Ever Wonder What's Inside a Transponder?

[John DeRosa OHM Ω http://aviation.derosaweb.net]

This YouTube video is from an Australian electrical engineer videographer that I have been following for quite a while. He has "mailbag" episodes from time to time to talk about electronic goodies that have been sent in to him (by me in one case). Some new, some historic, always fascinating ... to me at least.

From these items he sometimes creates tear down videos of interesting swag. This is the first time he has torn down an aviation device that I know of.. In this case it is a Australian build MicroAire T2000 transponder.

As a lowly bit-pusher type EE I don't *EVEN* hope to understand the 1Ghz stuff that goes on within these powerful little devices (pumping out ~200W of power). The TX and RX RF sections are amazing. Especially spooky is how a simple trace on a circuit board can be a inductor or a capacitor at these frequencies. The description of the comb filter at 19:20 baffles (my puny) logic. As they say, "its all FM & AM to me".

https://youtu.be/UE-LXmYl8Mo

Enjoy, John OHM

[2G]

On Friday, December 4, 2020 at 9:35:55 PM UTC-8, John DeRosa OHM Ω http://aviation.derosaweb.net wrote:
> This YouTube video is from an Australian electrical engineer videographer that I have been following for quite a while. He has "mailbag" episodes from time to time to talk about electronic goodies that have been sent in to him (by me in one case). Some new, some historic, always fascinating ... to me at least.
>
> From these items he sometimes creates tear down videos of interesting swag. This is the first time he has torn down an aviation device that I know of. In this case it is a Australian build MicroAire T2000 transponder.
>
> As a lowly bit-pusher type EE I don't *EVEN* hope to understand the 1Ghz stuff that goes on within these powerful little devices (pumping out ~200W of power). The TX and RX RF sections are amazing. Especially spooky is how a simple trace on a circuit board can be a inductor or a capacitor at these frequencies. The description of the comb filter at 19:20 baffles (my puny) logic. As they say, "its all FM & AM to me".
>
> https://youtu.be/UE-LXmYl8Mo
>
> Enjoy, John OHM

Dave's teardowns are always interesting and I always learn something from them. The "magic" of RF design is quite instructive because EVERYTHING becomes a circuit component, including wires. Note that there is no sheet metal in this design - it leaks far too much RF unless careful RF gaskets are used. Anybody interested in learning more about RF design can start here:
http://www.w1ghz.org/

Tom

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There's real fun to be had at 10gHz and above but only a handful of people to have the fun with.