Wayne: Yes, its a 5044 encoder. These were good little encoder chips, once you managed to suppress the RF pickup they were prone to - especially at 459 MHz! We had to build them with a double sided PC board, with an earth screen under the chip!
There is a switch marked "throttle mix", another unmarked switch, and a pair of sliders and associated trims on the top of the Tx!
I think it was intended for a twin-engine setup, with the ability to separate the throttles if desired. But I could be wrong!
I do have a Silver Seven encoder in an old Tx somewhere, but it only has the basic "plug-in" board with it.
Phil: No, the RF board is all my own work! My very first UHF experiment did use a (very complex!) Wood & Douglas board, but it started off from a 12 MHz crystal, used a varactor for one of the multiplier stages and had horrendous current consumption! You could pull the crystal across half the 459MHz band!
I've also got one of their later synthesized boards, which I've been meaning to build into a Tx since forever, but never got around to!
My own boards started off at 76.5 MHz (or thereabouts), multiplying by 6 to get to 459 MHz. Initially I used specially cut 3rd overtone crystals, following the Multiplex example, but later switched to 5th overtones when I discovered I could modulate them just as easily! The 5th overtones weren't always as easy to get going initially, but once you'd coaxed them in to life they were just as stable as the earlier 3rd overtones - and a lot cheaper!
P.S. Should have added: I'm in awe of Tobe's work!
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Pete