Tools of the Trade
As in any organization which performs remedial maintenance, there are always specialized tools which must be used in order to accomplish the task. This document will provide a a listing of those tools which were used to repair and maintain crypto machines.


These consisted of two opposing notched claws separated by a phenolic or plastic block.  Each claw was designed to grab opposite sides of a "bi-mag" and each claw had a separate wire that ran to a connector that could connect to an ohmmeter or an oscilloscope.

Submitted by: Doug Eyre
Hewitt, TX

Above and below: An example of a crab claw tool. Test wires could be soldered to the eyelets on the claws (Photo by Jerry Myers)

Doug Eyre and Ken Sutterfield describe the government-issue One Maker.  "We had a device that we called a "One Maker" which was used in conjunction with the crab grabber. This little gem was a two piece threaded cylinder made from solid aluminum stock and employed a "C" cell.  There were some very minimal electronics in one end.  The wall of the chamber for the "C" cell was at least 3/8 of an inch thick and there was a push button on the side.  Two two banana jacks were attached in lieu of the lens. These jacks provided a connection to the crab claw.

A tech would hook up the crab grabber to a bi-mag thus providing him with the ability  to induce a "one" state into the bi-mag's core. Doug says that One Maker served very little purpose.

This is a hand made One Maker, using probes from the period, was made by George Mace. There was an internal resistor to limit current flow. (Photo by George Mace)

It was a MAJOR and I do mean MAJOR cryptosecurity violation to attempt, in any way, shape, or form, to attempt to discover rotor wiring, even for troubleshooting.  Among the test equipment for this purpose was a jig which contacted all 36 pins at once, and the only test one was allowed to make was checking for continuity on all 36 contacts, thereby not knowing what was connected to what. If one had an open, or an intermittent, it was permissible to polish said contacts, and retest using the jig.  If one still had an open or an intermittent, the entire rotor set had to be returned to the Cryptosecurity Officer for return and replacement.

Submitted by: Gregory W. Moore


Dick Morris exlains the term.  "The seven-level screwdriver is actually nothing special . Quite properly , it would be described as "Screwdriver, Slotted, Pocket Clip; colour amber; Style: 1/8 in x 2.5 in. shaft." Many crypto techs carried one in our front shirt pocket. The USAF descriptton for the screwdriver was: "IVY TOOL GS" 1/8 inch slotted screwdriver with 1 3/4 inch yellow shaft.

I don't know how widespread the term was but it was common in the cryto world and may have also been common in the rest of the Air Force electronics world. The name derives from the journey level of the Air Force Speciality Code (AFSC). The apprentice cryto technician was a 30630, intermediate level was 30650, and journey/advanced level was 30670. 30690 was the management level. By the time you had earned your seven level you had the experience and had completed training to be a pretty good technician.

In checking my old course certificates, in 1977, I attended "L3AZR30670, Secure Communications Electronic Systems Technician." It was always referred to "Seven Level Class." It was a 318 hours long and split about equally between advanced electronic systems and circuit theory along with management skills including writing, speaking, and Air Force History. In the classroom were several types of cryptographic equipment, including a KG-13 with the serial number 1 on the outside case.

The seven level screwdriver is nothing more than a minature standard screwdriver. Amber was the proper colour for the handle. 

A modification to a crypto machine was known in the US military as a TCTO or Time Compliance Technical Order.  Before the mid-1970s, they were only known as Modifications or Mods. TCTOs had been around long before this for non-Comsec equipment but not for the crypto equipment. Designating them as TCTOs was apparently part of an effort to bring record keeping for crypto into the main stream.

The AFKAM-504 was another document used in the Air Force (the AF referred to Air Force). It provided all of the data codes required to document maintenance on COMSEC equipment. The prevailing edition around 1968 was AFKAM-504C. They were reissued with a new letter as revisions were done. About the highest number known was AFKAM-504K.

Each piece of equipment had numerous codes, starting from the end item and down to plugable components, such as circuit cards. Other codes were the type of maintenance (e.g., scheduled or unscheduled), How Mal or how the equipment malfunctioned. A favorite was 255, meaning no output/incorrect output. As someone else said, in the Air Force all maintenance actions were recorded on an AFTO Form 349, Maintenance Data Collection Record.

Each machine was affixed with a modification history label and the instructions would tell the technician to scrape off a specific number from the label or put an X through it. To avoid any confusion as to whether the label was intentionally scratched off or scraped off by mistake,  a tool used for circuit board repair was used to punch a hole in the label and lift off the specific number. The tool consisted of a hollow tube with one end sharpened to a chisel point.

Submitted by: Doug Eyre, Hewitt, TX with additions from Dick Morris.


Dick Morris provides some insight into the parts numbering system. "Other information of consequence relates to part numbers and Federal Stock Numbers for COMSEC equipment and parts manufactured specifically for COMSEC equipment. These number didn't cover common parts like transistors, tubes, or resistors, but they did cover circuit cards, modules as used in the KG-13 and KW-7, specialized hardware like pins for card readers, and entire end items. Most of the equipment I worked on used a part number such as "CE000000." The zeros would have been replaced by numbers. I don't remember the exact number of digits, but it was around that many. I vaguely remember that most of the KG-13 parts started with "CE188." The KW-7 had number of similar length, but was preceded by 0N0. I believe these were zeros, but we always said it "ooh, en, ooh"

The Federal Stock Number (FSN), redesignated to National Stock (NSN) in the mid-70s when they added two digits, placed COMSEC items in the 5810 supply class. In other words, the FSN for the COMSEC specific items would typically start with 5810. The formats were 5810-000-0000 and 5810-00-000-0000. All of the older items gained the two new zeros when the conversion was done. The FSN/NSN were used in the U.S., but I believe NATO used similar numbers."

Contributors and Credits:

1) Doug Eyre Hewitt, TX
2) Dick Morris <rmorris(at)>
3) Jerry Myers <jerry1joan(at)>
4) Kenneth D. Sutterfield <kenca387(at)>
5) George Mace <gmace8(at)>
6) M. Keith Markey <keith.markey(at)>

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Jul 1/11