[GreenKeys] Model 28 TD - use of dual shaft (LBXD) vs single shaft (LXD)

[Nick England]

I got to wondering about where the dual-shaft TD was used.

BACKGROUND FYI -
The single-shaft LXD has a single clutch magnet and operates with
direct action from "read the holes" to "key the loop" on every cycle.
The dual shaft LBXD has two clutch magnets with a transmitter shaft
(read the holes) and a distributor shaft (key the loop). They can
operate together (via a contact on the transmitter camshaft triggering
the distributor magnet) or separately - the 5 lines from the
transmitter and 5 lines to the distributor are brought outside so
"multi-wire" data can be read and/or inserted into the serial loop.

QUESTION
SO, I know the dual shaft versions are used in torn-tape transmitting
equipment where message header characters are inserted between TD
transmitter and distributor. And anywhere else that would be useful.
I'm not clear about where else they would be used.
Al K8WXQ has a 28ASR with LBXD but the 5 lines are just wired straight
from transmitter to distributor (This is its original configuration).
- so why is the LBXD used in that ASR instead of an LXD?


Note - there was also a single-shaft LXD with 5-wire output so you
could use that to drive something - I have a piece of torn-tape gear
that recognizes ZCZC, FM, TO, BT, etc, that way.

So MANY Teletype variants!!!

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