[AMPS] Bias for SB-220

[yo3ctk@qsl.net]

W8JI:

The real problem is wasted power and heat. Letting the bias run  in
full-tilt on condition is like putting a 600-1000 watt space heater
the room.

Ok, let me see: 1500 out at 60% efficiency means 2500 in. If the bias
current is set at 20% max. plate current, zero signal plate dissipation
would be 500W. You're 3dB off, Tom.

Further, for 50% on, 50% off contest duty cycle, "wasted" dissipation
would be just 250W. Not much of a heater.

On the other hand, I could understand the economics behind EBS approach:
for a few dollars in parts, the manufacturer could use a smaller blower
with corresponding cost reduction. Not sure if an economy in the cooling
system department is a good idea, though.

73 de Mike, YO3CTK



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