My First Zenith Trans-Oceanic!

[Electronic M]

Originally Posted by old_coot88

Be sure it's not mistaken for 1U4 or 1U5 which are different critters.



According to the posted article it is. But I can't verify it, and online info on it is scarce.



The paralleled resistor (same ohms value as the filament when hot) does not increase current draw (which is a constant 50 ma.) but splits it in half for the tube. Remember that in a series circuit, current thru the whole string is constant. Whereas in a parallel circuit (imagine 6V paralleled heaters), voltage is constant across the lot. Series = constant-current, parallel = constant-voltage.

I know how it works. I've done plenty of series-parallel resistor math and nodal analysis in college. I just don't remember how to describe it correctly at close to 1AM.