[R-390] RF deck, points of clarification

[nryan at mchsi.com]

It's true, no amount of whatever lubrication can overcome the effect of burrs on the split gears.  The fix is to take them apart and gently, ever so gently, dub the gear cogs.  Don't round them, just concentrate on eliminating the burr.

When reassembling the gears and loading their springs, engage the teeth sufficiently to get the gears to be slack-free.  Usually one cog's worth will suffice.

Mobil One 90W Synthetic, sparingly applied, is a good all-round lubricant for R-390* mechanisms.

73 all,
Norman

Any activity becomes creative when the doer cares about doing it right, or doing it better. -- John Updike


----- Original Message -----
From: rbethman <rbethman at comcast.net>
To: r-390 at mailman.qth.net
Sent: Wed, 6 Jun 2012 10:44:12 -0500 (CDT)
Subject: Re: [R-390] RF deck, points of clarification

I think - and correct me if I'm wrong - BUT the methods presented so far 
will make it smoother to operate - BUT - absolutely will not resolve the 
issues of an old RF Deck with many years of use.  The instance that I 
have is one of the first Collins Contract R-390As.  The wear on the 
front panel said a lot.  I did NOT find this in my '67 EAC.

The issue that first bites anyone, is the wear on the sides of the 
gears.  Chuck please chime in on this!

I feel the sides of the gears, and I can feel that very slight "edge" on 
the sides of the teeth of the gears.  You can clean, degrease, and lube 
with any concoction you so desire.  The reality is, unless you take the 
gear train apart, gently hone the sides to remove that edge, then you'll 
never get that spin by one finger smoothness of the gear system.

I've worked on gears of many types and cuts.  When you have "split" 
gears with a spring to take up the backlash, and they have and edge on 
the sides of the teeth, you have to fix the real issue before all this 
lubrication.

Bob - N0DGN


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