OK, what I know about TTY loops is from how the Navy ran things. Ships and shore stations typically had anywhere from 6 to 48 loops with bunches of reperfs and printers. They engineered a system to work reliably 24/7/365. So that’s what I have replicated in my basement. I can patch any machine to any TU. 

The “small” patch panel SB-1203 has 6 loops, each with up to 4 devices plus TU in series. One 1-amp 120vdc supply runs all 6 loops for one or two patch panels. Each loop has a rheostat so you can adjust it to 60ma. 
Larger 24-loop patch panels have connections for two 1-amp supplies. 

If you don’t have Navy equipment it isn’t hard to make an equivalent system with jacks and a power supply. 
https://www.navy-radio.com/rtty-patch.htm

https://www.navy-radio.com/tty-loop.htm

Nick England K4NYW
www.navy-radio.com


On Mon, Sep 23, 2024 at 8:15 PM Nick England <navy.radio@gmail.com> wrote:
I don’t understand. It’s a 60ma current loop. If you set the loop current to 60ma, every device gets 60ma. It is 60ma whether one device or three. It takes the same power whether one device or three. Period. 

A 120vdc loop supply and 1800 ohms or so will run a loop with TU, reperf, and printer no problem unless you’ve got some extra unnecessary resistance somewhere. I run that all the time with no problem. Maybe you need to adjust the KSR rangefinder because of extra inductance from the reperf causing some signal distortion?
What am I missing here?

I’ve got a whole bunch of machines in 24 separate loops running off two 1-amp supplies. 
https://www.navy-radio.com/misc/shack2/IMG_4828.JPG
Each loop is just 120v, 60ma. 

Nick England K4NYW
www.navy-radio.com


On Mon, Sep 23, 2024 at 6:35 PM Anthony Watson via GreenKeys <greenkeys@mailman.qth.net> wrote:
Does anyone know if patch panels with loop current are still around or are they unobtainium??? Or, maybe  a modern-ish-component schematic exists to make one? 

Would like to take a signal from my one loop source and propagate it to multiple machines - not enough juice in the one supply I have to power a useful daisy chain loop. Hence a patch panel that powers itself might be just the ticket.

At least trying to boost the Rx loop, the KSR selectors, reperf selectors, and motor shutoff control are just too hungry all at once.

I made a switch box and employed some VRs to conserve the loop power I have to go around and manually isolate the loop to the machines I’m using  That got me to reliable copy, which that’s not terrible but also not great, and still not enough to be reliable. The motor control seems to need a bit more than I got to trigger the relay.

Anthony
WB7PZZ
WatsonAC@aol.com
Sent from my iPhone
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