[R-390] R390A BFO /100kc calibrator not working

[Larry H]

Hi Chuck,  Congrats on the R-390A.  Have you replaced the filter killer cap (c553), yet?  If not, give it your highest priority.  Since your am reception is ok, your bfo filament is also ok.  It's in series with the pto filament.  If your poking around the bfo tube, be very careful not to short the filament to ground - bye bye the 3tf7.  While working on one of these, I like to put in a 12by7 temporarily.  They work great and the 2 oscilatores are stable from 110 vac to 120 vac with it.  A 12bh7 is also good.  You need the very simple mod, though.  To check the bfo output I like to scope pin 6/7 of v506, the detector,  I also connect my freq meter there to check for stability.  Since I assume you've swapped tubes in the bfo and cal, try cleaning the contacts with deoxit and exercise the pin contacts a little.  You can check that the bfo is getting b+ on a tube extender or 'bfo on/off' switch.  Sometimes the cal signal seems undetectable due to rf deck miss alignment or malfunction.  Make sure a 10 uv signal gets through, first.  Good luck.
Regards, Larry------------------------------------------------------------------------------------------------------------------------
-----Original Message-----
From: R-390 [mailto:r-390-bounces at mailman.qth.net] On Behalf Of Chuck Claus
Sent: Tuesday, November 24, 2015 6:17 AM
To: r-390 at mailman.qth.net
Subject: [R-390] R390A BFO /100kc calibrator not working

recently purchased Motorola R390A at local ham fest replaced most of tubes
AM mode receive fine but BFO and 100kc calibration does not work

any help greatly appreciated

Thanks

Chuck
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