Keithley 150A, 60Hz -> 50Hz conversion?

[zhtoor]

Hello Friends,

i am in the process of acquiring a Keithley 150A micro-voltmeter, pico-ammeter.
i understand that the unit is designed to operate on a 60Hz power supply,
but in the part of the world i live in has 50Hz power supply,
has anybody done a conversion to this effect?

regards and thanks.

-zia

[Echo88]

I havent done it myself and just read the manual: As far as i can see you need to change C107/117, also i think the chopper doesnt need to be changed, although Keithley has different labels for the 50/60Hz-versions. Keep in mind to check if the transformer-wiring is correct to accept your mains voltage.

[zhtoor]

thanks, i get it, we have a resonant amplifier at our hands... interesting...

don't you mean to change C106 (by adding a parallel .002uf cap) to resonate the tank @ 100Hz?
the trimmer C117 may not have enough headroom to adjust the resonant frequency.

btw, a very interesting design.

best regards.

-zia