[GreenKeys] Torn Tape Telay

[Nick England]

Duncan’s AWA talk here shows tape relay in action
https://youtu.be/XFkwWZ6ujy0

Lots more info on tape relay here
https://www.navy-radio.com/tty-relay.htm

And a history of the Navy’s teletype network which IIRC mentions the big
improvement from retyping to repeating
https://www.navy-radio.com/manuals/ntx/NTX-story.pdf

Yes one reperf per incoming line. And one (or two) TDs per outgoing line.

The 6 TD transmitting unit ran 3 channels and two TDs acted in ping-pong
fashion.
Here’s mine operating during testing.
https://www.youtube.com/watch?v=FRdK8ZvXNcI

The channels between torn tape relay stations were always connected -
either leased lines or full 24/7 radioteletype links.

Nick England K4NYW
Chapel Hill NC
www.navy-radio.com


On Thu, Jan 22, 2026 at 12:55 PM Harold Hallikainen via GreenKeys <
greenkeys at mailman.qth.net> wrote:

> This is all amazing history. There was mention of the reperf in torn tape
> relay. For some reason, I can see hand keyed relay for Morse, but retyping
> everything for relay just seems like a LOT of work. Anyway, this made me
> think of torn tape relay, which I think of as early packet switching (each
> message is a packet) and very clever.
>
> On torn tape relay, I THINK there was a reperf on each incoming line, and
> a TD on each outgoing line (and these may be the same wires through
> duplexing techniques). So, did one person watch several reperfs for end of
> message, tear the tape, and take it to the appropriate TD? Was the TD
> sitting there idle? If so, it seems like there would be a lot of wasted
> circuit capacity. Ideally, the TD would be transmitting continuously.
> Perhaps new torn tape would be spliced to the existing torn tape waiting
> to be sent. Or, the whole thing could be automated entirely
> electromechanically. Each message would have a series of routing codes at
> the beginning of the message. The receiving unit would decode the first
> routing code (possibly using a distributor and a bunch of relays), then
> pass the remaining message (with more routing codes) on to a reperf that
> is continuously feeding a TD on an outgoing line. The reperf/TD would be
> an electromechanical FIFO buffer.
>
> So... how did relaying work, and what was its history?
>
> Harold
> https://w6iwi.org
>
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