Guess I'm just lucky. I have used and use ARR preamps in all sorts of
situations with cavities and without, with many random pieces of feedline
and cabling, on bands from 29 to 470 mhz. and have never had an oscillation
problem. They have been very stable in my experience. (Of course, I never
hooked the output directly back into the input.)
Al, K9SI
Re: Preamp and attenuator
Posted by: "Bob Dengler" [EMAIL PROTECTED] no6b
Date: Thu Mar 22, 2007 11:04 am ((PDT))
At 3/22/2007 09:34 AM, you wrote:
>Bob,
>
>How would we know if the preamp is nonlinear or not?
Only way to know for sure is to connect a spectrum analyzer to the output
of the preamp & look for anything greater than, say -15 dBm. The
advertised 1 dB gain compression point (P1dB) for these preamps is +12 dBm,
though other brands I've measured clocked in a bit lower than this (+7 dBm)
so unless you measure it I'd assume the worst.
If it's oscillating you'll see a very strong continuous signal, possibly
near the 100 mW level so start the spectrum analyzer on a high reference
level with some internal attenuation.
Bob NO6B
