atcomsystems.ca/forum Forums Other TDM Phone Systems 1A2 and Comkey Telephones & Systems 1A2 dintintive ring on CA

Ed said: ...connecting a single pole slave relay that has its coil driven by the interrupter's "LF" output. The contacts on this relay would then switch the "RN" output. The LF and RN cadences were aligned so that it provided a perfect double ring. I just used this switched output to feed the appropriate line cards. It worked well.

I would assume I would need to pull the 551C KSU off the wall to access the backplane to wire as you suggested to the "LF" output?

As a temporary measure, I punched down the coil of the relay to "LG-L" for line 2 on the system 66-block, and put the relay contacts in series with the 118 ring generator. Works very nice, thank you. This scheme of course doesnt use CA for line 1 at all.

There is an LF terminal on the lower right side of the KSU's internal 66 block.

This is very interesting to me. I was in sales for Bell in early 1970 and sold one of the first ComKey 718 systems anywhere. No modifications were supposed to be allowed, but it didn't take long before they were made anyway. The same customer who bought the 718 upgraded to one of the first 1434's a few months later. As I recall, this was the first key system with optional music on hold and it sold like flapjacks.