At 7/31/2004 06:27 PM, you wrote:
>Funny how spoiled we are over modern radio
>equipment. ".5uV is a bit deaf" just makes
>me smile.
Well, considering the natural noise floor at 70 cm is near kTB (-132 dBm in
a 16 kHz bandwidth, or 0.056 �V) & 0.5 �V is 20 dB above that, I consider
it a bit deaf even considering the amount of signal above the noise floor
required to achieve 20 dB quieting. Fortunately, a GaAsFET preamp with
pass cavity ahead of it helps remedy that little problem.
2 meters is a little different since most G.E./Motorola radios have a
little better sensitivity, & the noise floor of 2 meters is much higher. I
once measured the 2 meter noise floor here to be ~3000 K, or -122 dBm in a
16 kHz bandwidth. That's wny I almost never recommend a preamp ahead of a
G.E. VHF receiver, but always for a UHF.
Bob NO6B
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