Suggestions please to improve attic installation.
 

Hello,
Here's a link to my TV fool report

http://www.tvfool.com/?option=com_wr...8230c75660bf63

I'm trying to get an in-attic installation working, and so far it's not great. I did have some success with a smaller antenna on a mast, so I was hoping that a larger one would be sufficient in the attic. We have shingles on plywood construction, single storey.

I'm using a Winegard 7697, and a LN-100 pre-amp located with the antenna in the attic. The antenna is aimed pretty much at 170 magnetic, +- < 10 degrees. The coax run after the amp is about 35 feet to a Hauppage tuner card. I'm getting only a couple of decent channels. removing or adding the amp doesn't change much.

Could I have a bad tuner card?

regards
Doug

Try it on something else, like a TV set, if you can.

Have you installed the Hauppauge signal monitor to help you with SNR and errors?
http://www.hauppauge.com/site/suppor...l_monitor.html

I have found that their software is not user friendly.

Hello,
Unfortunately, I don't have a TV with tuner for comparison. My output device is a 65" monitor.
I have installed the signal strength and SNR meter.

Is there anything obviously silly with my configuration?

doug

How about a leftover digital to analog coverter box?

In using mine this weekend I discovered my friends NEW Samsung TV has a crappy tuner. My Zenith converter easily picked up channels the Samsung had trouble with.

Yes
Not that I can tell

Can you try a temporary setup outside with the 7697? If it does well outside, it means that your tuner isn't very sensitive or the attic attenuation of signals is more than average.

Have you tried different locations in the attic?

Do you have any aluminum foil radiant heat barrier, like TechShield, in the attic?

What channels are you getting, by real channel number, and which ones do you want?

Thanks for the replies.

I'm reluctant to try a temporary external installation of the 7697. The thing had to be assembled in-situ and I don't actually have much wiggle-room even with the truss construction of our attic. It would be a real pain to take it apart and get it out. Fortunately, the attic faces in the right direction. I do not believe we have any foil insulation. I'd probably rather buy a cheap antenna, or make one, for an outside experiment.

I don't have any other tuners to use for testing. I am, however, coming to believe the card may just be dead. The signal is pegged on SNR of 0, and there are no bad connections, etc, that I can find (and I'm not a newbie with electronics). I'm thinking that the next step might be to get another tuner card such as the Hauppage 1213 or Hauppage 1196.

Doug

It's also quite possibly you have a defective antenna balun or a cabling fault.

Well, I've had some time to do some more investigation on this.

First I removed the amp from the equation. No difference, still no signal. I swapped in a different TV tuner card. Still no signal.

I started to look for cabling opens/shorts/damage. With the cable hooked to the antenna, I measured a few ohms between center and shield from my TV room. This was a bit surprising to me. Disconnected the antenna, and I get an open circuit. The cable seems ok.

The antenna is a Winegard 7698 (I think I got it wrong above).

Took the balun/cartridge thingy off the antenna, pulled out its PCB, and it looks ok. The (few) components seem to ohm out as they should.

With the balun off then antenna, I now get a DC open circuit on the balun so I turn my attention to the antenna.

The stiff rod/wire thingys going from the balun to the elements ohm out as open circuit on the front half, but the rear half seem to be shorted together... This seems unexpected to me. The rear elements on each side are connected to their own strip of metal that run above and below the boom. I would have expected them to be isolated from each other.

I pulled off the plastic end cap from the boom, and it looks like there are rivets going all the way through the assembly which look like they are shorting everything together.

I know that DC isn't the same as RF, but this seemed surprising to me. Could this antenna have an assembly error? Seems unlikely.

Thoughts?
doug

Well, I've partially answered my own question. After a bit of searching I've found on line commentary second hand from the manufacturer saying that these phasing lines do, indeed, measure a DC short.

Also, what's interesting is that mine seems to be assembled partially incorrectly. The VHF elements are supposed to alternate between top and bottom of the boom on each side. Instead half of mine don't alternate, which is different from the drawing in the manual.

I wonder if this might be a minor tuning change, accomplished by adjusting these distances? In any case it seems unlikely to account for my non-existent reception.

I'll call the manufacturer about this problem, but I fear my next steps might be to dismantle the antenna to get it out of the attic and experiment with mounting it outside.

doug

I had that same exact question, w/ the same exact antenna, a few years back.
A lady at Winegard told me, that the UHF section phasing lines DO in fact measure short between them.

The problem I had though, was that the rivet that connects them together through the boom, was rubbing on parts of the hole that hadn't been properly deburred, after being punched.

I drilled it out, replaced it w/ a bolt and put a couple layers of shrink wrap around the bolt.

Stereocraig: Were you measuring a short between the phasing lines and the boom too? How did you track down which rivet was causing the problem, theres a bunch of them?

doug

I'm sure mine was just one that slipped through, but you never know.

It is the vertical one all the way in the rear, the connects the flat phasing strips together.

Just pop the end cap to clip one of the meter leads to the boom and the other to one of the phasing lines. This will free up your hands to flex the assembly to check for intermittents.

Well, finally got to the bottom of it.

I replaced the UHF/VHF combiner-balun thingy and it now seems to be working fine. This must have been bad out of the box.

Winegard sent me a replacement, even though I had waited until the antenna was out of the 90 day warranty period to look into it. That was nice of them, but it shouldn't have been dead in the first place...

Doug

Thanks for the report, Doug. Good detective work.

ADTech was right.
handaspencer also had a problem with the CB-8269:

no uhf signal
http://forum.tvfool.com/showthread.php?t=15616

Winegard has a video:

https://www.youtube.com/watch?v=TlQke5QYbng

I'm not really sure what could fail on something passive like that, except for cold solders, or loose clips.

You will loose 10 dB relative to an outside antenna when "looking through" a roof with shingles. I determined this with extensive testing. In laymen's terms, the signal voltage is 25 percent of what it would be outside. If you could get the antenna nearer to a wooden wall facing the station, the signal will probably be better. If it is at all possible to try the same or similar antenna outside at the same height as the antenna in the attic to see if the signal is better than the signal in the attic. At least you will know if there is a problem in the attic, even if you cannot install the antenna outside, you will know if there is actually a problem with the attic equipment.