Jim -
I'm not sure what you are saying yet, but ...
I can't find anything pertinent on WB8RCR's site so can't
comment on that.
The ball bearings are 1/8 steel and are available from my
local True Value hardware store. I think it takes either
nine or ten bearings. They ARE held in the race by the
tapered collar on the threaded lead screw, just as you
suspected. The Allen head adjustment at the rear of the
mechanism is only to adjust the pressure on the ball
bearings at the front of the shaft.
The lead screw does NOT move lengthwise, only the threaded
follower moves as it threads along the lead screw.
The initial failure in your case was someone turned the knob
past the stop. What happens is that the grease hardens with
time and the plunger fails to come out to stop the rotation.
This allows the lead screw to keep turning until the
follower falls off the end!
What you need to do is to get the ball bearings back in
there, and then adjust the Allen screw at the rear to just
take out the side play on the tuning shaft.
The threaded follower that runs on the lead screw then needs
to be pulled forward while turning the main shaft until the
threads catch. You will have to retract the spring plunger
that is the end stop to allow you to turn it back far enough
since you are on the other side of the mechanical stop.
There is a brass guide rod that extends out the back of the
PTO through the phenolic block with the diamond shaped hole
in it.
Once you get it back together mechanically, you need to set
it for 4.955 MHz at the rear and 5.455 MHz at the front.
The plastic dial plate can be slipped by disengaging the
idler gear by pressing the spring loaded shaft to clear.
This is also used to get the plate in the right location so
the stop plunger comes out and engages the dimple in the
gear behind the dial plate. Takes some fiddling until you
get everything going in the right direction at the right
time! Fine adjustment of the dial plate is made by holding
the plate and turning the knob, slipping the plate on the shaft.
Let us know how you do. Or feel free to question anything
you don't follow.
73, Garey - K4OAH
Atlanta
Jim Pruitt wrote:
I recently dug into an R4B to try to find out why it was not working. One
thing that I found is the brass plate that sits on the threaded main shaft
that also push/pulls the coil slug in and out was at the back of the housing
and was out of threads so the main threaded rod was not picking up that
slide. I unscrewed the adjusting allen screw a half turn and that gave me
part of a thread for the slide to grab but that also pulled that threaded
shaft back enough that the ball bearings fell out and went everywhere.
So I am looking for a source for those ball bearings and also need some info
on how that pto goes back together mechanically. I have the article from
WB8RCR's site but do not see what I am looking for (to see how the ball
bearings are held in there and also whether a washer is needed between the
brass plate and the housing). I found a few of the bearings but I must be
missing something because there was nothing to hold them in the race they
had fallen out of so they fell again. I thought the tapered collar on the
threaded shaft also held the bearings into the race but I either can not get
that collar far enough forward and being too far forward the shaft will not
turn. If it is backed off slightly it will turn but the bearings fall out.
Also when all the way forward like the there are enough threads for the
brass plate and it runs off the end and will not start forward again.
Does anyone have a url or a good description of how the pto goes together
and still works and travels?
Thank you.
Jim Pruitt
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