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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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