Nostalgia. When drafted into the Navy is 1943
my first job was setting up ARC-5 transmitters
and receivers in 336 SNJ (AT-6) aircraft. (among
other things) Later after the war when there wasn't
much money around, I would rewind ARC-5 receivers
and use them for ten-meter converters. In those days
tapping on the case of just about any transmitter or
receiver would produce some modulation. Except for
Collins equipment. The ARC-5 VHF transmitters were
truly awe inspiring when they arrived. 73s W6BWY