jaymen

The servos used in the first Bonners were analog feedback types that used a pulse to voltage converter. The incomming pulse was converted to a voltage and compared with a voltage on the feedback pot to determine if the servo was tracking.

The range went down due to the high current draw of the harmonic servos, it dropped the battery voltage which reduced the receivers range, and additionally, each servo motor makes some noise which also can affect range.

The Controlaire S-4 was a true digital type PDM type, and was more current efficient than previous designs like the 2nd generation 4-RS. The 4-RS lacked failsafe, had a much more simplified and conventional encoder and decoder, and a small receiver with the first integrated circuits to ever be used in an R/C hobby radio.

JPL was where most of the NASA projects were done early on, including Explorer I, it was the biggest and premier developemental lab for space borne craft at that time, as it was part of Cal-Tech and it's founder Jack Parsons also had a hand in Aero-Jet company as well. I meant to say that by the mid 1960s, NASA had many other facilities come on line to expand their capabilities so JPL was lo longer their sole source of technology, but was still one of the top ranked labs in the world. Thanks for clarifying the dates, it's good to know them.

One can see that our hobby uses technologies and devices created for much larger markets, we get the low cost benefits of that as these technologies are mass produced in volume and we reap the cost benefits. If hobby radios were designed from the ground up with specialized technology intended soley for model radio control, the cost to us the user would be astronomical due to the initial design and investment, and relatively low sales number of manufactured radios, as R/C is a small niche specialty market.

Thus we are tied to hip with the state of the art technical developements and have to rely on spin-offs of those technologies to trickle down to us in order to have affordable radios for models. In the above case, we see how creative, sly, and determined a couple dedicated modelers were at geting that technology for the rest of us, and they took some risky steps in the process, no doubt not only for the hobby, but for financial gain as well...can you really blame them?

When I worked with Doug Spreng in 1982-3, he would always get quiet and not say much, or change the subject whenever I brought up him being the grand daddy of digital, and now I know why he was not very forthcoming, and also why he shied away from accepting acaldes and credit for it.