[Milsurplus] MC-385-A

[Al Klase]

Larry,

Early WWII Signal Corps equipment was designed to use high-impedance 
headsets similar to the ubiquitous "2000-ohm (DC) 'phones."  I believe 
the average AC impedance was assumed to be 4000 ohms.  At some point the 
entire military moved to headsets with an impedance in the neighborhood 
of 600 ohms.  The MC-385-A was issued to allow the use of the new 
headsets with the old equipment.  It contained an appropriate transformer.

Al

On 8/20/2013 8:52 PM, telegrapher at q.com wrote:
> I found one of these in the bottom of one of my junk boxes.  However, it had an external PL-055 attached to in instead of using the regular jack.  Why i don't know but it had a 280 ohm resistor soldered to the tip side of the jack inside.  Also was a note written on the capacitor as i can read it, 28 or 280 ohms input and 8 or 80 out.  Outside of the box says : Headset adapterMC-385-A high to low impedance, for use with Headset HS-33 or HS-38.  It doesn't appear that the 280 ohm resistor was standard and the only thing original in there are the PL-055 jack and plug along with the 3 wire capacitor.  Where was this used, what type equipment other than the HS-33/HS-38?
>
> Larry
> W0OGH
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-- 
Al Klase - N3FRQ
Jersey City, NJ
http://www.skywaves.ar88.net/