Brutal,
That might be the case on the Primus 660 but not the Telephonics RDR 1500B/1600/1700A systems. IIRC the L2 and 225 were fitted with RDR 1600 as standard in the UK so in Wx mode the receiver gain is preset and cannot be changed by the pilot. That is why I suggested a memory check for DB as I know he flew those types.
Shockingly scary? Perhaps not - it depends on your kit!