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Re: Another interesting pre-amp story

At 05:57 PM 3/24/06 -0500,Luc Leblanc VE2DWE <lucleblanc6@videotron.ca> wrote:
>On 24 Mar 2006 at 14:44, Vince Fiscus, KB7ADL wrote:
> > 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
> > ----
>Where was installed your preamps at the antenna or in the shack? I am 
>struggling with preamps
>actually and i don't want to makes steps outside the trail...
>Thank's Vince for your inputs
>"It not democratic to try to impose democracy"
>Luc Leblanc VE2DWE

My pre-amps are mast mounted.  Now I just have the 70cm landwehr in line at 
the mast and the 2 meter one is sitting on the shelf.   It really didn't 
matter how much power was going through 2 meter pre-amp when it was 
in-line, 5, 10, 30, watts, I still had desense on 70cm.  I did some meteor 
scatter and put 200 watts on the 2 meter side without the 2 meter pre-amp 
in and had no 70cm desense.  So it is something strange happening with the 
2 meter one in line.

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