KT-76A Wiring

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KT-76A Wiring

Postby gme9261236 » Fri Apr 11, 2008 4:04 pm

I am going to be wiring up the panel this coming week and I had a few questions for those who have been down that road. We have the Stratomaster enigma MFD as well as an ICOM radio and a KT-76A transponder. I understand how to wire up the rest of the items but the main question is the KT-76 wiring harness. Are you all finding/buying a 24 pin connector and an 8 or so pair cable or are you using individual wire and just buying pins and pushing them into the back of the transponder?

I figure it would be the most neat and simple to get a 24 pin connector and then an 8 pair cable which would give me the 16 wires I need all in one need cable instead of the 16 loose wires but I am not sure if that is a radioshack item or not. What are you all doing? Any tips tricks or hints in your panel wiring would also be helpful since I am diving in head first this week.
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Postby b1x4nqb » Fri Apr 11, 2008 10:08 pm

I'd suggest calling a shop like West Coast Avionics and just having them make up a cable for you.  If you want to make up your own, I'm certain they could sell you the pieces to make one up and maybe save a few bucks.

Paul, PA
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KT-76A Wiring

Postby Wes » Thu Apr 17, 2008 8:46 pm

The KT-76A is a good solid transponder, albeit not solid state final amp.
If you are wiring for mode C (alt. digitizer), then you have the following wires to run:
- 9 digitizer wires for the Grey code (assuming less than 31K for a max. operating altitude, no ext. Ident and no DME)
- 2 power wires
- 2 for panel lights (assuming 14V system)
The King recommended wire is 22 gauge for everything, but I would recommend 20 gauge for the power wires, especially if you have any distance to run to the breaker.
Try to keep the antenna coax away from all other wiring and as loss-less as possible (see other post).
Make sure that the tray antenna connector is properly inserted and mates well with the KT-76 box. Some of these mountings do not afford good antenna connections. A good check with the transponder tightened in the tray, is to use an ohmmeter and make sure the resistance from the stub antenna to ground is less than 5 ohms.
What altitude digitizer are you using? Can you get Grey code out of the Enigma?

Let me know if you need pinout info.

Wes
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Postby gme9261236 » Fri Apr 18, 2008 12:46 pm

Hey Wes,
the enigma does allow for grey code altitude encoding so that will not be a problem. I have the plug for the txpndr already done and has all of the jumpers as well as the power, ground and the illumination wire. The problem that I am running into is that the connector on the back of the enigma for the grey code is a dsub mini 15 pin which is almost impossible to find locally. I have been able to find a few online but they are less than a dollar and have a ten dollar minimum which I will probably just eat the cost to get the darn thing done. Since I have to buy the connector I was hoping to get lucky and find one already wired for whatever purpose then I could just cut the other end off and put pins on it and connect it to the molex on the back of the kt76. It is a bit of a hassle and I have to put it down for a bit since I am out for work on a 4 day but when I get back I am hoping to have the parts I need to get it done and finished. THere are pictures in the panel posts that I made, the run from the kt76 to the breaker is only 8 inches or so.

Thanks alot for your info, I may need to pick your brain quite a bit more to get this thing finished, I definately could have used your help when I was trying to figure out the intercom and wiring the jacks.
gme9261236
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Posts: 174
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Location: Hampton, NH 7B3

Postby gme9261236 » Fri Apr 18, 2008 12:46 pm

Hey Wes,
the enigma does allow for grey code altitude encoding so that will not be a problem. I have the plug for the txpndr already done and has all of the jumpers as well as the power, ground and the illumination wire. The problem that I am running into is that the connector on the back of the enigma for the grey code is a dsub mini 15 pin which is almost impossible to find locally. I have been able to find a few online but they are less than a dollar and have a ten dollar minimum which I will probably just eat the cost to get the darn thing done. Since I have to buy the connector I was hoping to get lucky and find one already wired for whatever purpose then I could just cut the other end off and put pins on it and connect it to the molex on the back of the kt76. It is a bit of a hassle and I have to put it down for a bit since I am out for work on a 4 day but when I get back I am hoping to have the parts I need to get it done and finished. THere are pictures in the panel posts that I made, the run from the kt76 to the breaker is only 8 inches or so.

Thanks alot for your info, I may need to pick your brain quite a bit more to get this thing finished, I definately could have used your help when I was trying to figure out the intercom and wiring the jacks.

If while looking at those photos in the panel posts something stands out as grossly incorrect I am very open to feedback before it is too late and it is all buttoned up. I can still move a few wires here or there or make some minor changes.
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