[R-390] TM11-5820 294-35/2

[ka9egw at britewerkz.com]

Found it:

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URGENT
Department of the Army Modification Work Order
MWO 11-5820-294-35/2 Modification of the Radio Receivers R-390/URR and
R-390A/URR to Eliminate Spurious Radiation
5 October 1959

Purpose of modification is to eliminate continious radiation at 340 mc as a
result of parasitic ascillations, by connecting the suppressor grid to the
cathode of the local audio output tube V603.

R-390/URR:
Unsolder and remove the jumper lead connected between pin 2 and fround of
tube
socket XV603.
Connect and solder a suitable length of No. 22 AWG solid wire between pins 2
and
7 of tube socket XV603.

R-390A/URR:
Unsolder and remove the jumper lead connected between pins 2 and 4 of tube
socket XV603.
Connect and solder a suitable length of No. 22 AWG solid wire between pins 2
and
7 of tube socket XV603.
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73, Brian KA9EGW