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Mulsanne 11-Sep-2013 5:51 PM

Do I have a bad pre-amp? Trying to trouble shoot
I moved into the Boston market a little over a year ago, c. 30 miles from the broadcast towers in Needham, Mass. Here is my TVFool report:

I put up a Winegard 7695 VHF/UHF antenna with an AP8700 pre-amp back then. The antenna is mounted c. 20' off the ground, on the gable end of my house, slightly above the roof line. It is pointed roughly 211. I have only one TV connected to it over roughly 50' of RG6.

Reception over the past year has wavered from good to poor. No sooner had I mounted the antenna, then there was a fire on the on the main broadcast tower that degraded reception for a period of a few months while it was repaired. Unfortunately, this being New England, we have had lots of inclement weather to deal with as well. I also have to point the antenna right at the crowns of some large ash trees that I can't get around. One channel in particular, WCVB, an ABC affiliate, has always given me trouble.

Over the past year, I learned more about antennas and OTA reception in my area. Since Boston is an all UHF town and almost all of the towers are located in the same place; I decided to replace my old antenna for a directional UHF one. So I put up a Winegard 9022. I don't care about the VHF stations, they are all either duplicates or in Spanish.

Reception improved on almost all of the stations since I installed it, although WCVB still gives me trouble. I have been trying to troubleshoot and improve the reception for it. I noticed something strange while doing this. All of the the stations I receive, I receive at the same signal strength of 21 on my receiver. (I do not know if this is in db or not, it isn't labeled on the receiver.) The strength never varies at all. It is always the same 21 on all frequencies. This is much lower than the signal I used to receive using the old 7695. Also, with the old antenna, the signal strength would fluctuate, both from station to station, but also on the same station. It would go up and down at least a little bit.

I disconnected the pre-amp and directly connected the antenna to the TV, although it still goes through the power splitter for the pre-amp, I disconnected the power and terminated the connection the port. I don't get WCVB, and maybe a couple of other low-power stations that broadcast from other locations, BUT the signal strength remains 21, all the time for every station I receive.

Continuing to troubleshoot, I put the old 7695 back up and I still get the same 21 on all the stations, even the VHF frequencies the 9022 doesn't receive. I have also tried switching out the cable from the antenna downlead to the mast-mounted pre-amp. And of course, I re-scanned, re-scanned, and re-scanned.

The only thing I can think of, is that the pre-amp is not working properly any more. Should I replace it? And if so, with what. We would really like to watch Modern Family when it starts up again.


jeff92k7 11-Sep-2013 7:54 PM

What "receiver" are you using to get the signal strength numbers? Is that your TV or another device?

Mulsanne 11-Sep-2013 9:34 PM

I'm using a Tivo Premiere. I tried leaving the Tivo out and going straight into the receiver in the TV with more or less similar results.

jeff92k7 12-Sep-2013 1:02 PM

Ha ha. I wondered if you had a TiVo Premiere when you said the signal strength showed the same for all channels.

There is a glitch in the current TiVo software version that causes the signal strength meter to freeze. If you restart the TiVo, the signal meter will work again and you can measure two or three channels, but then it will freeze again. When it freezes, all channels will then show the same value. It does not matter what that value is.

Unfortunately, this makes it very difficult to troubleshoot antenna issues. To further compound the issue, the TiVo Premiere tuner is not a great tuner and is susceptible to multi-path interference. Other tuners can often reject multi-path interference, so using another tuner to set an antenna may or may not make any difference to the TiVo performance.

What I had to do was use my TV signal meter to set my antenna, and hope that the TiVo would be better too. I'm still waiting for TiVo to fix the software issue so I can actually use the TiVo's meter to check my antenna placement/aiming. One thing to keep in mind is that the TiVo signal meter means absolutely nothing. The numbers don't seem to correspond to any power levels or anything. You just have to get the number higher. I have noticed that anything below about 60 on the TiVo meter will result in frequent signal breakups.

All that said, now we turn to your antenna. Personally, I don't think you have a big enough antenna. Excepting four channels at the top of your report, all of your channels are 1edge or worse. Meaning there is no direct path for the signal to travel from the broadcast tower to your antenna. Either the curvature of the earth is blocking it or other terrain or buildings are in the way. This drastically reduces the signal at your location, so while your antenna may be rated by the manufacturer for 30-40 miles line of sight, it's nowhere near big enough to pull in the weak, obstructed signals.

Second, your preamp is probably fine. Just keep in mind that a preamp isn't going to improve the performance of an antenna. If the antenna isn't receiving a signal, no amount of amplification is going to fix it. Preamps are meant to overcome later signal losses from long cable runs and splitters. They will keep your signal from degrading after the antenna, but can do nothing for the signal that the antenna receives.

Third, your channels come from different directions (looking at major networks). You'll likely need an antenna rotator to be able to turn the antenna, or multiple antennas.... Maybe use the current one to pick up the "green" stations on your report and get a better performing, UHF-only, directional antenna to aim towards the yellow stations. If you don't care about the green stations, since you mentioned WCVB which is an ABC affiliate just like WMUR, then you might be fine with a UHF only antenna aimed towards the yellow stations.

Lastly, it "may" also help to aim the antenna slightly up. This may help reduce multipath reflections from the ground that the TiVo can't overcome, as well as possibly strengthen the incoming signal.

Hopefully others will chime in here as well with suggestions.

Mulsanne 12-Sep-2013 2:19 PM

Thanks! You were correct. Restarting the Tivo fixed the signal meter being stuck at 21. I will try your other suggestions too.

teleview 13-Sep-2013 9:16 PM

Tivo's are known to have problems with reception of brodcast tv transmissions that are less then perfect.

--> All Broadcast Tv Transmission and Reception is Less Then Perfect.<--


Digital tuners can develop - Digital Glitches - that are not cleared out with simple channel scans.

Do Double Rescan.

teleview 16-Sep-2013 10:36 PM

Tv antenna rotation with a Tv antenna rotator Is Not Channel Surfing Friendly , must wait for antenna to rotate and Will Be Domestic Issues concerning the direction the antenna is aimed.

For reception of the most Tv stations and channels , recommend aim the antenna at about 211 degree magnetic compass direction.

Here is how to aim antennas ,

Use a Old School magnetic compass to aim antenna.

Your location has receivable Tv stations channels to the , North , North West , West , South west , South .

Install the antenna above the roof in such a manner that reception is not impeded and blocked by the roof and building in the directions of reception.

As always , trees and tree leaves , plants and plant leaves , have a Negative effect on brodcast Tv reception.


Absorbing reception.

Reducing reception.

Blocking reception.

Recommend install the antenna at a location that has the least amount to no amount of obstructions of any type or kind in the directions of reception including you own roof and building.

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