Amp didn't work

[sanjar]

I just installed my ota antenna (big Radio Shack UHF & VHF) with a rotator and a Channelmaster 7777 amp. To my surprize, I couldn't get any HD channels exept the NBC which is about 20 miles. After many tries I removed the amp and was able to receive all the HD channels even those from about 90 miles away. I have put a call to Channelmaster but haven't heard from them yet. Does anyone know why this is happeningh?

[kevinw]

You did not need an amp. It was overloading the signal keeping you from locking a channel.

[sanjar]

Thanks Kevin,

So when do you use an amp. My CBS channel from about 90 miles away is about 30-35% in strength. Shouldn't the amp help with this and increase the signal strenght rather than decrease it?

[Ratman]

Amps may or may not work. It depends on a lot of variables.

Keep in mind that amps are designed to compensate for long cable runs, not necessarily to boost a weak signal. While you may boost the signal, you also boost 'noise'.

[kevinw]

An amp should help pull the long distance station but it may be to powerfull for the close ones. It does seem odd that all the stations between 20 miles and 90 miles are all in the same line. My guess is the one that is far away is off at a different angle then the others.

I am suprised you even have a picture at 30%. Most people I know are not succesfull under 70% but then again different locations different problems.

[sanjar]

Thanks Guys,

Tonight is the real test for getting the Monday Night Football from ABC in HD which is about 90 miles away. I'll be playing with this for a few more days and will report back then.

Until then, Go Raiders.

[sanjar]

Well, Monday night I got home and was hoping to get Monday Night Football on ABC which I barely got it on Sunday after I disconnected my amp (see my earlier post). To my surprise I could not get anything. Since I had invited some freinds to watch the game in HD and show off my system I had to do something.

I decided to hook up the amp again but instead of hooking it up to the mast and run my cable (about 100 feet) from it to the TV I hooked it up at the TV after the long run of cable. It worked and I got about 50-65% reception which was enough to keep it going. All other channels still work even the close ones. I thought this might be of ineterest to some of you. If someone can explain it I would appreciate to know why it works in this set up. Thanks.

[kevinw]

I would guess something like tropo-conversion. Weather and conditions were just right the day you tried it. Hook the amp up properly. Remember it should have an adjustable gain. 90 miles is a REALLY long way. I have rarely heard of anyone getting adequate reception from that far away.
http://www.dxing.com/tvfmdx.htm

[sanjar]

Thanks for the info Kevin.

I'' keep trying different setup until I find the right one. Will keep you posted.