Tektronix and Keithley

Hi,

I have few basic doubts about 7012 and 7709 scanner cards.
1) We have a scanner card 7012-S, where we can see the relays are single side stable type. Can we use this card for long measurements, where relays will be on for long time?
2) Why 7012S has lower contact potential (<500nV) compared to 7012C (1uV)?
3) 7709 uses latching relay. So is it better to use 7709 for long measurements? But it has poor contact potential (<3uV) compared to 7012.

Regards
Sayak

1. The Model 7012 can be used for long periods of time. It is designed to remain closed or open until you change it or power is interrupted.
2. The Model 7012-S has lower contact potential because of the screw terminal connections. The Model 7012-C has a mass terminated connector which has somewhat higher thermal issues and there fore higher contact potential.
3. The latching relay is just a design that remains in the chosen position until you change it without using up any current. It just switches from state to state.
electromechanical relays require the cuerrent to be applied to keep it closed.