[R-390] That R-390A "BFO Thingy"

[Philip Atchley]

Hello all.
I use VERY sharp audio filters with my R-390a in the CW mode.  While my
receiver is easier tuning than 'most' I've had it can still be a little
difficult sometimes to exactly set the tuning in the center of the Audio
bandpass (my present sharpest filter is 80 Hz but I have a much sharper one
coming).  I sometimes like to tune my receiver where the desired signal
makes it through the filter and the undesired is off the slope of the
filter, sometimes hard to do with strong nearby carriers.

I sometimes use the BFO to "tweek" the audio note a tad but then have to
reset it back as I use the 100Hz IF filter too.  Resettability is good, but
could be better.

Some of the 390A's I've seen have a little BFO vernier for setting the BFO.
Are these good and resettable (seems like they would be).  Can they be
retrofitted to a receiver that doesn't have one or is it a pain?  And
lastly, are they available at reasonable cost?  Can't get one right now but
I'd be interested in hearing what the group has to say.

73 de Phil  KO6BB

Chasing NDB's (Non-Directional Beacons)with .....
LF Modified R-390A,'67 EAC (26 valves).
Homebrew 'Hybrid' Longwave CW receiver.
20 Meter Long Alpha Delta Sloper Antenna.
50dB Gain Low Noise Tunable Preamp.
Heathkit  HD-11 Q-Multiplier.
Merced, Central California.
37.18N  120.29W  CM97sh.