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Old April 13th 06, 10:49 PM posted to rec.radio.amateur.homebrew
 
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Default Lowering the noise figure in a preamp

Im guessing at the noise figure, im running a low level 1mv fr0m a
cushman service monitor to the preamp input. Im using a uniden 898t
scanner as a receiver because it has a digital S meter. When i turn on
the preamp jumps up 3-4 bars
but the modulation tone stays the same volume level. By this im
guessing the noise level has increased, the preamp had a ceramic
filter with the 50ohm input going directly into it and its output thur
cap to the 1st amp, the seller on ebay said just remove the filter and
move the input to the filters output trace, thats what i done but
results are poor even thou this is a commercial preamp pulled from
analog cell site. It looks to be a very well made preamp so it should
work if i figure out the
input match?