[AT] was generator=ee / tubes

[pga2 at hot1.net]

Ken,
Which warbird? I love the old WWII planes almost as much as old tractors!
Bless you for your work!

Phil

> While tubes have been removed and replaced over the years in a lot of
> systems, I found one recently that the modern electronics weren't able
> to cope with.
>
> There's a controller for the turbochargers on some radial-powered
> 4-engine aircraft (several different ones, actually) that some folks
> had tried to replace with modern electronics. Apparently they didn't
> get the system right because it ended up being removed and replaced
> with the original, 4-tube amplifier systems. The problem with the
> aging electronics is that the resistors are unreadable and the
> capacitors are literally falling apart (cases splitting, etc). I'm
> sure they never expected something build during WWII to still be
> flying today, and all the discussions with the obsolete electronics
> apply here: nobody really seems to know enough about them to want to
> go in and repair them (me included).
>
>      So when I was asked to see if I could repair or update the old
> controllers, I looked it all over and opted for a mix of technologies.
> The tubes were pretty much a requirement, since they worked and the
> folks have a long history of testing and maintaining that equipment.
> The point-to-point electronics were too rotted to repair, and the
> transformers had been overheated and needed replacement as well.
>       I offered to replace the point-to-point with a circuit board,
> put in new transformers (and worked with a shop to do the 400 Hz
> transformers). I also had to learn how to work with tubes. We touched
> on them in electronics school when I was there in the early 80's, but
> that had been awhile. I had to learn how they worked electrically in
> the circuit (yeah, the FET terminology is valid, but which type? I use
> a lot of MOSFETS these days... :). When I got the first ones complete
> and we tested them, I don't know who was happier... the customer or
> myself. They love the look of them; they still have the tubes they are
> familiar with, and they have new parts and components, reducing the
> intermittent "issues" the old controllers were experiencing.
>      Out the other end of it, I've received an education on tubes, the
> museum has a bunch of new parts (at a seriously reduced cost; I didn't
> charge them for the engineering time) and I have some pictures that
> will eventually go on my website. :) Oh, and the pride of keeping at
> least one old warbird flying a little longer.
>     It's been quite an experience, and there was another rewarding
> aspect of it. My retired neighbor who at one point worked for
> Honeywell in Minneapolis, looked at the controller and perked up. He
> knew the guy that designed it (apparently a lead engineer at Honeywell
> back in the day) and was quite happy to see the modernized version
> being built new over 60 years later. (My neighbor is also quite a
> storied individual, having served on the West Virginia after it was
> salvaged from Pearl Harbor, and later on designed and built gyroscopes
> that are still in production 40+ years later).
>    So not all of the "modern" electronics will be thrown in the trash
> when they reach the end of their usable lifetimes. I think many of the
> modernizations are way overzealous in the application of complexity,
> but I think we also see that in some of the old tractors. The ones
> that were too complex either got simplified or didn't survive in the
> field or in the marketplace. They are sometimes known as orphans or
> oddballs. History will repeat itself, I'm sure.
>
> Ken in AZ