Replace the setscrew with this 8-32 rod. Using a pair of needle-nosed pliers, securely
tighten the rod. Next, tin just the ends of the braid, not more than about 1/8th inch. Tin
the end of the threaded rod with resin core solder (it will “tin” pretty easily). Then, solder
one end of the braid to the threaded rod with the braid going in the direction of the frame
of the variable capacitor.
Tin the center of the frame of the variable capacitor, about 1/4 inch is plenty. Solder the
“other” end of the braid to the frame.
Rotate the main tuning shaft through the entire 5 turns and make sure that the braid
doesn’t touch any components. If it does, bend the point at which the braid attaches to
the threaded rod so that the braid “clears” everything.
The reason for using just a threaded rod only 1/2 inch long is that if a head was on the
screw, it will not clear the gear itself and any longer and the rod will interfere with the
worm gear and therefore the full 5 revolutions will not be possible.
The LMO utilizing the smaller gear is somewhat easier in the fact that an 8-32 machine
screw that is 1/2 inch long clears both the gear itself and the worm gear. Therefore, the
head does not have to be removed.
Replace the setscrew with the new machine screw. Using a screwdriver, tighten the
machine screw.
Tin the head of the machine screw. Attach the end of the section of braid and follow the
above directions to complete the attachment of the braid.
Replace the side panel removed before, making sure to replace the “lugs” which mount
the LMO to the chassis.
Finally, reverse the removal procedure to return the LMO to the unit.
Heathkit Linear Master Oscillators (LMOs) Page 126
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