David Newkirk recently put up a nice website on ham radio. The page below provides details on the amazing creation pictured above: The BGCD: "The Byron Goodman -- Clinton DeSoto Regenerodyne." It is a beautiful piece of work, made more beautiful by the metal containers used in construction: pencil, candy and tea tins. The circuit is based on a 1937 QST article.
David's site reminded me of the wonderful writing of his father, Rod Newkirk of "How's DX" fame. More on him in due course.
More on the BGCD here:
http://dpnwritings.nfshost.com/ej/pictures/pictures1.htm?fbclid=IwAR2-lmJ8E1kEBT_jsB3Q8UnPaN0vc472dP783ifABK7eSxgpe5M1Pl0N77g
I realize people use "regenerodyne" and ustify it by its design, but functionally this isn' very different from Frank Jones' "suoergainer" from about the same time. h
ReplyDeleteHe added a converter stage to a regen detector, simpler than a superhet but less finicky than a straight regen.
The difference is that the supergainer used a variable oscillator into the mixer, and the "IF" was fixed, and the "regenerodyne" used a fixed oscillator and the regen was variable.
I have never thought the difference warranted a name change. Frank Jones name describes how well it works, "regenerodyne" focuses on the regen detector, when both amount to simple superhets. It may make for simpler design by making the local oscillator fixed, but functionally both would have the same gain and other specs.
A direct conversion receiver with a converter ahead of it, a common design in the seventies, is considered a simple superhet, and can be made with a crystal oscillator into a variabke DC receiver, or with a variable oscillator and a fixed DC receiver.
Besides, a fixed regen can be imoroved by putting a crystal filter between the mixer and regen detector, allowing for single signal operation.
I intentionally used the term "Regenerodyne" over "Super Gainer" because it honors the use of that name by Gary Johansson, WD4NKA, who has long had a page up about his implementation of the idea, and because at the time I put my BGCD page together I was participating quite often in Facebook forums he headed.
DeleteI'll say also that I have long found Frank Jones's self-promotion "back in the day" to be sufficiently offputting to not want to further promulgate his nonsense in this millenium. ARRL publications managed to cover superhet-regens without such puffery, I think to the greater good of hamdom. (That's why we don't think of a grid-plate oscillator as the "Reinartz" oscillator, as it was promoted by John Reinartz in the 1930s.)
I do credit Jones with an early in-print usage of the "Boosted Pierce" oscillator-amplifier topology ( http://dpnwritings.nfshost.com/ej/boosted_pierce/ ) but also -- in a page currently not linked out of my "Enjoying Radio" homepage -- take him to task for intentionally configuring the drawings of his "Sure-Fire" oscillator ( http://dpnwritings.nfshost.com/ej/sure_fire/ ) to hide the fact that the "Sure Fire" is an oscillator + locked oscillator construct, which knowledge is essential to using the technique without transmitting unstable and/or out-of-band signals.
The name "Super-Gainer" comes not from any of the projects so named as having "super gain", but rather from the fact that in periodicals and the _Radio_ Handbook_ of the day Jones termed a straight regen a "Gainer", which when fronted by a frequency-conversion stage -- making it a superhet -- could be termed a "Super-Gainer".
Whatever; I am not as interested in the personalities as the techniques. I do for my own purposes refer to some of my constructs by identifiers that honor forerunners dear to me -- "BG" in BGCD because By Goodman was a personal friend of my father's and later of mine, and CD because Clint DeSoto was one of hamdom's great writing stylists of at least the 1930s, authoring many _QST_ articles and the classic early-ham-history book _Two Hundred Meters and Down_.
Building is tins is the epitome of rapid development: Need a hole? Make it with a push pin, enlarge it with needle-nose or long-nose pliers. Need to ground a component or anchor a tie strip? Scrape away the lacquer (commonly used in food-bearing tins, not always in tins intended for other purposes) and solder. Greenlee punches remain a great help with tins for tube sockets; thin steel doesn't ream or cut (as with a fly cutter) as more-solid metal does.
In parting: A crystal filter ahead of an oscillating regen is commonly a bad-performing and frustrating combination, as the filter crystal(s) reradidate(s) the detector's signal, but time- and phase-shifted, leading to terrible thumps and bangs and silences when we try to tune the detector around the filter passband to set our favorite pitch. _Far downstream_ of a crystal filter, such as at the tail end of a filters-plus-multiple-AGCed amplifiers strip, a regen can work fine, but not so electronically close to the filter that the detector receives its own signal as re-emitted by the filter.