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Re: Another interesting pre-amp story



Hi Vince,
   I don't have a Landwehr but I would bet it is RF switch capable, so they are tapping
off some of the RF, feeding it to a diode to get a signal to drive the automatic switching.
   Sending RF to a diode can create hash all over the place if it is not filtered well,you may
remember some people using a oscillator and a diode to make 2.4ghz signal sources!
  Just a thought of what the problem might be...

73
Kevin WA6FWF
Amsat-UK #6505

----- Original Message ----- 
From: "Vince Fiscus, KB7ADL" <vlfiscus@mcn.net>
To: <amsat-bb@amsat.org>
Sent: Friday, March 24, 2006 1:44 PM
Subject: [amsat-bb] Another interesting pre-amp story


>I used to have terrible mode J desense.  One day I decided to see if I could solve the problem.   I had the problem whether the 
>70cm pre-amp was in-line or removed.  I then removed the 2 meter pre-amp and the problem went away.  My pre-amps are Landwehrs. 
>Funny, it was the 2 meter one that was leaking the RF and noise.  I don't use a pre-amp on two meters now, but if we get a Mode B 
>HEO, I may need you figure out what to do.  Maybe a different two meter pre-amp will solve the problem.  I was surprised the two 
>meter was what was causing the problems.
>
> KB7ADL
> ----
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