Type: HF communications receiver.

Frequency range: 1 - 20 MHz in 4 bands.

Modes:CW, AM R/T, FM R/T.

Selectivity: 4-6kHz at -6dB, 13kHz at -40dB

Image rejection: 80dB at 1MHz, 20dB at 20MHz

Stability: 200Hz/MHz in first 60 mins from power on. (50Hz/MHz per degree C temperature rise).

Audio output: 50mW to built-in speaker, plus sockets for 2 sets of 150 ohm headphones.

Power supply: 12V DC, at approx. 1.5A.

Circuitry: 11-valve, single conversion superhet with a 460 kHz IF. HT from an internal vibrator. There is a noise limiter, and audio filter on CW.

Variants: The Mk.I has a 6V DC input and internal circuit differences. The Mk.III runs on 12/24V DC, or 115/220V AC mains.

Usage: Introduced in the early 1950's for general purpose use. Used in large mobile installations with the WS No.53 Tx.

Notes: This receiver has the advantage of being relatively small and light, and this makes it useful for field trips. The FM facility only really works well on the Mk.I set - it remains in the Mk.II but needs strong signals. It is unfortunately common to find the sets butchered by having the DC input or headphone socket swopped for something else: the correct plugs are available for those who search.