Bill Janssen wrote: I vote for the Bristol answer. I think I have a couple here
but it would

probably take a "crime scene" investigation to find them. I have a couple of
BC221
and the newer version with a CRT.

Bill K7NOM

That CRT comment was about as wrong as can be.
The "CRT" was a magnifier glass to read the film strip dial.

Should have looked at the unit before commenting.

Bill K7NOM