Contactor Unit BC-608-A of RC-96A System Pipsqueak NOS PV-2 Harpoon The small pointer indicates engine

The small pointer indicates engine RPM around the inner scale up to 50%

whereby upon decent

Thermometers

while the pointer labeled "M" indicates RPMs of the Engine

Nakajima J1N Bomber Gekko aka "Irving"

Contactor Unit BC-608-A of RC-96A System Pipsqueak NOS PV-2 Harpoon The small pointer indicates engineHere is an excellent example of the WWII era Contactor Unit BC 608 A, a component of the US Army Air Force's RC 96 A Contactor System intended to work with the the British RAF "Pipsqueak" system. Pipsqueak was a simple radio navigation system used by the British during the early part of World War II. Pipsqueak used an aircraft's voice radio set to periodically send out a 1 kHz tone which was picked up by ground based high frequency direction finding