[GreenKeys] patch cord question

[Richard Knoppow]

      I don't know of a good history of plugs and jacks but one would be 
interesting. The familiar "telephone" plugs and RTS type were either 
standard Western Electric types or derived from them.  At one time the 
standard patch cords used in broadcasting were dual 1/4" ring and tip 
type. The advantage of these was that you could reverse polarity by 
turning the plug over. These were replaced with the RTS switchboard type 
plugs probably around the 1950s because they took up half the space. 
Eventually, smaller plugs began to be used.
     The old tip and sleeve headphone plug and the TRS were used in the 
telephone system, not sure about the dual plugs but I think they 
probably also were. I have also run across some larger than 1/4 plugs 
that look exactly like the 1/4" ones, I think these were used on some 
Bell & Howell sound projectors for speaker connectors. I suspect they 
were custom made for this application.
    I have been retired from broadcasting for a couple of years now but 
when I left we were still using miniature TRS cords by the thousands for 
audio.  Note that WW-2 vintage headphones for use in aircraft had a 
"bail out" connector near the headphone, a short body 1/4" inch plug and 
jack for quick disconnect if necessary. A long body telephone plug will 
go into the female connector with some sticking out but a short body 
plug will not connect to a long body female cord jack.
     The original plugs probably date back to the teens if not before.

On 2/1/2017 10:04 AM, Jeffrey D Angus wrote:
> On 2/1/2017 11:54 AM, Doug Alderdice wrote:
>> They appear to be like WE 310 switchboard plugs.
> Yes, and they work quite well with Switchcraft long frame jacks.
>
>

-- 
Richard Knoppow
1oldlens1 at ix.netcom.com
WB6KBL