Needed my HP 8640B for troubleshooting some radio equipment after 2 years of not using it. Ended up with troubleshooting the?HP 8640B first.
The RF output is not being modulated in AM (don't know about FM) from the internal source. I have no audio source to test the external AM modulation input but likely that will not work either..?
Checked the signal AM output socket and that is fine on 400 and 1000Hz and the level can be adjusted as expected. The meter gives normal readings as well .
The RF output has a very faint 1000 Hz modulation of perhaps a few % dept with the level all the way up and on 400 Hz no modulation at all. The RF settings and output? are fine.
Any ideas where to look?
Thanks, Nico
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