[R-390] Interesting Problem

Thomas Hoyer thoyer1 at verizon.net
Wed Dec 8 08:07:27 EST 2021 

I have found that to be the case with my 309x radios. Once treated to a WD-40 cleaning bath / rinse, dried off and pivot points lubricated, the tuning and band changing is nice and smooth.

TomW3TA

-----Original Message-----
From: Jim Whartenby via R-390 <r-390 at mailman.qth.net>
To: r-390 at mailman.qth.net <r-390 at mailman.qth.net>
Sent: Tue, Dec 7, 2021 11:54 pm
Subject: Re: [R-390] Interesting Problem

I don't know how the rest of the group feels but for me most of the R-390A receivers I have seen are over lubricated.  Grease on gear teeth is a magnet for dust and dirt.  One R-390A I got in a lot of four was so bound up that both frequency knobs could only move a few degrees then freeze up.  
Lots of cleaning using WD-40, Krud Kutter. water and then alcohol repeatedly applied with an acid brush on a wood dowel eventually cut the grease.  Use the alcohol as the last rinse to get the water out of the gear-works.  Once clean, everything turned as it should.  I figured that the clock collectors and restorers would know pretty much everything about the care and feeding of the gear-works.  Their recommendation was to only lubricate pivot points.  Anything put on the gear teeth only attracted grit which would eventually bind or damage the gears.
It is amazing how easy it is to turn the megahertz and kilohertz knobs, especially if you re-center the two bushings that the two shafts use to go through the front panel.  I use Tufoil applied using a strait wire flattened at the end to put a drop at a time to the pivot points.  Others use Mobile One or similar synthetic oils to lubricate.  Don't forger the rollers and such that drive the slug racks.  
Nothing I have done mechanically is rocket science but it does take time and patients.
Regards,Jim

Too much agreement kills a chat.  E. Cleaver

-----Original Message-----
From: Jordan Arndt <Outposter30 at shaw.ca>
To: Ron.K3PID <ron.k3pid at sbcglobal.net>; r-390 at mailman.qth.net
Sent: Tue, Dec 7, 2021 4:05 pm
Subject: Re: [R-390] Interesting Problem

There are instructions in the manual for periodic maintenance which describe 
an interim lubrication procedure...

I've never had to take the gear train etc. apart, but I've become pretty 
adept at pulling the RF deck out...But you can always use a less intrusive 
method...!

While it may conflict with what I've always heard, one thing I've found is 
that the Zero Adj. mechanism usually requires a good flush with M.G. 
Chemicals penetrating oil or similar.
I've found that it's best to leave the panel on, as I needed to use the Zero 
Adj. control so I could flush the mechanism at both ends of it's travel and 
really free up the locking pins. Now, the Zero Adj. lockes and releases very 
easily within about 300 degrees of rotation and is smooth like butter...!

73...Jordan VE6ZT

----- Original Message ----- 
From: "Ron.K3PID" <ron.k3pid at sbcglobal.net>
To: "Robert P. Meadows" <rpmeadow at bellsouth.net>; <r-390 at mailman.qth.net>
Sent: Tuesday, December 07, 2021 12:03 PM
Subject: Re: [R-390] Interesting Problem


> Thank you Robert! I was not proposing to dissemble the gear train although 
> Chapter three in TM 11-5820-357-35 gives a pretty concise step by step 
> procedure for doing so. I  was simply inquiring if there was an 
> appropriate cleaning/lubing procedure that could be done while the front 
> panel is removed.
>
> Ron K3PID
>
>
> ----- Original Message -----
> From: Robert P. Meadows <rpmeadow at bellsouth.net>
> To: 'Ron.K3PID' <ron.k3pid at sbcglobal.net>, <r-390 at mailman.qth.net>
> Sent: 12/7/2021 12:34:33 PM
> Subject: RE: [R-390] Interesting Problem
> ________________________________________________________________________________
>
>
> Before you start cleaning and lubricating things, read the appropriate
> manual carefully.  Your radio might just stop working after such 
> "servicing"
> not in accord with the proper procedures.
> R
>
> -----Original Message-----
> From: r-390-bounces at mailman.qth.net <r-390-bounces at mailman.qth.net> On
> Behalf Of Ron.K3PID
> Sent: Tuesday, December 7, 2021 1:30 PM
> To: r-390 at mailman.qth.net
> Subject: [R-390] Interesting Problem
>
> So I was shutting down the rig last night and noticed that the R-390 
> didn't
> go dark as it usually does! in fact the OFF position on the function 
> switch
> didn't have any affect on the radio. A quick check with an Ohm meter 
> showed
> that the contacts P118-11 to P118-2 was closed for all positions of the
> switch. OK!
> Removed the front panel and observed that the cam was indeed pushing the
> microswitch in when in the OFF position. Looking around for an easy way to
> get the microswitch out I just happened to notice that the solder blob on
> the center pin on the switch was just barley touching the unused ( assume
> Normally Open ) pin. It was pretty easy to carefully bend the unused pin
> away from the center pin and Viola! Problem solved!!! Just to be sure I 
> put
> a piece of heat shrink tubing over the unused pin. Now I have never had 
> the
> front panel off before but I have only owned the rig for about 20 of its 
> 65
> or so years so I don't know what any previous owners had done. It's pretty
> hard to imagine how the wiring harness could have been pulled down enough 
> to
> get those two contact pins to touch but that must be what happened. Why it
> happened now is a mystery of course but all is well that ends well I
> guess...  While I have the front panel off I think I'll use a little 
> contact
> cleaner on the rest of the switches etc. They don't look "dirty" but 
> should
> I clean and lube the gear train before replacing the front panel?
> Recommendations?
>
> Ron K3PID
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