[Milsurplus] "Sick" R390/URR

[John King]

Hello Folks!! I have been tinkering with a Collins
made R390/URR for several days now and am not making
much progress. I have had it on the shelf for about 20
years.  

I have removed all connectors and applied De Oxit . I
have removed all tubes and treated the tube sockets
with De Oxit. I have done some tube swapping with
little result. I have not chanced the 6AJ5 because I
don't have one. I feel like the receiver is deaf
compared to other receivers I have such as KWM 2 and
several Drakes.

It receives after a fashion but has low sensitivity
and amplification within the receiver. It works on the
AM broadcast band with "not very loud" audio. I am
using a 70volt line transformer to 4 ohm Hammarlund
speaker. I copy a few CW signals on 160 meters and CW,
AM, and SSB signals on 80 meters. The shortwave bands
in the 6 mhz and 9 mhz are received fair. I get weak
WWV signals on 5, 10, 15 mhz. I hear nothing above the
12 mhz shortwave bands that I consider receiving a
useful signal.

I don't know the heterodyne scheme so I don't know if
various bands just aren't there because of hetrodyne
problems.

My "gut" feeling is that the RF stage isn't working
correctly as well as "some bands just aren't there"
for some reason or other.

If you have experience with the R390/URR and have
encountered these symptoms, I would greatly appreciate
your suggestions and guidance. Thanks for reading. 73,
John, K5PGW
















  



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