[GreenKeys] jackfields

[Jim Haynes]

On Tue, 17 Feb 2009, Sheldon Daitch wrote:

> The older VOA facilities at Greenville used dual TS for
> all audio.  I can't seem to locate a picture of the plus,
> but there were two 1/4-inch plugs with a common
> plastic case/handle.  Normally, the plastic handle had
> ridges on one of the small sides, smooth on the other, to
> keep the correct audio phase.
>
That is a design that dates from open-wire-line telephone days,
where you might want to test on a single wire.  I've seen it used in
broadcast stations circa 1950 even though everything was in cable.

Then there is a much later design where two TRS plugs are put together
with a similar spacer handle; these were used for four-wire or six-wire
patching in the telephone biz.