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Discussion Starter · #1 ·
I had been wanting to do this for a while. I'm glad I did.


Yesterday I bought three 3db and two 6db attenuators at RadioShack.com. I started inserting them at my STB and examining the effect on reception and "signal strength".


Turns out my unamplified medium size regular looking $40 antenna delivers 32 times the signal strength my STB requires. I have a nice amplifier with FM trap and variable gain for sale now, the one I installed then removed six weeks ago.


It is counterintuitive but true. I inserted 5 3db attenuators inline (2^5=32). All channels worked comparably to before. Some channels worked as well with 1/64th of the signal.


I have no way of knowing how accurate the rating on the attenuators is or how flat the response, but it was clear that each additional 3db would cut into the signal strength on the display as one would expect. I find I get the same reliability of reception with the signal strength meter barely showing anything. In effect, my meter (Samsung SIR-T150) appears to display how much more signal I have than I need!


This is consistent, in a way, with the experience I had with the amplifier. The signal strength indication went up, but the reliability of reception did not improve.


I conclude three things from this experiment:


1) My problem (at 8 miles out) has absolutely nothing to do with signal strength.


2) This is a worthwhile experiment for anyone thinking of installing an amplifier or a bigger antenna to try first.


3) This technique could be useful when optimizing antenna orientations. Put in just enough to make it fail, then orient to get it to work.



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-CB-


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With an outdoor antenna only 8 miles from high-power transmitters you might be in a situation where the signals could overload your tuner's frontend circuitry, in which case attenuators might help. The last thing you'd want is a preamp.


In my situation I use a preamp for distant signals and a variable attenuator that RS sells with no preamp for close-in signals that overload the tuners.


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HiDefDave


STOP HDCP!


[This message has been edited by Dave McRoy (edited 05-18-2001).]
 

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I had similar experience for the antenuator. For purely convenient reason, I clipped on a Terk TV 42 antenna to my oval dish. I got solid Fox and PBS but CBS and NBC became unstable. I used to get OTA channels through my old yagi antenna. I used to get excellent CBS, no NBC, excellent FOX and bad PBS. I called Terk and they suggested me to get a 10db in line amplifier to solve the problem. I tried all kinds of amplifiers from Radio shack and nothing works at all. Before I gave up, I saw the $2.99 6db attenuator. I told myself, what the hack, even if it doesn't work, I won't even bother returning it. The result, I am getting CBS, Fox and all PBS in the 90s and NBC solid in the mid 50s. What can I say.
 

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Discussion Starter · #4 ·
I got onto this by a combination of chance and advice.


When previously posting about my reception someone suggested that at 8 miles and with my antenna I should consider whether my signal was too strong rather than too weak. Later while changing things I saw the signal strength go to near zero but with solid lock anyhow. I had been so focused on getting the signal strength to go higher, I couldn't believe my eyes! The combination planted the seed in my head that I experimented with yesterday.


I had come to believe that my problems are totally signal quality related, not signal strength related, and this very much confirms that.


I have noticed that my STB either A)shows nothing on the signal meter and no picture or B)shows a number of bars (out of maybe 20 possible) with the number wavering by at most one and picture lock. Rather than waver more than one, I fall in to mode A) above. I think this is why two bars is as good as 10, because all I need is the "headroom" to lose one.


Now, about those signal quality problems...only happens when there's wind...



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-CB-


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Quote:
Originally posted by cbgenrich:
1) My problem (at 8 miles out) has absolutely nothing to do with signal strength.

2) This is a worthwhile experiment for anyone thinking of installing an amplifier or a bigger antenna to try first.
A bigger antenna may help even if signal strength is not your problem. The reason it might help is that larger antennas tend to be more directional such that they may suffer from less multipath. I think that is a problem I am having. I am 25 miles from the transmitters but my "signal meter" on my model 6000 bounces around from the 70s to 90s depending on the station. I think my problem is multi-path, not signal strength.
 
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