[R-390] R-390 Oscillation Spurs Update

[Patrick Nelson]

Hello All,

Thank you guys for all the help with the R-390.  I fixed the oscillation spurs.  It turned out to be the

solid state voltage regulator for the BFO and VFO filaments.  I noticed that the BFO was intermittently

not working at first, and then I started having problems with the VFO.  I looked at output of the voltage

regulator on my scope and it was very ugly ... 120Hz oscillation between +5 volts and +30 volts.  After

rebuilding the regulator using an LM317 and new capacitors, the BFO and VFO started working perfectly

and the oscillation spurs disappeared as well.

 

I also fixed the bad resistor on the cathode of the 1st RF amplifier, but it required removal of the crystal

oscillator drive shaft.  Turned out not to be as bad as I thought.  It requires removal of two gears in the

gear train assembly (thankfully didn't have to take it totally apart), but it slides right out.  After replacing

the resistor, the receiver really came to life.  It's starting to look like this radio has some potential.

Thanks again for all the suggestions!

-Patrick
 		 	   		  
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