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KT74 for ADSB out compliance


75M20F

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Hi,

 

I have a 75 F model and am bandying about a number of ADSB compliance solutions. My airplane is modestly equipped as a IFR daysailer with a mix of original equipment and a smattering of equipment I’ve had installed over my 19 years of ownership.

 

My GPS is a GTN650 and my present transponder is original equipment KT76A transponder. I have been quoted by the avionics shop I use on a garmin solution which is around $6000 out the door.

 

I was wondering if anyone has any insight into using a KT74 which I’m told is a slide in replacement for my existing transponder. Primarily my question relates to interfacing it with the GTN650 whether this is a standard cable or whether it has to be fabricated by an avionics shop? Additionally I’ve been told that an airspeed sensor has to be incorporated into the mix to determine when the airplane is flying or on the ground.

 

Google searches lead to a plethora of old data spanning back several years and I was wondering whether there is any recent wisdom on this.

 

Myself I do not need any of the sexy features of adsb as I get weather via XM and I’m happy with it. Traffic would be nice but I’ve been scared witless by shadow reports in the adsb equipped airplane I’ve been flying in - I’m looking for compliance at a minimum labor cost with real TSO’d avionics.

 

Any insight?

 

 

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Can't comment on GTN650 interface, since my experience was with the GNS430W.  However in addition to a very difficult time reading the KT74 display, one of the units we had installed did fail in about a year.  The code input suddenly became inoperative.

https://mooneyspace.com/topic/21210-king-kt74/?do=findComment&comment=436604

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The KT74 is supposedly an excellent unit. @neilpilot; did King make things right for you? I had some avionics work done recently and had them add a service loop to make the KT74 installable. 

 

If you have a 650, I would think that a Garmin In/Out solution would be best since you will get your weather and traffic on your 650. 

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Definitely not an expert but from what I've read...

Both the Trig TT31 and the KT74 are slide in replacements IF you don't care about ADS-B.  That is, you can get a new mode S transponder to replace your mode C for almost no install cost.

However, I've read what you've read; you need to install speed switch and also run a wire from your GTN to the transponder.  That means there will be some labor cost.  Maybe less than a GTX335, maybe not.

As for ghosting, we have not seen it on our airplane with a GTX345 and it sure is nice having ADS-B in traffic.

If you are looking for minimum cost to comply with ADS-B, you might look at the Garmin GDL-82 (about $1800) or the Uavionix Skybeacon (about $1900).  I've read reports of the Skybeacon being installed by an A&P in less than 3 hours rather than having to go to an avionics shop.  And I think they are close to certifying their tail mounted beacon too.  The only problem (?) with those is that you still have that old KT76A transponder installed that you have to maintain.  However, when that KT76A fails, you could probably do the KT74/TT31 slide in replacement.

Again though, I do love the ADS-B traffic.

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Supposedly latest firmware doesn’t require ground switch anymore, I’d double check with BK.

You want to mount it on the bottom of the stack, the display fades in brightness if looking up or level to it.

AFAIK, you need to integrate the transponder wires into one of the GTN’s massive D shell connector, so no premade cables.

 

Tom

 

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I need a solution that can be accomplished largely with an Allen wrench that replaces a 24 year old transponder that can have the adsb component hooked up by my A&P next December at annual when he’s got the belly panels off already and the back of the panel exposed to hook up an RS232 connection. At $2500 the KT74 meets that - if it works and doesn’t require 15 hours to remove and replace my panel




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22 minutes ago, FloridaMan said:

The KT74 is supposedly an excellent unit. @neilpilot; did King make things right for you?

87Q is actually on it's 4th KT74, all under King's warranty.  The 2nd was a failed attempt to improve the dim display.  Even a copilot in front of, and level with, any 4 of our KT74s could NOT easily read the dim display.  The 3rd was a loaner, after the code input failure, to be able to navigate the NY & DC traffic areas and return home.  The 4th and current was to return the loaner to King. 

Here's an interesting side note:  Months after the last KT74 exchange, 87Q appeared on Flightaware in several west coast flights, while 87Q remained in its AWM hangar.  After some detective work I was able to trace it to an aircraft that had received a KT74 from King.  That aircraft had installed a unit that retained our ICAO code.  I assumed it was one of the exchanged KT74s that King hadn't bothered to wipe clean.  Neither the aircraft owner or the avionics shop had programmed the KT74 for the new aircraft.  I had to track them down and ask them to remove 87Q's code (the FAA was no help in this activity).

Edited by neilpilot
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I had a KT 74 installed in my J in November of 2015 replacing the KT 76A it had when I bought it in 2013. I dropped the plane off at 8:00 and they called saying it was ready at 3:30. While they were in it, I had them run a wire from my 430W for a new 406 ELT. Everything done and out the door for ~$3500.

Been using it ever since then with no problems. It sits on the right side of the center stack about 2/3 of the way down.

Unfortunately, those of us who jumped on the bandwagon early did not get any of the FAA rebate money. 

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6 minutes ago, Oldguy said:

Unfortunately, those of us who jumped on the bandwagon early did not get any of the FAA rebate money.

We did get the rebate during the first round.  However, the $500 rebate wasn't $500 after paying income tax on it.

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[quote post="490025" timestamp="1552148033" name="Oldguy" userid="11386"
Unfortunately, those of us who jumped on the bandwagon early did not get any of the FAA rebate money. 



I never get any money back. I also fly round trips on the same route and experience headwinds in each direction

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I need a solution that can be accomplished largely with an Allen wrench that replaces a 24 year old transponder that can have the adsb component hooked up by my A&P next December at annual when he’s got the belly panels off already and the back of the panel exposed to hook up an RS232 connection. At $2500 the KT74 meets that - if it works and doesn’t require 15 hours to remove and replace my panel




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You can get the Mode S install accomplished on your own, if you can do the configuration. But you'll probably want to use your Garmin 650 installer for the Ads-b portion. Only Garmin dealers have access to firmware updates, install manuals etc.


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1 hour ago, 75M20F said:

I need a solution that can be accomplished largely with an Allen wrench that replaces a 24 year old transponder that can have the adsb component hooked up by my A&P next December at annual when he’s got the belly panels off already and the back of the panel exposed to hook up an RS232 connection. At $2500 the KT74 meets that - if it works and doesn’t require 15 hours to remove and replace my panel




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Then leave your KT76A and get the Skybeacon.  Probably under $2000 installed.  When the KT76A fails replace it with a literal slide in replacement TT31.

 

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The KT74 works fine, and I am using the old KT76A tray in the panel so it clearly works that way.

As noted above, "slide-in" replacement only works if you want the a mode S transponder.  ADS-B requires more:

  • You can use the old tray, saving install time, but
    • the harness still needs an additional wire/pin to the existing harness from your GPS source
    • You cannot use the interface that sends audio alerts to your intercom (for altitude, timer and TIS alerts) as well as TIS-A display info.  
  • you need an airspeed or gear switch installed to change between air and ground modes for ADS-B
  • IIRC, you need to replace your antenna wire with RG400 (if not done already)

While there may be a firmware update to change air/ground modes without the airspeed switch, note that the required STC for the ADS-B install is owned by Peregrine, not BK.  As such, I'm not sure that you could simply forgo the switch until Peregrine actually changes their STC.

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King KT74 and Avidyne AXP340 are both repackaged Trig TT31 transponders. Peregrine Aero STC : http://www.peregrine.aero/library/SA00765DE AML Rev G.pdf , lists the approved GPS sources for the KT74 and the Garmin GTN 650 is in the list.

As for installation, it won't be a plug'n play if you want the ADS-B out portion as it will use the GTN650 position and transmit it to the ADS-B antenna. It should be a few hours work to run the cable between the KT74 and the GTN650 and install the speed switch.

I have an Avidyne AXP540 and an AXP340 installed and don't need a speed switch as it uses the GPS to activate under an exclusive Avidyne STC, the only additional work, about 2hrs,  was the cable from the GPS to the TXP to collect position information.

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6 minutes ago, 75M20F said:

I replaced all my position lights last year with Whelen Orion’s so the position light solution isn’t appealing cause I love the way those lights look.


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If you happen to have the enclosed wingtips mod, the Skybeacon won't work anyway (it will if you have the original flat wingtips).  The Tailbeacon should work when it comes out.

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Have you considered a Stratus ESG?  It has the WAAS GPS source integrated and runs $2,995.  Our FBO got their rental Warrior done last year at a local shop that was installing these for a flat $500. (I assume they still do)  You would be out the door for less than $3500 after the rebate.

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4 hours ago, skydvrboy said:

Have you considered a Stratus ESG?  It has the WAAS GPS source integrated and runs $2,995.  Our FBO got their rental Warrior done last year at a local shop that was installing these for a flat $500. (I assume they still do)  You would be out the door for less than $3500 after the rebate.

Not really a good option for the OP- as he has a GTN 650 already.

the KT-74 should be a very painless way to get ADS-B out.  The cost to run that connection from the KT-74 to the GTN650 (literally one wire), should be under 1 hour labor.

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On ‎3‎/‎9‎/‎2019 at 4:23 PM, M016576 said:

Not really a good option for the OP- as he has a GTN 650 already.

the KT-74 should be a very painless way to get ADS-B out.  The cost to run that connection from the KT-74 to the GTN650 (literally one wire), should be under 1 hour labor.

There's also the time to install the airspeed switch, which should be pretty quick, and replace the cable with RG-400, which might not be and might apply to both.

I talked about my experience with the instrument shop in a previous thread.  They charged me for about 15 hours to install the KT-74 even though they used the old tray.   That sort of undoes a lot of the attempts to save money.

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I can’t even get an avionics shop to quote me on the install. My plan was to go mode S until my next annual in December and have my mechanic do the ancillary work while the belly was off and the back of the panel was opened up. My ASR is due then so we’d have the altimeter static and xponder checked at the same time


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14 minutes ago, 75M20F said:

I can’t even get an avionics shop to quote me on the install. My plan was to go mode S until my next annual in December and have my mechanic do the ancillary work while the belly was off and the back of the panel was opened up. My ASR is due then so we’d have the altimeter static and xponder checked at the same time


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I can't remember if the Peregrine STC requires an instrument shop do the ADS-B install or not, somebody else knew the answer to that previously.  If not, I would have gotten my own shop to do it and just have the instrument shop do the IFR cert.

When they gave me an estimate for the work, they estimated 15 hours, citing the difficulty working behind the panel.  I had already had the antenna cable replaced with RG-400 prior to that.

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