Quote:
Originally Posted by ms660
My old Hikock based I-177b valve tester used full wave rectification for the HT and full wave rectification for the grid bias supply, the HT via a mercury vapour rectifier to keep the supply impedance low to the DUT
Lawrence.
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The genius of Hikock's patented system was the fact that all of the voltages in the one unit were derived from the one mains transformer and the unit could be calibrated perfectly accurately with just setting the meter circuit calibration, it does not require a reference transconductance device. I wrote a detailed article on this and why this is so and the Hikock's basic circuit including remarks about the anode and grid voltage waveforms under different bias settings, which may be of some interest to the OP:
http://www.worldphaco.com/uploads/Hi...d_the_ACS..pdf