The Official AVS Antenna and Related Hardware Topic! - Page 461

MrBruce:

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If LithOTA doesn't give you the dimensions, they are at the bottom of this page, but are kind of hard to understand unless you are used to looking at the results of computer modeling:
http://www.ham-radio.com/k6sti/vhftv.htm



You are not expected to make measurements that precise, it's just the way the computer modeling program gives results. His dimensions are based on using tubing instead of wire for the elements, which would give slightly shorter dimensions for the tubing. LithOTA can tell you what dimensions he used for wire.

Okay don't laugh, but here it is as best as I can get the whole thing in the image.

Originally I had each element separated at the boom and ran a connecting wire from front to back running criss-cross from one side to the other.

I corrected that and now each element is connected as a solid piece, only the second from the longest one is separated it has the two wires from a circuit board which is part of an amplifier connected to just those two elements.

If you look at this image the left side is the director the right side with the coax sticking out from boom is the reflector, only the second element from the right is separated into two pieces and only that element is connected to the down feed wire.

The director is 25" wide

The driven element is 34" but separated in the middle as two separate elements connected to down feed wire.

Reflector is 38" long.

other 3 elements as can be seen are about 2 inches longer than the director element so element number 2 is 27 inches and so on until you get to the driven element which is 34" long.

Does this design work? Nope WEDN DTV 9 alias WEDN 53 Norwich which is basically 8 Miles away tower is almost in clear site minus a few houses in the way, it comes in at RF 25%, not good at all!

So basically this design is flawed!

Here is the image.


Attachment 211328

I am looking to transition from Dish to OTA and would like an antenna recommendation. I have plenty of room in my attic for a large antenna, and would like to avoid placing one outside. The attic does have rigid metallic insulation, so I'm not sure how that would affect reception. Here is my TV Fool report:
http://www.tvfool.com/?option=com_wr...8d177e6221789b

Price is not really a factor, and I would like to feed 3-4 tv's and possibly a tuner card in my computer.

Thanks,
Mike

MrBruce:

Thanks for posting your photo.

It should do better than that. You might be suffering from signal overload to the amp from the very strong CH9 signal; have you tried it without the amplifier?

Your tvfool report again for Norwich:
http://www.tvfool.com/?option=com_wr...8d1782cbaa8787

That report says 4.7 miles for CH9, so it's not as accurate as an exact address report would be.

Yeah, you dont need something that intricate. A simple holl_ands vhf-hi loop should work fine for you without an amp.

http://imageevent.com/holl_ands/loops/vhfloop


Maybe even a large paper clip would, heh.

M_Minnick:

You have many strong signals, but metallic insulation can completly block them. Is the insulation under the roof, or in the attic floor?

Is there any way the signals can get into the attic without having to go through the insulation, like through the end of the attic?

My wife and I live in an apartment that has an aluminum foil vapor barrier on the insulation for the exterior walls that completly blocks TV and cell phone signals. We have to use an outside antenna for OTA, and stay very near a window for the cell phone (or go outside).

First you need to get one set working OK, and then worry about more sets.

300ohm:

MrBruce said earlier that he wants 12 & 13, which is why he is considering the yagi, not only for the extra gain, but for the rejection of CH9 at the rear.

I take it youre not interested in the channels at 135 or 15 degrees, only the channels at 85 degrees above the 33.5 NM. (And FOX at 9 degrees, which could be a problem.)
Is that right, FOX, uhf 28, at 87.8 miles away and you still have a 41.0 NM LOS ?? WOW.

I would get a Winegard 7694P antenna with a HDP 269 preamp and a 4 way splitter. Or instead of the preamp and splitter, maybe a Channel Master 4 outlet distribution amp.
Going from 4 splits to 5 will cause more expense and maybe some problems.
If you decide on a higher power preamp than the HDP 269, then I would get an attenuator with that. Overloading in your case could be a tricky issue.
With a higher gain antenna than the 7694P, you decrease your chances of getting FOX.

If you cant get FOX with that setup, then youll need a separate uhf only antenna and setup in that direction.

Oops, didnt read his previous post.


Youre going to have to use better materials than that to bring in your channels 12 and 13, and to make it last outdoors.
Like 3/8" and 1" tubing from old antennas

On the other forum there are dimensions for a Wade Delhi 10Y12S, a very good single channel cut yagi antenna about 12.15 dBi (10 dBd) with low SWR, which can be rescaled for channel 13. The bandwidth would be enough for also channels 10, 11 and 12. And the way its constructed makes it fairly easy for DIYers.
Channel 13 would have about a 6' 9" boom.
http://www.wade-antenna.com/Wade/cutchannel.pdf

Here is a link to the design. AVS member Hollands has lots of other cool designs there too, info that's worth its weight in gold.

http://imageevent.com/holl_ands/yagi...hoac51.eagle_s

@ 300Ohm and Rabbit37.

This antenna will be used in an attic along with my UHF antenna.

Although I have UHF channels 26 WHPX New London CT and WPXQ which is really transmitting from Hope Valley R.I not Block Island R.I. those do not cause me any performance issues here.

I get DTV channel 29 WUNI from Massachusetts at 60% scale 98% of the time here.

Very strongly here here is the report on that station from TVFool :

Channel: 29 (27.1)
Network: Univision (SI)
Maximum ERP: 270.000 kW
Coordinates: 42.335926 -71.714792


WJAR DTV-51 From Providence R.I. comes in quite well as well as WLNE DTV-49.

As far as Connecticut stations west of the Connecticut river, only WTIC DTV-31 and WEDH DTV-45 show any possible meter readings here.

I am on a hill, my open clear shot areas are north-north east.

Ch 9 When is west of me channel 26 is south and in less than 3 miles is an FM station at 97.7 Mhz and WEDN has an FM transmitter at 89.5 Mhz I do believe.

I am trying to pick up my network feeds from R.I. since the CT stations are hard to get here.

Bruce.

Channels 12 and 13 are going to be very hard to do in an attic.


Update, I posted build dimensions for a 10Y13S (a rescaled 10Y12S) here, post #95 :
http://www.digitalhome.ca/forum/show...=139654&page=7

Its also good down to channel 9. Also posted a corner reflector version of it that is top of the line excellent for the entire vhf-hi range of 174 -216 mhz.

The insulation is under the roof. If the attic may/will be a problem, I can mount an antenna on the eave where the satellite dish is currently installed. The height will most likely be less than 15 feet there, but based on the TVFool report, it looks like I should still be able to pull in a decent amount of channels.

Thank you for the specific recommendations. Amazing that you can buy all the hardware for less than the pice of one month's satellite service. I'll see what kind of reception I can get in the attic, and if that doesn't work, i'll just mount it on the eave.

DING DING DING DING DING DING DING !!!!
If this secret got out, a lot of folks would go OTA.

Yeah, you just need basic equipment in your location. In your case, extreme, large high gain pricey stuff will be detrimental.
And you have the additional benefit of having almost all of your signals come from one basic direction. Thats actually pretty rare.

The preamp only needs to make up for the 7 db splitter loss and the small cable loss of a couple of db. The HDP-269 is the best available against overloading.

The existing J pole for the satellite dish should be fine for the 7694P.

(And FOX at 9 degrees, which could be a problem.)
Is that right, FOX, uhf 28, at 87.8 miles away and you still have a 41.0 NM LOS ?? WOW.

KBFX-CA on RF 58 carries FOX in HD and is up in the mountains east of Bakersfield with the other major networks.

Thats good to know.


Im still stunned at 88 miles and Line of Sight and 41.0 NM, heh. Man, that 219 KW transmitting tower must be waaay, waaay up high.

Looks like Mount Baldy at well over 8000 feet. Yeah, that'll get a bit of signal out!
A tower that high here is Flatland could probably be reliable at over 150.

Quick question,
Does a A/B switch used to switch input between two TV sets loose signal the way a two way splitter would?
One is a nightime TV the other is in my shop. They are almost never used at the same time.
Thanks,
Bernieoc

No, an A/B switch has very little loss. I would guess around .05db or less, compared to 3.5 to 4db with a 2 way splitter.

Several months ago I inserted this Remote Control A/B Switch between my satellite LNB (L-Band) and satellite receiver card (Twinhan 102G). IIRC, it did not change the signal level.

A/B Switch Loss is probably a bit higher...like 0.2 to 0.5 dB....or more...
F-Type connectors are NOT ultra low loss devices....
Plus the loss in the RF Relay itself, such as fol. "typical" TO-5 size devices:
http://www.teledynerelays.com/pdf/el...anical/732.pdf
http://www.teledynerelays.com/pdf/el...nical/s422.pdf

BTW: PIN Diode switches might be "all solid state", but insertion loss is even higher:
http://www.minicircuits.com/pdfs/ZMSW-1111.pdf

AWW ... don't confuse us with FACTS ... HOPE is far more better

TINSTASFL, and All General Statements are False.

I figured I should at least update everyone on my progress.

I built the VHF antenna 300ohm mentioned in his link.

I have success, WPRI DTV 13 and WNAC DTV 12 are booming in at a steady 55--65 %, I am also getting both stations sub channels 13.2 and 12.2.

I used 3 strands of copper wire on each element including the driven element.

Here are some picture of both in my attic.


This is the VHF Antenna

Attachment 212336


This is my UHF

Attachment 212337

VHF is pointing N-NE

UHF is pointing almost due north.

Both are connected to the same amp through a splitter and a single downlead to my HDTV receiver.

I built another 4 bay and tried pointing it to the w-n/w pulled in WTIC DTV 31 as well as antenna TV on 31.2 at roughly 45 % signal.

Also WEDH DTV 45.1 45.2 45.3 and 45.4 at 30%.

Ran into issues with WEDN DTV 9.1 9.2 9.3 9.4 and some what WHPX 26.1 26.2 26.3 and 26.4 over powering my amp a bit, being that Bozrah CT is almost due w-s/w.

I am gonna work on a possible shield to block signals from that direction, only thing it might kill my chances of getting would be WCTX 39.1

Bruce.

Nice use of the jack stand as a base.

A VHF+UHF combiner would likely work much better than a splitter.

Also, instead of the "jack" mounting, you could've just hung that antenna down from the roof trusses.

Glad it's working for you...love the "2 Ton" antenna base.

Tips:
To straighten wire, put one end in a vice, the other end in vice grips. Hit vice grips hard with hammer a few times until straight.
Technique two: put one end of wire in vice, other end in a drill. Turn drill until straight.
Technique three, build a wire straightening jig.

Techinque four, for really tough thick wire. Tie one end of wire to building, the other end to a high torque vehicles frame. Drive a few inches.

I should have included rabbit73 as well as 300ohm's names in my post above, it was the measurements in rabbit73's post that I used.

Also yes that is a 2 ton jack stand I used as well as an old broom handle for the mast.

The other UHF antenna I built is not pictured, so I will post a picture here.

Attachment 212427

This antenna, unlike the other one is portable, the other UHF antenna was constructed on an existing roof support 2x4, so it is basically incapable of being rotated.

The reflector and the elements are a bit messy looking at the moment was trying to make adjustments to get better signal when the wires entering the balun snapped, got a bit pissed off and through the thing down through the attic access panel LOL

Yes that is common household aluminum foil on cardboard for the reflector, hey didn't cost anything to build it, that is up till now, since I need a new balun, store down the street has Trisonic brand matching transformers (model number TS-1121A) for $1.99

I presently can not use the one pictured above because unfortunately the wires entering my balun broke just where it enters the balun housing, so time to buy a new balun.

I have to say this, the FCC made a mess of things with this new digital technology, true the picture quality is better, but the signal capturing is very annoying to say the least.

Stations that once served South-Eastern Connecticut with a viewable picture are almost impossible to get without having a 300 foot tower and high gain antennas.

They should have simply allowed all stations to increase their power output and better channel allocations so there isn't two stations within 150 miles of each other on the same channel.

Bruce.