I sometimes think _all_ WW2 era communications receivers were built to a weight specification as well as an electrical/performance one!
All the ones I've used have been in the 1 cwt./50 kg. class - AR88, S27C, R107 were all around that weight (and I have back pains to prove it).
The Admiralty were even worse, and appear to have required all kit to have been machined from the solid (usually steel or bronze) - and there was a requirement in the early days that the equipment could withstand the operator climbing up the rack (wearing steel-capped boots).
Best regards,
Chris.
(Who once nearly lost an R107 (on a folding trolley) down the gap between the train and the platform edge at Waterloo station. Admittedly it was a big gap due to the curved platform, but it gave me a nasty moment.)