1963 PA28-180 with Stratus ADSB newly installed. On several occasions within the first 25 minutes of the flight, getting message "Altitude Input Failure" displayed on transponder and ATC confirming that ALT is not being transmitted. Only happens when flying and can not be duplicated by the Avionics shop. Have replaced, encoder, wire harness & antenna. Today replaced power lead and ground to encoder. Any suggestions??
Encoder issues with Altitude not transmitting
- Thread starter Michael H
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Chip Sylverne
Final Approach
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Quit with the negative waves, man.
Do you have a grey code encoder to an RS232 digitizer feeding the xponder, or a digital encoder unit like the TransCal ssd120? If the former, replace it with the latter. If the latter, I got nuthin', except maybe a bad Stratus unit.
My encoder is a Sandia SAE5-35
Chip Sylverne
Final Approach
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- Jun 17, 2006
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Quit with the negative waves, man.
That's a grey code as well as digital encoder, and the stratus can accept digital RS-232 alt data. Do you have anything else hooked up to that encoder output, like an mfd or GPS, that shows failure? You could make up a DB9 connector and parallel the output to a serial port on a laptop and download the file in flight to see what's happening. I think here are two 232 ports on the Sandia, have you tried both? Data cables shields are properly terminated? Encoders are pretty bullet proof, if everything is configured for proper data protocol, I'd have to suspect the transponder.
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