Back to Contents...

(c) 1999,2010 Peter McCollum

The Delco 5300 Series HF Transceiver

The Delco 5300 is a portable solid-state HF transceiver developed in the early 60's. It resembles a small lunchbox, with a hinged lid. It transmits on four crystal-controlled channels, with a power output of 5W CW and 1.5W AM, and can be operated from a high-speed keyer such as the GRA-71. The receiver also has four (separate) crystal-controlled channels, and includes a BFO. Most models include a switch to select two bandwidths: 6 KC and 0.5 KC (the latter using a Collins mechanical filter). Power is supplied by a battery that provides 4V (receiver), 24V (transmitter), and 12V (for modulator, only required for AM). This set is unusual for a clandestine radio in that it supports AM voice transmissions on the HF band. The set's antenna matching circuitry is far less flexible than most earlier sets, so the user would be required to pay more attention to proper antenna configurations.

Some interesting 'clandestine' features include:

• A plunger-type switch that turns off the power if the lid is closed. If you're in a hurry, just close the lid - you don't have to remember to turn off the receiver or transmitter.

• A "whisper switch" which increases the microphone sensitivity.

There are two earphone jacks, and one mic jack - all are the submini "transistor radio" type of plug. The H-264 earphone for the PRR-9 is nearly identical to the PRC-64 earphone, and works well as an alternative. The earphone can also be used as a substitute microphone.

Differences between models in the Delco 5300 series:

• Delco 5300: tunes 3-8 MC, has no BW switch on receiver. This is the model that was originally adopted for CIA use. Unlike later models, the CW key is a true key, and is fully adjustable.

• Delco 5300A: tunes 3-8 MC, has BW switch on receiver.

• PRC-64: the Army adoption of the Delco 5300. Tunes 2.2-6 MC, has BW switch on receiver, battery-test circuitry is simplified (tests only the 24V), transmitter uses a larger type CR-89 crystal (so that receiver and transmitter crystals cannot be accidentally interchanged???). The CW key on the PRC-64 is implemented with a panel-mounted microswitch, thus perhaps making it easier to keep the front panel watertight.

• PRC-64A: same as PRC-64, except that there is an added 'daughter board' on the transmitter module that improves high-speed keying performance. The PRC-64A manual says that all PRC-64's were modified by the addition of the daughter board, thus making them PRC-64A's. However, the author has an unmodified PRC-64 that was formerly a "parts unit" at the Tobyhana repair depot. The ID plate on PRC-64A's indicates a contract date of 1968.

A PRC-64 transceiver. The white label inside the lid is not original, and the wire-bale knob is missing from the storage compartment lid. Author's collection.

According to Conboy and Andrade' (see reference [27]), the Delco 5300 was a replacement for the RS-1 with some Special Forces troops in Vietnam, and SOG ordered two sets in April 1966 (although the sets apparently had not arrived by the end of the year). The main advantages of the 5300 set would be its small size and battery power, meaning that it could be operated by an individual without a hand-crank generator. It appears that the 5300 may have seen duty somewhat similar to the "Village radios" (see separate section), which would involve use by relatively untrained operators. This type of usage provides an explanation for the AM-voice capability of the set, which is otherwise nearly non-existent on cold-war clandestine sets, due to the lack of security and the greatly reduced effective range.

Delco 5300A receiver schematic (209 KB)

Delco 5300A transmitter schematic (248 KB)

Delco 5300A modulator schematic (223 KB)

Next section...