Collins TDR-90 ATC Transponder Teardown

Tearing apart and analyzing a tdr-90 transponder. This one is for mode-s ATC communications and its a common unit on general aviation aircraft and private / business jets.

[@BGTech1]

Some things I forgot to mention: This transponder is not constantly sending out information to ATC. Rather, it only sends out the latest information on the flight in “pulses” when the transponder receives an interrogation signal from the ATC radar, about every 5 or so seconds. The newest information is then displayed on the radar screens for the air traffic controllers to monitor. Also, this transponder only sends out the aircraft's registration code, and it's altitude.

[@vorbeiei]

A few corrections maybe. You do not change the frequency on a transponder, they work on fixed frequencies. The thing you change is the transponder code (or squawk) as instructed by the ATC. Also from what I can find the TDR-90 is Mode A and C only as you pointed out in the video but incorrectly in the description and only will transmit the transponder code and altitude and no other information. Other than that, nice to see one of those from the inside, I usually don't get a chance to do that.

[@BGTech1]

@vorbeiei Thanks, I will fix that.

[@msylvain59]

Very typical Collins, interesting to see how they used basic ICs only, thanks for the video.

[@BGTech1]

Thanks for commenting. It’s possible that using basic logic ICs was a more reliable and proven method, rather than microprocessor based design which was newer at the time.

[@h7qvi]

kW transmission in short pulses. Really a radar TX

[@norbert.kiszka]

10:56 its a surprise for me, because kapton tapes are no longer allowed in aviation because it likes to disintegrate with humidity. They banned it in 90 I believe.

[@BGTech1]

Interesting, I did not know that. This unit seems to be made in the early or mid 80s

[@norbert.kiszka]

@@BGTech1 try to put piece of kapton tape into water for some (long) time and You will see its destroyed.

[@GoMaddogbassboost-zh4vo]

plz come back to youtube

[@BGTech1]

I’ve been pretty busy lately. I will be uploading 2 more shorts and I will start making more long format content.

[@rosariodagosto6484]

WHATS A TRANSPONDER DO BRO.....😊😊😊

[@rosariodagosto6484]

Well

[@BGTech1]

It’s a word for both transmitter and responder. When ATC sends out a HF signal (a message to request information) the device responds with the aircrafts speed, altitude heading etc.