From what info I can find seems to be no. 6 unc, as below
An 7/64 Allen key fits, I measure diameter to be 3.5mm and 7.5mm long. Thread is coarse so definitely not metric.
It is from a US made amp. .
[Edited on 23/9/17 by 02GF74]
first guess would be 2BA
do you have a photo of it? (preferably with a scale)
I doubt that you'd find a 2BA in a US amp. More likely to be UNC or one of their numbered screw sizes (e.g. 8x32, 10x24, or something like
that).
BTW: BA sizes are specified in metric units, despite being a bit of a UK antique range. For example, 0BA is the same as M6 coarse.
quote:
Originally posted by David Jenkins
BTW: BA sizes are specified in metric units, despite being a bit of a UK antique range. For example, 0BA is the same as M6 coarse.
A set of thread gauges and a Zues booklet cost very little and last a lifetime , takes all the guesswork out when identifying threads.