[Amps] filament supply options

[ka1xo at juno.com]

Dear Steve,

Does your intended amplifier use the filament to inject the input RF into the tube circuitry, or is one side of the filament perhaps tied to the cathode pin(s) on the tubes, with suitable bypass capacitance in various places?

Does your intended design use a set of bifilar-wound filament chokes with suitable bypass capacitance on the cold end(s)?

Does the design of your intended amplifier feed input R.F. to the center-tap of a possible filamant transformer?

In the above circumstances there are filament transformers with one side of the output tied to ground and other circumstances where the filament transformer is running with bothe sides isolated from ground and suitably bypassed.

If you were to substitute the switcher supply as a "black box" in place of a filament transformer is or are there any considerations relative to the above caveats that would cause you concern, (e.g., design considerations)?

Watts is watts, I agree. One of the criteria my work application dealt with when graduating from ferroresonant supplies to switcher supplies (other than the easily-swallowed cost savings) was the effect of a "complex" impedance on the operating radio bays, and if the power plants would be affected by all the RF. The final score has not been tallied yet. The MTBF for the Chinese (Delta) switcher supplies versus the MTBF for the older ferro's seems to be two orders of magnitude worse, and the Flat-Earth Society engineers all say "accumulated PLD's," while the D.C. True Believers counter with "R.F.hash."

Meanwhile, the Chinese are steadily sending replacements for the switcher modules....

Hal Mandel
KA1XO