During a recent trip ATC was reporting me at abut 600 to 700 feet lower than my GPS and altimeter displayed and requested I turn off altitude mode. So I guess there is an issue with either my transponder or my encoder. Are there any adjustments available for those?
MODE C Altitude off
- Thread starter ted heck
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Witmo
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Tim
None that can be made by an A&P or owner. An avionics tech with the right gear might be able to adjust it to within tolerance.
docmirror
Touchdown! Greaser!
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Take it to a radio shop with a TXP tester. They will put the tester next to the antenna and get a readout of the mode C altitude reporting. some encoders are adjustable, and some are not. Most will be able to calibrate either electronically, or with a small pot on the side of the unit.
If you are 6-700' off, it's typically not a problem with the signal sent to the TXP, but with the pressure sensing inside the encoder.
If you are 6-700' off, it's typically not a problem with the signal sent to the TXP, but with the pressure sensing inside the encoder.
Agreed,,,''The blind encoder is usually the culprit,,,
wilkersk
Pattern Altitude
Only way to know for sure is to take the whole airplane to a shop that does the 24 month IFR cert and have them check your system over. Sometimes, it can be as simple as pulling the transponder out and reseating it in the tray. Other times it can be the encoder, or worse. Just pulling the black box out and sending it to the shop , or just replacing the encoder, is an invitation for Murphy to show up.
BigBadLou
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