[ARC5] Receiver current drain

[Mike Morrow]

>We must remember that in military service, this tube was driving headphones
>at the 100-200 mW level so there was no requirement to generate a large amount
>of audio.

Is that really true?  WWII-era aircraft interphone systems (pre-AN/AIC-2) did NOT
amplify the audio of ANY receiver connected to the system.  They simply routed
receiver AF outputs to each station box.  Bomber installations of, say, the
SCR-274-N could worst case have ten headphones connected in parallel to the AF
output of the receivers. (Though most stations would be usually selected to the
interphone amplifier's AF output, itself usually a simple one-tube amplifier that
amplified *only* microphone audio.)

Apparently the AF output of the command, liason, and DF receivers was enough to
meet the demand.

>...some owners have in the past reported adequate audio output into a loudspeaker
>even with the original value...

In the 1960s, I often used a BC-453-B to monitor maritime Morse around 500 kHz.
I got adequate drive for a speaker by using an appropriate impedance-matching
transformer.  No receiver AF tag modifications were required.  (I used a 240 vdc
HV supply.)

Mike / KK5F