[Test-Equipment] Fusing HP 8640B RF Signal Generator

[Mike Czuhajewski]

I have the large, yellow, military version of that generator, which is also
known as the USM-323. I don't have the fuse assembly, but it looks like
you're on the right track with the one you have. According to the manual for
the unit (military version), the 11509A fuseholder contains a 1/16A fuse.

It also says that insertion loss is under 1 dB and output VSWR is under
1.35.

I note that your post uses the number 10509A repeatedly, and the manual
calls it 11509A over and over. But at least the "1/16A fuse" matches up! (I
also have the manual for the commercial version, and it calls it 11509A,
too.)