R: [amsat-bb] Mode J Recieve Desense Problems

["Sergio" <ik2mmb@xxxxxxxxxxxxxxx>]

And with wider bandwidth too...

----- Original Message -----
From: John Santillo <u1004467@warwick.net>
To: John Magliacane <magliaco@email.njin.net>; Richard W L Limebear
<Richard@g3rwl.demon.co.uk>
Cc: <amsat-bb@AMSAT.Org>
Sent: Tuesday, November 16, 1999 12:29 AM
Subject: Re: [amsat-bb] Mode J Recieve Desense Problems


> Watch out, a quarter wavelength open stub tuner at 145MHz is a 3/4
> wavelength open stub tuner at 435MHz (3rd harmonic of 145 is 435) this
means
> that the open stub tuner will perform the same function at both 145 and
435.
> It will short out 145 as well as 435.  Ouch.
>
> 73
>
> John
> N2HMM
>
>
> -----Original Message-----
> From: John Magliacane <magliaco@email.njin.net>
> To: Richard W L Limebear <Richard@g3rwl.demon.co.uk>
> Cc: amsat-bb@AMSAT.Org <amsat-bb@AMSAT.Org>
> Date: Monday, November 15, 1999 5:49 PM
> Subject: Re: [amsat-bb] Mode J Recieve Desense Problems
>
>
>  >On Mon, 15 Nov 1999, Richard W L Limebear wrote:
>  >
>  >> Trouble is that I can't remember whether you want a quarter-wave or a
> half-
>  >> wave ... and whether its open-circuit or closed. But I'm sure someone
> else
>  >> on the -bb will know this and post.
>  >
>  >If the open end is, in fact *OPEN*, then use a quarter-wave.  If it's
>  >shorted, then use a half-wave.  You can "snip" the quarter-wave stub
>  >a little at a time to find the "sweet spot", or insert a pin through
>  >a half-wave stub to do likewise.  Either stub will represent a very low
>  >Z at the opposite end, and attenuate the undesired signal as a result.
>  >
>  >
>  >73, de John, KD2BD
>  >
>  >--
>  >-=-=-=-=-=-=-=-=-=-=-=-=- John A. Magliacane,
> KD2BD -=-=-=-=-=-=-=-=-=-=-=-=-
>  >Internet  : kd2bd@amsat.org          |  Voice : +1.732.224.2948
>  >Satellite : AO-16, KO-25             |  Morse : -.-  -..
..---  -...  -..
>  >Packet    : KD2BD @ N2SMV.NJ.USA.NA  |  WWW   :
> http://www.njin.net/~magliaco/
>  >Video     : 426.250 MHz/439.250 MHz  |  FAX   : +1.732.224.2060
>  >-=-=-=-=-=-=-=-=-=-=-=- Linux Doesn't Cost.  It
> Pays. -=-=-=-=-=-=-=-=-=-=-=-
>  >
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