[R-390] Cleaning Gearbox Assembly

[ToddRoberts2001 at aol.com]

I found the Kilocycle Change control disc and split gears I needed for the 
play in the tuning mechanism, but before I put it in, is there any way of 
cleaning the gunk off the whole gear assembly in a 390 without taking it all 
apart?

Bob
KB1OKL
 
 
Hi Bob,
When you say "without taking it all apart" do you mean the gearbox assembly 
itself or taking it out of the radio?  If you can take the whole gearbox 
assembly out of the radio in one piece I have had good luck soaking the whole thing 
in a tub of kerosene for a few days, swishing around the gears and cams with a 
paintbrush from time to time and turning the bandswitch a few times. After 
soaking a few days the bottom of the tub will be covered with dirt and crud and 
the whole gear assembly will look like new. 
 
One thing you do have to watch out for with the kerosene is to remove the RF 
transformers first. The kerosene seems to get into the rubber washers in the 
small ceramic trimmer caps and swells up the rubber - I found that out the hard 
way. Keep anything with ceramic trimmers out of kerosene.
 
After soaking a few days let the unit air-dry for a few days. All this should 
be done outdoors if possible covered or in a ventilated workshop or garage. I 
have sped up the drying process by placing the unit directly in front of a 
dehumidifier and let it blow warm, dry air on the unit. When it is dry all the 
bearings or sleeves will be dry also. I have had good luck spraying everything 
with a light coat of penetrating oil then manually lightly re-oiling all the 
gears, bearings and sliding parts. Spraying the RF switch parts with some 
de-oxit is a good idea also before reassembly into the radio.
 
73 Todd WD4NGG



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