[R-390] Main Dial Tuning Friction

[Roger Ruszkowski]

Francesco Ledda, The R390 and it variant's are open case gear boxes. We just can not do an oil change with additives and spin the gear train clean smooth and debured. Stop and look at the mechanical leverage being applied in the cam racks.Nice clean slides and rollers. Free hanging cores. Minimum rack spring tension all come back to your wrist. Clean machines are friendlier pets. Compressed air. Vacuum shop vac with a short small diameter snout. A process called dry cleaning is where the front panel gears are hung off the edge of a table. spray in solventsand air blow dry. Hair dryer on Hi Fan No heat works well.  By all means check all your front panel bushings. Five each. Drop the VFO back and slide the washer out of the coupler. A lot less friction could be a VFO shaft lube problem.Same stiff operation and you can start looking for the friction points.Octave to Octave in the cam racks will each feel different. Roger Ruszkowski  -----Original Message-----
From: Francesco Ledda <frledda at att.net>
To: 'Ed G' <ed.n3cw at gmail.com>; r-390 <r-390 at mailman.qth.net>
Sent: Mon, Feb 25, 2019 7:29 pm
Subject: Re: [R-390] Main Dial Tuning Friction

It may be a misalignment of be the brass guide on the front panel behind the main tuning knob.  This is somewhat movable and needs to be properly aligned. Its purpose is to avoid bending the tuning shafts.

Best, Francesco K5URG

-----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 5:34 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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