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