Narco Transponder Mode C INOP

silver-eagle

silver-eagle

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Flew to MHT today in the Navion. Called up flighgt following and found the Narco Mode C was off... 1,000'. They let me into MHT and later out and through the Bravo Veil too. Anyone have experience with Narco? Worth fixing?
I am planning to do a whole panel update but thought Feb/Mar might be a better time frame. And for the upgrade, I was thinking to put in a L3 LYNX 9000 and a 530W. Anyone with experience with L3? The 9000 seems to have a lot of ready function.
 
Talk to Craig avionics in KCON ,he will check out your Narco ,then discuss other options,just had him install a Garmin 330 es for the ADSB upgrade.
 
Is the problem the transponder or the encoder?

If mode C is working, but the altitude was in error, seems more likely to be the encoder.
 
Kings Avionics (maybe now Butler) in Olathe KS had the Narco manuals and help me out with a transponder problem.
 
If it's transmitting an altitude, I would look at the encoder before the transponder. Sounds like it is getting the wrong information. If it was transmitting random altitudes it could be the transponder but a constant 1000 feet off points to the encoder.
 
Yeah, sounds like the encoder. I'd check that first.

The Lynx 9000 is awesome, but wow, it's massively overpriced. Ten grand for the box! I think their market research was way out of whack. They price that thing at $4000, they wouldn't be able to make them fast enough. As it is, I'd be surprised if they sold 500 of them, ever.
 
Encoders output a strange binary code called Gilliam. It allows for 500' steps and 100' steps. It would be helpful if you could find out from ATC if it were jumping in 500' steps as you climb, or 100' steps. A 1000' delta would be two discrete 500' foot steps, and should be discriminated by the ATC facility. You can advise them you are sure your encoder is not reporting right, and confirm your altitudes verbally.

If it a discrete(500') fault, the error is in the encoder output code, or the TXP converter. More likely in the encoder digitizer. If it is 100' increments it's more likely an analog failure of the encoder, and not the TXP at all. 1000' error strikes me as a fault of the A to D converter in the encoder, but that's only a best guess at this point.
 
Thanks for all the help. I had the local avionics shop walk over and check it out. It appears the encoder is INOP. Repair was a couple of hours diag and fix. $400.
I'll take it. That gets me a few months to work on a panel change/update/avionics upgrade.
 
ettsn said:
Yeah, sounds like the encoder. I'd check that first.

The Lynx 9000 is awesome, but wow, it's massively overpriced. Ten grand for the box! I think their market research was way out of whack. They price that thing at $4000, they wouldn't be able to make them fast enough. As it is, I'd be surprised if they sold 500 of them, ever.
Click to expand...

Lynx 9000 is $6,800 for new transponder, weather and traffic ADS B in and out
With install its $9,800.
So you're close at 10K
If they were 4K with install they'd be 7K
 
el con said:
Lynx 9000 is $6,800 for new transponder, weather and traffic ADS B in and out
With install its $9,800.
So you're close at 10K
If they were 4K with install they'd be 7K
Click to expand...

Just saw a 9000 Lynx in trade a plane for $7,995 installed, they are coming down:lol:
 
Yeah for 8K though you could get a GTX 327, GDL 88, FlightStream 210 and have ADS-B in and out on your GPS and iPad as well as flight planning, etc.

Way more bang for the buck then JUST a transponder. I have a Narco 150 myself and I'm just planning for the day it craps out on me..
 
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