[R-390] fixer-upper/ More

[Scott Bauer]

 I forgot to mention that I did also check the 3TF7. Still
no signals. B+ is 150.

 Scott

----- Original Message ----- 
From: "Scott Bauer" <odyslim at comcast.net>
To: "R390 List" <r-390 at mailman.qth.net>
Sent: Sunday, February 06, 2005 5:51 PM
Subject: [R-390] fixer-upper


> I decided to buy an old fixer upper to try and learn a little
> by repairing it myself. I have a couple of manuals and know
> how to solder and can follow a schematic just OK.
>
> Well, this is a little more of a hacked up, torn apart junker
> than I thought. Guess where I found it :-)
>
> I first discovered somebody had unsoldered a couple of the
> mechanical filters then stopped whatever they were doing for
> some reason. I ohmed them out and then resoldered them, then
> installed the IF into a working R390A. GREAT, the IF works!
> I then installed a grounded power cord and installed a spare
> PTO. This radio did not have one when it arrived. I know that I
> am going to be off here but this is just for educational purposes.
>
> I then checked every tube. All were bad, most missing. Replaced them all
> with good used ones. After checking under all of the other modules
> for smoke leaks, I checked all of the fuses and moved the function
> switch to standby for a few seconds and did not hear the antenna relay.
> Then moved it over to AGC. Silence.... Nothing. Darn! I noticed the
> OA2 was not burning so I shut it off. The fuse was blown. Geeze,
> What have I gotten into. After taking a closer look at the AF module,
> I noticed both caps were 45uf. I borrowed 2 known good caps from
> another radio and looked around a little more. Ahh... A cut wire
> in the harness. I don't know one was able to cut it without damaging
> any others, fixed it. I then noticed the RF gain pot had wires falling 
> from it.
> After re-doing the whole pot, I installed another 1/4 amp fuse and
> tried again. The antenna relay clicked in. Great so far!
> Ahh, the OA2 is lit, and I am getting hiss in the speaker!!
> No signals though, just hiss. No signal on any band. .
> No difference in noise when I pull the antenna off except for one thing.
> At around 140kc I hear a tone with the bfo on. I still have it on AGC
> so I move the switch to calibrate. The tone remains constant whether
> the switch is on AGC, MGC or Calibrate. Is the radio somehow
> stuck in the calibrate mode?
> I am now stuck. Any ideas? I have no test equiptment besides a volt
> meter.
>
> Regards
>
>
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