The Telecon Pack is a radio frequency broadcaster for the Mark III.
Sega really went nuts with the accessories in the 80s, but this one makes a lot of sense from a Japanese perspective. In Japan, consoles were designed to sit near the player, and run a long cord to the television. This is the reason Japanese controller cords are so short, and why the SG1000, Mark III and Master System have the pause button on the console – because it was assumed you’d have the console next to you on when playing.
The Telecon Pack would allow you to have the console on a side table at the back of the room with power cord tucked away, and avoid needing a wire to the television for the video and audio.
It connects via the AV port, and then broadcasts the composite signal via a Japanese TV channel.
It originally came with a satellite dish you could plug into your TV for reception, which I don’t have right now.
But it actually works fine with a regular television antenna – as long as the TV can tune in Japanese stations. My current TV can, and the results are surprisingly decent. Powering up one of my favourites Makai Retsuden:
RGB via Framemeister for comparison below:
It also works fine with the FM adapter, which has the composite signal passed through the adapter cord.
It looks super neat this way.
FM adapter plus Telecon pack on Mark III is the original Sega Voltron console.
Grand Master Sega Voltron Challenge – Telecon Pack to Game Gear TV Tuner
So now we have a Sega console that broadcasts, and a Sega console that can accept broadcasts. Time for the ultimate combo!
The only Japanese TV tuner I have is from the white Game Gear, but unfortunately the white Game Gear needs repair, so I cannot make an all white Sega Voltron.
So I’ll sub in a working recapped Game Gear. I touched the TV tuner’s aerial to the Telecon pack’s aerial for maximum reception.
Is it the least convenient way possible to officially play Mark III games? Almost certainly.
Nintendo Sega Japan! 
