Hi all,
Need some advice from someone who has done this. The SX-122 I am restoring
was missing the springs between the two gears on the main tuning cap. I think
this was an antibacklash arrangement. I put in some fairly strong springs I had
but when the mating gear is place against this dual gear there is still about
1/4" of backlash which make aligning and tuning the rcvr REAL interesting. Any
thoughts or advice on setting it up? Should the springs be really firm or soft?
Thanks ahead of time for reading this and replying. 73 Mike KF6KXG

TchrMe wrote:
Hi all,
Need some advice from someone who has done this. The SX-122 I am restoring
was missing the springs between the two gears on the main tuning cap. I think
this was an antibacklash arrangement. I put in some fairly strong springs I had
but when the mating gear is place against this dual gear there is still about
1/4" of backlash which make aligning and tuning the rcvr REAL interesting. Any
thoughts or advice on setting it up? Should the springs be really firm or soft?
Thanks ahead of time for reading this and replying. 73 Mike KF6KXG


My experience sez VERY firm for backlash gear springs. Might your 1/4"
of backlash be due to something else like pulleys, etc binding?
-Bill

Bill,
Thank you for replying. I am talking about the main tuning cap having the
antibacklash double gear. The large pulley with the dial cord that goes only to
the knob has the mating gear. The large pulley shaft also carries the round
main tuning dial. I feel the free play between the gears with no dial cord
strung. Isn't what I call free play and backlash the same problem? Mike KF6KXG

TchrMe wrote:
Bill,
Thank you for replying. I am talking about the main tuning cap having the
antibacklash double gear. The large pulley with the dial cord that goes only to
the knob has the mating gear. The large pulley shaft also carries the round
main tuning dial. I feel the free play between the gears with no dial cord
strung. Isn't what I call free play and backlash the same problem? Mike KF6KXG

I guess we're talking about the same thing. The two gear 'discs' should
be very tight together by virtue of the spring between them. You
shouldn't be able to very easily pinch them together with your fingers
and slide them back and forth. Should be quite tight.
But you mentioned 1/4" of backlash. I don't know that that alone would
cause so much error. If something else was binding or sticking it would
make more sense.
I'm wondering if a weak spring might cause more harm than no spring
considering that many radios don't use anti-backlash gears at all. Try
removing the spring completely as a test. With no anti-b at all you
MIGHT notice a tad but I wouldn't suspect as much as a pointer width
unless something else is happening.
GL,
Bill

Be sure that the gears are pre-loaded before you mate them. Rotate the two
halves of the anti-backlash gear in the (direction that compresses the
spring) at least one full tooth before assembling the mating gear.

A ball-point pen spring is usually about right.

"TchrMe" wrote in message
...
Hi all,
Need some advice from someone who has done this. The SX-122 I am
restoring
was missing the springs between the two gears on the main tuning cap. I
think
this was an antibacklash arrangement. I put in some fairly strong springs
I had
but when the mating gear is place against this dual gear there is still
about
1/4" of backlash which make aligning and tuning the rcvr REAL interesting.
Any
thoughts or advice on setting it up? Should the springs be really firm or
soft?
Thanks ahead of time for reading this and replying. 73 Mike KF6KXG

Thanks to those who responded. I've got fixed! It needed fairly firm springs
put in (a ball pt pen was too soft) and I preloaded it as suggested. That
solved the problem. 73 Mike KF6KXG