Comm Radios
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I noticed that when switching on the battery in cold 'n dark state, the radios also become operational. Avionics and radios are turned "off" (radio display is dark, so freq not visible). But on vPilot you can see the frequency tuned in on the radio, and Tx and Rx is working !
When only External power is applied (no battery), by switching on Avionics and the radios, the radios seem not to work (no Tx/Rx). Only when Battery is also switched on, the radios become alive.
I believe the radios should be operational when :
- either battery or external power is applied (or both)
- avionics are turned on
- radios are turned on
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This post is deleted!
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With the battery ON and with no other power, the electrics are at the EMGY level. At EMGY level the only comms available is VHF 1. Of course it should be ON (in practice they were never selected OFF as the avionics switches did the job). At the EMGY level the avionics master switches are bypassed by contactors to power VHF 1. So VHF 1 (and switched ON)should work with just BATT ON and is correct.
With a GPU plugged in and powered (BATT OFF) only the Ground Services Bus is powered. To power the main AC Bus bars requires the EXT PWR switch on the overhead paper to be selected ON. Only then will DC 1 and AC 1 become available and other avionics available when the avionics master switches are ON.
Hope that helps.