); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY The 10811 has an ANALOG oven control loop. The gain is set to be just below the oscillation point. This is due to the stability limits dictated by the oven mass and (believe it or not) the size of integrator capacitor that can physically fit. If you want to "soup up" at 10811 oven, externally wire in a larger capacitor in parallel and change the resistors to increase the gain. The 10811 designers did the best they could with what they had to work with, but you don't want to blindly copy them in new applications.
BTW, do not use a "metalized" plastic integrator capacitor. Must be "foil" type. I am extremely happy with the PII^2D control loop on the E1938A (I didn't design it, only tested it). I can't imagine anything being better. Rick Karlquist N6RK Bruce Griffiths wrote: > > > If a purely proportional control loop has such great performance why > does the 10811A use a PI temperature controller and the E1938A use a > PII^2 D controller? > > Surely the finite offset between the setpoint and actual temperature > achieved by a proportional controller is a source of long term > temperature instability? > If one uses resistive heating then some linearisation improves the > performance as the heat from the heating element is proportional to the > square of the voltage across the heating element. > > A state space controller may give improved performance but PI(10811A), > PID and PII^2 D(E1938A) controllers seem to work well when used to > regulate crystal oscillator temperatures. > > Bruce > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
