Manufactured by Phillips USTA  it was generally a very reliable machine with few failures. USFA means UltraSone FAbriek, a Philps company that produced military products.

Charles Kirk provides some background information on the Ecolex gear.

"The Ecolex crypto gear was the first "family" that  I maintained after graduating from crypto school at Ft. Monmouth. I received orders to go to CENTAG, Co. B in Germany.  The battalion was a multinational communications unit comprising of US, German, and French companies.  Company B was American with a detachment of French and one German noncom.  I was ready to be a super crypto repairman but when the NCOIC of the crypto shop asked me what I was trained on and I rattled off the American gear with a big grin on my face.  He said have you ever seen an Ecolex or an ECCTRM?  I said “no, what was that?” .  “That is all we have for crypto gear.”

The commcenter employed torn tape relay that was run 24/7.  The circuits were half-duplex with Siemens T68 teleprinters for the input/output.  The main crypto gear was the Ecolex unit.  We had ECCTRM units as backups and for “war games” circuits.  The present crew regarded the ECCTRMs  as bears to work on and used them as little as possible.

The Ecolex  units turned out to be very reliable.  In the 3 years I was stationed at Co. B, only a handful of units ever needed major repair.  Most of the maintenance comprised of removing the dust and chaff from the One Time Tape Reader.  Unlike the unit pictured, our unit only had one tape reader for the One Time Tape.  In the pictured unit I assume it could be configured to have a reader for the outgoing message.  The Ecolex unit could be configured to put “traffic” out on the line constantly so that message load could not be detected.  This was tested once or twice.  We went through the One Time Tape at a great pace.  The black lever in front of the tape reading units was the PlainText/Cipher switch.  If the circuit dropped synch you had to hold the lever to the right to converse with the other end.  I could not hold my knee and type so I developed a real fast one-handed typing skill.  Luckily the INT QRK queries were short  and to the point.

For teleprinters, the Siemens T68 was the main unit along with Lorenz LO15 page printers."

Another technician who worked with the Ecolex 4 provides this glimpse into its maintenance aspects.

"Worked on Ecolex IV equipment during the early '60s for NATO SACLANT (CINCLANT, Norfolk, VA). The equipment was used in a  naval shore station application. I trained at the Eindhoven plant where they taught me hydraulics in their attempt to teach transistor theory. This initially caused much confusion as my classmates seemed to have training in hydraulics and no transistor theory training.

The only problem that plagued the Ecolex IVs we used was their propensity to burn out current limiting resistors when used with Teletype Corp teleprinters in 60 ma current loops with external battery. The problem as observed at both 60 and 100 WPM speeds and occurred quite regularly.

I was able to resolve this problem by using a then standard teletype repeater relay to interface the internal Ecolex 20 ma circuitry with the external 60 ma teletype circuit. The relay was mounted on a blank mini panel panel located on the back of the Ecolex.  This avoided altering the electronics of the device;  the only modification was a hole punched in the blank plate to mount the relay socket and accept the wiring.  This solution worked satisfactorily.

My memory is a bit short, however I recall that the Ecolex models we used only had a single strip reader (a slightly different version reader) rather than two as depicted in the photos.  We used separate teletype tape readers for the plain language tapes.  I also can not remember seeing some of the sockets on the back of the machines that are depicted in your photos.  Perhaps we had a different sub model.  Our machines were apparently not ruggedized for vehicle use such as the ones depicted.  Also there is no blank mini panel shown in your photos.  I had an electronics problem with one machine that I can't recall having fixed before my enlistment ended.  They were not the easiest devices to troubleshoot.  Except for the resistor problem the Ecolex devices were relatively trouble free.

ECOLEX 4 General view. 
ECOLEX 4   - closeup of the tape readers. (Photos courtesy Jan Lispet) 

Contributors and Credits:

1) Jan Lispet <jw.lispet(at)>
2) Charles Kirk <ahondanut(at)
3) Tom  <>

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MAy 13/21