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Tubes Asylum Questions about tubes and gear that glows. FAQ |
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Tubes Asylum Questions about tubes and gear that glows. FAQ |
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In Reply to: RE: How does a lower current for the heater at the same voltage affect GM? posted by Chip647 on October 22, 2023 at 18:31:54:
the voltage is the same. 6.3 volts but the current draw of the heater is 200mA vs 7193 specs that call for a 300mA. Yes, if designed for the 200mA it should last longer but the tube also measures lower than the specs call for. That is what I am wondering about, the measurements. Having measured almost 100 NOS now, and some previous E 1148 NOS, they fall in the range of 2000 to 2300 GM where as a typical 7193 is 2700 to 3100.
Since the cathode is shorter on the E 1148, I think the lower mA is for the shorter heater, as less current is needed for the shorter cathode but at the same time, the way Hytron made the tube, as a 7193 type, the measurement is also lower but there are no notes etc., from Hytron regarding the lower GM measurements.
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