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Chappyd

Well Known Member
Hi All,

I got a few days off and started working on avionics harnesses. I have a Narco AT165 transponder, and looking through the manual raises some questions.

In the pinout diagram, there are 2 leads labeled as external suppresion, one + and one -. What are these? :confused:

Will this unit work with Narco's AR-850? Haven't bought that yet.

I have a call into Narco, but can't get a body on the phone-yet anyway.

Would appreciate any input from anyone who can help.

Thanks
 
That's an interconnect for either another transponder or a DME unit, I believe. That allows the two pieces of equipment to coordinate their transmits so as not to overload the other.
 
suppression

L band equipment tends to talk over other L band equipment (xpdr, dme, tcas etc). the suppression lines go to other L band boxes, and basically tells them not to transmit while another L band box is transmitting.
 
This might help...

grover said:
L band equipment tends to talk over other L band equipment (xpdr, dme, tcas etc). the suppression lines go to other L band boxes, and basically tells them not to transmit while another L band box is transmitting.
Click to expand...

..the Installation Manual is here -

http://www.narco-avionics.com/manuals/036090620kvs.pdf

They call the signal "DME SUPPRESION" (the "other" L-band device mentioned above) and say it may be connected.

So, if you don't have a DME just leave this wire floating. The second labelled wire you mention (the "-") does not seem to be in the IM pin-out, so it probably one of the ground connections.

The IM pin-out is on page 15 of the above document.
 
I've noticed that among the manuals for the various versions of the AT-165, there are a bunch of small differences.

Update on my call to Narco- they called 2 times today before lunch while I was out. Fella named Tom left me his direct #. I called him back and he was very helpful with all my noob questions. I not a very big avionics guy, and I'm at the beginning of a very big learning curve. I chose Narco because I had some of their equipment in my Mooney and it always worked well.

So here's a shout out to Tom at Narco. Thanks!
 
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