[R-390] Z-503 repair

[Paul Staupe]

Ross,

Thanks...In my original question, I refrained from using the "non-A"
designation for my R-390/URR, but to eliminate the confusion, it's a non-A.


Z503 is also the AGC can in the R-390A model, so using the non-A description
might have helped clarify my situation.  Looks like Z-503 is a weak link in
both designs.

A list member is kindly helping me out, but in the interim, I'm thinking
about trying to rewind this one.  Does the varnish respond to acetone or MEK
or what's the best way of removing it?  Also, what's the procedure to zap
the coil, presuming that hitting it with HV won't do further damage..

Thanks again to all who've helped out.

Best regards,

Paul W0AD

From: bavarianradio at comcast.net
To: Tisha Hayes <tisha.hayes at gmail.com>
Date: Thu, 10 Mar 2011 15:41:33 +0000 (UTC)
Subject: Re: [R-390] R-390/URR Z-503
Hi Tisha, The problem with Z-503 is that the windings  are encased in a
powdered iron cacoon and then dipped in varnish. I expect that the coil will
need to be soaked in acetone (or solvent of your choice)  to get it apart.
 My Z-503 is currently behaving itself but has been intermittent. I "zapped"
it with a high voltage arc and got it working, but I'm skeptical as to it's
reliability. My intentions were to find a good replacement and then go
experimenting with rewinding this one. As you suggested, this can't be brain
surgery.  BTW this coil does not exist in the "A" radios. (I already looked
at my spare "A" IF deck... rats!) 73's Ross W1EKG