@Mellow Hudson Mike posted:The two-tube requirement seems to apply to the phonograph feeding the mixer box, and not the mixer box itself.
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Right. That's fascinating how the instructions suggest you need a minimum of 2 tubes! I remember when transistor radios came out they were spec'd by how many transistors were in it. You paid extra to get a 5-transistor radio vs. a 4-transistor radio. 
OK. So presumably when going to buy a phonograph amplifier in 1950 you would tell the salesman that you needed at least a 2-tube phonograph system. And if you had a good job maybe you could afford a 3-tube phonograph! 
@Johnbeere posted:...
I'd love to get my tender working if possible, but I wouldn't know where to even begin. The mixer box probably needs to be gone through, it's in rough shape, and I don't have anything capable of playing the 78 records.
These didn't actually come with an engine - you were supposed to pair it with one you already owned, most likely an early postwar Lionel loco.
It might not be that difficult. My guess is the transformer might be functional but the condensors are shot. But those can be replaced with modern condensors (i.e., capacitors). Can you access and read any printed info on the condensors (it looks like 2 of them) like you can in the tender-side photo that has a condensor labeled "40mfd 150v.w. 225v.p."?
This may be getting into the technical nitty-gritty but I'm think the transformer is simply doing impedance conversion to couple the audio with the track voltage. That is, since this system also supported DC track voltage it's unlikely the track voltage went thru the transformer since a transformer cannot pass DC power.
As for not having a record player I wouldn't worry about that for now. There has been a nothing less than a renaissance in vinyl records so it will be simple to find someone to convert the records into some digital format like MP3 or whatever. You need to get the system working using whatever audio source you have such as your phone, PC, CD player, whatever. And then if you really want to go old-school with genuine spinning-phonograph and tube amplifiers there's the musician crowd that swears by tube amplifiers vs. the modern transistor/digital technology.
The actual nuts-and-bolts of how it works and then how faithful you want the restoration to be gets somewhat nerdy in terms of the technology but if you're truly determined to do so I think there's promise. That and a nod to St. Jude, the patron saint of lost causes! 
