The only diffference is the resistance of the heater, The W is the same.
Military aircraft and motor vehicles often use 24 - 28V electric systems.
4, 4cx350_s can make 1500W in AB1. The input circuitry is simpler than
g-g. The screen can be supplied from the LV end of the HV bleeder.
Screen V can be regulated and safely current-limited with a 400V shunt
zener string. //
Since the 350's grid-V is only c.30v, for use with a 200W-max radio, I
would use a 5.5-ohm grid terminating resistor fed from a 50-ohm in, 9 to
1 stepdown toroid transformer. Such a resistor can be made from 18,
100-ohm, 3W-rated Matsushita resistors in parallel. (note -- these
resistors will dissipate 12W each intermittently and they have c. 11nH of
inductance) For other than QRPP enthusiasts, anode supply potential
should be 2500VDC under load for CW/RTTY/FM/AØ -- and it could be a bit
more for SSB. Anode-current for 4-tubes should not exceed 1.2A - except
for those who have more money than brains. A transformerless grid bias
supply can be made by half-wave rectifying one side of the mains and
resistive-dividing the resultant -160VDC down to c. -30V on TX and c.
-60V on RX. This does not need to be regulated since there is zero
current consumed.
>Any of you fellas ever apply these to a project for amateur amplification?
>Is
>there any disadvantage to the 26.5 volts on the heater, or does it just heat
>quicker? Not much info on Rell's page via Richardson's Electronics. Let me
>know.
>Paul..
- Rich..., 805.386.3734, www.vcnet.com/measures.
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