WWII Radio Altimeter, BC-788-C

 I wasn't sure whether to call it a "Radio" or "Radar" altimeter. In WW2 radar, could have transmission frequencies below 30MHz, but nowadays radar is confined to the microwave bands. This set probably uses something between 100MHz and 300MHz? It's other designation is SCR-718. I notice the equipment also appears in my listing of Government Surplus Radio Equipment, where its IF is given as 30MHz.

This set uses a 6J6 transmitter and a similar valve for receive, each in a tuned lines configuration

The set used a DC input which powered the valve heaters and drove a rotary converter for its HT and connected to a small circular display unit which gave the aircraft's height.

...waiting for better pictures...


 Interior view showing typical high standard US construction


 Alas, aluminium corrodes easily... I should consider cleaning it up maybe?


 I wonder if it could be made to work??

Others have been successful.. see here

To see the output from the equipment one would need the matching display unit, connecting to the socket marked "To Indicator". Aerials are simple quarter wave whips. I understand this radar altimeter has the longest ever lifetime of any radar equipment, still being used into the 1970s; perhaps because of its simplicity and therefore ease of maintenance?

Return to Reception