That would be the 10 channel VHF 1985/6/7/8/9 series of Tx/Rx Radios fitted in just about every RAF aircraft flying after WWII (pre UHF). The 1985 set covering (100 to 125 Mhz), the 1986 (125 to 145 Mhz) and the 1987/8/9 (100 to 156Mhz) ... the 1988/9 sets were the standard VHF rig for the Chipmunk. The later sets could just about cope with 25khz spacing.
The crystals (Xtl's) mentioned by BEagle can be seen in the pic below located just above the main pre-set turning controls.
Historic Context : VHF Civilian Channel Spacing ...
Channel spacing for voice communication on the VHF airband was originally 200 kHz until 1947, providing 70 channels from 118 to 132 MHz. Some radios of that time provided receive-only coverage below 118 MHz for a total of 90 channels.
From 1947–1958 the spacing became 100 kHz; from 1954 split once again to 50 kHz and the upper limit extended to 135.95 MHz (360 channels), and then to 25 kHz in 1972 to provide 720 usable channels. On 1 January 1990 the frequencies between 136.000 and 136.975 MHz were added, resulting in 760 channels.
Increasing air traffic congestion then led to further subdivision into narrow-band 8.33 kHz channels (2,280 channels) in the ICAO European region for use by aircraft flying above 19,500 feet
Best ...
Coff.