Time was if you wanted to challenge QRPolitical Correctness, you advocated
the Direct Conversion receiver. Laud your Tejas Backpacker and you were told
it was an atavism. But now there is a new champion for those who yawn at y-
cut crystal filters and refuse to vouchsafe for VXOs. From a most unlikely
source, the Doerle is back and this time, no more Mr. Nice Guy.
A Doerle? Isn't that a one-tube regenerative (aka "Blooper") that hams used
before Frank Jones led them to the Regenerative Superhet? Well, almost. As
one learns in the newly released, 63-page "How to Build the Twinplex
Regenerative Receiver," (references below) The Doerle was as much a product of
technology as the modern miniature RXs and TCVRs based on the Ne-602. In 1933
it was the twin triode at a price for the masses that started it all. The
type 19 vaccum tube allowed a one-tube kit of the then-popular ham two-tube
rigs. The industerous Mr. Doerle put together a kit and it took off. Doerle
clubs were everywhere and, until cheap superhets appeared, continued to be a
force in SWLing.
It is T.J. Lindsay who recounts all this in his third book on the subject.
The first was an extended interview on regenerative technique with C.F.
Rockey, W9SCH, an early but influential figure in both QRP ARCI and G-QRP.
There were a splattering of solid state circuits in that book and none in "How
to Build Your First Vacuum Tube Regenerative Reciever," offered the next year
in 1997. But this year's book, after reciting the history and showing how to
make an original Doerle and a poor boy's 1950s model, gets to the stuff of
which success is made: silicone.
And Lindsay, who is a speciality publisher who does not handle anything to
offend feminists, does not just put two FETs in for the old twin triode's
elements. In fact, he shows you why you should not either. Instead, he
develops the circuit through several stages and presents numerous options for
the constructor. It is the highpoint of the book. He ends up with a close
tuning two FET, one bipolar rig that tunes WWV and 30M and doubles as a signal
generator. (If you happen over on the Glowbugs mailer, where they build
classic circuits, don't even think about saying that a regenerative circuit
without an RF amp radiates -- it is like advocating the Bible as Literature at
the Texas Baptist Convention.).
There are many constrction hints throughout the book. Those of us who
think we have seen it all should pay particular note to page 33 and a picture
of C.F Rockey's revisionist style of making plug-in coils -- he hacksawed
through the form and ran all the taps thru the resultant channel. The "Where
can I get the circuit board" crowd will be disappointed, and it is unlikely
anyone will offer a second kit of parts 64 years later. But whether you are
collecting kit radios from the 1930s or building them now from Radio Shack
parts, the new Lindsay is must do Summer reading.
References:
"How to build the Twinplex Regenerative Receiver," Lindsay, T., 1998, 63
pages, $7.95, Lindsay Publications Inc, Box 538, Bradley IL 60915-0538
http://www.keynet.net/~lindsay
by same author:
"Secrets Of Homebuilt Regenerative Receivers," 1996, 127 pgs
"How to Build Your First Vacuum Tube Regenerative Receiver," 1997, 127 pages
73 de ab5L, michael in dallas, student of Tecraft and International Crystal
(ICM) ham products and mementoes of Six Meters' Golden Age: 1957-58
Michael Hopkins
Box 226841
Dallas, TX 75222 MNHopkins@AOL.com
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