CM 4228 and PReamp

[GADGET71]

Put up my new Channel Master 4228 last night and low and behold I get NOTHING.   I read somewhere that a preamp could screw up this thing.  I guess I wanted to have my cake and eat it too.  Anyone think that this could be the problem or have experience with this antenna and a preamp?  That was the only thing I changed in my setup and I was watching most Madison stations which were fairly stable before, just trying to bring up signal strenght.
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Toyota M engine

[mhz40]

Signal strength = signal quality is a common misconception.

Without a signal survey using at a minimum of a signal level meter and maybe a spectrum analyzer, you have no way of quantifying the quality or levels of what you are getting off of your antenna.

Without this info...
- You could be overdriving the amp, creating distortion; or are now simply overdriving the tuner input.
or
- You could simply have too low of a level to start out, producing a poor signal-to-noise ratio.  Adding an amp in this situation does noting to change your original signal-to-noise ratio.
or
- The channel you are attempting to tune to is flanked on both sides by much stronger signals in the RF spectrum.  In this case, you would need filters to eliminate or attenuate the higher levels, or use a tuner with very good selectivity and/or AGC.
or
- The channel you are attempting to tune is being affected by multi-path distortion.  Multipath is where the desired signal arrives from a path directly in line with the antenna and weaker copy of the same signal (bouncing off a reflective surface somewhere) arrives milliseconds later.  An amp in this case also is ineffective.

IMO, in metro areas one should use low-gain highly directive antenna to avoid multipath distortion.  In the immediate suburbs, a single low-to-medium gain antenna in the attic or on the roof is enough.  In rural areas, a single hi-gain roof antenna, rotor and maybe a 10db (max) preamp directly connected to the antenna as the best option.
With that, you get what you get.  Getting any better performance gets you into channel filters, pads, antenna arrays and creative combining & splitting; all ending up costing many multiples of your initial antenna investment.
But that's just my opinion, I could be wrong.*

MHz40
tm: Dennis Miller

[GADGET71]

Mhz40-

I removed the amp last night(cold and windy as it was).  I am now getting a signal on all the channels I did before with the other antenna and preamp.  However signal strength indicator(valuable or not) is half of what it was on most of the channels I receive.  And to verify that the signal strength is indicative of signal quality.  I can tell you that I get more pixelation(consistently on some channels PBS Milwaukee, and Fox Madison) than I did before. I am now wondering if preamp placement had any factor in why I did not receive a signal.  I am too far away to overdrive this antenna IMO.

Gadget71
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Ferrari F2007 history

[borghe]

one thing you can try doing is buying a variable attenuator from radio shack.. stick it on the antenna line and play with it to see if your line is coming in to hot.. When Kemmer TV installed my antenna a few weeks back, he had to pad the line by quite a bit because it was coming in so hot.. granted without the amp you are probably not coming in that hot from Fort A, but you can try adding the amp and then padding the signal down to get the perfect signal level. or use a variable level amp and start at low amplification and slowly move up until you start running to hot again (seeing signal level go up then back down).

just my limited knowledge 2¢

[mhz40]

Originally posted by GADGET71
Mhz40-

I removed the amp last night(cold and windy as it was).  I am now getting a signal on all the channels I did before with the other antenna and preamp.  However signal strength indicator(valuable or not) is half of what it was on most of the channels I receive.  And to verify that the signal strength is indicative of signal quality.  I can tell you that I get more pixelation(consistently on some channels PBS Milwaukee, and Fox Madison) than I did before. I am now wondering if preamp placement had any factor in why I did not receive a signal.  I am too far away to overdrive this antenna IMO.

Gadget71

To clarify...
When I referred to strength, it was in dBmV, not what is reported on receivers.  I imagine in some cases, 'signal strength' may be determined by bit-error-rates, rather than 'strength'.
In an overdrive situation, high RF levels on unrelated channels can cause harmonics of that signal to fall in the area of the desired long-distance signal, wiping it out.  For example, a very strong channel from Madison could cause a distortion to fall upon the frequencies you are trying to receive from Milwaukee.
My point is that given the variable ambient RF levels in different areas, it is very difficult to say what will or will not work for any given problem...which sadly means amplifiers are not always the solution (especially when dealing with digital signals).
Not only does preamp placement factor into performance, but also the amps performance spec's.... noise figure, gain, bandwidth, return loss etc...

Best of luck on stabilizing your reception!

MHz40