We went through this tradeoff on the E1938A. Resistive heaters can be distributed. However, it is very inefficient to drive them with transistors, because then you waste a lot of power heating the transistors, which is waste heat if resistive heating is used. Prior to the 10544, they just put up with this. The 10544 used a switching regulator for up the efficiency, but it put a 1 kHz spur on the oscillator. The 10811 used two transistors on opposite sides to try to sort of distribute the heat. On the E1938A, we looked at an array of small surface mount transistors to have the best of both worlds. However, this turned out not to be manufacturable and we settled for resistive heaters (back to 1970!).
Rick Karlquist N6RK Bruce Griffiths wrote: > ); SAEximRunCond expanded to false > Errors-To: [EMAIL PROTECTED] RETRY > > Neville Michie wrote: >> >> If you use a transistor as a heater, the full supply voltage is >> across the >> element all the time, so heating is proportional to the current flowing. >> >> Neville >> > Neville > > However using a transistor has the disadvantage of a small area heat > source rather than the large area heat source possible with a heater > winding. > Using a small area heat source produces significant temperature gradients. > > 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.
