[ARC5] BC-348 Tuning Backlash

[k0ng at windstream.net]

>>>>> Hello Dave:

One of my BC-348 units has an interesting "attempt to fix the backlash". Apparently
the owner before me found that there was backlash between the worm gear on the end of the main tuning shaft and the gear that meshed with the worm gear. The 
whole main tuning shaft and worm gear can move "into and out of" the assembly
with cw and ccw rotation of the shaft. The previous owner made a small "C" shape
spring out of spring steel and that rests between the end of the main tuning shaft and the cast supporting the shaft bearing. As I recall, the C shape spring had 2 small holes that kept the spring centered on the end of the shaft. I gave some
thought to that idea and perhaps the C shape spring could be replaced by 2 flat
washers and a Wave Washer or 2, all in a sandwich at the end of the shaft.
I apologize for this description and it may not be exactly right as its been a long time since I looked at the change. Inspection of end to end play of the shaft  will tell you how much backlash is located there.

Good Luck and 73, DE Charlie,  K0NG   ..

PS:  What do you intend to do with the 6900 CR-1 Rocks ?? I may have some but
need to dig further back, HI.
much backlash 
---- 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 ;-)
> 
> 
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