[ARC5] Fw: Receiver current drain (AF output)

[Mike Hanz]

On 1/7/2011 1:30 AM, WA5CAB at cs.com wrote:
> The US Navy and Naval Air switched to low-Z audio sometime earlier (I have no info on
> when).

I'm not sure with any precision either, but the 20 August 1936 
publication "Aircraft Radio", written by the Naval Materiel School at 
the Naval Research Laboratory,  contains the apparently ubiquitous (by 
then) 49515 headset which had a 'per ear' impedance of 300 ohms 
(http://aafradio.org/flightdeck/Peripherals-headsets.html ).  There is 
no mention of earlier design specifications, so the switch had to have 
happened prior to that by enough of a margin to make historical remarks 
appear unnecessary to the authors.

Very 73,
Mike  KC4TOS