The AN/GRC-106 (and GRC-106A) Mobile and fixed HF transceiver.
from info supplied by Tony Helm

Frequency range: 2.000 to 29.999MHz, in 1KHz steps, with ±600Hz vernier.

Modes: USB, AM, CW, FSK.

Sub-units: (1) exciter/Rx unit (RT-662/GRC), (2) linear amplifier (AM-3349). The RT-662 is solid-state, whereas the AM-3349 uses two 4CX350A valves. The RT-662 includes the somewhat unusual features of noise squelch and VOX.

Tx output: RT-662 produces 100mW. AM-3349 increases this to 200W (AM/CW) or 400W PEP (USB).

Power requirements: 27 volts DC. RT-662 takes 10 amps. AM-3349 takes 40 amps.

Aerials: 15’ vehicle whip, or AN/GRA-50 wire dipole antenna.

Variants: an updated version, the AN/GRC-106A uses an improved exciter/Rx type RT-834, with the same amplifier. The RT-834 provides 100Hz steps over the same frequency range, and thus has a sixth tuning control.

Notes: These units are not going to be easy to find in the UK! Fair Radio in the US lists them at high prices, though cheaper with the meters missing. Given the complete system weighs some 125lbs, a better place to hunt will probably be Europe.