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The Official AVS Antenna and Related Hardware Topic! - Page 466

post #13951 of 16087
I have a Channel Master 9521 rotator controller, and the antenna has become misaligned. When pointing North, the controller reads 170 degrees (almost completely backwards). I have tried re-syncing it according to the instructions, but either it is too far off or the sync isn't working, because it still reads 170. The manual states:

Quote:


After severe storms, or an extended period of use, the rotator may appear to position the antenna incorrectly.
First try pressing the SYNC key to re-synchronize the system. If this fails, the antenna or drive motor may be misaligned on the mast.You may either go to the antenna and re-orient it, or reprogram the control unit to correspond to the new antenna orientation.

But nowhere does it say how to reprogram the unit. I would really like to avoid climbing up on my roof if possible. What do I do to program it so that North is North?
post #13952 of 16087
Quote:
Originally Posted by 4HiMarks View Post

I have a Channel Master 9521 rotator controller, and the antenna has become misaligned. When pointing North, the controller reads 170 degrees (almost completely backwards). I have tried re-syncing it according to the instructions, but either it is too far off or the sync isn't working, because it still reads 170. The manual states:



But nowhere does it say how to reprogram the unit. I would really like to avoid climbing up on my roof if possible. What do I do to program it so that North is North?

Mine does that too, but it's because I have a bearing on it that is actually a larger radius... Anyway, what I do is I get the antenna pointed where I want it and then just unhook the wires on the rotor, then rotate the dial or the remote control (in my case) to the desired number, then hook the wires back up. It kind of fools it. It works well for me.
post #13953 of 16087
Quote:
Originally Posted by holl_ands View Post

Each Splitter generally provides 25-35+ of Isolation between the input ports (YMMV).

Hence the signals from Antenna B are reduced by about 50-70+ dB before they reach Tuner A.
Unless you have some REALLY strong signals coming in on Antenna B, there should be no problems.

Ahhh..so it is isolated somewhat, but still is affected by the combine. Thanks again.
post #13954 of 16087
Quote:
Originally Posted by DEEPFRINGEGUY View Post

Mine does that too, but it's because I have a bearing on it that is actually a larger radius... Anyway, what I do is I get the antenna pointed where I want it and then just unhook the wires on the rotor, then rotate the dial or the remote control (in my case) to the desired number, then hook the wires back up. It kind of fools it. It works well for me.

Great solution...we used to do something similar in land surveying, where we would "fool" the data computer into thinking it was at a particular elevation. Works great, as long as you can outsmart it!

If this doesn't work for his rotor, another way is to turn the antenna to 170 and tighten the clamps there. I use this trick to put the north stop at 180 instead of 0, as most of my stations are on the top half of the compass, and it's a pain to go 300 degrees around.
post #13955 of 16087
I searched the avsforum, but didn't find any reviews or comments about the Radio Shack indoor amplified HDTV antenna (model 15-255). How does the antenna perform and compare with other models? I was told it was the replacement for 15-1892 (the UFO). With the current clearance price of $18, is it a good one to buy? Thanks!
post #13956 of 16087
Quote:


Each Splitter generally provides 25-35+ of Isolation between the input ports (YMMV).

Good point, I forgot about the splitters isolation.

So in a best case scenario, tuner A suffers a 3.5 db loss from splitter A ( approx 45% of the signal from antenna A). Tuner B suffers a 3.5 db loss from splitter A, a .5 db minimum coupling loss from splitter B, and a 3.5 db loss from the antennas pointing in different directions, for about 8+ db total ( approx 15% of the signal from antennas A and B).
post #13957 of 16087
Quote:


I searched the avsforum, but didn't find any reviews or comments about the Radio Shack indoor amplified HDTV antenna (model 15-255). How does the antenna perform and compare with other models?

The best place for reviews on it is the RS product page http://www.radioshack.com/product/in...howFullReviews

It rates 3.3 out of 5, based on 30 reviews.

Its an interesting looking thing, and it has a built in clock, heh. Its got some good points such as switchable gain. And one of the reviews says the inside uhf antenna rotates, interesting. Keep in mind its for local reception only. If its easy enough to return, I would give it a shot.
post #13958 of 16087
Quote:
Originally Posted by 300ohm View Post

Good point, I forgot about the splitters isolation.

So in a best case scenario, tuner A suffers a 3.5 db loss from splitter A ( approx 45% of the signal from antenna A). Tuner B suffers a 3.5 db loss from splitter A, a .5 db minimum coupling loss from splitter B, and a 3.5 db loss from the antennas pointing in different directions, for about 8+ db total ( approx 15% of the signal from antennas A and B).

That helps when you use civil-engineer friendly percentages. In the practical application of this scenario, antenna A's stations are all in the 0 to -5 NM range... 15% of that sure isn't much! The combine works, but not all the time, and not all the channels. But experimenting with it is fun, especially when a channel scan hits 80.
post #13959 of 16087
Quote:


That helps when you use civil-engineer friendly percentages.

Yeah well, I used Ken Nists decibel vs gain factor chart here :
http://www.hdtvprimer.com/ANTENNAS/basics.html

to arrive at an estimate of what was delivered to each tuner.

Yes, 15% of the total possible gain arriving at tuner B is crap, heh. (or in your terms, 7.5% from each antenna)

Quote:


In the practical application of this scenario, antenna A's stations are all in the 0 to -5 NM range...

I think the NMs would have to be above 40 (at least 30) to get any practical use of this setup.
At 0 to -5 NM, youre DXing, and you cant afford any db's in loss.
post #13960 of 16087
Quote:
Originally Posted by 300ohm View Post

At 0 to -5 NM, youre DXing, and you cant afford any db's in loss.

Oh, no, these are my local Milwaukees at 70 miles. After reading all of the great advice that you & the others have posted over the years, I've dialed things in so well that all 11 full-[pwer stations are 24/7 reliable. The 91XG and the ultra-low noise Kitztech have been a killer combination.
post #13961 of 16087
Quote:
Originally Posted by LithOTA View Post

Great solution...we used to do something similar in land surveying, where we would "fool" the data computer into thinking it was at a particular elevation. Works great, as long as you can outsmart it!

If this doesn't work for his rotor, another way is to turn the antenna to 170 and tighten the clamps there. I use this trick to put the north stop at 180 instead of 0, as most of my stations are on the top half of the compass, and it's a pain to go 300 degrees around.

One thing I worry about is synchronization between the motor and the controller. Say I set it so the current location is zero. It is actually almost 180 degrees off, so if I try to move the antenna to 360, what will happen? Will it bump up against the north stop halfway and then just grind away for a half rotation, leaving me in the same place I am now? Or can it go a full 360 from wherever the zero point is on the controller?
post #13962 of 16087
It won't go
past the stop but it won't grind away either.
The controller will continue to count down
Or up until it reaches the entered number, though.
This means you'll need to keep resetting it
If you mistakenly try to rotate it past the stop.

It's better to have it aimed true for this reason,
but if that's all you can do it's better than
nothing.
post #13963 of 16087
Why don't you just use the preset function of the 9521? (See page 5 of the manual) I have all my stations programmed in & don't really pay attention to the degree reading. This saves a lot of rotating time since most stations here range from northeast to north-northwest.

Physically orient the motor so the stop point is out of the way of your normal range of stations, then program presets into the controller.

 

9521man.pdf 103.8974609375k . file
post #13964 of 16087
I was wondering what kind of small antenna structures exist for highly-directional 2.4GHz transmission/reception that also fall nicely within the DIY realm?

thanks!
..dane
post #13965 of 16087
Quote:
Originally Posted by audiodane View Post

I was wondering what kind of small antenna structures exist for highly-directional 2.4GHz transmission/reception that also fall nicely within the DIY realm?

thanks!
..dane

Pringles can antenna...
post #13966 of 16087
You'll find a BUNCH of different DIY 2.4 GHz Wi-Fi Antennas here:
http://www.seattlewireless.net/AntennaHowTo
http://binarywolf.com/249/wifi_antennas.htm
http://sites.google.com/site/weefipr...tennas-howto-1 [Includes Yagi]
http://www.digitalhome.ca/forum/showthread.php?t=138125

Individual Wi-Fi antennas:
http://www.lecad.fs.uni-lj.si/~leon/...uad/index.html [Low Gain Bi-Quad]
http://www.cantenna.com/CantennaUserGuide.pdf [Commercial CanTenna]
http://www.cantenna.com/ [DIY Kit also available]
http://binarywolf.com/249/pringles_cantenna.htm [Pringles Can]
http://binarywolf.com/249/coffee_can_antenna.htm [Coffee Can - better than Pringles]
http://www.digitalhome.ca/forum/show....php?p=1218749 [High Gain Vertical Rhombic]
http://helix.remco.tk/ [High Gain Helix]
http://docs.google.com/viewer?a=v&pi...ZjBmZTRkN2I0Mw [Very High Gain Curtain Quad]
http://home.comcast.net/~ross_anders...MHzAntenna.htm [Very High Gain Curtain Quad]

Are you going for the record????
http://www.engadget.com/2007/06/19/v...ord-237-miles/

PS: I've seen metal trash cans for as low as $15-30, suitable for DTV Can-Tenna.
It would be a lot smaller than fol. UHF 2-Bay "Extended Reflector":
http://www.prism.gatech.edu/~wn17/We...20page%202.htm

FWIW: Avoid fol. Lo-Gain "Beer Can" TV Antenna design...unless you're desperate:
http://diyfreetv.blogspot.com/2008/0...-beer-can.html
post #13967 of 16087
Quote:
I was wondering what kind of small antenna structures exist for highly-directional 2.4GHz transmission/reception that also fall nicely within the DIY realm?

A bi-quad mounted on an old primestar or dish network dish (seem to be cheap or free and very common to obtain) will give you more than 24+ dBi very directional.
http://www.trevormarshall.com/biquad.htm

A usb wifi adapter in place of the biquad (with usb cable extention) with the dish will give a little less gain than that, maybe 20+ dBi, but is a dirt cheap no brainer wifi combo. The hardest part is aligning the adapter for max gain. If buying a usb wifi adapter, I would get one that has a SMA connector type antenna on it, for maximum performance and versatility.

A biquad with just a reflector with lips (I built one) will give you 10 dbi (stronger than most commercial wifi antennas) and a nice round radiation pattern, making aiming easy. (the radiation pattern in the above link is for the biquad with lips, not the combo with the dish. The combo radiation pattern looks more like a sharp flame)

I built mine to these optimum dimensions: http://www.lecad.fs.uni-lj.si/~leon/...uad/index.html

The biggest problem with wifi antennas is the enormous cable and connection losses at 2.4 GHz, even with super low loss cable. And USB has cable limits of about 30 ft, but for wifi adapters, 15 ft or less might be the max.
post #13968 of 16087
I live in a BIG condo building near National Cathedral in DC. Huge trees, other condos, Homeland Security - it's all here. I had tried the old RCA 'loop with rabbit ears' for OTA HD, with dismal results. With that antenna, the signal would pixelize, and disappear - even with WRC, which is less that 1/2 mile away. It nearly ruined our watching the Winter Olympics last year. So I reluctantly got cable.

Recently I had enough of the big cable bills so I cut off the cable, and thought I'd just watch shows on the internet. But, being a big fan of free OTA HD, I tried again - this time with a $55 Radio Shack 'Outdoor Amplified HDTV Antenna,' model number 15-257. What a difference!

It's advertised as an outdoor antenna, but I just sat it inside, on my window sill. It's not good looking, but not awful either - just a 12" by 6" gray block:

I face due east, right into a small forest.

With this antenna, I get all the Washington, DC High-Definition stations - WRC, WUSA, WJLA, WTTG, WDCA, WETA, and more. All with a signal strength of 80 - 98 using my Sony XBR's digital channel diagnostics. To my surprise, I even get WBAL in Baltimore, at a useable 72.

Once I saw it worked well, I split the signal three ways - one directly to the XBR, and one each to my two trusty TiVo S3's. All of them get reception perfectly...although the TiVo's don't 'see' the Baltimore station, while the Sony does.

I am flippin' amazed. That old RCA antenna came from Radio Shack too...I wasn't expecting much. In fact, when I bought the new one, I said to my daughter, 'I'll probably return it - indoor antennas never work very well.'

Later I said to her, "I am so glad I was wrong.'

I know antennas, esp. indoor ones in urban areas, are very specific to location, interference, building materials and more - but in my one case - this is good fit.
post #13969 of 16087
Go to www.tvfool.com, click on "On-line TV Maps" and enter your location (or just zipcode).
You can put the cursor on top of symbol indicating your location and drag it to a new location.
Check the box "Show lines pointing to each transmitter".

When done looking at the map, you can click on "Make Radar Plot".

There are over a DOZEN stations within 1-3.5 miles of National Cathedral.
So even with say 20 dB of attenuation due to the building and low-E glass, and
maybe another 20 dB of attenuation due to nearby buildings, and say 10 dB of
loss in a 2-Way Splitters & Cables, you should still have extremely strong signals.
[The amplifier in the antenna reduces the effect of that 10 dB down to under 1 dB.]

Your old antenna must be a dead short!!!!
Unless you are in some sort of "cone of silence", simply inserting an unfolded
paper clip (or better, a short piece of wire) into the center of the coax connector
on each box should bring in most stations.....

With such strong signal strengths, we usually recommend a NON-amplified antenna to
prevent "overload" (actually intermodulation noise prevents reception of weak stations).
You must have higher than usual attenuation from nearby buildings, reducing if
not completely avoiding the overload problem.
post #13970 of 16087
Quote:
Originally Posted by holl_ands View Post

There are over a DOZEN stations within 1-3.5 miles of National Cathedral.
So even with say 20 dB of attenuation due to the building and low-E glass, and
maybe another 20 dB of attenuation due to nearby buildings, and say 10 dB of
loss in a 2-Way Splitters & Cables, you should still have extremely strong signals.
[The amplifier in the antenna reduces the effect of that 10 dB down to under 1 dB.]

There are also many FM stations co-located with the TV stations. You should absolutely be drowning in RF, which makes the use of any amplifier virtually impossible for the reasons holl_ands cites.
post #13971 of 16087
Quote:
Originally Posted by Dave Loudin View Post

There are also many FM stations co-located with the TV stations. You should absolutely be drowning in RF, which makes the use of any amplifier virtually impossible for the reasons holl_ands cites.

Of course, given enough $$$, the technology DOES exist to filter out what you don't want and amplify what you do. Too many years ago, my employer made some cavity resonators allowing a transmitter 600 kHz away from a receiver to put 100 watts into the same antenna with minimal desensitization. They weren't cheap ... or small at 146 MHz. These were "band pass" designs, though, and for narrow-band-FM which is lots easier than for a (say) 10MHz wide (for tolerances) TV channel.

Could I notch an FM channel out ... yeah, and pretty effectively, even though it will be 200kHz wide vs. the 15 kHz or so with the F3E NBFM. Could I notch a multi-MHz TV signal out ... not for what I earn in a year. But how large is the pocketbook?
post #13972 of 16087
I need some sage advice. I've just moved--only about 2.5mi NW from where I was--and I'm struggling to get my Philadelphia Fox (29.1) and ABC (6.1) affiliates to come in. Here's my TVFool after the move.

I'm running the old-gen CM 4228 (UHF), a Winegard YA-6260 (low VHF), and a Winegard AP-8700 (amping both after joining). Because I have a channel in high and low VHF, I previously joined the signals with a conventional splitter (using my UVSJ ensured the high VHF that came off the 4228 got blocked).

Regardless of how I set it up, however, I really can't seem to get the above stations to come in. Amped, direct, etc.,; I can get sometimes 3-4 bars (out of 6, MediaCenter) for channel 6.1, but can't seem to get more than 2 for 29.1. Here are the channel maps:
6.1: http://dl.dropbox.com/u/1097147/6_1.PNG
29.1: http://dl.dropbox.com/u/1097147/29_1.PNG

Any suggestions? I may try putting the antenna on the ground tomorrow and see if that helps per a post a few pages back. If a new antenna is sure to do the trick, fine--it's about the cost of one month of FiOS. I've been off cable for six years now and I'm loathe to return.
post #13973 of 16087
Quote:
Originally Posted by Merconium View Post

I need some sage advice. I've just moved--only about 2.5mi NW from where I was--and I'm struggling to get my Philadelphia Fox (29.1) and ABC (6.1) affiliates to come in. Here's my TVFool after the move.

I'm running the old-gen CM 4228 (UHF), a Winegard YA-6260 (low VHF), and a Winegard AP-8700 (amping both after joining). Because I have a channel in high and low VHF, I previously joined the signals with a conventional splitter (using my UVSJ ensured the high VHF that came off the 4228 got blocked).

Regardless of how I set it up, however, I really can't seem to get the above stations to come in. Amped, direct, etc.,; I can get sometimes 3-4 bars (out of 6, MediaCenter) for channel 6.1, but can't seem to get more than 2 for 29.1. Here are the channel maps:
6.1: http://dl.dropbox.com/u/1097147/6_1.PNG
29.1: http://dl.dropbox.com/u/1097147/29_1.PNG

Any suggestions? I may try putting the antenna on the ground tomorrow and see if that helps per a post a few pages back. If a new antenna is sure to do the trick, fine--it's about the cost of one month of FiOS. I've been off cable for six years now and I'm loathe to return.

I can't help you with low-VHF (it's alien to me) but I bet I know what's wrong with 29.
Just a little bit below WTXF 29 on the TV Fool chart is WMPT PBS from Annapolis, also on RF 42. WTXF has only about 12 dB of noise margin over WMPT, which isn't much. On top of that, WMPT is 1-edge diffraction despite being 64 miles away, probably because most of the signal path is over the bay. WMPT's strong signal is stepping on WTXF's.
You need an antenna with better rear and side rejection. The 91XG excels at this, as I can even get stations with co-channels that are stronger than them. I'd also get a rotator, as you could receive most of Baltimore as well.
post #13974 of 16087
The antennas you have are more than enough for the signal strengths you have. But they are "edge" signals, so it will take some experimenting with heights, and maybe tilting upwards. It looks like you may have moved into more of a valley area than where you where previously.
Looking at the maps, it looks like youre near Iron Hill. They dont call it Iron Hill for nothing, heh. If you are, I would try pointing the antennas to the top of the hill.

Another thing is to first check the equipment, the preamp, the coax and the baluns. Baluns are easy to break.

Also try to locate the antenna that gives you a clear space, free of trees or other obstacles for at least 500 ft in front of the antenna if you can.

Im kind of surprised you have any problems with channel 6 given your equipment. Channel 29 I can understand more.
Ken Nists model for the YA-1026 channel 2 - 6 yagi shows a high mismatch loss of about 3.5 db on channel 6 between Raw Gain and Net Gain. That translates to a very high SWR of greater than 6.
http://www.hdtvprimer.com/ANTENNAS/comparing.html
For analog TV, thats not so bad. But for digital, that can be bad, basically distorting the 1's and the 0's. So while the gain is high, the signal isnt clean.
Since you have the YA-6260, the data could be different, but in general the old commercial vhf-low antennas had poor SWR on a lot of channels.
If you post detailed dimensions of the antenna, (detailed enough so anyone could build it from your description) I could model it.

Also, as youll note from Ken Nists data, using the CM4228 for channel 12 isnt a good idea unless the signal is super super strong.
(also note on the first graph, the Raw Gain for the old CM4228, AA, is not correct. Thats the Raw Gain graph for the new and de-improved CM4228, heh)
post #13975 of 16087
Below Gain Chart, click on "AA new Channel Master 4228HD 8-bay" to see correct charts for
new & old antennas. New CM-4228HD may be "de-improved" in some areas but old CM-4228
suffers from Gain loss on low UHF channels (unless it is modified).
post #13976 of 16087
Looks like you have a 3000 watt FM station on 89.9 Mhz which is likely making reception of channel 6 challenging. I would check FM Fool & see if you are closer or are pointing the antenna more towards 89.9 at your new location. Another 1700 watt station on 91.3 appears to be very close as well.

You may need to experiment with the variable FM trap on the 8700 to attenuate those signals before they are amplified.
post #13977 of 16087
Quote:
Originally Posted by Digital Rules View Post

Looks like you have a 3000 watt FM station on 89.9 Mhz which is likely making reception of channel 6 challenging. I would check FM Fool & see if you are closer or are pointing the antenna more towards 89.9 at your new location. Another 1700 watt station on 91.3 appears to be very close as well.

You may need to experiment with the variable FM trap on the 8700 to attenuate those signals before they are amplified.

The FM fool report for the coordinates shown on the TVfool report indicates that 91.3 would have a signal level of -22.2 dbm, 89.9 is -46.2 dbm. WPVI is -57.7 dbm. I'd tune the variable FM trap in the AP 8700 to 91.3 MHz.
post #13978 of 16087
Merconium:

If you're using a conventional splitter in reverse before your amplifier to join your CM 4228 and YA-6260 antennas, you might be losing too much signal from that splitter (-3.5 dB from each side) and/or introducing multipath into your system, because your antenna combining is not being done in a frequency-dividing way. Others can chime in on this, but I'm thinking that using either an HLSJ (which I believe would pass both UHF and VHF-high from your 4228 over the VHF-high side) or a channel 6 Jointenna might be the preferred (lower-loss (-0.5 dB) and frequency-dividing, multipath-preventing) way to combine your two antennas.

http://www.solidsignal.com/pview.asp?p=HLSJ
http://www.channelmasterstore.com/Ch..._p/cm-0576.htm
post #13979 of 16087
Quote:


Looking at the maps, it looks like youre near Iron Hill. They dont call it Iron Hill for nothing, heh. If you are, I would try pointing the antennas to the top of the hill.

IIRC, that hill even affects compasses, so Im not sure how accurate the TVFool data can be if youre really close to it.
On a positive note, it could also possibly be turned into a benefit for some distant channel dxing.
post #13980 of 16087
You guys are studs. Thank you so much for your help.

I spent more than a few hours on this today. I've kept the AP-8700's FM trap in--so, as I understand, it should be trapping all FM signals. I replaced all coax runs. I removed, cleaned, and tightened both baluns (a little tricky on the VHF--more in a sec).

Here's where I'm at:
1) lower placement yielded worse results. Tilting was generally irrelevant on the ground and on the roof.
2) I can get every Philly UHF I care about save WTXF 29.
3) I cannot, under any circumstances, get a signal on VHF WVPI 6. This is a change from two days ago. I don't know if the antenna took damage in the move/setup--some elements are just a little out of line--but hooked up directly, I can't get anything at all. Would folding in all the antenna elements and reseating them help? How delicate are these things?
I had a flawless signal for a year with it in the previous location.
4) I can get some stations, including a UHF version of ABC out of Baltimore. The PBS station out of there is also on UHF.

A few notes:
  • there are very few areas in Northern Delaware that would allow me to get a 500ft tree-free placement unless I build a 100ft tall tower. That's not a possibility on this property. Pointing directly into a treeline I can still get all my UHFs save WTXF 29 (42).
  • I don't think Iron Hill affects me. I'm aligning via an overlayed google maps compass and landmarks, and I can get 5/6 bars on every UHF station located in the same azimuth direction as those I can't get.
  • the VHF antenna's balun (the YA-6260) is the type with the little PCB card that grips the two sides of the antenna and outputs coax. I've removed and reseated it a few times, but that doesn't seem to affect the reception.
  • I have been using a conventional -3.5dB splitter as a combiner, but again, that worked fine for a year. Direct-to-preamp UHF doesn't get my WTXF 29 (UHF 42) nor can I get WVPI 6 (VHF 6). Using a USVJ doesn't do much for either.
  • Here's the TVFool for the last address. You can see I had more 1edge and LOS, and about a +3dB advantage.

In the new location I'm much more directly opposite Baltimore. Indeed, I can pick up the WMAR ABC 2 (38 UHF) using the backside of the 4228. At this point I may order a a 91XG--feeling that it is likely the direct alignment I now have with Baltimore that might be goofing the signal on 29 (UHF 42)--and see if that gets me WTXF from Philly, and then flip the 4228 toward Baltimore to pick up their ABC and PBS affiliates.

Would it make more sense to buy a big combo UHF/VHF like an HD8200U and aim it at Philly?

My thanks in advance!
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