KT-76 transponder — to ADS-B somehow

[DKirkpatrick]

So... BK says the kt-74 ADS-B transponder is a "slide in replacement" for the KT-76. Would someone lend some experience here? I gotta assume that means install a different transponder, rewire...
Airplane has a Garmin 400 for the primary nav...
What is a thumb in the breeze number to replace the KT-76 with the KT-74 ADSB transponder and get the airplane legal?
?
THANKS for the intel.

 

[jrcox19]

What is a thumb in the breeze number to replace the KT-76 with the KT-74 ADSB transponder and get the airplane legal?

Could already be legal. Do you fly in airspace that requires ADS-B?

 

[DKirkpatrick]

yes... and plan to. Lots of traffic around my homebase... probably a good, albeit stupid expensive, idea...

 

[bnt83]

So... BK says the kt-74 ADS-B transponder is a "slide in replacement" for the KT-76. Would someone lend some experience here? I gotta assume that means install a different transponder, rewire...
Airplane has a Garmin 400 for the primary nav...
What is a thumb in the breeze number to replace the KT-76 with the KT-74 ADSB transponder and get the airplane legal?
?
THANKS for the intel.

You need an all-in-one solution like the Skybeacon, Stratus or Garmin transponder with internal GPS receiver as your panel mounted navigator isn't an acceptable GPS source unless upgraded to WAAS.

 

[DKirkpatrick]

sorry. yes, the g-400 is WAAS unit. thanks

 

[bkspero]

It cost me about 6 labor hours to have my KT-74 installed in the tray left from my KT-76a, have a pressure switch installed in the pitot line and wired to the transponder, and have the KT-74 wired to a GNS-530w. Since then the need for the pressure switch (to change from ground to air mode) has been eliminated by a firmware upgrade which allows the KT-74 to use GPS speed for that purpose, so it might cut about an hour from the work.

Recognize that using the KT-76a tray limits some of the features of the KT-74 because the -76a tray has only 1 large electrical connector whereas the KT-74 can take advantage of 2 large connectors. I'm missing, for example, audio alerts to altitude deviations because of that. All of the required 1090es ADS-B functions operate just fine with the old tray.

 

[NordicDave]

How much is the KT-76a? The complete self contained Garmin GTX-335 is $3K.

 

[kshaw]

I did the KT-74 upgrade on my Warrior and installation was around $1K for ADS-B. I used the old tray and you only need to change if you want to use the altitude monitoring feature on the KT-74. You will likely have to upgrade your coaxial cable to RG-400, firmware updates on both transponder and your Garmin 400W may need to be done, and you will need the transponder check. The new STC no longer requires the speed switch and the transponder uses your GPS speed to determine whether you are on the ground or airborne.

 

[DKirkpatrick]

Great information and help.. I appreciate the posts back.
dan