KG-13 and KY-3 Crypto Gear
Here is the Crypto equipment I worked on in Vietnam. This stuff was pretty top secret in the 60's. The Walkers went to prison for life for divulging the schematics and other info about this stuff to the Russians. When the Pueblo was captured by the N. Koreans this equipment was aboard and was shipped to the Russians. I was in Vietnam at the time and I remember that we had to replace all the paper punch cards for the readers. This had to be done worldwide all at the same time..
I found photos of this equipment using Google. These photos were copied from: http://jproc.ca/crypto/kg13.html check it out.
KG13 Crypto equipment
Here's a photo of one of the card drawers ( below)
Below is a photo of the cards. Note the potted modules. These use discrete DTL logic circuits. Diodes, resistors and transistors on a small circuit board and then potted to protect it from the environment. The KG-13 was one of the last pieces
of electronics equipment made using this technology as LSI logic chips started replacing this shortly thereafter.
Below Left: Here's a fuzzy photo of two KY-3 Voice Ciphony sets. Note the safe-like design. There were two drawers inside. One Xmtr, one Rcvr tray. The KY-3 was voice encryption and its digital output was fed into the KG-13 which was a digital encryption set. So it was effectively encrypted twice.
Below Right: Stacked KY-3s - Photo compliments of: Denver Farley Ft Monmouth Crypto Instructor KG13, KY3 and others.