Products > Test Equipment
Hp 6181/6177 guard terminal
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coppercone2:
I am curious about the guard terminal on this unit, which is screw terminal A0.
The manual does not say much about it.
Are you supposed to use it with a triaxial cable for really low level settings?
I was planning on doing a lower current range mod , so it has a setting for 250uA full scale, described here in reply 10
https://www.eevblog.com/forum/repair/hp-6177c-dc-current-source-repair-and-restoration-(complete)/
Also, I thought about adding a guard banana jack to the front panel if that is what it does.... I thought it might be useful if you have it set to ~75 nanoamps (0.03 percent of 250uA range) if it works.
coppercone2:
my main concern is something with capacitance, I think. Can the guard thing deal with the cable capacitance
coppercone2:
ah, it looks like the imonitor is connected to guard and its a front panel thing.
but it says nothing about using it for guard shields. perhaps with a 250uA FS mod, it might make sense. Tempted to try bigger resistors there too see how low the full scale can go (i.e. 90k ohm)
at 100V it seems like it almost makes sense to have a guard capability. Like if you connect the guard to another prototype PCB's guard. Then the guard might even be useful, even if the cable is not the source of leakage, so its a good capability to have.
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