[R-390] Update on R390A, open question regarding scope and options fir lubrication

[Jim Whartenby]

JohnI haven't seen a reply to your question so here it goes.
The few R-390As that I have had to remove the heavy application of grease, I have not bothered to disassemble everything.  I have found that several cleaning cycles using WD-40 as a solvent, your favorite detergent in water, a through water rinse, in this order, and a final alcohol rinse as a water release agent will remove the most stubborn dirt and grease residue.  Cycle through different frequencies to expose dirty areas of the gears.  An acid brush on a dowel will get deep into the nooks and crannies during the cleaning process. 
My favorite lube is Tuffoil engine oil treatment.  I have been using the same 8 oz bottle for over 20 years. It doesn't take much to lube the R-390.  I only lube the pivot points, not the gear teeth which would attract dust and dirt.  I use a long wood skewer from the wife's stash to get deep into the gearworks.  Just a drop or less is all that is needed.  Over lubrication just leads to more problems down the line.  
Don't forget to loosen and recenter the two bushings on the front panel where the MC and KC shafts protrude.  This makes a big difference by removing the binding caused by misalignment.Regards,JimLogic: Method used to arrive at the wrong conclusion, with confidence.  Murphy 

    On Wednesday, June 19, 2024 at 11:43:06 AM CDT, jkharvie via R-390 <r-390 at mailman.qth.net> wrote:   

 I am slowly making progress with my EAC R390A receiver. I have removed all gears after preparation.  I have inspected, cleaned, and prepared each assembly  element  down to removing the cracked in debris found on a number of the gear teeth.  I process each gear in sequence, one at a time, noting and resolving any issues. Cam shaft bearings have been cleaned, both 10-turn limits have been cleaned, one was missing a brass washer between two steel stops, made a replacement.  I have cleaned the top surface and bottom of the RF sub chassis. The RF permeability cores were removed and carefully labeled and stored to the side.  Used about 500 cotton tip applicator swabs. Using reprints of manuals as guides.The RF cans have been unscrewed, indexed, cleaned, contacts cleaned, components measured,.As I am moving ahead in the cleaning phase I have encountered a number of areas that should be lubricated (that are not on the list) and some that could be lubricated, that traditionally were not.  
These frame out my question to the group.Among the open areas is some thinking that these receivers might benefit from a consideration of modern materials science and theories regarding measures to improve electrical switch performance.
 Key areas of reducing contact forces, reducing contact resistance, eliminating  oxidation, life-cycle etc.I got started by reviewing articles that appeared in April 1980 on the topic of using specific formulations of lubrication on electrical switches and potentiometers. 
>From 2001 article written by an engineer with NYE lubricants Inc. (Now foreign owned)
https://www.machinedesign.com/mechanical-motion-systems/article/21816000/the-right-lubricant-brings-out-the-best-in-electrical-switches

I am aware of the extent this receiver depends upon rotary multi-section electrical switches.  Many variable capacitor contacts as well.   I am not aware of any specific update to maintenance procedures to incorporate contemporary electrical lubricants into the receiver baseline. 
I am considering a product such as https://www.nyelubricants.com/nyogel-760g
What say the group?   Good for a subset, good for all?  Why or why not?
I would be more than willing to try this stuff out and give some feedback.
Thoughts and thanks

John (N3JKE)

You





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