[R-390] Z202-1

[Craig]

Dennis,

I've had in the past the same issues on several of the cans in the RF
section. Each time the best peaking was with the slug almost all the way
down. At times some of the gain would return by retweeking the slug, only to
be gone a few days later.

Cure: Replace the silver mica caps in that RF can; (all the silver mica caps
in that can)

Craig,

-----Original Message-----
From: R-390 [mailto:r-390-bounces at mailman.qth.net] On Behalf Of Dennis Wade
Sent: Saturday, April 11, 2015 10:51 AM
To: R-390 HF Receiver List
Subject: [R-390] Z202-1

Good morning all,

         Well I've pretty much completed (I thought) the work on my Motorola
390A.  Went through a complete alignment, set up the IF deck, rolled back
the gain some and took some final sensitivity checks.  I was very pleased to
see that spot checking all the bands yielded somewhere between 0.4 and 0.6
uv for 10 db S+N/N taken as described by Chuck, and this was without going
through any real optimizing of tubes and such.  This included the 1-2 mhz
band.

       ( When I adjusted the Z202-1 RF coil, I noticed there was quite a bit
of change from the last alignment settings.  All the other RF coils were
very close to their previous settings).

        Then one night I went to listen to a local AM station on 1530 and
its signal was way down...less than 20 on the carrier meter when it was
usually near 60+.  On a hunch I checked Z202-1.  Sure enough it wanted to
peak back where it was before the alignment, with the slug almost all the
way down.  Peaking it down that far yields better sensitivity, but not as
good as before.

         Anyone have a spare Z202-1 they want to let me try?  Or, how
re-buildable are they?

                Thoughts?

            Dennis



--
"If they trust you, it is an extraordinary privilege, and you simply can't
abuse it."
      - A. Alan Post  1914-2011.  California Legislative Analyst 1949-1977.

-------------------------
Dennis L. Wade
KG6ZI
Carmichael, CA
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