I42 ...
Yes ... you're right about frequency synthesis over crystals ... but I guess it all came down to size and weight at the time. Which is a bit ironic given that the TX198x Vhf radio sets used a 'Dynamotor' (which weighed a figurative 'ton') to produce the required HT
The inside of a TX1985.
Image Credit : Mr M Lambert
With the kind help of PPRuNe Member, Dan Winterland, here is the Dittel ATR720B 720 Channel Vhf radio set fitted in RAF EFTS Chipmunks during the late 80's/early 90's ... just shows how far technology had progressed by the 90's
Best ...
Coff.