Racal RA17 & Related Equipment.

Digital Frequency Readout & All-Mode Adapter for the Racal RA17.
Part 1: Introduction, Overview, Block diagram.
Part 2: Demodulators & audio stages.
Part 3: VFO input, 1MHz reference input, CIO.
Part 4: Digital frequency readout.
Part 5: Power supply, Construction, Improvements.

RA17 Adapters - Further Design considerations.
Part 1: Conversion schemes.
Part 2: Working Specifications.
Part 3: System control.

RA17 receivers, accessories, spares.
Racal RA17 C18.
Racal RA17L.
Low Frequency Adapters: Racal RA37 and RA137.
Valves (Tubes) for the Racal RA17 and RA117 series H.F. Receivers. (By Andy Cowley)
Valve / Tube equivalents; for the RA17 and related equipment. (CV List)

Reference (Thanks to John Crabtree for finding this):
Variable-Frequency Crystal-Controlled Receivers and Generators, by Trevor L Wadley.
Transactions of the South African IEE, Feb 1954, pp77-99.

Useful Links:
Keith's vintage RACAL enthusiast's site.
IJL (OH5HOI) Technical Pages (RA117 full manual etc.)
Skywaves (Al Klase N3FRQ - Radio articles, including RA17 - see 'Communication Receivers')