It continues to amaze me that people in the US are apparently flying with this
There was a plane I flew 20 years ago when training that had these. They seemed ancient even back then. Even for $200, what would you do with them? Especially since they have no yellow tags so can’t legally be installed in an aircraft.
Under Part 91, an A&P has the authority to inspect an avionics item and declare it airworthy (or not) – “avionics” comes under “airframe”. No papers needed with the item (not many people know this, and the industry likes to keep things that way 
).
However, it would be extremely dumb to spend any money on labour installing this stuff from new. I can see just two uses, and both involve very “tight” people:
There are quite a few syndicates out there who still have these and who cannot get agreement for an upgrade, so they just keep the radio barely working. Apparently, these radios do work ok when they work. And in the UK, nearly all GA 8.33 frequencies are the 5kHz add-on which is the same carrier frequency, so the old radios work… sort of, if the crystal is not too far off 
Peter wrote:
However, it would be extremely dumb to spend any money on labour installing this stuff from new.
I don’t know about N-reg, but on EASA-reg, it would actually be illegal to install them even on uncertified aircraft. Replacement for already installed boxes of the same model, yes.
As many will understand KX170Bs are solid state and extremely reliable but obviously they do break sometimes when they’re 40 years old. If sticking a used replacement in keeps somebody and their plane flying in Class D and up, it’s great that stuff like this is traded around easily and inexpensively. There are doubtless thousands of planes flying with KX170Bs and if you can replace one that’s not working with one that is working for $200 and 1 minute of labor, why not? The faceplates on at least one of these could be cleaned up fairly easily, if desired.
Apparently King made 100,000 KX170Bs.
I love the KX170b. Its a great radio simple to use has a quailty feel to it and if it works just keep it as a back up comm and Nav.
Although I suspect one shouldn’t do that thanks to the not FM immune crap.
Although most of the 8.33kHz spaced channels currently in use are the same carrier frequency of the old 25kHz spaced one, I suspect the crystal might have aged enough in those old KX170Bs for people to notice if you attempted transmitting with it :-)
I don’t know which is more amusing: the box or the asking price
This must surely pre-date Gemini, let alone Apollo.
Looks impressive – what is it?
The Narco Superhomer was one of the original Nav Com radios, circa 1957. Smithsonian article here
Some older US built planes originally had unusually large glove boxes at the sides of the instrument panel, with the idea that a radio of this size could be fitted directly (or almost) into the space occupied by the glove box, without disturbing the panel otherwise. Or if you didn’t need a radio, you had a very large glove box. The center stack concept came along as radios shrank and more people considered them important enough to occupy valuable panel space.
