[R-390] Main Dial Tuning Friction

[hamfish at comcast.net]

Ed,

Two things come to mind. The KC shaft passes through a bushing and the hole in the panel has a larger diameter than the bushing. Could be misalignment between the two. Have you checked how freely the PTO shaft turns??? The descant bag in my Motorola PTO had broken, can't tell you how that added grit to the works. 

There is lots of free play of the PTO bracket and the already mentioned bushing, getting everything into proper alignment takes just a few minutes.

Craig, 

-----Original Message-----
From: r-390-bounces at mailman.qth.net <r-390-bounces at mailman.qth.net> On Behalf Of Ed G
Sent: Monday, February 25, 2019 3:34 PM
To: r-390 at mailman.qth.net
Subject: [R-390] Main Dial Tuning Friction

HI Folks,
     Been following this list for many years, and appreciate the wisdom here. I have a Capehart R-390A in great shape. It works well and has no problems except that the main tuning dial (the “Kilocycle Change” dial) is somewhat tight…not excessively so, but a bit hard to turn.  I have cleaned the tuning mechanisms, and used Teflon grease in a few spots and synthetic oil sparingly on the gears.  Because the receiver is working so well I am hesitant to disassemble anything too far.
     I’ve read lots of R-390 material over the years, but don’t recall seeing much about a recommended way to approach gear train friction so that one ends up with the smooth, almost effortless tuning “feel” I have experienced on other R-390As (other than a total disassembly/rebuild).
     Perhaps there are certain problem areas in the mechanism that tend increase tuning resistance over time? Something I could address without a complete tuning module disassembly? Any recommendations would be appreciated.  
--Ed—


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