[R-390] Cooking Kielbasa 1 of 2

[Flowertime01 at wmconnect.com]

Fellows,

Installing diodes for 26Z5's in an R390. This yielded the following results 
from testing. With 26Z5's in the circuit, B+ was 320 volts on the plate of 
the 6082's. The cathodes of the 6082's were at 220 volts. We expect 180 
volts at this point and accept the difference as being meter error. The voltage 
drop across the 47-ohm resistors was 2.5 volts or .053 amps. This is .212 
amps for all four resistors. This is in line with the expected .200 amps of B+ 
for the receivers.

When the diodes were installed for the 26Z5's, the plate voltage of the 
6082's went up to 380 volts. The cathode voltage was unchanged and the voltage 
drop across the 47-ohm resistors was unchanged as expected. This is a 
60-volt increase at .053 amps for 3.18 watts in each half of each 6082. The drop 
across one triode of a 6082 is now 150 volts at .053 amp. I take this as 7.95 
watts.

As we expect the cathode of the 6082's to be close to 180 volts, I believe 
my meter is reading high and the values are in fact somewhat lower than my 
measurements. A 150 volts at .053 amp and 7.95 watts is about half the tubes 
ratings of 250 volts, .125 amp and 13 watts.

In conclusion we save 26.5 volts at .20 amps 5.3 watts of filament heat in 
each 25Z5 and move 6.36 watts of plate heat from the 26Z5's to each 6082 as 
plate heat. We move some plate heat (voltage drop across the tube at its 
operating current) and save about 10.6 watts of filament heat.

Roger AI4NI
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