Well, this is a tuner of sorts... if you think it belongs in one of the TV boards, please move it there! : )

I found this at a garge sale. My questions are:

1- how do I hook it up?
2- what can it do for me?
3- will it be obsolete when the digital switch happens? Note that I only have an antenna with a converter box.

Oh, here's pics...

I think you'll get more responses here, from the TV guys.

I dont think it's a tuner.
Its a stereo decoder, similar to - but not compatible with - something like a Dolby Surround decoder.
I suspect all it wil do is extract (decode) stereo audio from a broadcast TV signal.
The input is most likely the MPX signal from the TV set sound detector circuit - not a signal universally available on all TV sets.
(some AM tuners of the 1980s had IF outputs for add-on stereo decoders).

If your TV set has stereo aux outputs on it already, this device is unnecessary.

It would have been sold to go with a stereo TV that was sold just before MTS came out. These TVs had a jack to add an external decoder once the standard was finalized. It's similar to the multiplex output some old mono FM tuners have. It's a nice thing to have if you own one of these early stereo TVs, or VCRs, but otherwise useless. They are pretty rare since most people didn't bother to buy the adapter for their TV, and they weren't sold for long.

Yep, my dad bought a mono Trinitron 27" in '86 and opted for the outboard MPX adapter. I recall him using it and then when we moved he never reconnected it.

Its just a toy which was used to usher in MTS stereo broadcasts. Eventually, the person stopped caring or the TV broke down and they bought a set with integrated stereo sound.

True, they are rare though. Neat little gadget.

3- will it be obsolete when the digital switch happens? Note that I only have an antenna with a converter box.
Yes, it will be obsolete after February 2009 in the USA.

I have several MTS decoders: Recoton FREDs, an NEC, maybe another one or two. Some versions of the FRED could decode stereo TV sound without even connecting to the TV set; they used a probe on a wire that picked up the 4.5 MHz sound IF from the back area of the TV set.

They will still be useful on cable.

True it might be useful for cable, but more and more decoder boxes are connectible via baseband audio/video making that point kind of moot, at least if you're stuck using RF out from the cable box anyway. Since the transition to digital cable distribution, they aren't restricting you to RF output only from the decoder box.

Most cable systems still have analog versions of basic cable available for cable ready TV's and most of those will still be available after Feb next year and in some systems most of the channels have BTSC audio so the MTS decoder could still be used.