UHF OFF even after DTC Load. Need Help with Comms.
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I am having some issue with my UHF as it comes up from the start in OFF mode and I can’t get it to turn on. Even after I do a DTC Load, it’s still OFF. My Data Cartridge presets 1-14 are set to the original freq’s. Preset 15 is set to tower and is selected as Default. I did notice that I have a preset 0 set to freq 000.000. I am wondering if I should even have a preset 0, and if not how to get rid of it. Could this be my problem? Much appreciate any help with this. Thanks.
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im guessing you have to switch the CNI knob to UFC
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im guessing you have to switch the CNI knob to UFC
Yes, I have the CNI knob selected to UFC, but it still says UHF OFF on the DED.
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UHF radio to Main or Both (Main + Guard) position? (to power up the radio)
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Loading the cartridge doesn’t turn on the radio.
The UHF or Comm 1 radio is able to be run off the airplane battery. Power is applied by turning the Comm 1 volume knob away from the minimum volume position and turning the mode knob to either the MAIN or BOTH position. At this stage the DED will advise the radio is in “BUP” or back-up control. Turning the CNI knob to UFC allows normal control and the DED will no longer show “BUP”.
If the radio is on and under UFC control at the moment the data cartridge is loaded the default (initial) channel preference will be applied. If the DTC is loaded before the radio is UFC controllable the radio presets will still be applied but when the radio is later set normally the pilot must change to the desired channel.
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UHF radio to Main or Both (Main + Guard) position? (to power up the radio)
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Yes, the radio is in Main. But also tried Both. Still UHF OFF. Going to reinstall 4.33 U5. The problem seem to appear soon after I did the update the other day.
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Are you using DX axis comm 1 volume knob? Those require a specific callback to hop from totally off to the working range. Then the axis can function.
A good test is to take a working plane, like commit to taxi, set the parking brake and work backward shutting off stuff and then turning it on again. You should be able to go from a running airplane to a battery-only UHF on state. You can often learn a lot about a problem that “doesn’t start” by experimenting with the working state and flipping stuff off.
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Just to be sure, back up comms are working, but once the CNI is set to UFC you lose UHF?
Just trying to make sure I understand what you are saying.
If it does not work in either, I would say check the Comms 1 volume knob to make sure it is turned up.
Note: If COMM 1 knob is all the way left, UHF info will be absent in DED with CNI set to UFC.
HTH