[R-390] R-390 (Non-A) RF Gears Cleaning

[Jim Whartenby]

Norm
Very nice photography!  It does look like the R-390/URR receiver was gently used but it did clean up well.  What I have collected has seen some prolonged use with some half moons around the frequency knobs.  Did you get your R-389 from W5OR?
Regards,
Jim
Logic: Method used to arrive at the wrong conclusion, with confidence.  Murphy 

    On Saturday, February 14, 2026 at 02:31:27 PM CST, Norman Drechsel <norm at wa3key.com> wrote:   

 Hello to all on the group.  I've been a long time member and don't recall having ever posted, but couldn't help but chime in on R390 gear cleaning.  I have restored about two dozen R389, R390, R390A and R392 receivers over the years (and still have one dozen).  Gear cleaning was always a challenge and (unless something was broken) couldn't bring myself to taking all those split gears and shafts apart and then putting it back together.  It's a formidable task and I salute all who have been brave enough to meet the challenge.

Here are links to photos of an R390 RF deck I restored about ten years ago:

http://www.wa3key.com/r390/r390-11.jpg
http://www.wa3key.com/r390/r390-12.jpg
http://www.wa3key.com/r390/r390-13.jpg
http://www.wa3key.com/r390/r390-13.jpg
http://www.wa3key.com/r390/r390-15.jpg
http://www.wa3key.com/r390/r390-16.jpg

Here's how I do it.  The obvious first task is to drop the front panel and pull the RF deck.  After tying the connectors back and removing the Veeder Root counter, I attach four Nylon plates to the front panel like feet so it can be stood face down in a large ultrasonic cleaner.  I fill the tank with a mixture of water and Simple Green so the level covers all the gears but keeps the chassis and electrical components dry.  I then use an emersion heater to warm the cleaning solution and run the ultrasonic for about 15 minutes.  If all the gunk didn't come off I run for another 10-15 minutes.

Then the tank is drained refilled to the same level with WD-40 (yes that's a lot of WD-40, but it stays clean and is reusable) and run the ultrasonic for another 10-15 minutes.  This step displaces every trace of water, even from between the split gears and shaft sleeves.

Following the WD-40 cycle I reclaim the WD-40 (the water stays at the bottom so is easy to separate) and then spray the gear assembly (outdoors) thoroughly with compressed air which only leaves a film behind.  A thin application of synthetic motor oil with a brush is the only lubrication I use.

This process works great for the R390, R390A and R-392, but the R389 is a whole different "animal" and can only be done the hard way.

If you'd like to see the rest of the R390 photos, replace the digits following the "-" in the URL with "01" thru "42."  Or if you want to view the photos from all 3 restorations, go to

http://www.wa3key.com/r390/
http://www.wa3key.com/r390a/
http://www.wa3key.com/r389/

and you'll find a list where you can click on one photo URL at a time and use your browser's back button to return to the list.  I decided to take document these restorations because all three were original and unmodified.

73 de Norm - WA3KEY
norm at wa3key.com
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