pre-amps

[xjacob]

I am not sure if this is the right forum, but I hope people won't mind -
Does anyone have any experience with INDOOR UHF antennas and multiple pre-amps?
I have an amplified TERK indoor antenna and I receive HDTV programs for 10 minutes straight, whereupon the signal goes terrible for a minute, and then returns back to normal. This is actually very disruptive. I believe that's because my signal is borderline most of the time, and therefore small interferences can through it off. So I was curious if that little "extra push" I'd get from another pre-amp could do the trick. Has anyone attempted that?
(There is no way for me to get an outdoor antenna, i.e. the best solution most people are bound to suggest).
Thanks!
Jakub

[eakes]

I would not expect a second amp to help. As a matter of fact it is more likely to make matters worse. Simply speaking, a pre-amp does not increase the signal, it amplifies both noise and desired signal. If the desired signal decreases for some reason, the noise continues to be amplified - the likely result is reception will be out longer with the additional amp than without.

To get more useable signal you need a larger antenna or place the existing antenna higher or someplace with as little structure between it and the transmission tower as possible.

[arxaw]

Get rid of the TERK. Most of them are overpriced junk.

[xjacob]

Thanks for the replies.
Eakes, I understand that both the noise and the signal get equally amplified, but what's the point of amplification then? Perhaps I am losing the signal not because of increased noise, but instead because of simply decreased signal. In that case, wouldn't further amplification perhaps increase the signal beyond the threshold required by my tv?
Arxaw, I saw people saying that about TERK antennas on other threads. What indoor antenna would you suggest instead?

[arxaw]

Bottom line, you can't put two amps together to do what you are trying to do. You need a better antenna.

Check the AVSforum local reception info thread for your city here (http://www.avsforum.com/avs-vb/showthread.php?t=453241), for the best antenna to try for the specific channels being used in your area.

[davring]

Or check your situation out here:

http://www.antennaweb.org/aw/welcome.aspx

[Jim5506]

You may be experiencing multi-path (ghosting for analog) that will cause a viable signal to suddenly drop then come back.

This is a common occurrence with indoor and attic antennas near to transmitters

Objects in the house (even people) and/or attic (A/C ducting) often reflect signals around.

A more directional antenna is called for, preferable an outdoor antenna.

If you are in New York City, the signals are often strong and may be reflected off buildings and take multiple pathways even before arriving indoors. Cities with tall buildings are a particular problem with reflections everywhere.

[Scott in FL]

I have an amplified TERK indoor antenna and I receive HDTV programs for 10 minutes straight, whereupon the signal goes terrible for a minute, and then returns back to normal.

Jakub,
Cyclic problems are usually caused by man made interference (10 mins OK, 1 min bad, 10 mins OK, 1 min bad...). Preamps can make the problem worse.

As others have said, two amplifiers in line is not the answer. You would only do this if you needed more gain, and I don't think that's the case.

The reason you use a preamp is to overcome the loss of a long cable run to the tv (or splitters). Putting a low noise amplifier as close to the antenna as possible "sets" the noise figure of your system. Any attenuation before the first stage, whether it be a preamp of your tv's first amplifier stage, will degrade the noise figure. TV's have a pretty good noise figure these days, and indoor antennas don't have a long cable run to the tv. So indoor amplified antennas are usually not necessary or a bad idea.

There are some cases where the level out of an indoor antenna is too low for your tv and amplification will help. But this is usually not the case, and preamps will amplify noise as well. Plus they can overload or be affected by man made interference.