[Milsurplus] WWII-era USN headphone question

[Mike Hanz]

I think Robert has it right.  The 49000-49999 listing in NAVSHIPS 
900,109 is dated 1 August 1945 and I cannot find any high Z earphones 
above 1200 ohms listed in it anywhere.  The _Aircraft Radio_ training 
manual put out by the Naval Research Lab on 20 August 1936 lists the 
dual earphone set as 49015, exactly the same as in the August 1945 
directory, and that is portrayed as 300 ohms per earphone unit, so any 
institutional change from high Z to low Z (if it occurred at all) must 
have happened earlier than 1936 in the Navy. 

For those of us who chase mind-numbing numbers, I have some additional 
information at http://aafradio.org/flightdeck/Peripherals.html that 
might be of interest - look under "Headphones and headsets".

73,
Mike

WA5CAB at cs.com wrote:

>I don't have paper to prove it but would assume that since the Navy did much 
>the same as the Signal Corps and AAF with microphones (handheld RS-38 and T-17 
>used with both ground and aircraft sets), they did the same thing with 
>headsets.  
>
>However, throughout the entire 49xxx listing that I have, I don't see 
>anything but 300 or 345 ohm receivers and 600 ohm headsets.  So if Naval Air used a 
>Hi-Z headset, they either used HS-23 or something whose number I've never come 
>across.
>
>In a message dated 7/16/2005 11:29:15 AM Central Daylight Time, 
>kk5f at earthlink.net writes: 
>
>>I've been unable to find listings of the "official" headphone sets that
>>would typically be employed with WWII USN sets, other than the late WWII
>>H-1/AR helmet and the H-4/AR headband units, which I believe are 300 ohm.
>>There must have been earlier (pre-JAN) USN headphones, possibly of higher
>>impedance.
>>
>
>
>