King KT76A transponder wiring

johnM · Post by **johnM** » Thu Feb 28, 2008 11:55 am

Hi

I have acquired a KT76A transponder that I wish to install but do not have a pin out diagram. I have found one at
http://www.aeroelectric.com/Installatio ... 6C-78A.pdf

but there are 12 pins on the top and the bottom is listed as A - N.

Unless my maths is dodgy there are 14 letters up to N and so which two should be left out. ( I assume that I is one of them)

thanks
john

Steve Brown · Post by **Steve Brown** » Thu Feb 28, 2008 12:35 pm

The pin out detail gives connections to

A B C D E F H J K L M ie 11 letters

N is not used

Total 12 letters which accords with the plug diagram

Quite why King dont use G or I, I don't know!

Take great care to checking (& rechecking) the wiring in relation to the plug key between pins 3/4 and C/D and which way you are looking at the plug. Verifying with a multimeter that A & 1 pins is connected to case ground can be a useful additional check.

johnM · Post by **johnM** » Thu Feb 28, 2008 1:02 pm

thanks Steve

you obviously know what you are doing. that makes one of us!
My understanding is that the only number pins( as opposed to letter pins) that I use if I do not have a dimmer switch are:
1 GND
11 Power

Am I misunderstanding things?

Steve Brown · Post by **Steve Brown** » Thu Feb 28, 2008 1:56 pm

If you want the display lit (preferable I'd say while wiring the plug - with little downside ) then you need to connect pin 2 to 12volts and pin 3 to ground - this gives you 'always on' lights to the Txpr facia. If you wanted switched lights, you'd switch pin 2.

If you dont want a lit facia, then you dont need to wire up pins 2 or 3 at all

Note: If you are connecting up a remote altitude encoder, pin 8 is also used as well as most of the the letter pins for the altitude data interface to the KT76

Regards
Steve