ARC (Cessna) RT-359A Transponder-Not reading out mode C correctly and constantly in mode C

blurceo

blurceo

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So i have had the bad encoder replaced but now the transponder reads in consist mode C and its still not reading out right. The avionics shop says that the newer encoder probably has a different wiring pattern on the plug and the plug needs to be re-wired. I also could have a bad wafer on the control switch transponder. My question is is it easier just to buy a new transponder or let them try the fixed to the above? They say they can fix them and it should work.
 
It would be easier to find an avionics shop that has a clue what they are doing rather than one that is just going to poke at things with a stick. "Probably has a different wiring pattern." They should know for a fact what it is and shouldn't have made this change unless they are sure. You're going to waste a lot of money letting these clowns poke at your aircraft with a stick.
 
Are you talking to a real avionics tech on the phone or a customer service person who is not an avionics tech? I cant imagine anyone with real experience would be replacing parts without knowing this stuff beforehand.

Then there is the lack of functional testing before returning it to service that is making me cringe...
 
I think what is bad is that the guy has looked at it twice now. And served the transponder already. I think its going to be easier just to replace it and move on. Is there a slide in replacement for the 359? Or what is the easy of changing out to a different one?
 
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Nothing modern to my knowledge. I think some of the ancient Narcos are tray compatible but still, if it is the fact they screwed up the encoder install, just replacing the transponder isn't likely to do anything. Figuring out if it's a wiring problem versus something internal to the transponder would take a competent shop less than ten minutes to identify.

If you do want to replace the transponder, you may wish to evaluate what you're going to do for 2020 with regard to the ADS-B requirements. There are several strategies for that depending on what other avionics you have in the plane and what level of functionality you desire.
 
Yank out the whole thing (encoder too) and have your avionics shop install a new Sandia STX-165, It weighs 1.3 lbs, is the size of a medium sized intercom, has the digital encoder built in, and only uses a 1-amp circuit. The company has excellent warranty support, and it's one of the nicest transponders on the market. (It needs 1 power wire, 1 ground wire, an antenna cable, and a hookup to your static port, that's the basic install).

I installed one about 4 years ago, some of the best avionics money I've ever spent!

It takes longer to remove the old one, than it does to install this new one... It can even fit into an instrument hole if you have one available.
 
thomasdr72 said:
Yank out the whole thing (encoder too) and have your avionics shop install a new Sandia STX-165, It weighs 1.3 lbs, is the size of a medium sized intercom, has the digital encoder built in, and only uses a 1-amp circuit. The company has excellent warranty support, and it's one of the nicest transponders on the market. (It needs 1 power wire, 1 ground wire, an antenna cable, and a hookup to your static port, that's the basic install).

I installed one about 4 years ago, some of the best avionics money I've ever spent!

It takes longer to remove the old one, than it does to install this new one... It can even fit into an instrument hole if you have one available.
Click to expand...

Is it for certified aircraft? It's going to be going into a C-150?
 
You're still going to have to resolve the issue with the wonky altitude report. Even ADS-B needs the encoder to be working properly.
 
if you are thinking of buying a new transponder, then the first thing to think about is 2020. are you going to upgrade to be compliant? if so, how are you going to do it? do you have an approved GPS installed already? do you plan on upgrading to a one? are you going to go 1090 or UAT? if you are going to become compliant and do not have an approved GPS now and do not plan on installing one, then one of the new all in one transponders my be the economical choice. what is the price of a new transponder, and a UAT vs an all in one? if you plan on a new IFR gps in the future, then a mode s with es may be the way to go now.

bob
 
If you decide to go with a new transponder, you may want to look at the Appareo ESG. It is on par with same cost of a new transponder and also has ADS-B with built in gps source. You don't have to, but if you want you can output to an iPad with Foreflight. You do, I believe, also need the Stratus II.
 
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