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j3cubcapt
26th Sep 2003, 03:49
On the Classic B737 (300/500)

The question has come up "What power source does the Aux Nav radio recieve power?"

Senerio....
Capt or F/O is using the Aux Nav radio performing a F.D. or Autopilot approach. At G/S intecept the TR3 Disconnect relay opens, Will the Aux Nav radio loose power?


Thanks for the help!

J3

avioniker
26th Sep 2003, 21:21
None of the radios or nav receivers will have their power interrupted. The purpose of the relay is to isolate the power sources so that in the event of a failure during approach the radios won't all be affected at the same time.

Here's a link to a very simplified schematic that'll answer your questions.

http://www.b737.org.uk/schemeelectxt.gif