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Re: 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. -=-=-=-=-=-=-=-=-=-=-=-
 >
 >----
 >Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
 >To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
 >


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