Question about HP 8640b Signal Generator Knob Set
My experience of HP gear is limited, so bear with me.
A previous generator that I used, original 8940, did have the "muting" function as you described. Per Agilent, it is a design feature to prevent an unloaded output (mismatch) unless specifically configured. I never was able to get that deep into mine, as it was complete with maintenance agreement (gotta love off lease equipment!), and was serviced by Agilent Tech. Services. I also seem to remember an output disable function if the external reference (10MHz) was lost or drifted too far.
Out of curiosity, is your generator also configured with the option for Automated Testing (ie assembly line)? I forget what the option was for it, but it was available with rackmount kit and moved the outputs to the rear (2 sets of outputs total) and each set was electrically selectable / enabled via GPIB.
Posted on Aug 03, 2010
If it were me i would simply replace ALL switches/contacts on spec, I would imagine you have some sort of build up on the switch contacts, this may be acting as a resistor or maybe even a crude Diode... or as you suggest perhaps a contact that's not quite solid, it's making contact OK, but at a higher resistance than it should be, IE: It's acting like a series resistor? thus altering the current characteristics?
Also check your power supply for AC/RF ripple, check ALL electrolytic caps nearby. Also all RF filtering, and coupling/decoupling components.
Also check out ALL decoupling caps on the IC's you may find you have a leaky one?
It seems to me that something is damaging that 003 module, this is evidenced by the fact, that it was fine, then deteriorated,. I would imagine you have something that is slightly damaging, or causing to go out of spec, ECL is very susceptible to earth eddies, so ensure ALL earth connections are solid too. Spray ALL connections with a good contact cleaner and ensure ALL contacts are good and tight.
As for the meter not indicating as it should, there may be some sort of back feed to this meter, through a faulty decoupling decoupling component, this then would explain why it is doing what it does.
Hope this may help.
Posted on Aug 02, 2010
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Posted on Jan 02, 2017
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