[R-390] Zero Adjust - not quite

[Jordan Arndt]

Jerry...It sounds like there is a lot of 'gunk' built up in the Zero Adj 
mechanism...

It should release quite easily and allow for smooth zeroing...I've had to 
spray a few of them in 390As with penetrating fluid made for electronic gear 
and soak awhile.

Lastly, since I saw some msgs in that regard...

I'm rebuilding the 390A I bought from Jan right now, but I ran out of 26Z5W 
tubes. I went through my diode stash and found a tape string of 1N5408 
diodes and installed them with bypass caps across each of them. The thick 
leads plug right into the tube sockets very very tightly with zero chance of 
falling out.

One last thing for sure!:

Although I have spare 3TF7 tubes, I alwaysreplace them with 12BH7A tubes 
with Kynar Wire jumpers across the appropriate pins. I've never been able to 
measure any difference in stability between them.

I gotta get back to this PTO work...!

73...Jordan VE6ZT

----- Original Message ----- 
From: <k1jos at att.net>
To: "'Jacques Fortin'" <jacques.f at videotron.ca>; <r-390 at mailman.qth.net>
Sent: Saturday, November 09, 2024 1:34 PM
Subject: Re: [R-390] Zero Adjust - not quite


Hi Jacques,

Apologies for not describing it correctly.  When my Zero adjust is turned
fully CW, tightly, the veeder dial still moves as I turn the Kilocycle knob.
I cannot adjust for the 1.5kc incorrect readout.

Jerry

-----Original Message-----
From: Jacques Fortin <jacques.f at videotron.ca>
Sent: Saturday, November 9, 2024 3:09 PM
To: k1jos at att.net; r-390 at mailman.qth.net
Subject: RE: [R-390] Zero Adjust - not quite

Hello Jerry,

I do not believe that you can swap the R-390A mechanism into a R-390, as
they are different.
This is normal that the PTO still change frequency when you move the KHz
tuning with the Zero Adj. fully in: they are linked at all times.
This is the remaining of the gears that stops to move and the counter as
well.
I just checked with my own "non-A".

73, Jacques, VE2JFE in Montreal

-----Message d'origine-----
De : r-390-bounces at mailman.qth.net <r-390-bounces at mailman.qth.net> De la
part de k1jos at att.net Envoyé : 9 novembre 2024 14:25 À :
r-390 at mailman.qth.net Objet : [R-390] Zero Adjust - not quite

My R-390 electronically now seems to be workings quite well.  The dial
however is off 1.5kc and I cannot screw down the Zero adjust quite enough to
make the VFO adjustment.  Attached is a picture.  I can see the brass gear
move and the steel plate behind it move a fraction of an inch and the dial
mechanism is very tight to finger movement but not enough and the VFO
changes frequency despite the Zero adjust fully screwed CW.  Also, the
spring that I assume should provide some resistance when not screwed down
seems to have lost its tension completely.



I compared to the Zero adjust from a R-390A, also shown in picture.  Can I
swap the R-390A into the R-390?



Jerry


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