High Quality Content by WIKIPEDIA articles! The KG-13 was the first transistorized cryptographic machine developed by NSA in the early 60`s. It used the newly developed 2N404 germanium transistor instead of vacuum tubes. It consisted of a KG-3 transmitter a KG-12 receiver. The transmitter used about 500 transistors and the receiver about 300. The transmitter was switchable to function as a receiver.