[R-390] kilocycle/megacycle movement

Mon, 30 Dec 2002 11:48:17 -0600

While this indeed could be a problem, can the symptoms described be caused by backlash?  If tuning up from 3.8 to 4.0 and the radio becomes "deader" towards 4.0, the backlash would all be in the same direction.  I'm not sure how this could be the problem here.

Barry - N4BUQ

> 
> Don't forget the possibility of the split gears having
> burrs on them and being stuck together so that they
> can't take up the backlash.  They should be taken
> apart and honed flat.  Especially that little one on
> the right hand side that has the spring inside the two
> halves.  Mine was stuck TIGHTLY together.
> 
> Nolan would have raised this point.
> 
> Joe
> 
> 
> 
> 
> --- Barry Hauser <[email protected]> wrote:
> > Hi Dan & Gang:
> > 
> > In addition to a worn, bent or loose detent
> > spring/plate, check carefully
> > for a loose or broken gear clamp.  A broken clamp,
> > or one that isn't
> > positioned right, may snug up with the bristol
> > wrench, giving the false
> > impression that it's tight.
> > 
> > The situation sounds familiar.  I got one unit in
> > here a few months ago and
> > noticed the MC knob creeping.  One broken and one
> > loose clamp.  I don't
> > recall which ones.  You have to look carefully
> > behind the panel as you
> > rotate the KC knob with the MC set in various
> > positions, including the 4 MC
> > position.  The mechanics of the gearworks is such
> > that the backlash varies
> > over its travel, largely due to the spring tension
> > on the slug racks..
> > 
> > As suggested, gunked up gears could do this, but
> > they'd have to be pretty
> > bad.  Check all clamps using the close eyeball
> > inspection method.  And,
> > whatever you do, don't blink!
> > 
> > Barry
> > 
> > 
> > 
> > 
> > 
> > Dan wrote:
> > > Hi,  I haven't used my  390a much over the last 2
> > or 3 months and I was
> > > listening on 80 meters tonight and found a problem
> > tuning up near 4
> > > Mhz.  It seemed dead there and I could tune in
> > stations down near 3.9
> > > somewhat better (I started listening on another
> > set for comparison to be
> > > sure the band wasn't dead).  After awhile I
> > noticed that the megacycle
> > > knob seemed to move off its "lock" position and
> > was moving as I tuned
> > > the kilocycle knob.  It did this sometimes and
> > would get off the band
> > > position but not always.  Is this most likely a
> > lubrication problem?  I
> > > really never was able to pick up a known signal at
> > around 3.99 Mhz and
> > > I  tried rocking the megacycle knob to improve
> > things,  or to find if
> > > something else was "hanging up".  I haven't lubed
> > the set since about 2
> > > years ago when I did a pretty thorough job in this
> > regard and everything
> > > seemed very free.  I'll pull it open tomorrow and
> > take a look but was
> > > curious if there was an obvious known component
> > that causes this kind of
> > > symptom. It seemed ok on other bands but I didn't
> > spend a lot of time
> > > checking.   thanks,  Dan.
> > >
> > >
> > > _______________________________________________
> > > R-390 mailing list
> > > [email protected]
> > > http://mailman.qth.net/mailman/listinfo/r-390
> > 
> > 
> > _______________________________________________
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> > http://mailman.qth.net/mailman/listinfo/r-390
> 
> 
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