Yeah. Ok. Positive tip it shall be. My ST-6 puts out a whopping 180VDC for the loop voltage. I had originally built my jack field using TRS and long frame telco jacks for the reasons of safety. But dealing with those long frame plugs, the tiny screws needing the use of that special screw driver with the center pin, needing those tiny crimp-on ring terminals you name it, I gave up. I guess I could have gone regular ¼” TRS but I ultimately decided simplicity is the way to go and I’ll just have to be careful around the shack (or get a nasty reminder if I’m not careful).

On an similarly-related note, my two ST-6’s have developed a problem where the 6 position molex loop jack on the rear has had their “ears” break off so they are no longer being held in firmly into the square opening for them. They are now floating using just the rear wiring to keep them in place. I used to have an older ST-6 that had ¼” jacks but they moved to the molex for two reasons (according to the documentation). One was for safety reasons (as we’ve been discussing) and the other is that this would allow 2 loop devices as the 6 pin molex uses 4 pins for two loop connections. That latter benefit doesn’t seem like much of a benefit.

But the plastic used in these ancient molex connectors seems to be getting brittle with age, as is evidenced by two out of two ST-6’s having the same ailment.

73 Eugene W2HX

Subscribe to my Youtube Channel: https://www.youtube.com/@w2hx/videos

From: Nick England <[email protected]>
Sent: Thursday, January 19, 2023 6:53 PM
To: W2HX <[email protected]>
Cc: [email protected]; [email protected]
Subject: Re: [GreenKeys] jack field polarity?

How peculiar of AT&T, Western Electric, US Navy, Western Union, US Army, US Air Force, Teletype Corp, Defense Communications Agency, Dovetron, HAL, and a bunch of other people to not follow what some hams did…..

A ham shack is wired by the same person who will ever use it. So you can do anything you want and it doesn’t matter. If you are responsible for thousands of machines and thousands of operators/installers/repairers, it is nice to decide on something and stick with it.

YMMV

On Thu, Jan 19, 2023 at 6:07 PM W2HX <[email protected]> wrote:

Ok so maybe...Commercial products used TRS but Navy just used TS?

73 Eugene W2HX
Subscribe to my Youtube Channel: https://www.youtube.com/@w2hx/videos

-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of Harold Hallikainen via GreenKeys
Sent: Thursday, January 19, 2023 5:22 PM
To: [email protected]
Subject: Re: [GreenKeys] jack field polarity?

The TU-170 uses a TRS jack with the positive loop supply on tip, the keying transistor collector on ring, and ground on sleeve.

Ideally, I'd like all equipment to be the same. In my DSP TU ( https://w6iwi.org/rtty/DspTU/ ), I'm using an SSR to key the loop and an AC optocoupler to sense loop current. It is floating and polarity agnostic, just as my model 15 and 14 stuff is.

Right now, I have two TRS patch boxes as shown at https://w6iwi.org/rtty/ . One is driven by the TU-170, and the other by a loop supply. I can plug any piece of equipment (including the DSP TU) into either of these. Also, the positive end of the loop supply is on the tip of the connector.

Harold
https://w6iwi.org

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Nick England K4NYW
www.navy-radio.com