R390A, the Best Receiver of the Tube Era

Purchased this at Dayton in 2013 for a very low cost of $150 due to a rainy day.  Was able to repair the receiver in one day. 

To make this work:

• To match the 600 ohm audio output to a modern 4 ohm speaker I used a 12V transformer.

• To prevent the GFCI outlet in my basement from tripping every time i plugged in the radio i had to bypass the OEM power entry module, using 0.01uF safety bypass caps across the line.

• I developed a scheme to transmit SSB with this radio by splitting the VFO output (which is fairly high power), feeding half of it to a VFO frequency converter.  The output of this converter feeds directly to a 5 MHz VFO input on a 20m SSB radio that I developed (Home Brew 20M SSB Transciever).  So now the R390A tunes my 20m SSB transmitter allowing me to transmit back to those stations I tune in on the R390A.  An article on this will be published soon in QST hints and kinks.

Publications

G. L. Charvat, “Transceiving with an R-390A,” QST Magazine “Hints and Kinks” Column, March 2014.

Mike Szczys, "Hacking The R-390A Military Shortwave Radio Receiver To Transmit As Well," Hackaday, June 6, 2013.