11 Set stuff

[Chris Suslowicz]

Originally Posted by cletrac

I bought this voltage meter off ebay but I'm not sure if it's the one that was used with the 11 set. I also got a grungy microphone NO 3 for $10 to get the plug for a headset I have.
When did they use the muffs on the 11 set headphones? I have 2 pics with them being used and lots of pics without them.

Hmmm... that's a somewhat modified civilian voltmeter, and definitely not part of any military set.

Note that the microphone and headset plugs are different, and it is for a reason. The microphone plug is No.10 and has a straight barrel. The headphone plug is No.9 and has a wide "step" at the base.

The reason for the "step" is that originally all microphones had carbon granule inserts and required a 3 volt supply to operate. This was supplied by dry cells. If you plugged the headset into the microphone socket, this would discharge the battery fairly quickly (in addition to the set not working at all well). The step prevents the headphone plug from being inserted far enough into a microphone socket to make contact with both of the contacts, thus avoiding the problem.

As to the "muffs", British headsets tended to use plain Bakelite earpieces, the American ones for the WS19 had circular felt or velvet over sponge rubber muffs, and the Canadians excelled themselves with chamois leather covered sponge (oval) muffs that went around the ear instead of pressing on it, making them supremely comfortable and also excluding background noise - ideal for long periods of use.

Chris.

(There's also a 3-contact version of the No.10 plug, used with Microphone, Hand, No.7 with the ZC1 transceiver - the third contact is needed for transmit/receive switching.)