Dino: Yes the parallels are really eerie OM. There is that Turner mic. I still have mine too, but I had to replace the element with an Electret. Mine brags that it is Transistorzed. Wow!It apparently had three transistors in it. Therefore it was a Turner +3. I also had a Vibroplex bug, but I never really used it and it fell apart. Pieces were donated to a restoration of the K3ZO bug in the Dominican Republic. I kept the base, which now holds a straight key that I use very infrequently. There is of course, the Drake. In the other picture (below) I see your HQ-100 (A model). Please tell us more about that DC receiver. Homebrew? Solid State? Band? Where did you get the schematic? I also see that you had a good library even back then. FB OM. I remember fondly the Zoom visit to the Williamsburg club. And I still use the coffee mug! 73 to all. Regards to Toby. Bill N2CQR
Dino writes:
Bill - saw your 15-year old pix on the blog today and
immediately found a distinct likeness in my teen ham pix!
And me, WB6FZN at the time, I probably had a similar
plaid shirt too:
Come to think about it all of us “of an age” look a lot
alike back then. I still have the Vibroplex key, Turner 454-C mic and
Drake MS-4 speaker/AC-4 power supply. My dad bought me the TR-4 when I
got my General license and that setup was north of $600 if I recall correctly
from AES; that was big money for ~1969 as he was a bartender, bless his
heart. Sold the TR-4 in Alaska during our first duty assignment with the
blessing of my YL Toby KLØSS and got the Drake C-line to replace it which I
also still have.
You visited our Williamsburg Area Amateur Radio Club’s
“Builders Group” via Zoom during Covid and guys still talk about that session
we had with you.
BTW, you can see my first direct conversion receiver in the aluminum chassis
sitting on top of my Hammarlund HQ-100A here:
First, a big THANK YOU to Grayson KJ7UM and to Zeynep, his wife and video editor. The above video is a really excellent look at not only the technical characteristcs of thermatrons, but also at the history of their development. There is a lot to be learned in this wonderful video. I am glad that no one was shocked in its production. And I am glad that SolderSmoke is no longer the only podcast/videocast using a "shamless commerce" segment!
Grayson's video and his "modest proposal" are eerily timely for me. Just yesterday I dragged out my old thermatron 80/40 receiver and got it inhaling. It uses 6U8s and 6EA8s which were featured in this video. This morning I used this old thermatron receiver to listen to Tim WA1HLR, who has been using thermatrons for many years.
I have also been talking about Compactrons -- specifically the 6T9 -- on the podcast. This prompted Jeff Tucker, W9TH to send me the PC board for the simple 6T9 circuit that I should have built as a teenager. I also got words of encouragement from Mike WA6ARA. The pressure is building!
Finally, this gets us to Grayson's "Modest Proposal." See: https://kj7um.wordpress.com/2026/09/16/a-modest-proposal/ He proposes that we STOP calling these devices "tubes" or "valves" and instead refer to them as thermatrons. I am with him on this. But I warned him that his proposal (even with modesty) would provoke HOWLS of protest from the many, many change-averse radio amateurs in the US and, especially in the UK. I know from personal, lived experience (four years in London) that the Brits love their valves. But, hey, Grayson is right! So I will pledge -- whenever possible -- to use his preferred term. Gentleman, don your Kevlar now!
Thanks Grayson for the video, and for the modest proposal!
The frequency 3885 kHz is inextricably tied to one of the most iconic military radios of World War II: the BC-611 Handie-Talkie (part of the SCR-536 radio set).
Manufactured by Galvin Manufacturing Corporation (which later became Motorola), the BC-611 was the world’s first ubiquitous handheld, two-way AM transceiver. It was the "walkie-talkie" you see clamped to the ears of infantrymen in every classic WWII movie.
The technical marriage between this specific radio and 3885 kHz came down to how the military deployed them and what happened immediately after the war:
1. The Channels Were Commandeered
The BC-611 could operate anywhere from 3.5 to 6.0 MHz by swapping out internal plug-in coils and quartz crystals. Because the U.S. government temporarily shut down all civilian amateur radio operations "for the duration" of WWII, the military freely assigned tactical frequencies right inside what used to be the ham bands.
For company and platoon-level communications, 3885 kHz became a standard assigned military channel.
2. The Great Surplus Avalanche
When WWII ended, the military had hundreds of thousands of BC-611 units, along with mountains of spare FT-243 crystal units, sitting in warehouses. The government liquidated them to the civilian market for pennies on the dollar.
Hams returning from the war snapped them up. Because these units were strictly crystal-controlled (you couldn't just spin a dial to change frequency), you were locked onto whatever crystal was inside. Since a massive portion of the surplus BC-611 inventory came pre-installed with the military's 3885 kHz crystal and tank coil, thousands of hams suddenly possessed portable AM rigs fixed precisely to that exact spot on the dial.
3. A Lasting Living Tradition
Even though a BC-611 only pushed out a fraction of a watt of AM power (using a tube filament battery and a 108-volt B+ battery), hams quickly realized that if they gathered on 3885 kHz, they could hear each other locally. Operators with larger, higher-powered home stations began parking on 3885 kHz as well, just to act as "big ears" to pick up the faint signals of the handheld walkie-talkies.
That specific frequency choice was entirely forged in the surplus markets of 1945 and 1946. Eighty years later, the tradition is so deeply ingrained that military radio collectors and vintage AM operators still hold a massive, synchronized check-in on 3885 kHz every year during the Dayton Hamvention weekend.
-- I like the repeated demonstration of the reality of envelope detection. Too often people have bought into the idea that envelope detection is not real, and that some form of mixing using the carrier in lieu of the local oscillator is what is really happening. That is just not true. Envelope detection as described in this film is real.
-- The description of mixing is very simplistic. They describe the generation of the difference product, but not the sum. But hey, the film is only 17 minutes long! It takes a lot longer than that to fully describe mixing (ask me how I know!).
-- At the very end, there is a shout-out to the BC-348. FB.
More spark today. I really liked how Robert Dalby demonstrated spark transmission and reception. He used a simple Piezoelectric flame starter (like the one that many of us have in our shacks) as the transmitter, with a homebrew coherer connected to an LED and some batteries as the receiver. Ingenious. As with CuriousMarcs video of yesterday, you can see how Marconi's system really worked. Brilliant.
This demo also shows how many devices can generate part of the noise we hear in our receivers. We see and hear the noise generated by a nearby electric fence, and the noise made by a simple electric motor. Many new builders have trouble accepting the reality of noise. Noise happens.
The entire YouTube channel is very interesting. Check it out here:
It is based on the amazing collection of Dieter Beikirch (I think he is DJ5RS) and is presented by Robert Dalby. Here is how they describe the channel:
German avionics in the era of the vacuum tube.
Join us as we investigate the most critical period in the rapid development of electronics, especially airborne electronics, from the first spark-gap radios of WW1 to the advances in radar technology in WW2.
CuriousMarc provides a good demonstration of how spark transmitters work with coherer detectors. His measurements are really illuminating. His device just needed a "tapper" to de-cohere the metallic filings. We see the tapper in this wonderful "Secret Life" video by Tim Hunkin:
On December 1st 1924, the 20kW Alexanderson Alternator with the call sign "SAQ" was put into commercial operation with telegram traffic from Sweden to the United States. 101 years later, the transmitter is the only remaining electro-mechanical transmitter from this era and is still in running condition. On Christmas Eve morning, Wednesday December 24th 2025, the transmitter is scheduled* to spread the traditional Christmas message to the whole World, on 17.2 kHz CW.
You can listen to the CW from Ciprian's setup above. I listened to it carefully and clearly heard the "KW ALTERNATOR" words at around the 3:30 mark in Ciprian's video. I wondered if this was in fact the SAQ Alternator (but then again, who else would be on 17.2 kHz on Christmas Eve?). I looked at the video from Sweden (below) at around the 49.37 mark we see the operator send "200 KW ALTERNATOR." Through Ciprian's video, I copied "KW ALTERNATOR." So Ciprian's operation was a success. Congratulations Ciprian!
That is a question we get fairly regularly when we tell the other fellow that our rig is homebrew. I often get the feeling that the question stems from a certain insecurity -- the guy who asks it may feel a bit insecure because the "rig" he is running is completely commercial and his only role in its production was to flash a credit card number.
But lately I have been reading through Jim Williams' wonderful book "Analog Circuit Design -- Art, Science, and Personalities" and I can see that there may be something to this question.
It was the chapter by Barrie Gilbert that made me think more about this. Barrie is the legendary designer for whom the Gilbert Cell is named. This circuit is at the heart of the NE602 chip that many of us used to build our first "Neophyte" receivers and other homebrew rigs. Barrie's chapter is entitled "Where do Little Circuits Come From." Uh oh.
Barrie grew up in the post-war United Kingdom. He father had been killed in a German bombing raid. As a kid, he built crystal radios and, with his brother, "shortwave sets" on softwood bases. He used a TRF receiver that employed Manhattan-style construction. Barrie, it seemed, was one of us.
But then, he suddenly seemed more advanced. He wrote:
"Later, I began to build some receivers of my own but stubbornly refused to use circuits published in the top magazines of the day, Practical Wireless and Wireless World. Whether they worked as well or not they had to be "originals" otherwise, where was the satisfaction? I learned by my mistakes but grew to trust what I acquiered in this way: it was 100% mine, not a replication or mere validation of someone else's inventiveness."
Wow, that is certainly hardcore. I will note, however, that in getting back to the the question about whether I have "designed" the rig myself, I have NEVER had the questioner come back to say that HIS rig was homebrewed from HIS OWN original design. Never. Not once.
And I will note that building a rig from the schematic is an enormous challenge. It is not easy. It is not the mere replication of someone else's inventiveness. Anyone who thinks it is easy should try to homebrew a simple direct conversion receiver. They will discover that it is NOT easy.
I guess this comes down to what we mean by "homebrew." I prefer to stick to the old ham radio meaning of the term: It is homebrew if it was built at home, even if it is built from a schematic done by someone else. When Jean Shepherd built his Heising Modulator, was he working off a schematic from a ham radio magazine? He almost certainly was. But he gathered the parts, laid out the chassis, and put the circuit together. Most importantly, when trouble cropped up, he was able to step in and make the needed corrections. Was his modulator "homebrew?" Of course it was. Did he design it himself? No, his name was not Heising!
More than 100 people built our SolderSmoke Direct Conversion Receiver. We resisted pressure to turn this project into a kit. The folks who built it worked off schematics that we had prepared. They gathered the parts and built their own circuit boards, Manhattan style. They struggled to get the whole thing to work, to make sure the VFO was on the right frequency and at the right level, that the AF amplifier was not oscillating. Were these receivers "homebrew?" Of course they were.
Jim Williams warned that Analog Circuit Design was "A wierd book." He strongly discouraged collaboration between the authors, and noted that this would probably result in "a somewhat discordant book." We see that discord in the hardcore position taken by Barrie Gilbert. Many of the other designers seem to take a more flexible, less austere position. Some even seem to downplay the role of mathematics.
I think Barrie had a right to be proud of his fundamentalism. But not all of us are capable of that. Writing in Jim Williams' book, Samuel Wilensky sums it up nicely:
"I classify analog designers into one of two categories. There are those who do truly original work, and these I consider the artists of our profession. These individuals, as in most fields, are very rare. Then there are the rest of us, who are indeed creative, but do it by building on the present base of knowledge."
First off, what a great name. It is a real ham radio name. Grote Reber. And he was indeed a ham: W9GFZ. We don't have names like that anymore. But we should.
Second, Grote Reber's mother was also the teacher of Edwin Hubble. Hubble was the guy who discovered that there were OTHER GALAXIES in the universe, and that they were all moving away from each other. That was a BIG discovery! Later, Grote's mom also had her son in her class. Both students were from Wheaton, Illinois.
Lest there be any doubt about Grote's dedication to radio, consider the following. (Much of the following comes from Wikipedia. https://en.wikipedia.org/wiki/Grote_Reber)
When he learned of Karl Jansky's work in 1933,[5][6][7] Grote Reber decided this was the field he wanted to work in, and applied to Bell Labs, where Jansky was working.
In the summer of 1937, Reber decided to build his own radio telescope in his back yard in Wheaton, Illinois. Reber's radio telescope was considerably more advanced than Jansky's, and consisted of a parabolic sheet metal dish 9 meters in diameter, focusing to a radio receiver 8 meters above the dish. The entire assembly was mounted on a tilting stand, allowing it to be pointed in various directions, though not turned. The telescope was completed in September 1937.[8][9]
Here is a really great article from Sky and Telescope magazine (July 1988) about Reber's homebrew radio telescope:
He was limited by the size of locally available 2X4 lumber. Neighbors thought he was trying to control the weather or to bring down enemy aircraft. Between Wheaton and the NRAO site in West Virginia, Reber's telescope spent some time at the National Bureau of Standards site in Sterling, Virginia. I was in Sterling just yesterday. I wonder if there is a plaque or something noting the telesccope's stay in that town. I note that at age 15, Reber had built a ham radio transceiver.
AND THEN HE MOVED TO TASMANIA
He did this because of propagation and low noise conditions. (This reminds me of how we sometimes said that very few people have actually said the words, "And then we moved to the Azores.")
Starting in 1951, he received generous support from the Research Corporation in New York, and moved to Hawaii.[12] In the 1950s, he wanted to return to active studies but much of the field was already filled with very large and expensive instruments. Instead he turned to a field that was being largely ignored, that of medium frequency (hectometre) radio signals in the 0.5–3 MHz range, around the AM broadcast bands. However, signals with frequencies below 30 MHz are reflected by an ionized layer in the Earth's atmosphere called the ionosphere. In 1954, Reber moved to Tasmania,[12] the southernmost state of Australia, where he worked with Bill Ellis at the University of Tasmania.[13] There, on very cold, long, winter nights the ionosphere would, after many hours shielded from the Sun's radiation by the bulk of the Earth, 'quieten' and de-ionize, allowing the longer radio waves into his antenna array. Reber described this as being a "fortuitous situation". Tasmania also offered low levels of man-made radio noise, which permitted reception of the faint signals from outer space.
His Homebrew House in Tasmania
In the 1960s, he had an array of dipoles set up on the sheep grazing property of Dennistoun, about 7.5 km (5 miles) northeast of the town of Bothwell, Tasmania, where he lived in a house of his own design and construction he decided to build after he purchased a job lot of coach bolts at a local auction. He imported 4x8 douglas fir beams directly from a sawmill in Oregon, and then high technology double glazed window panes, also from the US. The bolts held the house together. The window panes formed a north facing passive solar wall, heating mat black painted, dimpled copper sheets, from which the warmed air rose by convection. The interior walls were lined with reflective rippled aluminium foil. The house was so well thermally insulated that the oven in the kitchen was nearly unusable because the heat from it, unable to escape, would raise the temperature of the room to over 50 °C (120 °F). His house was never completely finished. It was meant to have a passive heat storage device, in the form of a thermally insulated pit full of dolerite rocks, underneath, but although his mind was sharp, his body started to fail him in his later years, and he was never able to move the rocks. He was fascinated by mirrors and had at least one in every room.
To Canada -- And a Rejection of the Big Bang
The same July 1988 issue of Sky and Telescope magazine has a good historical vignette of Reber, with a focus on his actvities in Canada late in life (click on the image below). Reber had big doubts about the big bang. Unfortunately this seemed to spill over into scorn and ridicule for those who -- well -- believed in the big bang. We see this at the end of the article. Oh well, even great people sometimes get cranky.
Three cheers for Grote Reber.
I had trouble making the WayBack Machine links to work on my blog. But they seem to work on the Wiki page. So to see them, go to https://en.wikipedia.org/wiki/Grote_Reber Then go to the Reference section and take a look at the second and third items.
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