Thanks, Jacques, for that clarification. Mention of an Oldham coupler threw me just a bit and I wasn't seeing the heart of the problem. Fortunately, I've never had to deal with a broken clamp there.
A two-piece clamp would work nicely there because, if I'm thinking correctly, once it's in place and tightened, it isn't necessary to loosen and adjust it like some of the other clamps might need. Thanks, Barry - N4BUQ On Mon, Jun 15, 2026 at 9:30 PM Jacques Fortin via R-390 < [email protected]> wrote: > Hi Paul, > That circular "ring" is a part of the travel stop mechanism and is actually > pinned to the shaft. > Reference to your sent picture, if you turn the MC shaft 180 deg. did you > see a hole on the other side ? > If yes, you have to use a 3/32" drift pin thru that hole to push the lock > pin out. > Be careful, as you will have to re-install it (and all the travel stop > disks) when you will re-assemble it. > And this is not the only difficulty: there is also a circlip locking the > shaft on the other side, plus a lot of shims. > > IMHO, you will have to remove the whole RF deck from the set to be able to > work properly on that problem. > Another way is a disassembly + reassembly of the front plate. > > Last idea: if you can remove the remnants of the broken clamp, you can > machine a 2-part clamp that use 2 screws to jam the gear to the shaft. > Advantage: no lock pin to remove (will be a PITA, guess how I know) and no > front mechanism plate removal and reassembly. > > Some other people on this forum can have different opinions, if so, go on ! > > See the attached pictures (from my "spare" R-390A RF deck). > > 73, Jacques, VE2JFE in Montreal > > -----Message d'origine----- > De : [email protected] <[email protected]> De la > part de PAUL ROCHE via R-390 Envoyé : 15 juin 2026 20:24 À : > [email protected] Objet : [R-390] Removing Megacycle Change shaft > > Just got my first R-390A and the Megacycle Change shaft just spins and > spins; the Oldham coupling clamp is broken. But the problem is to remove > the > shaft I need to remove the circular "ring" attached to it. I am looking for > a setscrew, but this doesn't look like any setscrew I have ever seen! I > might have to drill it out unless someone has a better idea; what is this > thing and how to i get this circular ring loose so I can pull the shaft to > add a new clamp? > > Paul > ______________________________________________________________ > R-390 mailing list > Home: http://mailman.qth.net/mailman/listinfo/r-390 > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________ R-390 mailing list Home: http://mailman.qth.net/mailman/listinfo/r-390 Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
