[Hammarlund] Repair Vernier Tuning Capacitor

[Bob Harris]

NEED HELP REPAIRING HQ 170 AC VERNIER TUNING CAPACITOR C30

I am the original owner of my HQ 170 AC and am looking for information, 
help, and or advice on repairing or replacing the Vernier Tuning capacitor 
of my receiver.


On the front panel of the receiver, the capacitor is labeled:  “Vernier 
Tuning + or – 3 KCS.”   On the schematic, the capacitor is labeled C30 but 
no value is given.  There is no parts list in my manual.  However, a very 
cooperative ham at the Hoss Traders flea market allowed me to look at the 
manual for his HQ 170 receiver that he was selling, and the part number is 
listed as K42040-2, but, again, no value is given.

In terms of repair potential, the capacitor appears to be in good shape with 
one exception, the rear of the rotating shaft is "disconnected" from the 
frame of the capacitor.  This of course, causes the plates to touch each 
other, making the vernier tuning inoperable.  It appears that a single ball 
bearing may have held the rear end of the shaft in place and that the single 
ball bearing was “pressure” fit in between a hole in the end of the shaft 
and a "dimple" stamped into the rear of the frame of the capacitor.   I have 
never seen a working capacitor, so I am a bit uncertain about how the rear 
of the shaft was actually connected to the frame of the capacitor.

Other than a loose shaft, the capacitor is in good shape.  The plates are 
not bent.  Four ball bearings are in place to hold the shaft at the front of 
the capacitor frame.

Here is a more detailed physical description of the capacitor C30:

Number imprinted on rear of capacitor frame

R/C 273 6222 154
42040-2

4 fixed plates
5 moving plates
Plates are 1 1/4 inch in diameter, mounted 1/8 apart.

Metal frame, 1 3/8 wide, 1 1/4 high, 1 1/8 deep.  All measurements in inches

Dual concentric shafts.  Inner shaft holds knob.  Outer shaft is for red 
pointer.

I would appreciate and help, suggestions, ideas, or any information you can 
provide.  Many thanks in advance.

Bob, K1FLK


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