Cliff -
Well done on the bearings! The grease is the trick, as you discovered.
Looking down on the PTO "gearbox", there is a shaft that supports the
large gear on the left side, that has a spring pulling the shaft towards
the lead screw.
The hole in the front wall of the gearbox is "oval" in shape. So if you
pull that shaft to the left against that spring, disengaging the large
gear that drives the dial, you can freely rotate the dial to the correct
100 kHz marker. Be careful, because with that gear disengaged, the dial
spins freely and can get away from you! :-)
That should get you real close, to where you can align the dial with the
knob skirt so that the long mark on the knob skirt lines up with the
fiducial mark and the 100 kHz mark on the dial. If the dial is still off
by a small bit, you can slip the dial on the shaft by holding the dial
FIRMLY and turning the knob to get it lined up just right.
Hum in the 2-C is almost always dried out electrolytics C40, C48 and C86
if a later serial number.
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 4-B, C-Line& TR-4/C Service Supplement CDs
<www.k4oah.com>
[email protected] wrote:
Firstly, thank you all who contributed to the questions I asked on
these subjects. Some suggestions did not pertain directly to my model
number, nevertheless they contributed to the overall knowledge of the
subject.
As for the ball bearings which fell out of the main tuning shaft on
the T-4XB transmitter, my wife and I spent a long time trying to get
the bearings back in and staying in place. She has a much steadier
hand than do I.
I removed the can from the VFO and by backing off the adjustment screw
(seen at the front end of the VFO assembly) with a long handled Allen
wrench 3/32 in size, it produced a wider gap on the bearing race and
the bearings went in easily, BUT, they would fall right through and we
would start the process again.
Finally I figured that I should fill the race with new grease which
would help keep them in place and also prevent their falling through.
My plan of attack then was to tighten the set screw just to the point
where I could not get a bearing to slip into the race, and by keeping
a small amount of pressure on the bearing I backed the set screw off
just to the point where the bearing would go into the race and after
that it was a matter of placing the other nine bearings in the race
maintaining the same gap so that the balls would just nicely slip into
the race. A small tightening of the set screw then completes the job
but do not tighten it too much. Overdoing it would likely wreck the
ball bearings.
By the way, yes there are ten bearings although at first glance it
looks like there should be 12, however they all come together when the
set screw is tightened a wee bit after installation. And by the way I
dropped the balls in at the same point in the race, just pushed them
around as each ball was inserted.
I should mention that I stood the T-4XB on its nose on top of a few
large books high enough that I didn’t have to break my neck to look
in. Looks more shaky than it really is. Just be careful and don’t let
the rig fall over. I had no problem. The point is you will need to be
able to work the main tuning knob a bit when putting the bearings back
in and you can do that when the radio is propped up between two stacks
of books.
Now the bad news. I have taken out and re-installed the bearings three
times, (getting pretty good at it by now) but as careful as I could be
I could not get the dial calibration to stay put. I expect the stress
of re-installing the bearings, stress on the set screw and certainly
on the cover can, it would throw the calibration off which was and is
a pain in the you know what.
Does anyone have any suggestion short of giving this transmitter to my
grandson to see if he can learn anything by taking it apart, as to how
I can get the actual frequency of the transmitter to accurately
coincide with the plastic dial reading? At the moment its about 100
Khz off although I did have it about 15 Khz at one point.
Again, thanks so much to all who have helped on this and also the hum
in my 2-C receiver which I have not tackled so far. I appreciated it
no end.
73... Cliff
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