Nope, no diodes or capacitors. No, the loops are not interconnected except sharing a common negative lead (usually ground). The plus lead of the loop is isolated via the current limiting resistors. Loop 1 doesn't care whether Loop 2 is 60ma or 0 ma. The one thing that you can't do is stick a grounding piece of gear (like a TU) into the middle of a loop, because then devices downstream in that loop get bypassed..

plus---fixed resistor---rheostat----TTY1----TTY2----TU1----minus (ground)
plus---fixed resistor---rheostat----TTY3----TTY4----TU2----minus (ground)
etc.

Nick England K4NYW
www.navy-radio.com


On Tue, Apr 4, 2023 at 12:04 PM Jeff G <jeffg@junknet.net> wrote:
If I'm not mistaken, they have diodes and resistors (and maybe caps) in line to isolate each loop channel. In working at the ship with 24 loop panels I wondered the same thing, although in those cases it seems most of the loops/panels are a mix of loops and just straight equipment jacks.

Jeff

On Tue, Apr 4, 2023 at 11:59 AM Paul Heller <paul0926@comcast.net> wrote:
I’ve always wondered how one power source could supply six loops. Don’t they each need a dedicated loop supply? Or are all six channels joined together into one loop?


Paul
W2TTY

On Apr 4, 2023, at 3:31 PM, Nick England <navy.radio@gmail.com> wrote:


NO built-in supply. Normal use is to attach a supply to two terminals. That powers six separate loops, each with fixed current limiting resistor, rheostat, and jacks. 
IF you want to power a loop from a separate supply (like built-in to a Dovetron), there are jumpers to change the source. If that separate supply already has current limiting, then you should jumper the 1203’s fixed resistor for that loop, as Tom said. 
This is an excellent device to connect all your equipment together with lots of flexibility. 
The manual is here

The “extension” on top is just a cover for cable exit if wanted. 

Cheers
Nick

On Tue, Apr 4, 2023 at 8:19 AM W2HX <w2hx@w2hx.com> wrote:

Tom, are you saying the 1203 has a built-in loop supply (local power)? I noticed in RH’s pictures that one was taller than the other. What is the difference between them?

 

 

73 Eugene W2HX

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

 

 

 

From: greenkeys-bounces@mailman.qth.net <greenkeys-bounces@mailman.qth.net> On Behalf Of Tom Hunter
Sent: Tuesday, April 4, 2023 12:45 AM
To: GreenKeys@mailman.qth.net
Subject: [GreenKeys] 1203

 

For anyone who buys a 1203 from R.H. Goff make sure to download the book from navyradio. It is a small book but it is essential.

 

Even with the book it took me nearly a week to install my 1210 and work the bugs out.

 

Now I like it very much.  I have loops 1, 2 and 3 wired for remote power from three terminal units with built-in loop supplies. 4, 5 and 6 use local loop power. I plan to key two of those with relays, I have a 120 VDC power supply that is capable of running those three loops with ease.

 

I always keep one locally powered loop free for testing individual Teletypes,

 

For remotely powered loops be sure to short the appropriate fixed wirewound  resistors. The remotely powered loops must be wired the reverse of the locally powered ones to have the meter read  to the right on all loops.

 

I wired my Teletypes to the "set" jacks. The abiIity to patch is amazing. I also chose to wire my "misc" jacks into each vertical loop to give me an extra patch point. I have two excellent external meters that I patch there, so I can meter three loops at once. They also show me that the meter on the my 1210 is not very accurate. It reads low.

 

Test each loop as you wire it. Then kill all loop supplies as you wire the next Loop.

 

A few Tips learned the hard way!

 

Tom N3CRK

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