{Collins} Re: 75S-3 advice



As far as the 6BF5 audio output tube in the S-Line receivers, I don't think
it's a matter of Collins "running them hot".   The thing draws 1.2 AMPS of
filament current!  That's over 7.5 watts just to light it up!   That's where
the heat comes from.  The plate dissapation is nowhere near that much, so
regardless of how the circuit is set-up, the major cause of the brown spot
is the heater power itself.

If you sub a 6AQ5, the heater power drops to under 3 watts, BUT, the cathode
resistor must also be changed due to the differences in the tube's
characteristics.

73' Charlie k3ICH


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