John,
Thanks for your reply. Sorry I haven’t responded, I didn’t get a notification.
Yes, this was exactly the problem! Looks like one of the rings about halfway down the stack was either sticking or was slightly out of position, so it just kept sticking.
It’s in a really awkward position to service, and so I couldn’t see what it was at first. I thought about taking the entire VFO assembly out but didn’t want to deal with the (quite tight) desoldering, so I bought a broken Frog from eBay, stripped that down, and worked out fairly quickly what was going on. Good job too, the tuning spindle has nine ball bearings in it, and readjusting these rings guarantees they’ll all fall out.
In the end, and because it was a fiddly job, I replaced the entire set of rings with those from the donor, which were in great shape.
I’ve tried to highlight the problematic component in the attached picture, in case anyone else comes up against this issue. FYI, to reassemble the mechanism without un-mounting the VFO, you need the radio panel-down on a desk so the spindle is vertical and the ball bearings are held by gravity. Not easy.
Now I just need to get it on a known-good antenna so I can see if it’s aligned correctly or if I have another problem (difficult to fully fine-tune even strong signals like Shannon VOLMET). I have a 7700 winging its way to me just in case!
Thanks again, and if anyone wants a non-functional late-model FRG-7 with a detachable VFO, give me a shout!
