From the manual-

"NOTE: Anyone patching or unpatching circuits from a TTY panel must be sure to pull the plug from the looping jack (LPG) before removing the other plug from the SET (machine) jack. Pulling the SET jack first interrupts all TTY message traffic on that channel. IT ALSO PRODUCES A DANGEROUS DC VOLTAGE ON THE EXPOSED PLUG!"

On Fri, Dec 2, 2022 at 9:46 PM W2HX <[email protected]> wrote:
> Gives new meaning to the word “spacing”
> 73 Eugene W2HX
>
> From: Jeffrey Golas <[email protected]>
> Speaking from enlightening experience, no safety involved ;-) Silly me plugged in a loop the other day, and for a split second I was part of the loop.
>
> Jeff KC3GJX
>
> On Dec 2, 2022, at 9:28 PM, W2HX <[email protected]> wrote:
> Aaah ok. That probably explains things. For some reason I had it in my head that the TRS were used to provide some measure of safety where the sleeves weren’t used. That is how I did my jack field but now I know better. Thanks!
> 73 Eugene W2HX
>
> From: Nick England <[email protected]>
> Use only a 2-conductor plug - tip/sleeve.
> None of this new-fangled TRS stuff like on your Koss Pro/4 stereo headphones
> Nick K4NYW