[R-390] FW: Zero adjust on R-390 receiver

[Bob Young]

The front panel is fine and I'm pretty sure the clutch plate is original and I would think it was dried lube except that Chuck Rippel restored it 7 or 8 years ago and I know it was very well lubed when I got it back and it still tunes like butter except for between 300 and 400 Kc going down. I'll have to bite the bullet and pull it out of the case to see what's up, I'm pretty sure it was fine when it came back.

Bob
KB1OKL

> Date: Sat, 16 Mar 2013 14:21:43 -0500
> From: n4buq at knology.net
> To: r-390 at mailman.qth.net
> Subject: Re: [R-390] Zero adjust on R-390 receiver
> 
> That's the way my  Motorola clutch worked (or, more correctly, didn't work).
> 
> A couple of things to check.  Are all the screws in the front panel?  If 
> not, it could be allowing the panel to bow more than it should.  Second, 
> is the clutch plate (the disc that's on the end of the front panel screw 
> thingee) solid and made like it should be?  My Motorola had a rather 
> home-made looking device which I replaced (it still didn't work like it 
> should, though).
> 
> Could be that there is dried lube between the clutch plates.  I don't 
> think they're supposed to be lubricated with any kind of "wet" lube" 
> like oil, etc. (maybe, if anything, a dry lube like talc(?)).  If so, 
> the plates could just be sticking together with grease/oil.
> 
> I seem to recall Roger having some thoughts on this way back when I 
> worked on mine.  Maybe he'll chime in.
> 
> Barry - N4BUQ
> 
> On 3/16/2013 2:07 PM, Bob Young wrote:
> > Is there an adjustment in there? Mine needs about a half a turn to separate the surfaces but it gets difficult to turn once it gets to the point where the surfaces start to separate, these is some drag also and I have to turn it back and forth a few times to get it to stop turning the whole mechanism. I have it adjusted so it can't go in more than half a turn, if I turn it in anymore than that I feel like I'm forcing it and it creates drag (bending something?) when tuning from about 400 to approx 300 but only when tuning down,
> >
> > Bob
> > KB1OKL
> >
> >
> >> Date: Sat, 16 Mar 2013 14:40:24 -0400
> >> From: rbethman at comcast.net
> >> To: r-390 at mailman.qth.net
> >> Subject: Re: [R-390] Zero adjust on R-390 receiver
> >>
> >> You shouldn't need to drop the front panel to adjust it.
> >>
> >> Turn the radio upside down.  You the have access to the assembly.
> >>
> >> Bob - N0DGN
> >>
> >> On 3/16/2013 2:34 PM, Bob Young wrote:
> >>> Mine has never worked correctly either, it takes a lot of effort to separate the clutch and it mating surface, it does work but with effort. It is probably adjusted incorrectly and I haven't had the time to drop the front panel to check it out and see what the problem is.
> >>>
> >>> Bob
> >>> KB1OKL
> >