[R-390] Megacycle Knob slips

[Dan Merz]

Robert,  sounds like the clamp is broken,  in light of the fact that you can
tighten it until the lips close. I had one stay in place and look ok but in
fact it was cracked on the thin part of the clamp.    You should be able to
tip the radio onto its back and see the clamp as you rotate the knob or the
gear.  If broken,  I would guess on the side opposite the tightening screw
and maybe not immediately apparent.    You can replace the clamp by pulling
out the knob and shaft,  replacing the clamp and re-inserting the knob and
clamp.  I don't remember whether the shaft is retained or just slips out the
panel bushing. I think it just slips out once the clamp is loosened.  That
seems consistent with what I read in the manual.  I made a replacement clamp
for the one that was broken on my radio,  not this one but another one on
the other side of the set  I was not impressed with the stoutness of the
original.  I'm looking at a R-390 but I think the R-390a is similar,  except
it's in a cabinet and not so easy to view as the R-390.  Dan. 

-----Original Message-----
From: r-390-bounces at mailman.qth.net [mailto:r-390-bounces at mailman.qth.net]
On Behalf Of Robert Sisco
Sent: Saturday, May 21, 2011 6:09 PM
To: r-390 at mailman.qth.net
Subject: [R-390] Megacycle Knob slips

Friday, I ordered the PD-2 product detector for my R390A. Wouldn't you know
it.
Saturday, the next day,  the Megacycle knob slips/spins. I found the clamp
in front of the Megacycle gear loose, but I tightened it all the way, until
it's lips closed. The Megacyle knob still turns, without moving the
Megacycle gear. I can move the Megacycle gear with my fingers.
All the gear mechanisms work properly.
What do you think needs to be replaced, the horizontal shaft. the Megacycle
gear, or the clamp? What holds the shaft in there? Is there any way to avoid
taking the front panel off? (I have the Bristol wrenches.)

Regards, Robert Sisco K5LYT
361 992 9348
When it rains, it pours.
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