EEVblog

Teardown of a Made in Australia MicroAir T2000 aircraft transponder.
microair.com.au/products/26/T2...
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#Teardown #Aircraft #Transponder

[@swilwerth]

DC: that's a short, you cannot pass.

[@Thesignalpath]

Its a diplexer Dave. Not to be mistaken with a duplexer.

[@flymypg]

Designs like this are clearly short-run labor-intensive items that are nearly impossible to upgrade. At the aircraft instrument manufacturer where I worked, we called them "bricks" (where the old-school electro-mechanical instruments are called "steam gauges"). Instead, we put 100% of our effort into the RF PCBs, so the chassis could be generic and used by multiple different instruments. Yes, our instruments were double or triple the cost of this one, but ours were readily field-upgradable as standards or needs changed, and we went to great lengths to make the upgrades affordable and easily installed.

[@han5vk]

I'm fairly convinced RF electronics are just magic.

[@tomsmith5893]

Bought a radio from Micro Air once. They wrote on the customs declaration that it was being returned after repair (saved me some import duty, thanks lads). Their reason for repair was "radio sounded like a frog in a pipe". Most Australian sentence ever 👌

[@gblargg]

9:30

[@pherdantler707]

Your 'comb' filter is a combination bandpass-bandstop filter. The removable part with longer elements is very limited bandwidth 1030 MHZ bandpass, the shorter elements integral to the case are bandstop, 1090 MHZ (Tx freq) and 3270 MHZ (Tx freq 3rd harmonic)

[@Sailingon]

The shorting is the bit I've never been able to get my head around. Been a radio ham for 30 years and still gets me.

[@gglovato]

i'd love for The Signal Path to take a look at this device and do a detailed analysis and experiments on the filter with his equipment!

[@barrieshepherd7694]

For those interested in ADS-B transponder 'RADAR' you can use a USB TV stick and a Raspberry Pi to make your own receiver, no RF knowledge really necessary and happily track the aircraft around your vicinity - up a range of around 200km depending on your antenna / location.

[@sirflimflam]

Man I love that machined aluminium housing.

[@Dave5281968]

The best teardown you've done in months! Thanks, Dave.

[@xjet]

While you were doning the "ohm" mantra I was thinking of a line from Kath and Kim: "It's Kardonay you shunt" :-D

[@PilotPlater]

Good explanation at the beginning on how it is operated.

[@rene0]

Waiting for the reassemble video and, after getting it to work, illicitly broadcast your studio as hovering over Australia.

[@MarkNewtonFlies]

I’m really pleased to see this tear down, because John got it from me: This transponder used to be in my aircraft, a Vans RV-6, callsign VH-SOL.

[@Boffin55]

It's not part of TCAS, that would require a different (mode S) transponder.

[@SeanPearceUK]

"What happened to the TO220?"... "The front fell off" :-D

[@74HC138]

The need for that comb filter - the transmit and receive antennas are connected together, and the receiver probably won't like 150 watts of power being dumped straight into it, so you need a really good filter that will pass 1030 and block 1090 (and its harmonics).

[@TheHuesSciTech]

Maybe that super fancy filter is to get the attenuation required to prevent the 200W transmission at 1090MHz from blowing the receiver up while letting 1030 MHz incoming signals through. (Edit: in other words, a diplexer [thanks Shahriar!]) You're not going to achieve that with a 2nd order Butterworth filter!