stations are of modest power,
most below 10kW, but there are quite a few nearby. The 115 dBu
contour for a 6kW station is a radius of about 0.6 mi. In addition to using
a more directional antenna, I would try an FM trap, even if you are not
using an amp (which you probably don't need).

Since you have already built some dipoles, I would add Yagi parasitic
elements (reflector and multiple directors) until it becomes directional
enough to overpower the multipath. Even if you then want to buy a
commercially built antenna, you will have a better idea of what will
work at your location. If you get a UHF/VHF combo, you probably could
leave off the UHF corner reflectors, making the antenna flat such that it
could be mounted flush to the ceiling.

If you end up needing a very directional VHF antenna to ward off the
multipath, you may end up with overload of your tuner. You may need to
insert an attenuator. UHF/VHF joiners are cheap and work well, so do
not be too concerned about using separate UHF and VHF antennas.

As a final resort, you might have to build a Farraday cage around the
antenna to block signals from all directions other than that of your
antenna farm.

Good luck overcoming your reception problems.

ctdish

07-19-09, 12:42 AM

Those are some ugly patterns. I cant see the detailed numbers, but it does look like uhf gain is flipped in the opposite direction of vhf gain, and both are skewed to some degree.

The link is a PDF and you can read the scale if you blow it up. The skew is odd. It looks like they did a measurement with the rotator and antenna misaligned. The UHF F/B ratios look to be in the 8 to 15 region. Not great but sort of believable.
The VHF peak response is probably correctly pointing to the rear of the UHF’s antenna's front, as the screen would act like a director since its width is less than a half wavelength.
John

hphase

07-19-09, 09:56 AM

My UHF channels are marginally affected by the PCs. the VHF charnels, on the other hand, become unwatchable.
Your computer might be radiating interference on VHF frequencies. Or it's something else...

the problem with Hi-VHF, from what i have been able to gather so far, is that -- even though the FCC is well acquainted with this particular band -- their experience is mostly founded on its use to broadcast NTSC signals. people behind the ATSC format seem to have worried too little about reception in the following scenarios:

a) in the cities.
b) with indoor antennas.
c) on Hi-VHF.

to make things worse, the FCC seems to also have performed too little tests in the 3 scenarios above. in other words, both the creation of ATSC and its deployment have been done in a rather sloppy fashion. a few days ago, I was reading about other over-the-air DTV technologies (http://en.wikipedia.org/wiki/Digital_television) such as the ones employed in Europe (DVB-T), Japan (ISDB-T) and Brazil (ISDB-Tb).... the latter 2 are basically the same and were designed from the ground up with indoors and city reception in mind.

obviously, we all stand on the shoulders of Giants. all DTV formats used nowadays have sipped heavily from the ATSC Fountain (which started it all) and learnt the Good, the Bad and the Ugly. the question is, will the FCC fix ATSC someday? the use of VHF seems to be its biggest blunder....

all my personal opinion of course... :cool:

It's easy to take pot-shots at ATSC and claim sloppy work. I don't think those claims would stand up. ATSC was originally developed to replicate analog TV requirements and usage in North America. Indoor and inner-city reception has sucked for a long time. Cable TV was introduced in the 1950s to address these shortcomings.

The other DTV technologies and systems you mentioned were still in the womb when ATSC was in its adolescence. Also, These new system don't travel as far, and don't carry as much data as the ATSC systems. While perhaps appropriate for SD or close-in transmission, they would not work as well at long distances, which is what was required in the US as television grew up. I doubt that a TV station would be willing to spend any money to put in repeater transmitters that would be required to serve me if they abandoned their big-stick infrastructure.

by the way, is it possible to build the converter boxes so that they can handle multipath better?
As DTV became popular, and before DTV signals were carried on cable, it became apparent that the cliff effect of DTV was causing problems in urban reception, primarily due to multipath (echos.) DTV receiver chip designers went through many generations of chip design, each improving the performance in the presence of strong, early echos. That affected both VHF and UHF equally.

so in all likelihood, the FCC won't change a thing about how DTV gets deployed. the industry, on the other hard, will adapt its tuners and antennas to compensate for the bad decisions made so far.
Yes, that seems to be your opinion. The FCC is adapting its rules for DTV on VHF, but the impulse noise and building penetration problems will persist. ATSC actually was designed to perform better on impulse noise than the more modern systems you mentioned. VHF frequencies were included in the DTV "core" because there wasn't enough room in the spectrum for all the stations after removing channels 52-69 (and 70-82 before that.) Also remember that there are many more OTA networks and stations in the US than there traditionlly have been in much of the rest of the world. When you only have one or two programmers and not a large area to serve, its easy to find space on the dial for everyone. Or you go to satellite.

If you can design a signal that can blast through buildings and interference, yet still not travel far enough to interfere with other stations on the same or adjacent channel, you should be creating a cure for cancer, not solving television reception.

holl_ands

07-19-09, 11:12 AM

Those are some ugly patterns. I cant see the detailed numbers, but it does look like uhf gain is flipped in the opposite direction of vhf gain, and both are skewed to some degree.
W-G HD1080 spec sheet scale becomes visible when blown up. Here's a screen shot.

F/B (worst case) for Ch14 would be about 5+ dB vice "-2 dB" in the spec sheet.
The other numbers appear to be much closer (after losing the minus sign).

I'm not all that surprised to see more VHF gain towards the "back"....which would
make the F/B numbers -1, -2 and -4.4 dB for Ch9, 11 & 13...which of course
begs the question of whether these negative numbers are included in the
(negative) VHF Gain numbers. If true, the UHF Reflector elements are acting
more like Directors at VHF than Reflectors....

Since the antenna feed, et. al. are balanced, the patterns should align with the antenna,
rather than being skewed. I have to agree with your "wrong rotator alignment" comment,
although it is also possible the test lab simply copied the raw data chart, rather than
normalizing data to match the antenna alignment (same result, different twist).

The only good way to really find out the "true" performance is for someone
to actually measure the antenna dimensions so we can run a NEC model......

300ohm

07-20-09, 02:17 AM

The skew is odd. It looks like they did a measurement with the rotator and antenna misaligned.
I was going to guess they did the measurements with a USPS/UPS/Fed Ex shipped bent up antenna, to simulate real life scenarios, heh, heh.

I'm not all that surprised to see more VHF gain towards the "back"....which would make the F/B numbers -1, -2 and -4.4 dB for Ch9, 11 & 13...which of course begs the question of whether these negative numbers are included in the (negative) VHF Gain numbers. If true, the UHF Reflector elements are acting more like Directors at VHF than Reflectors....
My modeling with adding vhf elements to uhf antennas shows its very easy to get the vhf gain going in the opposite direction to uhf gain.
While that scenario is useful for some people, (and Winegard should more prominently mention it, if that was their intention), I think most people would want and expect the vhf and uhf gain to go in the same direction.

Satcom15

07-20-09, 05:25 PM

My modeling with adding vhf elements to uhf antennas shows its very easy to get the vhf gain going in the opposite direction to uhf gain.

While that scenario is useful for some people, (and Winegard should more prominently mention it, if that was their intention), I think most people would want and expect the vhf and uhf gain to go in the same direction.

Yup, most people probably would expect VHF amd UHF gain to be in the same direction, I know I would. :D

flcs3

07-21-09, 12:23 AM

... probably due to ATSC's heavy susceptibility to multipath interference in the VHF band.

Here is an example of battling multipath with a Faraday cage:

http://www.prism.gatech.edu/~wn17/ (http://www.prism.gatech.edu/%7Ewn17/)

Do note, however, he was working on the UHF band. A VHF band equivalent will be larger. Since this is not so practicable indoors or even on a balcony, first working with both a more directional antenna and an FM trap makes a great deal of sense.

nordloewelabs

07-21-09, 12:42 AM

Another possibility is interference induced by strong FM stations. fmfool suggests that most of the NYC stations are of modest power, most below 10kW, but there are quite a few nearby. The 115 dBu contour for a 6kW station is a radius of about 0.6 mi. In addition to using a more directional antenna, I would try an FM trap, even if you are not using an amp (which you probably don't need).

i got one of these basic http://rover.ebay.com/ar/1/711-53200-19255-0/1?mpt=1132460735&adtype=1&size=1x1&type=3&campid=5336055023&toolid=10001 RadioShack FM Traps (http://rover.ebay.com/rover/1/711-53200-19255-0/1?type=3&campid=5336055023&toolid=10001&mpre=http%3A%2F%2Fshop.ebay.com%2F%3F_from%3DR40%26_trksid%3 Dm38%26_nkw%3Dfm%2Btrap%26_sacat%3DSee-All-Categories) from eBay.... just in case. the antenna i've ordered is the Winegard HD-7694P (http://www.solidsignal.com/prod_display.asp?PROD=HD7694P&xzoom=Large). delivery will take a week. one of my PCs causes interference on the Hi-VHF stations. i dont know which componenet is the culprit but i'm guessing it's either the PSU or the hard drive. i'll perform test to narrow this down later.

i'll check out the cage. thanks for the info!

flcs3

07-21-09, 04:11 AM

one of my PCs causes interference on the Hi-VHF stations.

Ah, missed that earlier. Sorry to suggest the two most obvious things:
be sure that the case is screwed together solidly, and that there is EMI/RFI filtering in the AC power paths (e.g. Tripplite ISOBAR).

tjlmbklr

07-21-09, 10:53 AM

I recently went Antenna only...no more Cable/Satellite/Uverse (I have had them all).

It's strictly a money thing. The wife and I are completely happy with basic TV (I like the HD channels w/ no compression).

We live in Milwaukee WI and I would estimate we are 10 miles or so from the tower farm. I can't complain about the channels we receive but keep in mind for the last 15 years of my life I have had at least basic cable.

One of the channels we love is ME-TV Mostly old stuff like Hitchcock, Twilight Zone other great classics. I think (may be wrong) that this channel is broadcast in Racine. Racine is 180 degrees the opposite direction. Every now and again we get a choppy signal. So I was contemplating using a second anttena. Is this possible, how do you set it up then?

I am using a Monoprice (http://www.monoprice.com/products/product.asp?c_id=109&cp_id=10901&cs_id=1090102&p_id=4730&seq=1&format=2) antenna mounted to a pole on my chimeny (one story house some trees around)

Thanks in advance for your help!

JimP

07-21-09, 11:05 AM

tjlmbklr

07-21-09, 11:27 AM

tjlmbkllr

Many here are using dual antennas, some are fairly exotic.

Unless you get lucky with someone living in Milwaukee, for the rest of us, we need you to plot on TVfool.com and post the link here.

TVfool hey? I will look into that. But in the mean time I realized I posted this in a existing topic. I will have to copy paste it to a "New" topic to get better exposure.

But as for TVfool.com I will post this later I am at work and need to hit the road.

Thanks for your help!

nordloewelabs

07-21-09, 11:32 AM

be sure that the case is screwed together solidly, and that there is EMI/RFI filtering in the AC power paths (e.g. Tripplite ISOBAR).

if this is something buyable, i can get one.

i checked the cage.... i had seen that page before, a long time ago. that's a very interesting project but unfeasible for an apartment because it's huge. :)

johnpost

07-21-09, 12:36 PM

TVfool hey? I will look into that. But in the mean time I realized I posted this in a existing topic. I will have to copy paste it to a "New" topic to get better exposure.

But as for TVfool.com I will post this later I am at work and need to hit the road.

Thanks for your help!

an existing topic is fine. your posting was noticed enough to get a reply.

but you could post into

http://www.avsforum.com/avs-vb/showthread.php?p=16809448#post16809448

which is the forum for people in the Milwaukee area to talk about info and reception. there are probably people who are trying to get the stations you are and can comment on what they used.

nordloewelabs

07-21-09, 01:10 PM

and that there is EMI/RFI filtering in the AC power paths (e.g. Tripplite ISOBAR).

i have 2 surge protectors here:

- an APC SurgeArrest Home/Office
- Tripp-Lite.

is there a particular feature i should make sure they have? my *guess* is that both have EMI filtering (coz it sounds like something that should be standard). the PC is connected to the APC one, which also has a 75-Ohm coaxial filter. i tested this filter before and did not notice any improvement, so i decided to connect the antenna straight to the converter box. i think the model i have is http://rover.ebay.com/ar/1/711-53200-19255-0/1?mpt=1152922732&adtype=1&size=1x1&type=3&campid=5336055023&toolid=10001 this one (http://www.amazon.com/gp/redirect.html?ie=UTF8&location=http%3A%2F%2Fwww.amazon.com%2FPerformance-Surgearrest-11OUT-Nema-Splitter%2Fdp%2FB000F5NG38%2Fref%3Dsr_1_4%3Fie%3DUTF8%26s%3D electronics%26qid%3D1248195755%26sr%3D1-4&tag=5336055023-20&linkCode=ur2&camp=1789&creative=9325). should i get a different one?

btw, i'll be using a Winegard HD 7694P (http://www.solidsignal.com/prod_display.asp?PROD=HD7694P&xzoom=Large) indoors (talk about eye-sore...). is grounding necessary???

ProjectSHO89

07-21-09, 01:17 PM

nordloewelabs

07-21-09, 03:22 PM

There is no requirement to ground an indoor antenna.

just trying to make sure there's no misunderstanding.... the Winegard HD-7694P is an outdoor antenna, that i will mount indoors. still no grounding needed?

holl_ands

07-21-09, 04:02 PM

i have 2 surge protectors here:

- an APC SurgeArrest Home/Office
- Tripp-Lite.

is there a particular feature i should make sure they have? my *guess* is that both have EMI filtering (coz it sounds like something that should be standard). the PC is connected to the APC one, which also has a 75-Ohm coaxial filter. i tested this filter before and did not notice any improvement, so i decided to connect the antenna straight to the converter box. i think the model i have is http://rover.ebay.com/ar/1/711-53200-19255-0/1?mpt=1152922732&adtype=1&size=1x1&type=3&campid=5336055023&toolid=10001 this one (http://www.amazon.com/gp/redirect.html?ie=UTF8&location=http%3A%2F%2Fwww.amazon.com%2FPerformance-Surgearrest-11OUT-Nema-Splitter%2Fdp%2FB000F5NG38%2Fref%3Dsr_1_4%3Fie%3DUTF8%26s%3D electronics%26qid%3D1248195755%26sr%3D1-4&tag=5336055023-20&linkCode=ur2&camp=1789&creative=9325). should i get a different one?

btw, i'll be using a Winegard HD 7694P (http://www.solidsignal.com/prod_display.asp?PROD=HD7694P&xzoom=Large) indoors (talk about eye-sore...). is grounding necessary???
The fleabay link didn't work...

APC website no longer has specs for DL11VNT, but it seems similar to P11VNT3:
http://www.apc.com/products/resource/include/techspec_index.cfm?base_sku=P11VNT3
Note EMI/RFI Noise Suppression specs for P11VNT3 say 70+ dB (100 kHz to 10 MHz),
so it is unknown what the suppression is in VHF and UHF TV Bands....
It's probably doing some suppression, we just don't know how much....

Manual for (some) Tripplite Isobar products say 30+ dB for 6-1000 MHz:
http://www.tripplite.com/shared/techdoc/Owners-Manual/931411.pdf

You didn't say which Tripplite you have...nor whether it was an Isobar model.....

PS: If you use a Preamp, plug it somewhere else, other than the EMI protected power strip.

nordloewelabs

07-21-09, 04:12 PM

APC website no longer has specs for DL11VNT, but it seems similar to P11VNT3:

[...]

You didn't say which Tripplite you have...nor whether it was an Isobar model.....

i dont know exactly which ones i have coz the model numbers must be underneath in both. i'll try to get them at some point. thanks to you, now i know what to look for on the manual. i might buy new surge protectors.

would a supresssion of >30dB on the 6-1000 Mhz band stop the PC from interfering with the antenna? should i put the converter box and PC on different surge protectors?

nordloewelabs

07-21-09, 04:17 PM

The fleabay link didn't work...

which one? the one showing the RadioShack FM Trap?
http://shop.ebay.com/items/?_nkw=fm+trap&_sacat=0&_trksid=p3286.m270.l1313&_odkw=fm+trap&_osacat=0
they are all the same model i think.

JimP

07-21-09, 04:26 PM

What exactly does the FM filter do? Obviously it filters out the FM signal, but how does that improve reception?

nordloewelabs

07-21-09, 04:28 PM

What exactly does the FM filter do? Obviously it filters out the FM signal, but how does that improve reception?

http://www.kyes.com/antenna/interference/fm/fmfilter.html

holl_ands

07-21-09, 04:40 PM

which one? the one showing the RadioShack FM Trap?
http://shop.ebay.com/items/?_nkw=fm+trap&_sacat=0&_trksid=p3286.m270.l1313&_odkw=fm+trap&_osacat=0
they are all the same model i think.
The other one: rover.ebay.....

Yes put the PC on a different EMI/RFI protected power strip than Preamp & Tuner(s).
Of course if each is 30 dB isolation, total would be 60 dB....via powerline leakage path....

If PC is still interfering with TV reception, then leakage path is probably
somewhere else.....such as cables going in/out of the PC....which can
be helped with clamp on Ferrite Cores (for different size cables):
http://parts.digikey.co.uk/1/1/425576-ferrite-cylinder-clamp-4-5mm-28a0592-0a2.html
http://parts.digikey.co.uk/1/1/65779-ferrite-cylinder-clamp-black-28a0392-0a2.html
http://www.audiosystemsgroup.com/RFI-Ham.pdf

holl_ands

07-21-09, 04:46 PM

What exactly does the FM filter do? Obviously it filters out the FM signal, but how does that improve reception?
And not all FM Filters perform the same....you generally get what you pay (more) for:
http://www.tinlee.com/Graph_ALL_FM_filters.php

nordloewelabs

07-21-09, 04:55 PM

And not all FM Filters perform the same....you generally get what you pay (more) for:
http://www.tinlee.com/Graph_ALL_FM_filters.php

i was planning to get Winegard FT7500 (http://www.solidsignal.com/prod_display.asp?prod=FT7500) which filters the whole FM band by 26dB. however, that model has been discontinued. i dont understand how the FT76000 (http://www.solidsignal.com/prod_display.asp?prod=FT-7600), its replacement, works (it seems it can only filter 2 stations). besides, it uses screws for which i dont have tools. that lead me to the RadioShack option.... :(

NTNgod

07-21-09, 05:23 PM

One of the channels we love is ME-TV Mostly old stuff like Hitchcock, Twilight Zone other great classics. I think (may be wrong) that this channel is broadcast in Racine. Racine is 180 degrees the opposite direction

WBME is a Racine station in name only. Its digital signal (which isn't the strongest) is broadcast from Milwaukee.

holl_ands

07-21-09, 05:52 PM

Optimum Circular Loop diameter for the Hi-VHF Band is 24-inches using 1/2-in pipe,
23-inches for QuarterInchCopperTubing, 21.5-inches for AWG12 and 21-inches for
AWG26 (tiny wire taped to window):
http://imageevent.com/holl_ands/loops/vhfloop
So Loop Reflector would probably be about 5-percent larger....next on my list...

Other antenna analyzes can also be found here:
http://imageevent.com/holl_ands/
Using 4nec2, I "found" quasi-optimum dimensions when adding a Loop Reflector to a Circular Loop,
presuming Half-Inch and Quarter-Inch Copper Tubing (which are already "bent"):
http://imageevent.com/holl_ands/loops/looprefl
Half-Inch Copper Tubing (OD=0.514-in, aka "3/8-in I.D.") could cover entire Hi-VHF band with
acceptable SWR (under 2.4), but QuarterInchCopperTubing had trouble covering Ch7 (SWR = 3.3).

Although Gain (6-8 dBi) and SWR were a concern, these designs targeted the
dimensions which would ensure the F/B and F/R Ratios were the "best" they could
be across the entire Hi-VHF Band....i.e. equal at the highest and lowest freqs.

I did not consider smaller diameter elements for the Circular Loop, since it would
make more sense to use a Square Loop design instead (e.g. Quagi):
http://www.k5nrh.org/Downloads/The%20Quagi%20Antenna%20Turns%2030.pdf

EscapeVelocity

07-21-09, 06:23 PM

You Rock!, holl_ands.

IDRick

07-21-09, 08:56 PM

Nice work Holl_ands! Can't wait to see the RCA ANT751 data!

Best,

Rick

flcs3

07-21-09, 10:25 PM

i checked the cage.... i had seen that page before, a long time ago. that's a very interesting project but unfeasible for an apartment because it's huge. :)

And one for a VHF antenna will be bigger. OTOH, depending on the source of the multipath or other RFI, a partial shield may be enough to help. It might be feasible on a balcony, if you have one. Unfortunately, you may have to be concerned with multipath coming at your antenna in all three dimensions, not just the plane parallel to the ground.

flcs3

07-21-09, 11:18 PM

i have 2 surge protectors here: ...
my *guess* is that both have EMI filtering (coz it sounds like something that should be standard).

No, that is an extra feature. If you go to a store with a large number of different surge suppressors, you will find that the boxes on some will have specs on their EMI/RFI, i.e. so many dB of suppression over a specified frequency band. Even the brickwall folks have a separate "audio" surge suppressor with RF filtering.

the PC is connected to the APC one, which also has a 75-Ohm coaxial filter. i tested this filter before and did not notice any improvement, so i decided to connect the antenna straight to the converter box.
That is unlikely to have any useful RFI filtering, though it might help by grounding the coax outer shield. Otherwise, I presume that it is supposed to provide some surge protection for cable modems.

i think the model i have is http://rover.ebay.com/ar/1/711-53200-19255-0/1?mpt=1152922732&adtype=1&size=1x1&type=3&campid=5336055023&toolid=10001 this one (http://www.amazon.com/gp/redirect.html?ie=UTF8&location=http%3A%2F%2Fwww.amazon.com%2FPerformance-Surgearrest-11OUT-Nema-Splitter%2Fdp%2FB000F5NG38%2Fref%3Dsr_1_4%3Fie%3DUTF8%26s%3D electronics%26qid%3D1248195755%26sr%3D1-4&tag=5336055023-20&linkCode=ur2&camp=1789&creative=9325). should i get a different one?
What holl_ands said already...

btw, i'll be using a Winegard HD 7694P (http://www.solidsignal.com/prod_display.asp?PROD=HD7694P&xzoom=Large) indoors (talk about eye-sore...). is grounding necessary???That is a well regarded antenna (and you
probably won't need to install the UHF corner reflectors). It should not need grounding, though grounding the coax outer shield might help by shunting any shield currents induced by undesired RF signals. Probably more useful would be using quad shield coax and/or another method of suppressing shield RF current, perhaps something along these lines:
http://www.ham-radio.com/k6sti/balun.htm
Of course, we still don't know the source(s) of your interference. How much is your interference reduced with the computer powered off?

I did notice a few weeks ago that the ARRL has a book on dealing with RF interference:
http://www.arrl.org/catalog/9892/
I may have to acquire a copy sometime soon. 8-)

So, is your PC case fully enclosed, with all the screws tightened down and all the unused expansion card slots filled with cover plates?

nordloewelabs

07-21-09, 11:53 PM

Probably more useful would be using quad shield coax and/or another method of suppressing shield RF current, perhaps something along these lines: http://www.ham-radio.com/k6sti/balun.htm

i'm getting a quad-shield RG6 for really cheap at Monoprice.

How much is your interference reduced with the computer powered off?i performed lots of tests and posted the details in 2 posts here (http://www.avsforum.com/avs-vb/showthread.php?p=16767522#post16767522).

So, is your PC case fully enclosed, with all the screws tightened down and all the unused expansion card slots filled with cover plates?case closed, screws tightened, all slots covered. the PC is on the floor, with its back facing the spot where i mounted the antenna. there are dozens of cables connected to that PC. that PC also has a wireless Logitech trackball connected to its USB port. i'm sure that i can, by elimination, find out which specific peripheral or internal component is causing this interference.

i might hunt down the source of this interference tonight....

flcs3

07-22-09, 01:10 AM

i performed lots of tests and posted the details in 2 posts here (http://www.avsforum.com/avs-vb/showthread.php?p=16767522#post16767522).

I believe that most wireless runs in the 2.4GHz range. Another pellet to add to the blunderbuss arsenal might be a low-pass filter, to block frequencies above, say, 700 MHz. For example, the Pico Macom LPF-700 costs on the order of $20-30. You have such an RF-rich environment!

there are dozens of cables connected to that PC. that PC also has a wireless Logitech trackball connected to its USB port.
Ouch. That's a lot of cables. I don't know what the wireless mice use for comms. I bought a wired USB Logitch trackball for my laptop, since I don't trust all this RF stuff. 8-)

i might hunt down the source of this interference tonight....That would be sweet. Good luck.

nordloewelabs

07-22-09, 01:42 AM

For example, the Pico Macom LPF-700 costs on the order of $20-30.

i'll check it out. thanks! just finished testing the PC. here are the results.

1) with the PC off, i was getting ch-13 at 50%.
2) with PC on signal dropped to ZERO.
3) i unplugged *all* peripheral cables. signal still dropped to ZERO.
4) i unplugged the 2 IDE hard drives. signal still dropped to ZERO.
5) i unplugged the CPU fan and case fan. signal still dropped to ZERO.
6) i removed modem, TV tuner, video card and all memory modules. signal still dropped to ZERO.

at this point i stopped unplugging things.... so the culprit must be:

a) the Asus motherboard.
b) the Athlon XP 3000+ processor.
c) the 500W Antec BP500U PSU.

JimP

07-22-09, 07:00 AM

i'll check it out. thanks! just finished testing the PC. here are the results.

1) with the PC off, i was getting ch-13 at 50%.
2) with PC on signal dropped to ZERO.
3) i unplugged *all* peripheral cables. signal still dropped to ZERO.
4) i unplugged the 2 IDE hard drives. signal still dropped to ZERO.
5) i unplugged the CPU fan and case fan. signal still dropped to ZERO.
6) i removed modem, TV tuner, video card and all memory modules. signal still dropped to ZERO.

at this point i stopped unplugging things.... so the culprit must be:

a) the Asus motherboard.
b) the Athlon XP 3000+ processor.
c) the 500W Antec BP500U PSU.

Does your motherboard have built in wireless? If so, maybe you can disable it in device manager.

ngarrang

07-22-09, 09:10 AM

I find myself trying to pick up the last remaining one or two channels in my area. (http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3daead16a4a4222f)

Currently, I have 2,5,9,12,14,16,19,43,48 and 64. During good weather at night, I can get 54. 7 is about to install a new antenna, so that will correct itself. My goal, though, is to try and pickup WOTH (virt: 25.1, real: 47). They are a low power station, 15kw.

I am currently using a Terrestrial Digital DB4 mounted on the roof, about 25 feet from ground level.

So as you can see from the tvfool into, I am receiving very well bidirectionally from Dayton and Cinci. The antenna is pointed to Cinci.

I had thought that moving to a DB8 would help me to receive WOTH, but the small directionality of a DB8 has me concerned that in the process, I may lose some or all of my dayton stations from behind.

For others who have such a large disparate angle of bidirectionality, and have tried a DB8, did you lose your other direction?

Alternately, maybe I could try a ChannelMaster 4221 since it has longer bowties than my TE-DB4. That should move the sensitivity of the DB4 down lower.

An A/B switch is not an option I want to pursue at this time.

hphase

07-22-09, 09:59 AM

Sorry to potentially hijack this thread, but all those plots made my head spin. I'm not too concerned about gain, but F/B ratio is very important for me, especially on channels 11 and 13.

What is a believable F/B number to expect for a YA-1713? I'm still tempted to build K6STI's 5-element Yagi, primarily for its F/B ratio. Should I build or buy?

Thanks!
Well, I tried a brand-new YA-1713 this weekend, and the F/B ratio of that antenna is woefully inadequate to reduce the co-channel interference on channels 11 and 13 in my location. Looks like I'm going to have to build K6STI's Yagi after all. Does anyone have any build tips or pictures of their construction?

I want to receive stations that are about 40 miles away, but I'm getting stronger signals from other, more distant stations about 60 miles away on the same channel(s) almost directly behind me. I tried rotating the antenna slightly to try to drop the co-channel stations into a null, but no dice. If I spin the antenna about 180 degrees (the heading to the other market) I can pick up the stations I don't want to watch. With this same orientation I can still pick up other VHF stations (off the back side of the antenna) from the market I do want to watch, but that don't have co-channel interference.

As you can see, antenna gain is not nearly as important for me as F/B ratio. Time to lower the antenna and find something to block the signal from the stronger, but more distant stations so that I can keep them from interfering with the ones that are closer.

nordloewelabs

07-22-09, 12:42 PM

Does your motherboard have built in wireless? If so, maybe you can disable it in device manager.

no. my desktop PCs have no wireless capability. i have a TabletPC (basically, a laptop) that also causes interference on the Hi-VHF band if placed less than 5 ft away from the antenna. at about 8 ft away, the TabletPC causes no noticeable interference. more details on how i tested the desktop PCs and the TabletPC can be found in these 2 posts (http://www.avsforum.com/avs-vb/showthread.php?p=16767522#post16767522) (for those intrigued enough).

i really thought the culprit was the hard drives and was surprised when i saw the interference still present after unplugging both of them. i might perform more tests later today. maybe i'll unplug the Asus motherboard from the Antec power supply.... that would be the ultimate test as it could rule out both the mobo and the Athlon processor as the source of the interference. the blame would then rest easily on the power supply.

Tower Guy

07-22-09, 02:25 PM

As you can see, antenna gain is not nearly as important for me as F/B ratio. Time to lower the antenna and find something to block the signal from the stronger, but more distant stations so that I can keep them from interfering with the ones that are closer.

Get a second YA1713 and stagger stack it. You'll gain almost 20 db F/B ratio.

http://www.anarc.org/wtfda/stagger.pdf

AntAltMike

07-22-09, 02:36 PM

I want to receive stations that are about 40 miles away, but I'm getting stronger signals from other, more distant stations about 60 miles away on the same channel(s) almost directly behind me. I tried rotating the antenna slightly to try to drop the co-channel stations into a null, but no dice. If I spin the antenna about 180 degrees (the heading to the other market) I can pick up the stations I don't want to watch. With this same orientation I can still pick up other VHF stations (off the back side of the antenna) from the market I do want to watch, but that don't have co-channel interference.

As you can see, antenna gain is not nearly as important for me as F/B ratio. ..

A couple of years ago, holl_ands posted something showing how to develop some kind of quarter-wave stack, where you put two antennas on the same mast, pointed at the desired station, you set one 1/4 wavelength behind the other and you cut the two downleads to lengths that differ by (edit) 1/4 wavelength, and so the desired signal will be in phase, whereas the undesired signal will be 180 degrees out of phase.

Unfortunately, tuning this rig to channel 12 (207 MHz) might not get you as much rejection as you need, and if it doesn't, you would need to build a 201 MHz and a 213 MHz stack. Fortunately, the parts you would use are not expensive. Each stack would use two commonplace highband VHF antennas that you can probably buy for under $40 each.

300ohm

07-22-09, 02:56 PM

at this point i stopped unplugging things.... so the culprit must be:

a) the Asus motherboard.
b) the Athlon XP 3000+ processor.
c) the 500W Antec BP500U PSU.

Ahh, nforce2 motherboard ? My Abit NF7-S did produce more TV noise than any other mobo Ive used. Good overclocking mobos though.

Also is it a steel case or aluminum ? I find steel cases block RF a bit better.

nordloewelabs

07-22-09, 03:07 PM

Ahh, nforce2 motherboard ? [...] Also is it a steel case or aluminum ?

VIA chipset. i dont know what the case is made of... :\

i did the last test.... unplugged the motherboard from the power supply. no lights went on! no noise, no nothing. it looked as if the machine was still off. i guess the power supply was running but there was no component asking for power.

well, with the mobo unplugged, there was no interference. so it could be the mobo or the processor. whatever the case might be, how can i stop the interference from reaching the antenna? maybe i should get a super-duper surge protector.

hphase

07-22-09, 03:31 PM

i did the last test.... unplugged the motherboard from the power supply. no lights went on! no noise, no nothing. it looked as if the machine was still off. i guess the power supply was running but there was no component asking for power.
Switching power supplies need a minimum load in order to work, but I thought you knew that.

Looks like the answer is the same as the answer you get from the doctor when you say, "Hey Doc, it hurts when I do this."

hphase

07-22-09, 03:39 PM

A couple of years ago, holl_ands posted something showing how to develop some kind of quarter-wave stack, where you put two antennas on the same mast, pointed at the desired station, you set one 1/4 wavelength behind the other and you cut the two downleads to lengths that are 1/4 wavelength, and so the desired signal will be in phase, whereas the undesired signal will be 180 degrees out of phase.

Unfortunately, tuning this rig to channel 12 (207 MHz) might not get you as much rejection as you need, and if it doesn't. you would need to build a 201 MHz and a 213 MHz stack. Fortunately, the parts you would use are not expensive. Each stack would use two commonplace highband VHF antennas that you can probably buy for under $40 each.

You're right, I don't know if the stacking would work on both channels 11 and 13 if I cut and tune the rig for channel 12. Someone with better modelling skils than I would have to figure out far down the notch would be + and - 6 MHz.

But if I did do it, could I put my UHF 4221HD in between the stacked V's?

holl_ands

07-22-09, 04:32 PM

STAGGER STACKING and HORIZONTAL STACKING links are found here:
http://www.avsforum.com/avs-vb/showthread.php?p=14593948
PS: I had to fix two outdated links...

Tower Guy

07-22-09, 07:56 PM

Unfortunately, tuning this rig to channel 12 (207 MHz) might not get you as much rejection as you need, and if it doesn't, you would need to build a 201 MHz and a 213 MHz stack. Fortunately, the parts you would use are not expensive. Each stack would use two commonplace highband VHF antennas that you can probably buy for under $40 each.

I'd design the stagger stack for 12, halfway between 11 and 13. It will still increase F/B by about 13 db on both 11 and 13. That should be enough.

300ohm

07-22-09, 09:38 PM

Switching power supplies need a minimum load in order to work, but I thought you knew that.

Yep. He could jumper the green wire to a black wire on the 20 pin plug to make the psu run. A simple paper clip works.

http://www.hardwaremods.com/guides/psu_jump/psu_jumping.html

nybbler

07-22-09, 10:29 PM

Jumpering the wire will make the supply start, but it won't be able to regulate properly and it'll oscillate all over the place. You need to put a dummy load on the supply (used to be the 5V line was what mattered, I don't know if that's still true). An auto headlight works.

systems2000

07-22-09, 10:57 PM

How does K6STI design compare to the design that comes out of VK5DJ's design calculator (2.6.0) for DL6WU yagi's?

dr1394

07-23-09, 03:11 AM

How does K6STI design compare to the design that comes out of VK5DJ's design calculator (2.6.0) for DL6WU yagi's?

Do you mean YO from K6STI? It's more of a tool to optimize existing commercial designs. While the VK5DJ program just gives you DL6WU yagi dimensions for a certain frequency and boom length.

Ron

nordloewelabs

07-23-09, 03:15 AM

Switching power supplies need a minimum load in order to work, but I thought you knew that.this crossed my mind but i wasnt sure.

Yep. He could jumper the green wire to a black wire on the 20 pin plug to make the psu run. A simple paper clip works.

i have a better idea. i'll leave the case's fan plugged and unplug everything else. maybe that fan will create enough load.

still, that wont solve the problem. does anyone have any suggestion on how to suppress the interference that emanates from the PC. by the way, my TC1100 TabletPC also causes interference so i think it's natural to all computers to interfere with nearby antennas....

The Hound

07-23-09, 06:59 AM

i think it's natural to all computers to interfere with nearby antennas....
True, thousands of contacts being made and broken cause interference in the air.
Most boxes have been sheilded now days.
In the comp room at work nothing gets in, FM, cellphone, TV, nothing.
I have run antennas outside the room to get reception.

systems2000

07-23-09, 11:45 AM

While the VK5DJ program just gives you DL6WU yagi dimensions for a certain frequency and boom length.
More like frequency and elements, since it has eight directors, a reflector, and the driven (Di-Pole or Loop). Boom length is determined by the frequency. It's ultimate output gives you a 14dBi gain.

It's the one I've been playing with. Is there another that I should look at?

JimP

07-23-09, 11:47 AM

Can a wireless bridge also intefere with TV reception?

hphase

07-23-09, 12:23 PM

I'd design the stagger stack for 12, halfway between 11 and 13. It will still increase F/B by about 13 db on both 11 and 13. That should be enough.
Thanks. I forced myself to do a few calculations to see how much being + or - 6 MHz from the designed frequency would affect the F/B improvement. I came up with similar numbers, but I admit it's just a guess considering the difference between a theoretical null and real-world realizable improvements.

So, other questions arise:

The recomendation for the vertical spacing of stagger-stacked arrays seems to be about 0.5 or 0.6 wavelengths. BUT, the Australian source suggests that if you have a long boom, you should space the antennas by an amount equal to the boom length. This seems to imply that, since a longer boom implies an antenna with more elements, and thus more gain, a higher gain antenna has a larger "capture area." Is this a correct assumption and therefore a good recommendation?

Regardless of the spacings, and hating to "waste" space on the mast, can a UHF antenna be placed between the spaced Hi-VHF antennas without screwing things up completely? (I am interested in improving VHF F/B ratio, after all.) With a 4221HD I would primarily be worried about the horizontal elements in the reflector part of the antenna, seeing as they are getting close to the length of the VHF elements.

The stagger stack seems like it might be what I need, but I don't do this sort of stuff often enough to pretend I'm particularly good at it. Comments are welcomed!

300ohm

07-23-09, 01:23 PM

Can a wireless bridge also intefere with TV reception?
It shouldnt, unless its defective. Wifi is on 2.4 and 5 Ghz bands, well above the TV frequencies.

does anyone have any suggestion on how to suppress the interference that emanates from the PC.
Increase the distance between the pc and the antenna.

Tower Guy

07-23-09, 01:29 PM

The recomendation for the vertical spacing of stagger-stacked arrays seems to be about 0.5 or 0.6 wavelengths. BUT, the Australian source suggests that if you have a long boom, you should space the antennas by an amount equal to the boom length. This seems to imply that, since a longer boom implies an antenna with more elements, and thus more gain, a higher gain antenna has a larger "capture area." Is this a correct assumption and therefore a good recommendation?

Yes, it's a correct assumption. A pair of 10 element Y1713's should be stacked about a wavelength apart. That's about 4.8' on channel 12. The dimension isn't critical. Anywhere between 4-6 feet should work.

Tower Guy

07-23-09, 01:40 PM

Regardless of the spacings, and hating to "waste" space on the mast, can a UHF antenna be placed between the spaced Hi-VHF antennas without screwing things up completely? With a 4221HD I would primarily be worried about the horizontal elements in the reflector part of the antenna, seeing as they are getting close to the length of the VHF elements.

My gut reaction would be that the UHF antenna is unlikely to ruin the benefit of the stagger stack. The VHF antennas may slightly impair the the F/B UHF antenna, but I doubt that you'd notice it.

psychoboy

07-23-09, 02:06 PM

Nice work Holl_ands! Can't wait to see the RCA ANT751 data!

Best,

Rick

I too would be interested in this antenna, the ANT751. I currently have one and it is not the "performer" I thought it would be. Let me know if any measurements or pics are needed, before I return it to wallyworld.

nordloewelabs

07-23-09, 02:17 PM

I too would be interested in this antenna, the ANT751. I currently have one and it is not the "performer" I thought it would be.

i'm curious too, although i'm not planning to buy it. no website that sells it has specs for it. my guess is that the figures arent impressive and RCA decided it wasnt worth the trouble. this antenna has become some of a legend in the forum, despite the lack of specs.

i'll be eagerly waiting for the analysis. thanks, holl_ands!

mclapp

07-23-09, 03:33 PM

Regardless of the spacings, and hating to "waste" space on the mast, can a UHF antenna be placed between the spaced Hi-VHF antennas without screwing things up completely? (I am interested in improving VHF F/B ratio, after all.) With a 4221HD I would primarily be worried about the horizontal elements in the reflector part of the antenna, seeing as they are getting close to the length of the VHF elements.

The stagger stack seems like it might be what I need, but I don't do this sort of stuff often enough to pretend I'm particularly good at it. Comments are welcomed!

You may want to consider using your 4221 for channels 11 and 13 by adding a screen reflector 36" high by 36 - 40" wide should get you around 20 - 30 db front to back.

I know a 4221 isn't much of a VHF-hi antenna but the old style 4221 with the wider reflector has positive gain on channels 11 - 13 somewhere in the order of 4 - 7dbi and the front to back ratio is above 20db if using 2x4" fencing or smaller.

Computer models show spots in the rear where it approches 30+db rejection.

This would be a simple mod to try, simply cut some wire fencing to size and hose clamp it to the back of the exsisting reflector. It should not negatively affect the UHF in fact it may slightly enhance it.

I have not tried this mod on a 4221hd but the dimensions are very close to the same as the original 4221 so it should work.

Just a suggestion to try if your willing to experiment and have access to the materials needed.

holl_ands

07-23-09, 05:35 PM

How does K6STI design compare to the design that comes out of VK5DJ's design calculator (2.6.0) for DL6WU yagi's?
VK5DJ says his Yagi Calculator is based on DL6WU design equations
(same as the on-line K7MEM calculator):
http://vk5dj.mountgambier.org/Yagi/Yagi.html
It maximizes Gain for a very long Yagi antenna (over 3 meters at Hi-VHF)
and reportedly is optimized for 50-ohm vice 75-ohm.

I ran the same design frequency (190 MHz) for an 8-Element Yagi as in K7MEM.
All of the dimensions came up the same (within a couple mm), EXCEPT the Driven
Element length was 760 mm per K7MEM (presumably NOT a Folded Dipole) and
per VK6DJ it was either 760 mm for a Folded Dipole or 745 mm if NOT....hmmmm....
The VK6DJ Yagi Calculator also has some useful utilities, such as a Balun calculator,
but yields results roughly the same as the on-line K7MEM calculator.

Yagi 4nec2 runs can be found here: http://imageevent.com/holl_ands/yagis

A 2-percent difference in Driven Element length only caused small differences in Net Gain
and Front/Back Ratio, see attached. Like most Yagi designs that maximize Gain on
a single frequency, DL6WU derived designs only perform well on 1 to 3 adjacent channels.
Whereas the lower gain 5-Element K6STI Yagi is optimized for the entire Hi-VHF band.

dr1394

07-23-09, 05:41 PM

More like frequency and elements, since it has eight directors, a reflector, and the driven (Di-Pole or Loop). Boom length is determined by the frequency. It's ultimate output gives you a 14dBi gain.

It's the one I've been playing with. Is there another that I should look at?
The DL6WU taper is an excellent design. Here's some additional information.

http://www.cebik.com/content/a10/vhf/wu.html

You have to register, but it's free.

In general, yagi designs can be optimized for forward gain, bandwidth or front to back ratio. But not all three parameters at the same time. It's sounds like you need maximum gain, so the DL6WU fits your application pretty well.

Ron

IDRick

07-23-09, 05:46 PM

i'm curious too, although i'm not planning to buy it. no website that sells it has specs for it. my guess is that the figures arent impressive and RCA decided it wasnt worth the trouble. this antenna has become some of a legend in the forum, despite the lack of specs.

i'll be eagerly waiting for the analysis. thanks, holl_ands!

Legendary might be a stretch for this antenna... :) But, there is interest since it is a new design. I have firsthand experience and have compared it to mclapp's DIY 4-bay. The DIY has 6 to 7 dB higher margin to dropout than the EZ HD (same thing as ANT751). Presumably, that means that the DIY antenna has 6 to 7 dB higher gain. Mclapp's modeling efforts project UHF gains for the DIY 4-bay at ~12dBd, UHF scale. I'm interested in seeing how well my testing compares to the models for both antennas.

holl_ands

07-23-09, 06:03 PM

Legendary might be a stretch for this antenna... :) But, there is interest since it is a new design. I have firsthand experience and have compared it to mclapp's DIY 4-bay. The DIY has 6 to 7 dB higher margin to dropout than the EZ HD (same thing as ANT751). Presumably, that means that the DIY antenna has 6 to 7 dB higher gain. Mclapp's modeling efforts project UHF gains for the DIY 4-bay at ~12dBd, UHF scale. I'm interested in seeing how well my testing compares to the models for both antennas.
Is this for UHF or Hi-VHF??? (I would guess only for UHF.)

IDRick

07-23-09, 06:16 PM

Is this for UHF or Hi-VHF??? (I would guess only for UHF.)

The 6 to 7 dB improvement was for UHF.

hphase

07-24-09, 09:12 AM

You may want to consider using your 4221 for channels 11 and 13 by adding a screen reflector 36" high by 36 - 40" wide should get you around 20 - 30 db front to back.

I know a 4221 isn't much of a VHF-hi antenna but the old style 4221 with the wider reflector has positive gain on channels 11 - 13 somewhere in the order of 4 - 7dbi and the front to back ratio is above 20db if using 2x4" fencing or smaller.

Computer models show spots in the rear where it approches 30+db rejection.

This would be a simple mod to try, simply cut some wire fencing to size and hose clamp it to the back of the exsisting reflector. It should not negatively affect the UHF in fact it may slightly enhance it.

I have not tried this mod on a 4221hd but the dimensions are very close to the same as the original 4221 so it should work.

Just a suggestion to try if your willing to experiment and have access to the materials needed.
I thought that the part of the 4221 antenna that allowed reception of VHF was the reflector screen. I can see how a larger screen might help F/B at UHF frequencies, but how does that translate to F/B ratio at VHF frequencies?

Of course, it's easy enough to just try it to see if it works. I guess I'm looking for a bit of the "why." Thanks for the suggestion.

mclapp

07-24-09, 12:35 PM

I thought that the part of the 4221 antenna that allowed reception of VHF was the reflector screen. I can see how a larger screen might help F/B at UHF frequencies, but how does that translate to F/B ratio at VHF frequencies?
No, the reflector actually hurts some VHF-HI channels, the stock reflector is just the right size to be a director on the lower channels and totally screw up the impedance match. The larger screen will actually perform as a reflector on VHF-hi. Here is a test I ran on a old style 4221 along with a VU90 and some homemade antennas. I don't know if the new 4221hd will perform exactly the same but it should be close. http://www.frontiernet.net/~mclapp/Antennas/plots/4%20bay%20VHF-hi%20Compare%204221.gif
I did test the front to back on the large screen and it was pretty good but I didn't actually plot it so all I have to go by is the computer models I ran.

Of course, it's easy enough to just try it to see if it works. I guess I'm looking for a bit of the "why." Thanks for the suggestion.
Give it a shot :)

EscapeVelocity

07-24-09, 01:28 PM

Legendary might be a stretch for this antenna...

LOL! Really.

The 6 to 7 dB improvement was for UHF.

If you go with the UHF specs for the Winegard 7000R those would be right in line with RCA ANT751 UHF gain +6 to 7db = 11dbd to 13dbd.

holl_ands

07-24-09, 02:04 PM

Huh???
Although the Rear VHF part of the HD7000R is 3 times wider to cover Lo-VHF, the front, UHF part
looks the same as EZHD and RCA ANT-751.

HD7000R UHF Gain specs are 3.6 dBd (5.8 dBi) on Ch14, rising to 5.1 and 6.0 dBd (7.3-8.2 dBi).

mclapp's Super-Sized 4-Bay is 6 to 7 dB higher (11-13 dBd or 13-15 dBi) on UHF.

EscapeVelocity

07-24-09, 02:17 PM

5 to 6dbd + 6 to 7 db = 11 to 13 db in my book. Or maybe Im missing some nuance.

300ohm

07-24-09, 05:52 PM

Could I be overloading my TV? According to TVfool, my High VHF signals are 18.5, 16.6, 15.5 and 12.7 NM(dB). My UHF signals start at 7.0 dB down to 1.7 dB.

Not unless that CM7777 is defective. Looks like the biggest problem you have is most channels are 1 edge. So I would either try to raise the antenna, or aim for the tops of the hills.

axolotls

07-26-09, 12:53 AM

First off, thanks for everyone's suggestion on my OTA.

I chose the 7697 as suggested by arxaw and others.

I opted for the chimney mount.

I have two VHF channels and one came in at 100%, the other 70%.

The UHF channels are located on the same tower as the VHF's but come in between 10% and 70% with an average of 40%.

I am splitting it (one active) and the RG6 length is a whopping 140' (100' feet before the split into separate 40's)

So, I am losing about 12db.

All my reception is coming from 35 miles away, one edge, with about three hills in the way.

Will a pre-amplifier mitigate the signal loss -and- boost the signal?
If yes, should I just get a UHF only booster since the VHF comes in fairly well?
Are there any other options. Maybe one to counteract the cable length and splitter and another to pull in those UHF channels a little better (especially that 10% one).

TIA

Ax

ProjectSHO89

07-26-09, 08:20 AM

JimP

07-26-09, 09:55 AM

300ohm

07-26-09, 12:50 PM

My RG6 quad cable has a loss of 1 db every 18 ft, the same as typical RG6. Some other quad cable has slightly more loss, like 1 db every 20 - 21 ft.

The better splitters will tell you the loss, the cheapy ones wont and are lossier.

EscapeVelocity

07-26-09, 12:52 PM

About 1db at VHF frequencies and 6db for upper UHF frequencies and about 3db for lower UHF frequencies per 100ft of RG6. Higher losses for RG59. Higher losses for lower quality cable.

Satcom15

07-26-09, 01:00 PM

Which brings up a question. About how much signal loss is there using quad cable for every 25' (or whatever unit)? Axolotis has 140 ft plus his splitter. Most splitters will tell you what the loss is. How about the cable?

Below is data from the Beldon catalog for several of their cable types. Note that attenuation is cable type and frequency dependent.

1152 CATV Cable & 1189AP Broadband CATV Coax
Freq (MHz)|Max Attn (dB/100 ft)
1|.3
10|.66
50 | 1.6
100 | 2.2
200 | 3.0
400 | 4.6
700 | 6.6
900 | 7.7
1000 | 8.2

1189A Broadband CATV Coax Cable & 1190 CATV COAX
Freq (MHz)|Max Attn (dB/100 ft)
5 | .67
55 | 1.60
211 | 2.87
270 | 3.24
300 | 3.43
350 | 3.72
400 | 4.00
450 | 4.26
550 | 4.71
750 | 5.59
870 | 6.00
1000 | 6.54

EscapeVelocity

07-26-09, 01:21 PM

I was pretty close.

hphase

07-26-09, 01:25 PM

No, the reflector actually hurts some VHF-HI channels, the stock reflector is just the right size to be a director on the lower channels and totally screw up the impedance match. The larger screen will actually perform as a reflector on VHF-hi. Here is a test I ran on a old style 4221 along with a VU90 and some homemade antennas. I don't know if the new 4221hd will perform exactly the same but it should be close.
I did test the front to back on the large screen and it was pretty good but I didn't actually plot it so all I have to go by is the computer models I ran.

Give it a shot :)
Well, I tried, and nothing really changed. I did note that it seems that the 4221 is pretty much omnidirectional at channel 8. That was the only channel I could pick up on the 4221 in any configuration. I don't have any other test equipment, so I can only use sucessful reception as a go-no go test. The "signal strength" meter can't tell the two co-channel interferers apart.

Granted, channel 8 is about 20 miles away, while any other VHF channels are either 40 or 60 miles away, but I was still surprised how easily the 4221 picked up the channel signal at almost any antenna heading.

Satcom15

07-26-09, 02:32 PM

I was pretty close.

Yup, EV I agree - your numbers were pretty good for the problem at hand. I guess the take away is a 4 way splitter introduces a lot of loss. As EV points out and the numbers in the table indicate cable losses for 140 foot cable are around:

VHF ~1.4dB
Lo UHF ~4.2 dB
Hi UHF ~8.4 dB

Inserting the splitter in there pushes total losses to ~13.4 dB, ~16 dB, and ~20 dB
Cheers

holl_ands

07-26-09, 05:45 PM

axolotls

07-26-09, 07:22 PM

Yup, EV I agree - your numbers were pretty good for the problem at hand. I guess the take away is a 4 way splitter introduces a lot of loss. As EV points out and the numbers in the table indicate cable losses for 140 foot cable are around:

VHF ~1.4dB
Lo UHF ~4.2 dB
Hi UHF ~8.4 dB

Inserting the splitter in there pushes total losses to ~13.4 dB, ~16 dB, and ~20 dB
Cheers

Thanks everyone! It's the High UHF channels that are coming in marginal and that helps explains it!

I am so friggin' happy with my OTA channels now. And I scouted my entire neighborhood and I am the only one out of 1,000+ residences that has it.

mclapp

07-26-09, 08:37 PM

Well, I tried, and nothing really changed. I did note that it seems that the 4221 is pretty much omnidirectional at channel 8. That was the only channel I could pick up on the 4221 in any configuration. I don't have any other test equipment, so I can only use sucessful reception as a go-no go test. The "signal strength" meter can't tell the two co-channel interferers apart.

Granted, channel 8 is about 20 miles away, while any other VHF channels are either 40 or 60 miles away, but I was still surprised how easily the 4221 picked up the channel signal at almost any antenna heading.

That's too bad, I wish I had a new 4221 to test with, I was doing some field testing this weekend with a home made 4 bay with a 36" wide reflector and checked the front to back ratio. It was getting all of 20db front to back on VHF-hi the channels were 7,8 and 11. 7 and 8 are very strong and I maintained a lock no matter which way I pointed but the spectrum analyzer showed 20+ db reduction when pointed away from the stations. The ch11 station is over 70 mi. away so I couldn't get a front to back reading because it would drop out totally if I moved the antenna away a few degrees.

I want to test the old style 4221 in the field next to compare it to the home made version, I'll be sure to stick a large reflector on it as part of the test. I also have a ch11 yagi I'm going to test I'll try to get some field measurments on that as well.

I know that the new style 4221 has some differences even though the whisker elements are the same as the old style, there may be something in the new one that doesn't allow it to work the same.

300ohm

07-26-09, 10:48 PM

Thanks everyone! It's the High UHF channels that are coming in marginal and that helps explains it!

I am so friggin' happy with my OTA channels now. And I scouted my entire neighborhood and I am the only one out of 1,000+ residences that has it.
Yep, youre losing a lot of signal and a low noise, quality preamp will do you wonders. If you think youre so friggin' happy now, just wait until you get the good preamp ! :p

Satcom15

07-26-09, 11:10 PM

RG-6 Cable Loss (and construction) varies quite a bit, even from a single manufacturer:
http://www.generalcable.com/NR/rdonlyres/55F61B9E-9619-4C50-9093-2DED4E2238E3/0/Pg059_065_CoaxCblRG6U.pdf
http://www.belden.com/pdfs/03Belden_Master_Catalog/06Coaxial_Cables/06.34_39.pdf

holl_ands
That's pretty interesting, didn't realize there was so much variability. Just for grins I went out to the Andrew (now Commscope) to look at the RF coax cables I used to work with. Of course these cables are well beyond what your typical home TV viewer would use (don't think too many people would run and LDF12-50 2-1/4 inch diameter cable with N-Type connectors into their house :eek: ). I was curious to see how they compare with the puny RG-6 cable we use. :D

Lo and behold, I see they have stopped making my favorite cable: LDF5-50! Now they have an aluminum outer conductor cable that supposedly is "better". Yeah, sure. They still make a copper outer conductor cable - but I'm sure its more expensive. And I see they have reduced the number of cable options. Bummer. Anyway, here are the results for several cable types at several frequencies that correspond roughly to VHF/UHF frequencies: 50 MHz (Lo VHF), 200 MHz (hi VHF), 500 MHz (Lo UHF), 800 MHz (Hi UHF), 1000 MHz (Just for Grins). The attenuation values are in dB/100 ft. Also included is the average power rating (in kW) for each frequency. So for example, AVA 5-50 at 800 MHz has an attenuation of 1.014 dB/100 ft, quite a bit less than the 6-8 dB/100ft we'd expect on RG-6, and can handle 2.53 kW of RF power.

BTW that LDF12-50 cable is pretty tough to work with, especially in cold (and I mean real cold as in -30 degree F installation temperature cold). LDF5-50 is manageable, but still not easy. Bend radius is more like 3 feet in those temps. :D Anyway, here are the numbers. Enjoy.

LDF4-50 (1/2 in diam)
50 0.463 5.02
200 0.946 2.46
500 1.53 1.52
800 1.968 1.18
1000 2.220 1.05

AL 5-50 (7/8 in diam - Aluminum outer conductor)
50 0.264 8.95
200 0.538 4.39
500 0.871 2.71
800 1.120 2.11
1000 1.264 1.87

AVA 5-50 (7/8 in diam - Copper outer conductor)
50 0.237 10.81
200 0.485 5.28
500 0.787 3.25
800 1.014 2.53
1000 1.145 2.24

AVA 7-50 (1 5/8 in diam)
50 0.137 16.14
200 0.284 7.81
500 0.465 4.76
800 0.604 3.66
1000 0.685 3.23

LDF 12-50 (2 1/4 in diam)
50 0.119 30.64
200 0.253 14.45
500 0.426 8.58
800 0.562 6.49
1000 0.644 5.67

300ohm

07-27-09, 01:43 AM

Too bad you couldnt get it up to 2.4 GHz. Larger though, seems to be better. Thats the pattern.

Satcom15

07-27-09, 02:09 AM

Too bad you couldnt get it up to 2.4 GHz. Larger though, seems to be better. Thats the pattern.

Yup, bigger IS better. And as for 2.4 GHz, ask and you shall receive. Here are some values for 2.5 GHz from the Andrew site for their more common cables:

1/4 in diam - 6.914 dB/100 ft
1/2 in diam - 3.685 dB/100 ft
7/8 in diam - 1.911 dB/100 ft
1-5/8 in diam - 1.169 dB/100 ft

Nothing for 2-1/4 in diam, but its probably around 1 dB/100 ft. I used a lot of the 7/8 in diam cable for L-/S-Band satellite communications (1680/2027 MHz) so know its properties pretty well.
Cheers.

Tower Guy

07-27-09, 03:32 PM

Nothing for 2-1/4 in diam, but its probably around 1 dB/100 ft.

2 1/4" cable doesn't work right at 2.4 GHz. It looks more like waveguide than coax at that frequency.

holl_ands

07-27-09, 07:33 PM

Aluminum has historically been a lot less expensive than copper, and had
a cost growth curve that was much less severe than copper, so should be
no surprise to see more use of aluminum.....just not in my house wiring:
http://www.indexmundi.com/commodities/?commodity=aluminum&months=60
http://www.indexmundi.com/commodities/?commodity=copper&months=60

PS: I especially liked LDF5-50 because the flexible, solid shield didn't leak like normal coax,
so interconnecting cables weren't a leakage path between transmitters & receivers under test.

Satcom15

07-27-09, 08:00 PM

PS: I especially liked LDF5-50 because the flexible, solid shield didn't leak like normal coax,
so interconnecting cables weren't a leakage path between transmitters & receivers under test.

Me too. I see that they have also gone to "cheaper" connectors too. But supposedly they are "better". Yeah, right. Worked with Andrew LDF5-50 cable and N-Type connectors for years. Used it on HF through satcom systems. Sorry to see it "improved". Guess its all about the bottom line - forget quality. :(

axolotls

07-27-09, 08:47 PM

Yep, youre losing a lot of signal and a low noise, quality preamp will do you wonders. If you think youre so friggin' happy now, just wait until you get the good preamp ! :p

I just read in the Local OTA threads that all the UHF channels I am getting are on temporary antennas and that they are going to raise them 500' by October.

The VHF one that comes in at 100% is the first antenna they raised, which is probably the reason why the signal comes in perfectly.

300ohm

07-27-09, 09:13 PM

Aluminum has historically been a lot less expensive than copper
For metal prices, I like this site : http://www.metalprices.com/

hayj

07-30-09, 12:23 AM

I was hoping I could get some advice on the next antenna I buy. It may help to give a little background. I recently switched to ota and checked antennaweb as to my local broadcasts. Here's the situation, the last numbers being angle, distance, and rf station.

WDRB-DT 41.1 FOX LOUISVILLE, KY 308° 14.8 49
WHAS-DT 11.1 ABC LOUISVILLE, KY 309° 15.0 11
WAVE-DT 3.1 NBC LOUISVILLE, KY 314° 14.8 47
WBNA-DT 21.1 ION LOUISVILLE, KY 212° 15.6 8
WMYO-DT 58.1 MNT SALEM, IN 308° 14.8 51
WKPC-DT 15.1 PBS LOUISVILLE, KY 313° 14.8 17
WKMJ-DT 38.1 PBS LEXINGTON, KY 313° 14.8 38
WJYL-CA 45 TBN CLARKSVILLE, IN 314° 14.8 45
WLKY-DT 32.1 CBS LOUISVILLE, KY 314° 14.8 26
WBKI-CA 28 CW CAMPBELLSVILLE, KY 309° 15.2 28
WBKI-LD 34.1 CW CAMPBELLSVILLE, KY 309° 15.2 34

It turns out the WKBKI HD station on 34 isn't at this location, but 50 miles away at 169 degrees on RF 19. I bought a Terk HDTVo, based on 34 broadcasting in Louisville. However, pointing it at 169 degrees I can get WBKI in but the Louisville stations suffer too much for my liking. I have bought a cm4228 for WBKI and planned to use the Terk for the Louisville stations, but I have noticed the Terk has been dropping out in the mornings every 5-10 minutes so I think I will return it. I was guessing multipath? This is a suburban areas with a lot of large trees as well. I plan to mount on the eaves, on opposite sides of the house. The cm4228 shows a signal strength of 65% on the roof and a signal quality to be 75%. (I took this to be Signal to Noise Ratio) The minimum values according to SiliconDust is 50%. So I think with a preamp I will be good for WBKI. So my question is what antenna should I replace the Terk with for the Louisville stations? I was thinking the Winegard 7695P. Also, what would be a good preamp for the 4228? I have a Jointenna for channel RF 19 for the WBKI station on digital 34. Does this sound like a reasonable approach before I make any more purchases? Thanks.

Tower Guy

07-30-09, 08:25 AM

Does this sound like a reasonable approach before I make any more purchases? Thanks.

It does to me.

You'll miss ION on channel 8 if that matters to you.

jtbell

07-30-09, 10:36 AM

hayj

07-30-09, 11:40 AM

At 15 miles, you shouldn't need a 4228 and a pre-amp, unless you're behind a big hill or something. Something smaller like a 4221 or 4220 should work fine for UHF.

Instead of Antennaweb, try tvfool.com, it gives more detailed info. Use the "Maps" option, enter your address, and then adjust your location if necessary by dragging the marker on the map. If you have hills nearby, small changes in position can make a big difference in signal.

Yeah, after the WBKI confusion, I'm using TVfool. The 4228 would be for WBKI at 50 miles to the south. It would be only for that station. Then combined with my stations at 15 miles through a Jointenna. I was thinking the 7695P for the ones at 15 miles.

It does to me.

You'll miss ION on channel 8 if that matters to you.

Is there any hope of the 7695P getting in Ion even pointed at 310 degrees? The Terk gets it in now reasonably well and drop outs aren't as big of an issue for this station. I thought the Terk was highly directional but I can't find the stats so I don't know what it's acceptance angle is and at what gain. Anyone have a situation like this? Three antennas won't fly. I'm pushing it with my wife with two antennas.

Tower Guy

07-30-09, 03:13 PM

Is there any hope of the 7695P getting in Ion even pointed at 310 degrees?

Maybe. There's probably enough signal. It depends on multipath.-

hayj

07-31-09, 03:41 PM

I was wondering if it would be possible to avoid buying a second antenna for my closer stations, point the 4228 at WBKI (RF 19) and use a preamp with a lot of gain and low noise, say this one (AP8275):

http://www.solidsignal.com/prod_display.asp?PROD=SAP8275

I know its a lot of gain, but since WBKI is at 50 miles and the 4228 is fairly directional I was thinking the stations at 15 miles wouldn't saturate. Would multipath kill me? Anyone have an opinion? I attached an image of my broadcasts.

kedirekin

07-31-09, 06:15 PM

Tower Guy

07-31-09, 06:36 PM

hayj

08-01-09, 10:52 AM

Try pointing the 4228 at WBKI and see if you still get your local channels. They're close enough there's a good chance you will.

If you find WBKI is almost there, or there but not 100% reliable, a pre-amp may be in order, but you definitely don't want a high gain amp - not with such strong signals close by. One of the harder lessons to learn with pre-amps (because you have to un-learn conventional wisdom) is that it's not so much about making the signal as strong as possible, but more about preserving the signal-to-noise ratio (SNR) right at the antenna, where SNR is at its best. You only want to amplify it enough to make up for down-stream cable losses and such, plus a little bit. Too often, excessive gain just creates problems.

Thanks for the advice. I agree, StoN is the important value. I probably should have mentioned that I've had the 4228 on the roof and looked at the signal strength and signal quality (which I took as StoN) on my HDhomerun. The signal strength was 65% and the signal quality was 75%, this being after my cable run, so I expect the StoN to be slightly higher at the antenna. Silicon Dust quotes a minimum signal strength of 50% and recommends a strength of 75% and a minimum signal quality of 50%. So I think I have enough StoN to amplify the signal and bring the strength up into a more suitable range so, in the event of a drop, I don't lose it in the noise. I guess I was a little zealous with my gain levels as it sounds like others are as well. I just found the translations from percentages for the HDhomerun. From their forum

"A 3dB change in signal level will result in a 5% change in reported signal level.

100% is approximately 0dBmV or approximately -49dBm.

The rev2 can handle 40dB higher than 100%."

As far as StoN, I could only find that 90% is 29dB

"snq=90(29dB)"

But that doesn't speak to the saturation on the preamp. When I mount it, I'll let you know what I find after watching it a bit.

It's possible that you'd get nothing with that configuration. If you get anything, expect dropouts. My 4228 and HDP-269 preamp overloads. I'm 9 miles from the Albany antenna farm.

I assume you have your 4228 pointed at WBKI as well and the preamp is overloading from the Louisville antennas?

rgharrin

08-02-09, 07:54 AM

JimP

08-02-09, 08:36 AM

ctdish

08-02-09, 01:22 PM

I have an Archer (Radio Shack) combo antenna.
It has 8x2 arms for VHF. Since there are no 2-6 channels, where I live, is it possible to trim the arms for those channels to better pick up channels 7-13?

In most of the 2-13 antennas the long elements have a function on the high VHF channels as well as on the lower channels so trimming them without doing some computer modeling will probably cause the antenna to have less gain on all channels.
I you want a smaller antenna buy one of the VHF high antennas.
John

baud

08-02-09, 02:04 PM

rgharrin

I have cut a VU-190 down and it works great.

Look at the Channel Master CM 2020 it's almost the same.

http://www.solidsignal.com/prod_display.asp?PROD=CM-2020

rgharrin

08-02-09, 02:54 PM

rgharrin

I have cut a VU-190 down and it works great.

Look at the Channel Master CM 2020 it's almost the same.

http://www.solidsignal.com/prod_display.asp?PROD=CM-2020

I have a VU160. How do you know what length to cut the long to?
I suspect I could match the shorter ones.
I'll look at the 2020

baud

08-02-09, 03:39 PM

I only cut the boom and feed lines, then re drilled the holes for the mounting u bolt.

Before i cut it i used it without the back end for awhile and it worked fine.

If the VU-160 is joined together the same as the Vu-190 you could try that first.

300ohm

08-03-09, 12:18 AM

Before i cut it i used it without the back end for awhile and it worked fine.
Thats a good way to test to see if it will work fine for you. Just cut the feed lines going to the back elements. Then if it doesnt work good enough, attach them back.

Like ctdish said, without carefull computer modeling (or a simple reversible cut test) its not advisable to cut down a full vhf antenna. On a LPDA, the back elements act as reflectors for the front elements. Removing the back elements can also seriously distort the gain curve. But depending on the situation, it may be fine for you.

JimP

08-03-09, 05:01 AM

I finally got my antenna amplifier yesterday and installed it.

I still get an occassional dropout(mostly audio at 10 minute intervals) which raises some other questions.

Can you tell from just looking at the signal strength meter if the dropout is between you and the station? We had some pretty bad weather but not between me and the station...I don't think. It appeared from the weather map that it was west south west of their transmitter which makes me think that it can be between them and the satellite. For that matter, the weather at the network's uplink facility can be a factor.

So what I guess I'm trying to figure out is have I got my system as good as it gets for 95% of the time and some of the rest would require doubling the size of my antennas and even then you still have to deal with weather before it gets transmitted from the station.

bump....and another question I'd like to ask. Is it possible for an antenna preamp to affect picture quality by changing the contrast. None of my stations go over a signal strength of 92 with the winegard HDP 269 preamp which is only a 12 db gain preamp. My reason for asking is that it appears to me that no only with this preamp, but another one I had with a slightly different antenna array, that the picture looked better without the preamp.

Tower Guy

08-03-09, 06:00 AM

bump....and another question I'd like to ask. Is it possible for an antenna preamp to affect picture quality by changing the contrast.

No, not with a digital signal.

systems2000

08-03-09, 12:18 PM

Another way to use a Combo antenna and eliminate the VHF-Low is to install a VHF-Low/High combiner. Run the antenna to the VHF-High port and terminate the VHF-Low port.

OOPS! Forgot about the UHF. :)

hayj

08-05-09, 12:26 PM

OK, so I got the mast mounted and attached the 4228. When I first put it up, I pointed south to WBKI and relied on the backside for the locals, 15 miles away. Unfortunately the local stations dropout too much for this to be a viable setup. I then turned the antenna to the stations that are here in the city and still got dropouts. It wasn't looking good. Then I decided to check my pointing, used Google Earth to draw a line from my roof to the transmitters, and checked the signal. No dropouts. So it may have been a pointing issue all along. Maybe as much as 30 degrees. So this makes me wonder about this being a mulitpath issues. Maybe I had the highest gain of the antenna pointed at a reflection and then that made the reflected signal near the strength of the direct signal? There is a major medical center with 3 hospitals a few miles away in that direction. Lots of concrete and metal.

Anyway, I called Channel Master and Winegard about this problem. They recommend the CM-2016 and the HD-1080 respectively. What do you guys think for the stations at 15 miles out? I was a little concerned about their size and less directionality. Right now the 4228 is doing great but it has a smaller acceptance angle doesn't it? Getting something with a wider angle could be problematic as demonstrated form my previous problems. I was thinking a 7695p.

Tower Guy

08-05-09, 02:41 PM

Getting something with a wider angle could be problematic as demonstrated form my previous problems.

I think that your real problem was caused by misaiming, not a wide angle antenna.

Your plan of a HD7695P would work, but even the smaller HD7694P should be OK when aimed directly at the stations.

The problem is CW. There's no good way to add a channel 19 to another antenna that also has a 17. I suggest that you use their analog LPTV station on channel 28 until they build their digital LP station on channel 34. The aim for those are the same as the other Louisville stations.

To get ION use a Y5-7-13 and a channel 8 Jointenna.
http://www.solidsignal.com/prod_display.asp?PROD=Y5-7-13
http://www.amazon.com/Channel-Master-Jointenna-0578-Combiner/dp/B001RUB4BQ/ref=sr_1_5?ie=UTF8&s=electronics&qid=1249497497&sr=1-5

hayj

08-05-09, 02:55 PM

The problem is CW. There's no good way to add a channel 19 to another antenna that also has a 17. I suggest that you use their analog LPTV station on channel 28 until they build their digital LP station on channel 34. The aim for those are the same as the other Louisville stations.

Unfortunately that won't work. I have a HDhomerun that's a digital only tuner. I can watch 28 on my tv, but then there's no dvr. I already have a jointenna for 19 but you think it's going to attenuate 17 so much it's not strong enough? I have the 4228 pointed at 17 now, I guess I could pass it through the "all channels" portion on the filter and see.

hayj

08-05-09, 04:05 PM

I suggest that you use their analog LPTV station on channel 28 until they build their digital LP station on channel 34.

I didn't mention that WBKI has no plans to add a digital station here in Louisville. I called and asked them about it. The rep. said there are currently no plans to add a digital broadcast in the foreseeable future. I originally planned to do as you mentioned until I found this out.

Tower Guy

08-05-09, 08:16 PM

I guess I could pass it through the "all channels" portion on the filter and see.

That's worth trying.

rgharrin

08-06-09, 10:13 AM

TV Fool says point the antenna at 342 degrees.
I get poor results.
If I point at 5 degrees, the improvement is dramatic.
I am 65 mi away.
Two different antennas show the same results for stations 7, 9, 31.
Unusual?

hayj

08-06-09, 10:26 AM

I assume you have your 4228 pointed at WBKI as well and the preamp is overloading from the Louisville antennas?
This probably made no sense to you. When you mentioned the Albany antenna farm, I misread and thought you were in Louisville and in a similar situation. Our antennas sit outside of New Albany, outside Louisville. I noticed your in New York.

Anyway, the Jointenna drops channel 17 by about 9dB. Its now at 70% signal strength and StoN, down from 85%. The HD7695P looks to have about 2dB less gain on channel 17 (I couldn't find an exact number) so I'll be looking at a drop of about 11dB. 75% is the recommended level so I'll be well below that. I think I could use something like the HDP-269 to make up for the loss. I'm fairly confident it won't saturate on my other channels. The four major networks are showing 89%, 92%, 94%, and 72%. SiliconDust claims the tuner can handle 40dB higher than 100%. First though I'll probably try without the preamp and shorten the run, as the cable is a little longer than I need because I wanted to wait until final placement. Given this is the HD7694/95, still a good candidate?

rgharrin

08-06-09, 10:37 AM

JimP

08-06-09, 11:13 AM

Does make you wonder if your compass can possibly be defective.

hayj

08-06-09, 02:26 PM

The thought occurred to me that since I'm getting reliable performance on the 4228 with my stations at 15 miles, I should instead buy another antenna specifically for channel 19 at 45 miles and keep the 4228 pointed where it is. I think I could get better gain and maybe avoid a preamp this way. I was looking at the Antennas Direct 91XG or Winegard HD-9032. Reviews lean towards the 91XG but this site claims the lower UHF difference is only slightly better and the HD-9032 is considerably less.

http://www.hdtvtruckee.com/AntennaComparison.htm

Pagoona

08-07-09, 06:20 PM

dr1394

08-07-09, 06:44 PM

Pagoona

08-07-09, 07:00 PM

A tower belt is crucial. It's the only way to have both hands free. Here's what I use.

http://www.onvsafetybelt.com/listings.asp

Specifically, the "747 REGULAR SAFETY BELT WITH LANYARD".

Ron

Thanks. Now that you mention it, I can't imagine fiddling with the antenna unless I had both hands free. However, that belt is much more than what I'm willing to pay. Do you think they have harnesses or belts for rental at a home improvement store?

johnpost

08-07-09, 07:09 PM

Any advice/tips for climbing an antenna tower? I'm sure someone here has experience climbing their own. It's about 35 feet tall and 25 of those are attached to the house. I trust its integrity and I'm sure I would be fine climbing it unsupported but I would feel much better if I had some sort of harness to wear, protecting myself from any unforeseen slip of the foot. Any suggestions?

yes be careful.

have a person on the ground there at all times, they shouldn't stay where something could fall on them if dropped. if you fell or got hung up they could get help. also they can fetch tools you for you so you don't have to make multiple climbs which increase risk.

wear shoes with the stiffest hardest soles with good heels (to catch the rung), this will help with foot fatigue which helps keeping sure footed.

don't lean back, work and climb close to the tower.

haul up all tools or parts by rope, only carry yourself up (maybe with an empty tool belt) with this hauling rope tied to your belt behind you. when you get to your work spot you tie that to tower. use a tool belt that you wear or a bucket tied to tower to hold tools.

if you don't have a butt or body harness then you could improvise. If you had some rope in good condition with a weight limit twice your weight. you should minimally tie a bowline knot and tie yourself to tower (let yourself have 3 or 4 feet of rope, gives you freedom and if you fell it is easy to recover from small drop) when you get to your work spot (could even try rescue knots which loop legs and waist, i don't have example at the moment). even with belt or rope it is safer and feels better to work with an arm wrapped around tower or mast (hook tower part with inside elbow and your hand is free to hold or work).

you can even macrame an improvised safety belt using square knots in not too much time, make it as wide as a store bought belt. can tie off with a couple lengths and have about the same security as a store bought.