[ARC5] [Milsurplus] Anti-Backlash Gears
Mike Hanz
aaf-radio-1 at aafradio.org
Wed Jan 25 08:24:28 EST 2012
On 1/25/2012 6:32 AM, David Stinson wrote:
> Like many rigs, the -288 uses several split
> "anti-backlash" gears to stablize tuning.
>
> I use a "jeweler's screwdriver" blade to carefully
> flex the split gear by inserting the blade in one
> of the gear teeth, turning the screwdriver to put
> the two gears under tension, then pulling the blade
> out. The gears should instantly "snap-back" into
> place. If they don't or are sluggish, there's a problem.
>
> There are all kinds of ways to make this worse,
> like using the wrong spray to drive the gunk even
> deeper between the gears or add
> even more goo to the mix.
> How do you address this problem in your sets?
I try to remove and take apart the gear in question. Yeah, I know, I
know - it can be a lot of work - but there is no magic spray that I've
found that will give you the complete smoothness of a newly lubricated
anti-lash gear set, and some (like WD-40) will work for a short while
until the solvent evaporates and then be worse than before because the
waxy water displacer/protectant will be left in between the gears as a
nice glue. The original film of grease has long since lost its lighter
petroleum components, and in theory one would think that a simple
injection of a solvent would be all that is needed. The problem is that
few of these sets have been stored or used in a pristine environment,
and dust, smoke, even fine sand particles seem to get in between those
gears somehow. It's magic... The heavier components of the original
grease oxidize to a degree over time, so even that doesn't remain stable.
If I don't have time to do it right, then a decent instrument oil,
preferably synthetic, is a reasonable place to start. Again, it will
depend on the radio's environment, but sometimes you get lucky. If that
doesn't work as well as hoped, then a syringe with acetone in it is the
second line of defense, followed by a couple of drops of the instrument
oil once the excess solvent has evaporated. I think I would stay away
from motor oil, though lots of folks use it because it's handy. Its
detergent and water suspension properties are the problem here, at least
theoretically.
Anyway, that's how I would approach it. Your method of exercising the
interface is a good one to work the lubricant in between the gears.
73,
Mike
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