Click for homepage
USA
Rotor
NSA
KL-7
  
PSU →
  
KL-7 toolkit
Operator maintenance kit

Each KL-7 cipher machine came with a set of supplies, spare parts (tubes) and maintenance tools, packed together in a compact grey metal storage case labelled: Operator Maintenance Kit. Like the machine, it was distributed to the users by the United States National Security Agency (NSA).

The box measures 160 x 160 x 135 mm and weights approx. 2400 grams, depending on the exact contents. It is painted in the same neutral grey colour as the KL-7 itself and contains spare valves (tubes) and a tool to extract the valves.

It also contains tools to clean the contacts of the KL-7 and its rotors. It was very important to use the right materials as – according to former KL-7 users – the machine faced a number of reliability issues that were all contact-related. Apparantly, cleaning the contacts with a soft cloth and a cleaning agent like alcohol, was not sufficient.
  

Instead, the contacts of the rotors had to be cleaned by rubbing them over a wooden block lined with cloth, that was supplied as part of the kit. More serious contact problems were treated with an ink eraser that was also supplied. The transpartent cylinder that is visible in the image above – stowed diagonally in the case lid – is a moisturiser, or humidifier, for the pre-gummed paper.

 KL-7 Operator Maintenance Kit
Front
KL-7 Operator Maintenance Kit
Inside the maintenance kit
Contents of the maintenance kit
Inside the lid
Eraser detail
Gummed tape moisturiser
A
×
A
1 / 8
 KL-7 Operator Maintenance Kit
A
2 / 8
Front
A
3 / 8
KL-7 Operator Maintenance Kit
A
4 / 8
Inside the maintenance kit
A
5 / 8
Contents of the maintenance kit
A
6 / 8
Inside the lid
A
7 / 8
Eraser detail
A
8 / 8
Gummed tape moisturiser

Contents
  • Contact cleaning eraser, Parapink Faber-Castell 701
  • Finger-mount tape cutter
  • Tube puller (2 sizes), a.k.a. Chinese Finger Trap
  • 4 x 2D21 valve
  • Dust brush
  • Bristle 'tooth brush'
  • Contact cleaning block, with spare cloth strip
  • Set of lint-free cleaning cloths, CE87298
  • Spare light bulb for 'Shift', General Electric NE-48
  • Spare light bulb for 'Keyboard illumination', W313
  • Moisturiser for pre-gummed paper tape
  • Tube pin straightener (2 types, for 7 and 9-pin valves)
  • Metal can of red coloured cleaner/lubricant
  • Hex wrench
Contact problems
From its introduction, the KL-7 had reliability issues, which were mainly caused by contact problems of the rotors. As the spring-loaded contacts at one side of each rotor are made of beryllium-copper (BeCu), they easily oxidise and become non-conducting. Cleaning the contacts with alcohol does not help, but rubbing them with the tools supplied in the maintenance kit does.

WARNING — Although the percentage beryllium used in the contact is fairly low (0.5–3%), you should be aware that it is a harmful carcinogen when inhaled or digested. In general, dust containing beryllium – for example from sanding, grinding or filing – should be avoided. In solid form, beryllium can safely be used [1].
References
  1. Wikipedia, Beryllium copper
    Visited 25 September 2023.
Further information
Any links shown in red are currently unavailable. If you like the information on this website, why not make a donation?
Crypto Museum. Created: Sunday 09 August 2009. Last changed: Tuesday, 16 April 2024 - 10:04 CET.
Click for homepage