[Collins] 75A-2 tuning shaft collar set screw thread (and source)?

[Christopher J Galbraith]

Hi gang,

I am replacing the tuning shaft on a 75A-2 that was bent in shipping.
The original had a pin securing the 10-turn stop's collar on the tuning
shaft.  Luckily, the collar is also tapped for 2 set screws, so the
replacement shaft can be a simple section of 1/4" stainless steel round.


The problem is, I don't know what the thread size is and I haven't found
a match at the local hardware store (in either a set screw or a machine
screw).  I think it might be 3-48 or 4-48 (definitely a finer pitch than
4-40) but I have not found a fastener to check this.

Does anyone happen to know (or can make a good guess) at the thread
diameter/pitch of the set screw threads on the tuning shaft collar for
the 10-turn stop on the 75A-2/3?

Also, does anyone know a source of this set screw in quantities of 10 or
less?

Thanks very much for any help,

73, Chris KA8WFC