Paul, Excellent photos! The only reason these two pieces of metal have began touching each other is that the invar plunger or the silver tuning sleeve have become bent.
This could be due to some rough handling of the units....probably when you were absent? Personally, I would drill a series of small holes around this top plate to produce a larger hole,cleaning up with a small round file, giving about 1/8" clearance between the plunger and the sleeve. I agree that any kind of heating would ruin the plating.. If the plunger is now free of the tuning knob then perhaps you could slip some heatshrink tubing into the gap and fix it with a heatgun.. Ian G8PWE ----- Original Message ----- From: Paul N1BUG To: [email protected] Sent: Wednesday, October 24, 2007 7:36 PM Subject: Re: [Repeater-Builder] DB4062 woes... Progress! Scott, or anyone... I got one of the knobs off. Removing them is not such a big deal as I thought. It turns out the brass insert in the knobs is threaded. They are screwed onto the rods AND soldered. Sheesh! The hole in the top metal end plate of the plunger is indeed just a little bigger than the rod... not much more than .010". Photo: http://www.n1bug.com/cavity2.jpg If there originally was an insulated insert I suspect it was a special item for this application (or at least not hardware store variety). But if there wasn't one then I'm left with the original mystery of why it didn't have this noise problem until fairly recently. So what now? I think I could solder the rod to the top of the plunger without dislodging the whole end plate. Is that a bad idea? Better ideas? Alternatively, I think I could just squeeze some .005" PTFE sheet in that gap, but there isn't enough clearance to allow overlapping the ends at all. Also it might not stay put or hold up well with time and vibration. I still can see no other possible source of the noise/desense in this cavity. Paul N1BUG
