KT 74 Installation

Hi All-

My old KT76A finally gave up the ghost a few weeks ago, and so I bought a KT74 to replace it. I was sold by the whole ?slide-in replacement!? idea. Plus, since I have a GTN650, I liked that it?ll get me 2020 compliant with minimal headache.

Of course, ?slide-in? means ?it fits in the tray, but you need to wire a bunch of stuff and your ball and rod antenna won?t work and hey do you have an R400 cable? because you need one of those...?

So I figured, no biggie. I knew I?d have to do some wiring, of course. I?ll just look in the manual and... Oh. No installation manual. Awesome.

So, has anyone done this? It seems like I need:

-Two wires:
(1) RS232 FROM the 650 to the main connector on the KT74, and
(2) RS232 OUT from the 74 to go to the 650 to display traffic. I know there?s other stuff like the ADIRS out on the second connector, but I don?t want to change the tray, and I?ve read on other forums the 232 out will provide info to the 650. I know this won?t display ALL traffic (TIS-A only?), but that?s fine. I use a Stratus 2S with Foreflight for traffic and weather. I don?t want the altitude alerts either.

-A new coax cable. No idea how to check mine to see if it?s the 400, but it was installed around 1990, so I?m pretty sure it?s not.

-A blade-type antenna like the KA 61

So am I on the right track? This is my first avionics install, so I expect it to take a lot more time than it would for a smart person, but I?d really like to try and do it myself. A manual would make it easier, but Bendix is stingy with those unless you?re a dealer.

Thanks for reading. Fire away.

A few thoughts.
You need the manual! At a bare minimum, see if whoever sold you the box will send you a diagram of what pin goes to what. Sometimes people post manuals on the internet. Google is your friend.
As you probably know, this unit is a Trig clone. Looking at Trig manuals may help.
For the 650, set the format on the RS232 output port you use to ?adsb+? (note the single plus sign). This is tbe format Trig can read.
The ball and stick antenna is not as good as a blade, and probably costs you 1/4 knot airspeed. But if it?s in good shape (including the connectors) you could keep it. But the coax is nearly 30 years old. Replace it with RG400. Check the connectors needed. Some Trig models use a TNC instead of a BNC connector.
Again, you really need a manual, to program how the box will change over from airborn mode to ground mode. You used to need an airspeed activated switch but I think it?s done with software and gps ground speed now.

Thanks Bob!
All good thoughts. So far no dice finding a manual on the Internet. Not even a Trig one. I was hoping somebody here might have access to one and at least provide the answers I need. Of course, the next step is to ask the dealer for a copy and/or some help.
It’d be GREAT not to have to swap the antenna, so maybe I’ll try with that first and see.
The output setting from the 650 is great info. Thanks. That’s exactly the kind of stuff I’m looking for!
Keith