[R-390] Zero Adjust - not quite

[Barry]

I'm impressed with the clutch in the R-390/URR.  It releases so much better than the ones that I had in my R-390A/URRs.  I had one that was just plain old stubborn and, try as I might, I could never get it to release as good as I thought it should.

While I was working on the gear train in my R-390/URR a couple of months ago, I ended up disassembling the clutch and cleaning it up just to make sure.  I really can't tell much, if any, difference before and after but it does work well.  Fortunately, I think it's a rather not-too-deep dive into the front part of the gear train to get that out and service it.

Good luck with it,
Barry - N4BUQ

> 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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