Yo! Bruce:
Thursday September 19 1996 15:56, Bruce Clark wrote to Bill Cheek:
 JB>> Can anyone recommend a good wide-band preamp. I want to use it on a
 JB>> roof-mounted antenna so it must be designed for outdoor use.
 BC>> There really is no such thing. Seriously.  Best bet is as good of an
 BC>> antenna, installed as high as you can get it.
 JB> For the 50-1000MHz range, what about a VHF-FM-UHF signal amplifier
 JB> especially one where the power supply and amplifier are seperate,
 JB> with the amplifier mounted at the antenna? Of course this would also
 JB> increase bleed over from close, strong signals.
You are talking about a TV preamp, though.  Big difference.  Television 
signals need to be about 1000-uV to the receiver for good video.  But a 
100-uV signal will barely disrupt the "snow".  Yet, 100-uV is a whopping 
strong signal for a scanner.
TV preamps are designed for an input of 100-500 uV and to output 1000-5000 
V.
This degrades the performance of most scanners most of the time, though there 
may be unique situations where it will work some of the time to a passable 
degree.
Scanners usually get a clean, noise-free signal with 1-uV input.  Barely 
detectable signals are in the .25-uV range.  TV preamps aren't designed for 
such weak signals.  But there are few, if any, preamps that are, and still 
cover the wide range of 25-1300 MHz.
There is MUCH more to preamp design than mere gain.  Gain is easy.  Keeping 
noise and spurious down; linearity up; and flat gain response across the band 
is the trick.  An impossible dream.......
Bill Cheek | Internet: bcheek@cts.com | Compu$erve: 74107,1176
Windows 95 Juggernaut Team | Microsoft MVP
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