[R-390] Re: A tale of Two R-390A's

[Patrick Jankowiak]

No one replied to my question, so I'll have to answer it myself, at least 
for the dead R-390A.

13 tubes later, it's working. Never seen so many bad tubes in one radio.

I'm still looking through the data for the mods.

PJ


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Date: Wed, 05 Oct 2005 22:08:42 -0500
From: Patrick Jankowiak <recycler at swbell.net>

Hello ,

I'm new to this list, but have owned an R-390 or two in the past.

I have never had to repair one yet. In the last month, after 10 years
without an R-390, I went from zero to two R-390A's. I would appreciate from
this wize list any comments or suggestions which come to mind after these
acounts:


Stewart-Warner R-390A #1258.
This unit is nice an clean, but does not work. All the tubes light up, and
the 600 ohm speaker emits a low hiss which can be controlled by the RF gain
and the audio gain control. It will not receive any signal. If I unplug the
VFO's Rf cable, the hiss goes away. I also found that the OA2 was bad and
the radio had been run before with 240VDC in the 150V regulated line. I
replaced the tube and cured that, but still no workie. The AGC voltage is
0.8 (or zero if I switch to manual) and the RF gain control properly varies
the cathode bias line. I have not gotten out the test equipment yet, but I
wonder if the power supply malfunction might have cooked something.


R-390 #2: label is missing, no idea how to tell..
This one seems to work reasonably well, except for the BFO, and the VFO
tracking is off a little.
The main thing I am searching for here is what the "record of modification"
label on the back indicates.

The label is USAFSS form 245.

Here are the mods, listed by publication and date.

publication        date
MB +04 +03 +01     03 FEB 69
MB 4-4-2            8 FEB 69
MB 4-4-8            8 JUL 69

Anyone know what mods these might be?


Thanks in advance,
Patrick


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