Thank you very much, Lee. That gives me some things to think about.
I've accumulated four of these rigs and have finally decided to spiff
them up. So far I've removed three of the PTO's and have found none
with felt washers yet, though the PTO rebuild instructions do mention
them (possibly on other models I suppose). There's sure no reason not
to try them on a C-21, though. I'll give that a shot.
As you said, adjusting the bearing plate on the back, hasn't yielded
much, backlash-wise.
I'm curious as to how that "backlash rod" functions, in fact, just what
its function is. I'm intrigued especially about the purpose of the
little wedge shaped piece that rides on the rod and butts up against the
pistol. Maybe you might enlighten me?
I agree with your comparison between the C-21 and my other favorite, the
HW-16. In fact, one of these Centuries is traded for some HW-16's.
Entertaining and informative, indeed! Someone must have hijacked my
call again.
73,
Tom NØJMY . .
Hayseed Hamfest Co. - Multi-section Can Capacitors
for vintage Heathkit, Drake, Halli, Hammy, more...
www.hayseedhamfest.com
wa3fiy@radioadv.com wrote:
> Hi Tom. Welcome. Good to see you here. I greatly enjoy your entertaining
> and informative posts to GlowBugs. :-)
>
> To your question. I'm no expert on the matter but I think the unidirectional
> backlash is due to a spring being compressed when you turn the tuning
> knob CCW. That spring pressure is pushing back against the "pistol" and
> trying to turn the Acme screw thread. This is a case where you want a little
> more friction in the system. Try loosening the main tuning knob and see if
> there is a felt washer or two between the knob and the 0-100 dial plate. If
> not you need one or two, can't recall what TT uses. Hold slight pressure on
> the knob, compressing the felt washer slightly, as you tighten the setscrew.
> That will provide some friction between the knob and dial plate which turn at
> different rates. Play with that and see what you get.
>
> There is a plastic bearing on the back end of the PTO enclosure which is
> spaced from the enclusre by one or more flat washers under the two fixing
> screws. That spacing adjusts spring pressure on the screw thread which in
> turn adjusts the pressure on the ball drive. I sometimes play with that
> spacing as well but I think it has more to do with eliminating slippage in
> the
> ball drive than in minimizing backlash.
>
> Good luck. The Century 21 is an interesting rig. Sort of solid state HW-16,
> but not quite. :-)
>
> 73,
> -Lee-
> WA3FIY
>
>
> On 29 May 2009 at 20:05, Tom NØJMY wrote:
>
>> Hello. New member here. I have some Century 21's here which seem to
>> all exhibit dial backlash (maybe I should call it knob backlash) when
>> turning the tuning knob counter-clockwise. The closer you get to the
>> CCW end of the dial travel the worse the backlash becomes. There is no
>> backlash when turning the knob clockwise.
>>
>> I've read quite a bit about dial slippage and rebuilding the PTO in the
>> C-21, but these units have all been cleaned and lubricated, turn freely,
>> and there is no dial slippage.
>>
>> Have any of you fellows run into this problem? Is this an inherent
>> characteristic of the C-21 PTO, or is it a problem that can be fixed?
>>
>> Thanks in advance,
>>
>> Tom, NØJMY . .
>>
>> _______________________________________________
>> TenTec mailing list
>> TenTec@contesting.com
>> http://lists.contesting.com/mailman/listinfo/tentec
>>
>
>
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