Model 28 Transmitter-Distributor (TD) Component Guide

The TD consists of a Transmitter (tape reader) and Distributor (parallel-to-serial signal converter)

Note: There are M28 (5-level) and M35 (8-level) equivalents for most of these. 
These can also be modified for 6-level or 7-level use - the parts manuals usually have the modification info.

One Shaft, Single Contact - The tape reader sensing pins set transfer levers. These are used by the camshaft to open/close the contact assembly of a mark/space signal generator (like the one in a 28 keyboard).  td_8404.JPG (1542802 bytes)
Two Shaft, Multiple Contact - The tape reader sensing pins are operated by one shaft and set a bank of storage switches. 
Then a second shaft turns the distributor cam which sequentially samples the storage switches and sends out a serial character.
The two shafts have separate clutch trip magnets so that timing can be controlled as desired.
td_8387.JPG (2027152 bytes)

 


Unit

Base

Cover

Contacts

Head

Mechanism

LD

LRSB ? Multiple Contact n/a One-shaft
Distributor only with no tape reader - 5-wire parallel input, serial output
Manuals 234B, 1159B

Distributor cam and contact assembly
td_8388.JPG (2616892 bytes)

LX

LXDB LXDC Multiple Contact Fixed Head One-shaft
need photo Tape Reader only with no distributor - 5-wire parallel output only. Manuals 235B, 1161B

LXD

LXDB LXDC Single Contact Fixed Head One-shaft
For stand-alone LXDB, multiple unit LMXB, or ASR mounting. Usually provides serial output only (but with an option that adds 5-wire parallel output)
Manuals 235B, 258B, 321B, 1161B
td_8404.JPG (1542802 bytes) Photo shows LXD on Miniature LXDB base

LAXD

- - Multiple Contact Pivoted Head Two-Shaft
Used in 28ASR and in 28RT. The Pivoted Head (climbing head) sensing pins move along a taut tape to read the last character from a reperforator. Provides 5-wire parallel output from tape reader. Or provides serial output from distributor. Also can take in 5-wire parallel input to distributor and provide serial output. 
Manuals 251B, 252B, 1170B, 573-127-800TC
td_8386.JPG (2156565 bytes) td_8387.JPG (2027152 bytes)

LBXD

LBXB LBXC Multiple Contact Fixed Head Two-Shaft
Used in LBXB stand-alone base, in ASR, or in LMXB multiple-mount base. Provides 5-wire parallel output from tape reader. Or provides serial output from distributor. Also can take in 5-wire parallel input to distributor and provide serial output. 
Manuals 242B, 243B, 1165B, 573-127-802TC, 

LCXD

- - Multiple Contact Pivoted Head + Fixed Head Two-Shaft
Used in 28ASR. The Pivoted Head (climbing head) Reader moves along a taut tape to read the last character from a reperforator. The Fixed Head Reader is used to insert additional message tapes. Both heads feed a single distributor. Provides 5-wire parallel output from tape reader. Or provides serial output from distributor. Also can take in 5-wire parallel input to distributor and provide serial output. 
Manuals 253B, 254B, 1171B, 573-127-803TC
td_8389.JPG (2244263 bytes) td_8392.JPG (1980864 bytes)
td_8391.JPG (1591615 bytes) td_8393.JPG (2238707 bytes)

LDXD - What is it ??

--

LEXD

- - Multiple Contact  Fixed Head Two-Shaft
CARDATA - Card or Tape Reader (M35)
Manual 574-242-100TC

LFXD

- - Multiple Contact  Fixed Head Two-Shaft
Tape Pull-Back Unit. For use in ASR
Manual 1182B

TD Bases

Mystery Base? - allows M28 TD to be used in M14 base?

td_8395.JPG (1590855 bytes)
td_8396.JPG (1990011 bytes) td_8397.JPG (1405724 bytes)

LBXB

Stand-alone base for multiple-contact TD (LBXD)
Manuals 249B, 250B, 1169B, 573-128-800TC

LCXB

Base for mounting TD to ASR
Versions for LXD, LAXD, LBXD, and LCXD
td_8393.JPG (2238707 bytes) photo shows LCXD on LCXB base

LEXB

what is it used for? (not an LEXD)
td_8398.JPG (1936328 bytes) td_8401.JPG (49342 bytes)

LFXB

ASR base for pull-back TD
need photo Manuals 1182B

LMXB

Triple-TD base for single-contact or multiple-contact TD units

28-trip-td-02.jpg (77217 bytes)

LRSB

Stand-alone base for LD distributor

LXDB

Stand-alone base for single-contact LXD TD

LXDB base + 
LXDC cover

tt187-ug-11.JPG (79937 bytes)

LXDB (miniature)

Stand-alone base for single-contact LXD TD - uses smaller motor and base

tt187a-ug-12.JPG (132536 bytes)

tt187a-ug-11.JPG (78494 bytes)
td_8403.JPG (1795921 bytes) td_8402.JPG (2553892 bytes)