[ARC5] BC-348 Tuning Backlash

[Dennis Monticelli]

Many years ago when I was much younger and foolish, I completely
disassembled an R-390A down to the last tiny part.  All the gears were
broken down including the anti-backlash gears and planetaries, cleaned in
carburator cleaner, and minimally lubricated.  Of course that did the trick
for smooth operation the gearing, racks and cams.  Yes, it all went back
together and was successfully aligned.   I will never forget that
experience......and I never did that again!

Dennis AE6C

On Sun, Nov 14, 2010 at 2:30 AM, David Stinson <arc5 at ix.netcom.com> wrote:

> While we're discussing the BC-348,
> let's address the most common problem with them:
> tuning backlash.
>
> The tuning in a 348 uses a whole series of
> "split-with-tensioning-spring" anti-backlash gears.
> Over the decades, oil, grease and dirt get
> between the halves of the gears and disable the
> feature.  The springs also get "wimpy."
> I've used a heat gun and penetrating oil
> on the gears to flush out the old, coagulated
> grease film with some success.
>
> You can use the tip of a jeweler's screwdriver
> inserted between two teeth to flex the halves
> by twisting it back and forth.  The halves should
> spring back without resistance after you tension them
> with the screwdriver.  If not, you still have gunk
> between them and backlash. I've also carefully
> re-tensioned a couple of the springs
> (and spent a wonderful afternoon crawling around
> on the floor after one of them went
> "SPROOOOOOING" and vanished into the black hole
> into which all dropped hardware finds its way).
>
> Removing all the gears for a proper cleaning and
> re-lubing would be a nightmare which few of us
> could or should attempt.  I certainly wouldn't.
>
> What have you done to address this problem?
> What has worked and what hasn't?
>
> 73 Dave S.
>
> p.s.  Just douching everything down with WD=40
> don't work so good.  Been there ;-)
>
>
> ______________________________________________________________
> ARC5 mailing list
> Home: http://mailman.qth.net/mailman/listinfo/arc5
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:ARC5 at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>