MLB 100 APX340 Install
Printed From: Avidyne
Category: Avidyne General
Forum Name: SkyTrax Series ADS-B Receivers & Transceivers
Forum Description: Topics on the Avidyne SkyTrax 978 MHz Receivers & Transceivers
URL: https://avidynelive.com/forum_posts.asp?TID=1466
Printed Date: 26 Mar 2026 at 4:50pm
Software Version: Web Wiz Forums 12.07 - https://www.webwizforums.com
Topic: MLB 100 APX340 Install
Posted By: Msieger
Subject: MLB 100 APX340 Install
Date Posted: 22 Feb 2018 at 3:06pm
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Hi, New installation here. All is working well except when configuring the MLB with the UAT software I cannot get the pressure altitude to display correctly. I get -1025 instead of around zero. Pressure altitude is correct on the 340 display. I have checked all wiring between the two units and all is well. What am I missing????? Mike ------------- Mike |
Replies:
Posted By: AviTJ
Date Posted: 23 Feb 2018 at 3:17am
Mike, Can you send the wiring/configuration info you have to techsupport@avidyne.com ? There are a handful of things we would need to see to make a best guess at what's causing this.
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Msieger wrote:Posted By: Msieger
Date Posted: 23 Feb 2018 at 3:17pm
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Hey TJ thanks for the response, Here is what I found out today. I talked to Roland this morning and he advised me to disable the pseudo squat switch in both the the 340 and the 540. I did and no changes. I then pulled a new 340 transponder from my aircraft and slid it into the tray and everything worked without even doing any configuration changes to my transponder. Sooooo this tells me I either have configuration issues with the first 340 or we have a bad 340 that is not repeating the encoder info via pin 6 to pin 7 on the MLB. I believe this also verifies my wiring. Only other thing I noticed is the TIS-b flag is displayed on the 540 all the time. This system is wired according to Rev 5 diagram using RS232. I am also having issues enabling the wifi and bluetooth on this customers new 540 just a heads up. Mike ------------- Mike |
Posted By: DavidBunin
Date Posted: 25 Feb 2018 at 3:30am
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"-1025" is the UAT's way of telling you that it isn't receiving valid altitude data from its source (whatever you have it wired to). |
Posted By: Msieger
Date Posted: 25 Feb 2018 at 12:00pm
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That is correct, but is it due to some config issue or is it due to transponder that is not repeating said altitude???? I will know more tommorow. Mike ------------- Mike |
Posted By: Msieger
Date Posted: 25 Feb 2018 at 12:02pm
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It works with another 340 that is not even configured to that plane. So Im going to configure this transponder to the aircraft and see what happens. That will prove once and for all whether or not its the transponder. Mike ------------- Mike |
Posted By: AviTJ
Date Posted: 26 Feb 2018 at 4:01am
Mike, The "Repeated" altitude out of the 340 should be active at all times (if wired). I've honestly never checked one out without having first programmed the tail number, ADS-B parameters, etc. It may be that it's not configured, and that output may not go active until it is. I'll have to investigate if that's how it's "supposed" to work. The default protocol for that output is "Icarus" format, and is not configurable. Let me know what you find.
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Posted By: Msieger
Date Posted: 26 Feb 2018 at 3:05pm
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TJ, I programmed the second transponder and it worked great so I doubt its a config issue. For some reason pin 6 is not repeating the altitude. Thats what I found today. Roland is checking on warranty status for me. Im fresh out of ideas and have to call it a bad transponder as of now. Call me tommorw morning if you want to go over the config. Mike 314-267-3773 ------------- Mike |