[R-390] Lubrication

[Cecil Acuff]

Well....I don't think "Silky Smooth" has ever been used to describe the 
tuning on any R-390 series radio.  Noisy, clanky, mechanical feeling and 
sounding is pretty accurate.  All that said it should be free to turn 
without excessive effort.  First I would make sure the dial lock mechanism 
is not dragging on the disk behind the front panel.  Beyond that the gear 
train may be in need of cleaning and lubricating.

I would not recommend spraying it down while in the radio for sure.  If you 
are going to tackle cleaning it properly it needs to be removed from the 
radio.  Not for the faint of heart but it is doable.  If you should decide 
to just lubricate it a bit in obvious places I have used a syringe type oil 
delivery system and Mobil 1 synthetic lubricants.  Mostly their motor oil. 
Some use the heavier differential lubes, your choice.  I do recommend the 
synthetics though because they won't gum up over time.

For a few years while I was pulling a travel trailer with my Chevy Tahoe I 
was running Mobil 1 oil in the engine and when I changed the oil I would 
collect the drainings from the new oil bottles overnight and I put that into 
a small peanut butter jar.  I draw from that with the syringe.  Half a cup 
of the stuff will last forever it seems.

Another thing that makes these things hard to drive is over tensioning of 
the split gears.  If the springs are stretched out they may be over 
tightened causing stiffness in the tuning.  It usually only requires about a 
two tooth offset max to keep the backlash out of the gear train.  Sometimes 
only a one tooth offset works well and leaves the tuning as light as it's 
going to get but keeps things tight enough and keeps the springs in place.

Also make sure all the rollers that ride the brass cams are free to 
turn...that will create drag on things as well....

Just some thoughts...hope it helps a bit!

Cecil Acuff
WB5VCE
Gulfport MS


----- Original Message ----- 
From: "Rick Brashear" <rickbras at airmail.net>
To: <R-390 at mailman.qth.net>
Sent: Friday, August 18, 2006 10:22 AM
Subject: [R-390] Lubrication


> Hi all,
>
> I finally own my first R-390 (non A) and need advice about a few things. 
> The "Kilocycle Change" seems to me (remember, this is the first one I have 
> ever turned) to be a little stiff or maybe better described as hesitant. 
> I reset the bushing where the shaft enters the front panel and that seemed 
> to help considerably, but it still is not silky smooth.  The receiver is 
> not real dirty and works relatively well, however, the gear mechanism may 
> be in need of cleaning and lubricating.  What is the best cleaner and 
> lubricant to use in this area?  And, what are the pitfalls I should be 
> aware of before tackling this task?  I know it will need further work and 
> alignment, but on the advice of a friend I want to be sure I am not 
> damaging anything due to the stiff tuning first.
>
> Thanks for any and all advise you may offer.
>
> 73,
> Rick/K5IZ
>
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