[R-390] Megacycle Change Stuck R-390

[Barry]

If you turn the radio over, those stops are quite visible (there is a set of them on both the KC and MC shafts). 

BTW, is this an R-390 or R-390A? It shouldn't make much difference for this but would be good to know. 

Barry - N4BUQ 

> Thank you both! Is adjusting the 10-turn stop something that would require
> removal of the crystal oscillator or RF modules?
> -Alex

> On Thu, May 1, 2025 at 10:53 AM Barry < [ mailto:n4buq at knology.net |
> n4buq at knology.net ] > wrote:

>> Hi Alex,

>> There are a series of "wings" on the shaft that determine where the stop point
>> should be at both ends of rotation (I think those limit the shaft to just a tad
>> over 10 turns end-to-end). If all of those are completely stopped against each
>> other, then that would cause this and the solution would be to loosen the clamp
>> and adjust those stopping points. If the stop point is reached but those
>> "wings" can still be rotated slightly with your fingers (be aware there is
>> power near that point so best to unplug the radio to try this), then something
>> else might be a problem but I think the 10-turn stop is the problem.

>> Good luck,
>> Barry - N4BUQ

>> > Hi All,

>> > I have an R-390 that has recently been restored. It is performing very
>> > well, with one exception...

>> > Last night I attempted to tune up through all of the megahertz bands all
>> > the way to 32 MgHz for the first time. I got to '30' on the megacycle
>> > change knob, and the knob wouldn't rotate any further to 31. I could get
>> > it to go slightly towards 31, but it was obviously stuck and I didn't want
>> > to attempt to jam it.

>> > What would potentially be the cause for this being stuck?

>> > Thanks,
>> > -Alex
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