[Johnson] Johnson KW Matchbox

[Steve]

Thanks to each of you for the advice. Sorry to take a few days getting 
back here to respond.

With respect to the second setscrew as a locking device . . . there 
appears to be enough thread in the knob for a 1/4in setscrew and no 
more. The 1/4in setscrew presently in use leaves no threads available 
for a second "locking" setscrew. Feasible to use a 1/8in setscrew and 
then a locking setscrew behind it?

The flat area on the shaft has some appeal. Given the layout of my 
operating table, the shafts are not easily available, but sooner or 
later I'll have things disassembled and could access the shafts. Wonder 
what was the factory set position of the TUNING and MATCHING capacitors 
for zero reading on the knob skirt?

I'll probably try the Threadlocker Purple and see how that goes.

Thanks again everyone for the thoughtful help.

Steve, K8JQ

************************************************************************

Edward B Richards wrote:

Yes.
Install a second set screw on top of the first to lock it in. It works.
You can also grind a flat place on the shaft for the set screw to seat
on. 

Ed K6UUZ

************************************************************************ 

On Sat, 04 Jul 2009 12:33:27 -0400 Steve <steve65 at suddenlink.net> writes:
  

I have two of the Johnson KW Matchboxes.

The TUNING knob on one and the MATCHING knob on the other were loose 
on 
their shafts recently and I tightened the knobs' set screws.

I haven't kept any notes, but the knobs seems to loosen on the 
shafts 
often enough that it's an annoyance. I don't recall if it is the 
same 
knobs that keep loosening on their shafts.

I guess that with use and over time, the set screw backs out a 
little, 
thus allowing the knob to freely turn on the shaft.

Is there a method to tighten the set screw and expect it to stay 
tight?

Thanks.

Steve K8JQ

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