Avidyne Homepage
Forum Home Forum Home > Avidyne General > AXP340/322 ADS-B Transponder
  New Posts New Posts RSS Feed - AXP340 long delay for Press Alt at startup
  FAQ FAQ  Forum Search   Register Register  Login Login

AXP340 long delay for Press Alt at startup

 Post Reply Post Reply
Author
Message
CardinalRG View Drop Down
Newbie
Newbie


Joined: 02 Aug 2015
Location: Canada
Status: Offline
Points: 12
Post Options Post Options   Thanks (0) Thanks(0)   Quote CardinalRG Quote  Post ReplyReply Direct Link To This Post Topic: AXP340 long delay for Press Alt at startup
    Posted: 12 Nov 2016 at 4:44pm
Recent problem with my AXP340.   Was fine for past year or so....

Most days, on first flight of the day, I don't get Pressure altitude output for 10 minutes or so.  It starts in ALT mode and transponder squawk works fine, but The AXP screen shows Pressure Altitude shows FL---.  After 10 minutes or so, the AXP340 starts reporting the correct Press Alt.

This started a few weeks ago.  No recent panel work done.

Any troubleshooting suggestions?

Joe Brunski
1977 C-177RG with two IFD540s + AXP340 + MLB100


Edited by CardinalRG - 12 Nov 2016 at 5:01pm
Back to Top
DavidBunin View Drop Down
Senior Member
Senior Member
Avatar

Joined: 20 May 2015
Location: Rockwall, TX
Status: Offline
Points: 742
Post Options Post Options   Thanks (0) Thanks(0)   Quote DavidBunin Quote  Post ReplyReply Direct Link To This Post Posted: 18 Nov 2016 at 8:08am
Sounds like the heater is going out in your altitude encoder.  Altitude encoders normally contain a heater to bring the pressure sensor to an above-ambient operating temperature (usually around 140°F) which means they can eliminate temperature as a variable in the pressure sensor logic.

Most encoders have a warm-up time of no more than 30 seconds before they go valid.

Have your altitude encoder removed and bench tested at an avionics shop.  My guess is you'll be buying a new one.  They are not terribly expensive.

David Bunin
Back to Top
 Post Reply Post Reply
  Share Topic   

Forum Jump Forum Permissions View Drop Down

Forum Software by Web Wiz Forums® version 12.01
Copyright ©2001-2018 Web Wiz Ltd.

This page was generated in 0.124 seconds.