[R-390] R390 progress

[Dan Merz]

Hi,  I listened to the R390 tonight for the first time after repairing -
more to go.
So far:
Put 12BW4's in place of 26z5's that were missing and rewired the sockets
Added two 75 ohm-10 watt resistors below the rectifier sockets in place of
missing 47 ohm resistors - a trial to start with,  seems ok
Jumpered pins 4/5 to 2/7 and used 12BH7 in place of missing 3tf7
Straightened a badly bent twinax female antenna socket
Wired a replacement power connector obtained from Fair
Added a missing knob, also from Fair
Cleaned gear train in place with mystery oil


The radio worked once I realized the previous owner had used enameled magnet
wire on some added wiring on the rectifier sockets - my connection to it
looked good but only connected after I did some scraping to get rid of that
enamel !!

It appears to be reasonably aligned and  reads about 10 khz high on both
ends of the 1000 khz range.  So far only one dead band found up to 20 Mhz
which was as high as I checked.   7 to 8 Mhz is dead.  I haven't cleaned any
switches so hopefully that's the problem but only one other band showed any
sign of intermittent connection.  The line meter appears dead.  The carrier
level meter appears ok.

I still need a male twinax connector for the antenna socket - one listener
indicated he had one but I'm having trouble getting more info from him to
pay him so he can send it.  One other response offered an IBM server cable
with two connectors that were said to fit,  so that's my backup source at
this time.  My local electronics junk collector couldn't help me on this
one.

Roy Morgan indicated he would provide a drawing/description of the fan he
installed on his R390 to cool the 6082 tubes.

I was relieved that the radio worked and pleased that it's working so well
at this point.  The seller said it played weakly - at this point it is
better than that in my opinion and I haven't messed with the tuned circuits
at all or changed any of the tubes.  I suspect that the haywired resistors
that were stuck in the 3tf7 socket were part of the problem before.  I
removed the i.f. chassis to jumper the ballast tube pins and was pleased at
how nice it looked underneath there.  

Now I have to study the manual a bit to see how the alignment goes on the
390 vs. the 390a - more similar than different I suspect,  Dan.