[Heathkit] LATE SB-102 W/TRANS VFO & SB640 FREQ SHIFT QUERY

[Van K7VS]

HAVE A SB-102 WITH TRANSISTOR LMO AND SB-640 EXTERNAL LMO UNIT WITH TUBE LMO 
UNIT THAT I AM NOT ABLE TO ADJUST EXTERNAL SB-640 FREQUENCY SHIFT PROPERLY. 
I CANNOT GET THE EXTERNAL LMO UNIT TO SHIFT PROPERLY FROM USB TO LSB.  CAN 
GET TO WITHIN A COUPLE OF KHZ OF ZERO BEAT.  AM WONDERING IF THERE WAS A 
"MOD" TO COUPLE THESE TWO UNITS UP AS BIAS MAY BE INCORRECT TO SHIFT THE 
CRYSTAL DIODE PROPERLY TO ALLOW UPPER TO LOWER SIDEBAND ON THE EXTERNAL VFO 
UNIT?  ANY THOUGHTS FROM ANYBODY?  THANKS MUCH.  VAN, K7VS MEDFORD, OREGON

PS.  STILL LOOKING FOR A DECENT FRONT PANEL FOR MY SB-301.  ANYONE HAVE A 
SPARE THEY WELL SELL.