NFKM Radio Central
Five Unit Code
Quick Brown Fox
Old Inventory List
Old Look For Items
- Items we're looking
Model 10 Page Printer, and/or documentation on this, the first Teletype.
- Model 37, any model, no documentation necessary.
- Model 38, wide carriage, no documentation necessary.
- Type 2 Dataspeed Sender and/ or Receiver, no documentation necessary.
- Type 4 Dataspeed Sender and/ or Receiver, no documentation necessary.
- Type 5 Dataspeed Sender and/ or Receiver, no documentation necessary.
- CX Reader, with or without base
- Any portion of a teletypewriter selective calling system,
especially the station selector itself.
- 100A Key Telephone System
- 101A or 101B Dataset for Model 15, 19, or 28 Dial TWX service.
- Model 14 R/T Cabinet, or portion of
- Model 28 R/T Cabinet, or portion of
- 911 Data Test Set
- 921 Data Test Set
- 903 Data Test Set
- 904 Data Test Set
- Dataspeed Oscilloscope
Thanks again for any leads. We are a California Not-For-Profit,
Public Benefit Museum. We can provide tax deductible receipts for
donations. Values are set at approximately 50% of original price. I
have many pricing books from Teletype Corporation and a cross
reference for military equipment designations.
In the 28 line the standard store-and-forward unit was the R-T stand;
however the LRXD was made to the same form factor as the FRXD so it
could be a direct replacement - besides the regular XD, there is a two-headed
XD that was used, mostly by the military I think, as a sort of cheap
two-channel time-division multiplex. The distributor faceplate had
the code segments cut in half, and sent the character from one head
on the early segments and the other character on the late segments.
Receiving this was just a matter of fiddling with the range finder on
the printer or reperf so that it sampled early or late in each bit
cell, and hence copied only one of the two characters. Another
two-headed XD is the Vernam cipher; one head carries the message
tape and the other carries the one-time-key tape, and the two
characters are exclusive-ORed to generate the encrypted signal. Then
the same machine can be used for decryption by putting the tape
containing the encrypted signal in one head and a copy of the key
tape in the other.
There were several packages in the World War II period, consisting of
an approx. 30" cube cabinet with an XD and Model 14 reperf on
top. (132A1 comes to mind, but may be completely wrong) One of these
was simply the tape equipment and the cabinet held a couple of
repeaters so the thing could be run neutral or polar or whatever.
Another thing in a similar appearing cabinet had an electronic timer
that supplied start and stop pulses - intended to synchronize with
tape sending on a radio circuit and correct for mutilated start and
stop pulses. I have often wondered how effective this was. A third
one was for the Vernam cipher sort of machine. The box held the
relays that did the mixing; and on top there could be a key generator
box to take the place of the one-time tape.
Also from WWII period are the AN/FGC-1 FSK converter and its
companion AN/FRR-3 receiver, each in a seven-foot tall relay rack. A
number of hams used these things in the early days of RTTY, tho the
size and weight were always obstacles.
Speaking of the Vernam cipher, I've read that Vernam or some people
who came after him had a key generator that used several endless tape
loops, each of a relatively prime length compared to the others. And
that Wm. F. Friedman was able to break that encryption; it wasn't
strong enough. With a true one-time tape the encryption is
unbreakable, but there is the problem that you need as much key as
you have message, and you have to get the key tapes to the two points
that wish to communicate. The tape loops scheme was to try to cut
down on the amount of key needed.