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RE: g-5500 RF noise



Thank you for sharing that.  I just deployed a g-5500

-----Original Message-----
From: owner-AMSAT-BB@AMSAT.Org [mailto:owner-AMSAT-BB@AMSAT.Org]On
Behalf Of kevin schuchmann
Sent: Saturday, November 22, 2003 1:04 AM
To: amsat-bb
Subject: [amsat-bb] g-5500 RF noise


Hello All,
   I have been fighting a noise problem that went from 40 meters up past
144MHz, the noise was 20 over s9 and around 60kHz wide on 40 meters and
would
slowly drift in frequency,sliding down and then only to seemingly appear
from
the top again, and it would come and go...

     Tonight I was fed up and went on a witch hunt for it and I found the
source, my Yaesu  g-5500 rotor box and not just one of them but both... each
one creating a similar sounding noise but on  a different frequency, so I
feel that this is not an isolated case and someone else will probably see
this problem..

       Turns out the 6 volt regulator that supplies the rotor pots is
breaking
into oscillation, the length of the rotor cables changes the frequency where
it seems to start and the temp causes it to drift...

 The normal rule of thumb for 3 terminal regulators any distance from the
power supply caps is at least a .1uf cap  on the input and output... for
whatever reason Yaesu has only  put a .01 on the output side and it seems it
isn't cutting it...

 The fix was easy unplug the rotor box from 110, remove the cover and remove
the 4 meter screw which frees up the board, I added a small disc ceramic
.1uf
cap to both the input and output of the Q2 7806 regulator on the bottom side
of the board, leaving the original .01 on the topside.

  And the noise is gone....  ahhhhhhhh.....


73
Kevin WA6FWF


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