The HL-1 (aka X22) was used to read 5 level encoded or plain text tape into the KL-7 or alternately a SIGABA device.

It has no cryptographic parts but it did include a stepper to bypass the spaces in the 5-letter groups received via teletype. During a decoding operation, the operator placed the punched tape on the reader taking care to ensure that the tape started at the first code group after the indicator groups. Next, the start switch was enabled and the KL-7 would start to type clear text. Alternately, the HL-1 could read plain text tape which could be encoded by the KL-7.

Click here for HL-1/X22 data sheet.

x22_hl1_s.jpg This HL1 has the TSEC designator affixed below the control panel and the placard indicates it is fitted with 50 wpm gears. Click to enlarge.  (Photo via Jan Lispet) 
There was an option to make the KL-7/HL-1 assembly work online, but at least in Denmark it was considered too prone to TEMPEST analysis so it was not used. The HL-1 was an unclassified device and in Canadian service is was affectionately called "The Mule".

Plugable, flatpack IBM relays were used within the HL-1 to convert the teletype code into a signal  suitable for the KL-7. Output from the reader appears at a pair of 24 pin female Cinch Jones (C-J) connectors situated at the back, bottom of the chassis. The reader was interconnected to the KL-7 by a cable terminated with a pair of 24 ping Cinch Jones male connectors on one end and the mating KLX-7 connector on the other end.


The HL-1 had a small control panel consisting of a Start/Stop switch, a three position rotary switch marked D E P (Decode, Encode, and Plain text), a toggle and pushbutton switches.

HL-1 control panel closeup.  (Photo by Jerry Proc)

In the Decode position, the HL-1 would skip space characters on the tape. In the Encode position, the the HL-1 could be used as to encode messages on the KL-7. The Plain Text position would only be used for printing a plaintext tape directly on the gummed tape of the KL-7, without engaging any other component of the machine other than the printer. At least one operator says that it was something they never did.

The Toggle switch to the right of the D E P switch was used together with the pushbutton for manual stepping of the tape with the function of the toggle switch being to reverse the direction of the tape.  Most likely it was one step for each push of the pushbutton.

The round item above the tape reader assembly was a tape notching device. An operator could place the last character of a message on an index mark in this device, push the round button and "notch" the tape edge. The sensing of the notch would make the reader stop on "end of message".

HL-1's were built by the Teletype Corp. They incorporated a small AC powered motor made by Bodine and were powered from a 120 VAC mains source.

HL-1/X22 with cables attached. The gray metal box on the right is the 220/100 volt transformer with the power connections on the top and just below the removeable lid. This was the NATO version of the machine. The 220 volt mains power plug is the European Schuko (Schutzkontakt) system used mainly in the 1950s and 60s.  (Photo via Jan Lispet) 

Cinch-Jones female receptacles were installed on the SIGABA and the HL-1 devices.

One cable assembly had Cinch-Jones male plugs on each end and was used to interface the HL-1 with the SIGABA. The second cable assembly contained two male 24 pin Cinch-Jones plugs on one end and a smaller rectangular plug on the other end to connect with  the KLX-7.

The HL-1 has a pair of "dummy"  24 pin Cinch-Jones receptacles installed in a cascaded fashion on the wooden shipping pallette on the left and right sides.  When shipping, the cables would be inserted into these dummy connectors to ensure that the male pins of the cable would not be damaged.

Cinch Jones 24 pin connectors were used with HL-1 cables. Electrical Ratings from the  FEDLOG DATA are: 10 Amps per contact @ 730 VAC. Contacts are copper-alloy cadmium plated. Body is black plastic phenolic with metal hood and 180 degree rear entry with strain relief. The male plug bears a National Security Agency PN: CE 88241; Federal Stock Number  5935-587-9671. (Photo via E-bay)

x22_connectors.jpg Closeup of the dummy shipping connectors. (Photo by Jerry Proc) 


Top view looking towards the front.
Rear view
With cover off - rear view looking towards the front. 
View of right side
Tape reader detail. Above it is the tape notching device.
Paper tape reader details. Someone has cannibalized the motor in this unit. 
All photos by Jerry Proc. These HL1/X22 examples are held by the C & E Museum in Kingston, Ontario


Contributors and Credits:

1) Bjarne Carlsen  <bca(at)fakse-ldp.dk>
2) George Mace e-mail: <gmace8(at)comcast.net>
3) Jan Lispet <jw.lispet(at)casema.nl>
4) Helmuth Jim Meyer <dj2ei(at)yahoo.de>
5) Communications and Electronics Museum, Kingston, Ontario
6) Nick England <navy.radio(at)gmail.com>

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Feb 26/15