SolderSmoke Daily News

A Tale of Two Old Analog VFOs -- Artificial Intelligence's Role. PLEASE COMMENT!

2026-10-13T08:41:13.366-04:00

The Kenwood VFO under test, with 2 Yaesu VFOs Standing By

I have sung the praises of the VFOs taken out of the old Yaesu FT-101s. I am using them in two homebrew 20 meter SSB transcievers, one in the Dominican Republic, the other here in Virginia. We started buying these things just for the anti-backlash reduction drives. But the vendors would send along the reduction drives AND the entire VFO module. These circuits were all analog, and all discrete component. I understood them, and had completely homebrewed circuits very much like them. So I felt comfortable using them.

Somewhere along the line, I got the VFO from a Kenwood TS-820s. My motivation was the same: I wanted the anti-backlash reduction drive. But as with the Yaesus, the entire VFO box came with the purchase. The frequency on this one was much lower than the Yaesu. the Kenwood ran from 5-5.5 MHz, the Yeasu was up around 9 MHz. On this alone, the Kenwood seemed better.

I recently put the Kenwood on the bench and began testing it. I used Artificial Intelligence (AI) in the tests. The results were good and bad. Sometimes AI helped, sometimes it made matters worse. Mike WU2D recently used AI to look at the tubes of an old receiver he was working on. He too was impressed by the usefullness of AI, but I think he too had some misgivings. Here are some of Mike's conclusions:

Let's start with a fundamental question: I asked Gemini which of the two "ages better." Gemini said that the Kenwood was superior in this regard. I disagree. Here is why:

-- Tuning on the Kenwood was very jumpy and very scratchy. AI correctly said that this was probably due to corrosion over the years on the connections between the main tuning capacitor and ground. Strike 1! AI recomended cleaning with DeOxit. As a last resort they recommended putting some solder wick between the rotator shaft and ground. I did that and it fixed the problem (you can see the solder wick in the picture above), but I never had to do that with the Yaesu VFOs.

-- The schematic of the VFO shows a .9 V RMS output from the VFO. But it does not specify a 50 ohm load. Here is the Yaesu schematic:

AI kept insisting that I use a 50 ohm load. When I did, the output was reduced down to 54 m V rms. I questioned AI about the load, but it kept insisting on 50 ohms. Only later, did AI point out that in the Yaesu, the VFO would feed into a HIGH IMPEDANCE load. Strike 2.

-- Gemini kept warning about the Q3 and Q4 transistors. They were 2SC460 transistors with weird (ECB) pinouts. And they were prone, it said, to a horrible sounding disease: "Original Hitachi 2SC460 transistors are infamous in vintage ham gear for silver migration ("black foot disease"), where the lead plating oxidizes, turns black, and causes severe noise, leakage, or intermittent oscillation failure." AI happily recommended replacing them with 2N3904s. I did this, but the voltage on the emitter was way off. AI blamed this on the new transistors (that it had recommended!) saying that their hfe was too high (so, uh, why did you recommend them?). It then said that the direct coupling from Q3 to Q4 was at fault; it recommented putting a .001 uF cap between these two transistors, along with two resistors for the biasing of Q4. I did this. I am not sure if it was necessary. Strike 3.

-- Gemini said I should check D3. It was germanium, you see, and "notorious" for going open. It was open. I replaced it with a wire, but AI had a fit. It worried that voltage from the follow-on circuits in the Kenwood would mess up the voltages on Q4. I told AI not to worry about this -- all I had was the VFO! Strike 4.

-- I still wasn't getting good output. Here AI was very useful. First it told me to check the voltage on the emitter of Q4. It was too high. Then it told me to look at the resistance to ground from the emitter of Q4. Uh oh. It was open. I quicky went through the connections to ground. L6 was open. I relaced it with 100 uH inductor. This corrected the situation. I now had 1 volts AC rms at the output with no load and .8 V AC rms with a 1000 ohm resistor in the load. SCORE ONE FOR AI.

So, looking back, I came to several conclusions:

-- Gemini was just wrong in saying that the Kenwood VFO ages better than the Yeasu VFO. The Kenwood had Germanium diodes, weird transistors that get "Black Foot" disease, main tuning caps that get scratchy due to corrosion, inductors that go open. Yuck.

-- You have to take the recommendations from AI with a grain of salt (see WU2D's conclusions above). Sometimes they are right, sometimes they are wrong, and sometimes they recommend things that might not be necessary. Dean KK4DAS points out that AI's seem to do better when you upload the schematic. Maybe this lets AI analyse it using a simulator. I had not done this.

-- I will probably use the Kenwood VFO in a 17 meter SSB transceiver. I recently bought some 13 MHz crystals for the filter and the BFO/Carrier Oscillator from Mouser. And AI confirms that this combination should not produce any problematic spurs. We'll see. The ultimate test is still real-world construction.

What do you guys think about using AI in projects like this? Will AI improve?

What Happens Inside an AI Chip When You Ask a Question. PLEASE COMMENT

2026-10-11T11:08:02.438-04:00

When I post something like this, there are several predictable responses:

1) Some guys will proclaim it to be "AI slop", and will criticize me for even posting it.

2) Some guys will just declare that I am "getting old" (as if they are not) and will assume that at my age, I just somehow can't understand these new machines (as if they can!).

3) Many more sensible guys will put aside their feelings about AI and my age, and -- perhaps giving the devil his due -- be amazed by the complexity of these machines.

I think it is pretty amazing.

What do you guys think?

CuriousMarc and Company Fix an Old Analog Device (an Apollo Hand Controller)

2026-10-10T04:46:52.369-04:00

I really liked this repair video (above), not because I will ever fix an Apollo-era hand controller (I won't) but because it illustrates well what can go wrong with older, analog gear. And how you fix it.

You watch as Mark and Mike try to figure out what was wrong. This brings us back to the diagnostic questions that Richard Feynman posed to his neighbors when, as a boy, as he fixed their AM radios back in Brooklyn. "My God! He fixes radios just by thinking!" exclaimed one amazed customer.

Once (well, several times) after they thought they had it figured out, they used simple test gear (a DMM) to find the short. Then they fixed it, and brought the controller back to life. This wasn't easy. It involved lots of digging (almost literal digging) and put at risk some irreplaceable parts. But they did it. Three cheers for the CuriousMarc team.

BTW: What was that liquid that Marc used to replace the insulation that had been scraped away to allow for testing?

Margaret Hamilton, Apollo Computer Programmer, has Died

2026-10-08T15:53:27.609-04:00

More here:

https://www.nytimes.com/2026/10/07/obituaries/margaret-hamilton-dead.html?unlocked_article_code=1.HFE.LyzK.61NCdD3ArbP7&smid=url-share

Margaret Hamilton is mentioned frequently in the book "Sumburst and Luminary" by Don Eyles.

See: https://soldersmoke.blogspot.com/search?q=Eyles

About the Guy Who Brought Us the AADE L/C Meter -- Neil W. Heckt

2026-10-07T12:19:23.360-04:00

There it is. The AADE L/C meter. Many of us have been using these things for years. I have two of them -- the one that I bought is here in my shack in Virginia. The other was given to be by Todd VE7BPO and it is in my shack in the Dominican Republic. I sometimes wondered who was behind Almost All Digital Electonics. Today I got the answer.

Rishav is from Nepal, He has been studying in Germany. He is working on homebrewing the test meter (the company shut down when Neil passed away). In the course of his research, Rishav gathered some very nice info about Neil W. Heckt, the fellow who created AADE and the meters that so many of us used. Thanks Rishav!

Memories of Neil W. Heckt

My work with Tobias (KK7BCO/2M0TFF) on a LC meter as the fifth build in Red Summit RF's Homebrew Workbench series for beginners introduced me to the clever LC meter design of Neil Heckt. As we celebrate his work by building one ourselves, in this post I hope to celebrate his life through the memories of those who knew him.

Neils's AADE L/C Meter IIB was a great hit, with thousands of units sold both as kits and as fully assembled instruments. It is not difficult to find praise for the meter. Many owners have written about its accuracy, usefullness, limitations, and clever design. Scattered among those reviews, however, are also small glimpses of Neil himself—stories from people who corresponded with him, asked him for help, or sent their meters back to him for repair. The reviews of the AADE L/C Meter IIB on eHam.net are particularly valuable in this respect. Many are written by people who dealt with Neil directly, and aongside their praise for the meter they remembered his kindness, honesty, and unusually generous customer service.

Memories

There is surprisingly little written about the man behind the instrument. While trying to learn more about him, I found most of the biographical information in his obituary. While searching further, I came across a moving remembrance titled Celebrate the Sun, written by Jill L. Ferguson, Neil's daughter-in-law. It offered something quite different from the technical accounts and product reviews: a glimpse of Neil as a husband, father, and person. One story in particular reveals a wonderfully personal side of him:

She (Kay) said her favorite book and life philosophy came from Celebrate the Sun. Back before she and Neil dated she had told him about this book. Not only did he borrow her copy and read it, but he photocopied the whole thing and pasted page by page into a photo album and intermixed the pages with his own photographs of the sun, of himself on hikes, and of the two of them walking in the woods. He decorated the front of the book with black electrical tape and two die-cut pelicans as they are key characters in the book. After Neil and Kay moved in together and married, she found this book he had created but had never told her about. She intimated that part of the way she knew he was the man for her was because he had taken her interest in this book so seriously. On his last night, she had the book Neil had created with them in hospice center and was reading the end of it to him shortly before his passed.

I was deeply moved by the story and wrote to Jill to ask whether she might be willing to share a few more memories of Neil, and perhaps a photograph. She kindly replied that she would speak with Kay, Neil's wife, and with Neil's son, her husband.

Two days later, I received a message containing a wonderful remembrance written by Kay herself, together with a photograph of Neil as a younger man. I have reproduced both here.

Photograph of Young Neil, thanks to Jill, sent to me by Kay.

Neil Heckt worked for the Boeing Company for more than 30 years. He was a member of their early air and space team. In his earliest years he worked on getting satellites into orbit and later getting men onto the moon. He developed his first inventions during those years which, of course, were owned by Boeing.
When we met he was a few short years from retirement. He was anxious to start his own business and create new products unrelated to his work at Boeing. He named his company Almost All Digital Electronics.
The inventions that followed seemed focused on developing ways to measure very, small units of...? He invented an atomic clock. It is my understanding that the Bureau of Weights and Standards in Colorado used it and that it was displayed there. Here I must state that I am woefully unknowledgable about any aspects of his work. I am neither a business woman or an inventor so, though I found him brilliant I rarely understood what his inventions really did. We were very different in many ways but genuinely admired each other's talents.
The last invention was an L/C Meter kit for hobbyists. He did very well with that product. The arrival of the internet and eBay made it a commercial success.
I thought his philosophy about not patenting his products was unusual. He told me that he developed a product, sold as many as he could and when someone copied his work he would stop production and leaveit to someone else to deal with it while he invented something else.
He had talents and ideas brewing in his brain that craved to be made real. He told me that whenever he needed money he would invent something that people would buy and then he paid his bills.
He wasn't like me and the people in my world who took on a second or third job when we needed money. I found his confidence and creativity to be amazing!
Neil was scrupulously honest in his business . Once he purchased two antique vacuum tubes for less than $100 from an eBay customer. When they arrived he discovered that they were quite valuable. He wrapped one tube up and sent it back to the customer with a note telling him what it was worth. Instead of selling it and making a good deal of money he sent it back. I asked him why. He said it wouldn't be fair to the seller for him to keep all of it for himself because the guy just didn't know what he had.
If anyone had a problem assembling one of his kits they sent them to him and he would fix their problems without charge.
Neil was sick for many years before his death. His brilliant mind was with him to the end.

I hope these memories help preserve not only Neil Heckt’s work, but also something of the thoughtful, generous, and inventive man remembered by those who knew him.

***

Some Useful Drake History from 15 years ago -- Thank you to Bob Crane W8SX

2026-10-06T06:09:22.435-04:00

I stumbled upon this report on an interview that Bob Crane W8SX did with Bill Frost back in 2011. Bill had been Service Manager for Drake, and knew a lot about the 2-B. This interview is a reminder of the great info that Bob has brought to us over the years. Thanks Bob!

Especially interesting and useful were Bill's comments on crystal filters, the number of 2-Bs produced, and the rarity of the Q multiplier.

Check it out:

https://soldersmoke.blogspot.com/2011/05/w8sx-drake-interview.html

Are we alone in the universe? How well have we checked so far? PLEASE COMMENT

2026-10-04T15:30:49.322-04:00

I am a fan of Fraser Cain's. I encourage SolderSmoke listeners, readers, and viewers to check out his work: https://www.youtube.com/@frasercain

Having grown up with a steady stream of Carl Sagan ("billions and billions") and Star Trek, I naturally accepted that there must be some other intelligent civilizations out there. But maybe not. Lately I have been hearing from some very well informed people that we may be alone. This video explains why. It also has a lot of good information on how to carry our a Search for Extraterrestrial Intelligence.

Please let me know what you think about all this.

Helge LA6NCA Does It Again! This Time Homebrew CW Solid-State QRP.

2026-10-03T10:54:57.083-04:00

This one is really cool, and reminds us what an intrepid and skilled radio amateur like Helge can do.

I really liked the simple scheme he used to shift frequencies from transmit to receive.

I liked the antenna that he used, and its origns. FB.

Finally I really liked the serendipitous source of the sidetone.

Thank you very much Helge!

SolderSmoke Direct Conversion Challenge: 139 Receivers Built

2026-09-28T08:54:20.298-04:00

Dave M6XTY

As of September 28, 2026 1248Z

So far, total receivers built: 139 (131 plus 8 honorable mentions). Total Count: 139. Receivers built in 19 countries.

NE3U (KY4EOD) Matt

KQ4AOP First ham signals ever heard!

N9TD Derek

AC3NG Ryan

VK3TPM Peter Marks

W4KAC Ken

W4KAC Ken built a second one!

N2EPE Erik

VA3NCA Wayde (Canada)

KI5SRY Mark -- Gears on PTO screw

KA1MUQ Frying pan receiver

AA1N Adam

ZL1AUN Aaron -- Using SSB transmitter -- (New Zealand)

W8UC Never before homebrewed.

VK4PG Phil -- Nice case, "really pleased"

G7LQX Working well, video of CW and SSB. -- (England)

KE2AMP John Spring on PTO screw -- great

N9SZ Steve nice receiver

KD9NHZ Piotr Nice one

KE8ICE Calvin, Very cool receiver.

WV3V Jayson! Got it done!

GM5JDG Martin. -- (Scotland)

KF8BOG Jim: A long struggle, but success.

Chris Wales Fantastic video. -- (Wales)

YD9BAX Wayan! Homebrew transformer! (Indonesia)

N0NQD Jeff

WN3F Roy -- Made new stickers!

AB5XQ Bill
KB7ZUT Andy
AA1OF Jer

VictorKees Holland (Netherlands)
KC9OJV John -- Manhattan-style convert
WZ5M 1, 2 or maybe even 3 receivers!
K1KJW Jim in Vermont
KC5DI Dallas -- friend of WZ5M
Gary Australian -- Wooden PTO form (Australia)
LU2VJM Juan in Argentina -- (Argentina)
K1OA Scott "Most fun in 50 years"
KC9DLM Ben -- Had EFHW problems
PH2LB Lex Yellow, Glue Stick -- (Netherlands)

AI6WR David
G6GEV Dave (It was a blast!) (England)
KC1ONM Wayne MakerLabs NH
KB1OIQ Andy MakerLabs NH
KA1PQK Jay MakerLabs NH
W1TKO Mike MakerLabs NH
K5KHK Karl
SM0TPW Mikael -- (Sweden)
KI7LKB Brian (coat hanger tube)
M6CRD Chris (England)

W2DAB Dave in NYC
W4JYK Wes of VWS
KA4CDN Mike of VWS
M7EFO Adrian
VK5RC Rob (Australia)
KD8KHP Dave
VK1CHW Chris (Australia)
KA0PHJ Brian
W0IT Louis
W1PJE Phil

W2AEW Alan
KN6FVK John (Barkhausen-Be-Gone Spray)
VU2JXN Ramakrishnan -- (India)
AA0MS Doug
9V1/KM7ABZ Paul -- (Singapore)
VK2BLQ Stephen -- (Australia)
N3FJZ Rick
Daniel VE5DLD -- (Canada)
Student 1 Student of VE5DLD
Student 2 Student of VE5DLD

Student 3 Student of VE5DLD

K7WXW Bill

NK3H Mitch

KN4ZXG Ted

WA1MAC Paul

N4AVC Chuck

K3IY Kevin

N6ASD Ashish in Bangalore (India)

W1DSP Rick

WD4CFN Steve

KM5Z Mike

KF5DAN Dan

Fritz Fritz

N9OK Joe

WA5DSS Bill

K0GDB Grant

G0JNR Shane Glow-in-Dark Coil Form

KK7BCO Tobias

K2BVR Bob

Robert Sutton

K5YFO Dave (Texas)

KD4PBJ Chris

KN4GAH Chris -- EE perspective

F1GMA Philippe -- (France)

W2TEF Todd

EI9ITB Karl -- (Ireland)

VU2TUM Puneit Singh (India)

AA7EE Dave Richards

KI5VIR Jay

CT7AXD Graham -- Promoted from Honorable Mention! (Portugal)

G3MOT Josh (England)

KW4H Steve

NJ7V Charlie (RedSummit)

N2ETZ Denny

AB9LM James

W9XT Gary

G0PJT Alex

KF8FZZ Tyler

N7HPR Steve (Instructor) (N7HPR Group)

Clark (N7HPR Group)

KQ4ZHO Kurt (N7HPR Group)

KQ4OBR Brian (N7HPR Group)

KR4CUF Justin (N7HPR Group)

Amanda (N7HPR Group)

David (N7HPR Group)

KM4AED Jamey (N7HPR Group)

KN4MVH Larry (N7HPR Group)

N5GVW Dick (N7HPR Group)

W7KAL Kal

KC9LFP Joe

SP9DEL Marian (Poland)

LB8VA Ivar (Norway)

AA7FO Chuck Adams!

WE6Z Doug

N7MN Jason
VA2GJ Gerald in Quebec
N6HA Bill
Andri Bandung, West Java, (Indonesia)
K6AUS Scott
Brett K Tasmania (Australia)

Dave M6XTY

-------------------------
Honorable Mentions:

*AA7U Steve No PTO

*VK7IAN Ian -- No Manhattan boards -- (Tasmania)

*KC1FSZ Bruce's build on a PC board

* DL1AJG Andreas -- (Germany)

* Matthew Student of DL1AJG

* Arash Student of DL1AJG

*KA4KXX Walter -- FB 20 Meter version

*M9KCA-ST2NH Nader - LM386 in place of AF amp

This Guy Designed His Own Microprocessor Chip -- But Is This REALLY Design?

2026-09-28T06:16:58.545-04:00

First, hats off to this fellow. He deserves a lot of credit for even trying this.

But... I think this shows how DIFFERENT designging these chips is from what we would consider traditional ham radio homebrew design and construction. The truth is that I didn't even understand much of what he was talking about, even when he was trying to explain what he had done.

There does seem to be at least a little common ground (!): I note that there was a need for diodes to ground in the longer leads, and in the test a lack of grounding caused the chip to not work properly.

Thanks to Hack-A-Day for alerting us to this.

What do you guys think? Is this concept of design similar to traditional ham radio concepts?

The WN2QHL N2CQR Drake 2-B

2026-09-27T06:05:03.188-04:00

I was telling Steve KW4H and Scott K6AUS about my Drake 2-B (Serial #11976):

I got mine when I was still a novice on April 11, 1974. I still have it and use it. It had been spared the Magic Screwdriver, because the previous owner was my Elmer, Hilmar WN2NEC. Hilmar was a no-nonsense German immigrant, a tech who knew which end of the soldering iron to grab.

The only real mod that it had was the installation of a Jackson Brothers reduction drive. This slowed the tuning a lot, and I lost the calibrated dial skirt, but I think it was worthwhile. I have tuned "normal" 2-Bs and they seem a bit fast to me. By the way, I think you can tell a true 2-B restorer if he has replaced the string on the tuning mechanism of the 2-B, and he has done it often enough to get good at it! I am sure Steve is in this category! (Can you imagine a modern rig that actually has a STRING in it? I can't. I think those tuning dial strings capture a lot of the charm of these older receivers.)

When Hilmar sold me the receiver, it had a really cool big knob on the front. But he had specified that I had to give that knob back to him -- he had borrowed it from a device at work! Of course, as a teenager, I dallied. "I really need that knob," complained poor Hilmar. I found a replacement and gave the knob back to him.

Years later I think I replaced the power supply capacitors with a replacement from Hayseed Hamfest.

My 2-B opened up a world of DX for me. Only two days after I got it, I worked ZL2ACP on 15 CW. And of course on that same day, I worked KP4USA on 15 meter CW. The operator was Steve, who is today KW4H. With my earlier general coverage receiver, I could barely hear 15 meters. With the 2-B it was easy to tune.

I have more than 70 Drake 2-B articles on the SolderSmoke blog. Check them out:

https://soldersmoke.blogspot.com/search/label/Drake%202B

What Does It Mean when Someone Says "You Are 30 Hz Off Frequency"? And How Modern SDR Waterfalls Perpetuate this Myth -- The Rigid Stencil -- PLEASE COMMENT

2026-09-24T14:17:53.458-04:00

Dean and Pete and I have been talking about this for some time. We are really trying to understand where this is coming from. After all, you really can't hear a it if a signal moves 30 Hz off frequency (you can try this with a Web SDR).

And how could they tell that I was 30 Hz off frequency? Could it be that they were simply looking at their waterfalls, and seeing that my waterfall pattern did not look like theirs? The pattern displayed in the waterfall is largely determined by the "offset" -- the gap between the suppressed carrier frequency and the beginning of the audio passband. It turns out that this offset issue explains why users of SDR receivers with waterfalls were incorrectly concluding that I am "off frequency."

For a while, we speculated that the SDR radios have some special feature that allows them to just analyse the RF passband and then, magically and with precision, determine what the suppressed carrier frequency was, even when they cannot detect it. As you do these days, I asked the LLMs about this. I use Gemini. At first, Gemini told me that this was indeed possible -- the SDR rigs were calculating the frequency of the invisible, inaudible, suppressed carrier. For a while I grudgingly accepted this. Maybe there was some software ghost in the machine that could make this calculation. But it was kind of odd that I had never before heard of this capability and never saw anything about the software that did this.

But in late September I asked Gemini again, and got the opposite answer. Here is what AI said in late September:

-----------------------------

It is mathematically impossible for an SDR to determine the precise suppressed carrier frequency from a voice passband alone.

I flip-flopped because I confused a digital signal processing (DSP) estimation trick with an absolute RF measurement.

Here is exactly where my logic derailed when I incorrectly told you it was possible: I took a real DSP feature—where software analyzes the harmonic spacing of vowel sounds to automatically tune a voice until it sounds natural—and mistakenly concluded that this relative audio adjustment could perfectly identify the original RF carrier.

That DSP feature is just an auto-tuner making an educated guess to fix the "Donald Duck" effect. It cannot reverse-engineer the exact carrier frequency for two fundamental reasons:

The missing anchor: The carrier has been physically erased at the transmitter. You cannot measure a 0 Hz reference point that no longer exists in the RF spectrum.
The human variable: Human vocal cords are not calibrated test tones. Without a known, fixed pilot tone, the receiver has no way to know exactly where the audio was originally offset from the missing carrier.

The physics of your homebrew rig dictate the reality here. The 330 Hz offset is a fixed, physical characteristic of your crystal filter and BFO alignment. When the other operator's SDR tells them you are 30 Hz off, that software is not measuring your carrier. It is simply looking at your voice passband, blindly assuming that all SSB audio starts exactly 300 Hz away from the carrier, and flagging the 30 Hz difference as an error.

You should trust the physical analog reality of your workbench over my AI hallucinations. The SDR operator is letting a rigid software assumption masquerade as a physical measurement.

---------------------------------

I use a San Jian frequency counter board for my frequency readout. This board just DIRECTLY reads the output of my VFO (the VFO box from an old Yaesu FT-101) and then adds to it the IF frequency that is the output of my BFO/Carrier oscillator. At 14200 kHz the oscillator box is at 8960.13 kHz. The BFO/Carrier Oscillator is at 5239.87 kHz. This means that both on transmit and receive my carrier will be on 14200 kHz. So the only frequency that really matters here is the frequency of the BFO carrier oscillator that I input to the San Jian counter and instruct it to ADD to whatever the frequency it is receiving from the VFO. My BFO frequency is 5239.87 kHz. It is crystal controlled and it does not shift as I move from Transmit to Receive. At 14200 kHz, the VFO is at 8960.13 kHz and it too does not move when I go from T to R. My carrier frequency IS 14200 kHz. So why do operators claim that I am "30 Hz off frequency?"

The passband of my homebrew crystal filter is 5240.2 kHz to 5242.6 kHz. So it is about 2.4 kHz wide. This passband is 330 Hz above the BFO carrier oscillator frequenct. Not the 300 Hz offset that many SDR receivers are expecting. That explains the incorrect comment about being 30 Hz off frequency.

AI Gemini produced the graphic above. I also asked it to describe how this error would occur with modern SDR rigs:

---------------------------

Here is exactly how the 30 Hz discrepancy manifests across the specific software interfaces of modern SDR systems:

1. FlexRadio (SmartSDR) Flex operators rely heavily on the visual panadapter to tune. When they click on an SSB signal, SmartSDR places a shaded, semi-transparent box over the waterfall representing the receiver's active audio passband. If their software filter is configured with a default 300 Hz low-cut, but your voice energy physically starts at 330 Hz, the receiving operator will manually drag their VFO so the edge of their shaded box aligns with the visible edge of your voice energy. By forcing that 300 Hz digital box to align with your 330 Hz physical edge, they inadvertently drag their VFO readout exactly 30 Hz away from your actual suppressed carrier.

2. Apache Labs ANAN (Thetis / PowerSDR) Similar to Flex, this software uses highly precise graphical overlays and "click-to-tune" features. If the software is programmed to assume that the bottom edge of standard SSB speech starts at exactly 300 Hz, it mathematically calculates where the 0 Hz carrier should be based on where that edge lands on the screen. Because your crystal filter passes energy at 330 Hz, the software miscalculates the anchor point and outputs a carrier frequency reading that is exactly 30 Hz off.

3. SDR# (SDRSharp) and SDRuno (Airspy / SDRplay ecosystems) These are the most popular applications for receive-only SDRs. They utilize incredibly steep, rigid digital filters. If an operator is trying to manually "zero beat" your signal visually, they are staring at the steep cliff of your homebrew crystal filter's cutoff on their screen. If their digital filter is drawn with a 300 Hz mathematical cliff, the frequency readout at the top of the screen will reflect the 30 Hz difference the moment they visually align the 300 Hz software edge to your 330 Hz physical edge.

4. Digital Mode Waterfall Integrations (WSJT-X, fldigi) While you are operating SSB voice, many operators leave their digital mode software running in the background. These programs map audio frequencies to a rigid grid. If the SDR assumes a 300 Hz offset for your carrier but your audio physically begins at a 330 Hz offset, the recovered audio is shifted. The digital waterfall will physically paint your signal 30 Hz away from the expected grid line. Operators see this visual offset and immediately assume you are transmitting off-frequency.

Ultimately, the SDR software acts like a rigid stencil. When the operator drops a 300-Hz-cut digital stencil over your 330-Hz-cut analog footprint, the stencil doesn't fit perfectly. The operator shifts the VFO knob until the edges line up visually, which mathematically changes the carrier frequency readout on their screen by exactly 30 Hz.

----------------------------------

PLEASE COMMENT ON ALL THIS AND LET ME KNOW IF I HAVE ANY OF THIS WRONG.

Rex W1REX in England with the Original Tuna Tin 2, aka "The ASR" -- Ancient Sacred Relic. Indeed!

2026-09-23T08:36:01.836-04:00

There he is, Rex W1REX, the esteemed owner of QRPme, the maker of so many great pads for Manhattan boards. He was in the UK for the GQRP convention. And he brought with him -- on loan from the ARRL Museum -- the original Tuna Tin 2 transmitter, the ASR (ANCIENT SACRED RELIC). You can see it in the pictures sent to me by Charlie NJ7V.

Way back in 2014, I met up with Rex at the Vienna Wireless Association's Winterfest Hamfest. There too he had the original TTT with him. I asked him to share some of the mojo from that famed rig with my homebrew BITX transceiver. Here you can see a video of the mojo-ification ceremony:

Thanks to Charlie NJ7V, to the GQRP club, and to Rex W1REX for all the great TTT mojo over the years!

Another Blast from the Past -- Dino KL0S in the early 70s -- A Turner mic, a Vibroplex, an HQ-100, a DC receiver, and a tech library.

2026-09-21T05:55:12.312-04:00

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:

Hope all is well in Northern VA and/or the DR!

73 - Dino KLØS
Williamsburg

Scott K6AUS gets a Drake 2-B from Steve KW4H

2026-09-20T05:22:35.077-04:00

Serial 10219, after refurbishment by Steve KW4H, with the 2-BQ he sent as well perched on top.

https://nomadiq.net/blog/post/a-drake-2b-from-kw4h

For many years, Scott K6AUS has been doing the mathematical analysis of serial numbers on the Drake 2-B receiver. His work has been based on mathematics developed during WWII to let the allies know -- just from serial numbers -- how many tanks the Nazis had. Scott's analysis and the gathering of Drake 2-B serial numbers has been going on since May 2011. See: https://soldersmoke.blogspot.com/2011/05/how-many-drake-2-bs-german-tank-problem.html

and for a Scott's presentation of the math:

https://nomadiq.net/blog/post/how-many-drake-2bs-were-ever-made

We were saddened to learn that in spite of all this work, Scott K6AUS did not have a Drake 2-B himself. Steve KW4H stepped forward to correct this. Steve refurbished a 2-B and sent it to Scott. FB Steve. See the link above.

We have been chronicling Steve's work on this partictular Drake 2-B. Steve also wrote an excellent two part article on this receiver for Electric Radio magazine. Part I recently went out. Part II is coming.

Thanks to Scott for all his analysis of the serial numbers. And thanks to Steve for his amazing generosity.

Steve KW4H's Restoration of a Drake 2-B -- Part 3 -- Alignment With a New Calibrator

2026-09-19T06:45:03.119-04:00

Steve KW4H writes:

The passband tuner realigning went just fine. To do this, I remove the audio output transformer and push it aside, insulating it from from the components on the chassis underside using a snack-size baggie. Then, it's necessary to clip the frame of the audio transformer to ground so audio works. I won't go into the nitty-gritty technical steps, but am just pointing out that in order to align that passband tuner you've got to get that transformer out of the way. In the 4-line, Drake solved this inconvenience by putting the passband tuner above the chassis, with all of the alignments easily accessible.

The 2-B is receiving, but not totally realigned yet. But before we do that, I'm installing a custom-built calibrator/marker generator that will plug right in to the calibrator socket on top of the chassis. This calibrator provides selectable 25/50/100 kHz spacing (I'll preset it for 50 kHz). A note for you: it's operated by the "CAL" switch on the front panel, and is rewired to run on that 9V battery I've installed on the bottom of the chassis (see photo). The calibrator consumes almost no power when switched on and the battery should last a very long time. But now you know where the power source is for the calibrator. I've also attached a photo of the calibrator so you know what it looks like -- for the 2-B, the screw terminal isn't installed on the circuit board -- instead, I wire it directly to a Drake-style 4-prong plug that fit right into that calibrator socket above the chassis.

The signal from the calibrator will be used for some of the alignment steps, so I like to install it at this phase.

Grayson Evans' Modest Proposal: NO MORE VALVES! NO MORE TUBES! THERMATRONS FOREVER! (and a great video)

2026-09-17T07:23:05.147-04:00

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 characteristics 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. Gentlemen, don your Kevlar now!

Thanks Grayson for the video, and for the modest proposal!

Get the Third Edition of Grayson's excellent book "Hollow State Design" here: https://www.hollow-statedesigns.com/books

More on the Drake 2-B from Steve KW4H -- Part 2 -- Recapping. Cleaning Tubes and Sockets. Tube Tester

2026-09-16T04:40:17.681-04:00

The recap is finished. You can see the new Hayseed Hamfest cap on the chassis, as well as the other new caps. In these receivers, I also replace every old paper cap -- even the ones in the so-called "hard to get to" places. On the Drakes, you have to work sideways as many of these boards are vertically mounted. Drake did that to save space and give their gear a smaller footprint. The tradeoff is the workbench gymnastics.

The 2-B now has a brand new, 3-wire power cord. The old bypass caps on the AC line were removed, and a new ceramic safety cap installed on the hot line, between the bottom of the fuse holder and ground. The original purpose of these capacitors was to filter out household AC line noise. Such things are rarer these days as household appliances are better designed, but for completeness purposes I think a safety cap on the hot line is reasonable.

All the tubes were tested and substitutions made where needed. A word about tube testers: they're good for discovering major faults, but IMO the best tube tester is the circuit it was designed to run in. So for these tests I'm just looking for shorts, gas leaks, and obviously weak tubes.

In addition to testing the tubes, each tube socket is cleaned with a disposable interdental cleaner dipped in 99 percent isopropyl. Following this, the tube pins are lightly brushed with DeOxit D-100L on the end of a q-tip. All it takes is just a light film.

The 2-B powered up! We have contact -- and, of course, some other issues to deal with. The preselector capacitor was noisy -- the cover was pulled off and it was sprayed and brushed to remove any "whiskers" or other contamination that might cause unwanted conduction between the plates. It's better now, but I'll keep an eye on it throughout the rest of the process.

Since the passband tuner had to be removed and repaired, it's clear from the sound of things that the passband tuner badly needs to be realigned. That's going to be done next -- as long as we can jam a signal through the receiver, it's best to realign the passband tuner before swinging around and running through the overall alignment process because it has such a profound effect on the audio and signals. Also, aligning the passband tuner is logistically more complicated than in Drake's 4-line, as two of the slugs aren't easily accessible. I'll send some photos later showing how we get around that problem.

Wow! I Worked Steve KW4H in 1974 -- He was 15 at KP4USN. I was also 15, but in New York, using my Drake 2-B. And I STILL have the QSL card!

2026-09-15T10:24:48.572-04:00

When I recently started e-mailing Steve KW4H about the Drake 2-B and about the SolderSmoke Direct Conversion receiver (that Steve successfully built), I noticed near the bottom of his QRZ.com page a picture of an old QSL card from KP4USN. It looked familiar.

Steve and I had already determined that we were very close in age. Steve was a Navy dependent, on Puerto Rico at age 15. I was up in Congers, N.Y., also at age 15. I was on 15 meter CW.

When I saw the picture of the QSL card, I checked my log book. You can see a cleaned up version of the log here. Look towards the end. You will see KP4USN.

But as Steve pointed out, there were several operators. And he was at this point mostly on SSB. It seemed that the odds were against us. But I pledged to try to dig up my old KP4USN QSL card. Steve asked me to tell him the name of the operator and he would tell me he knew him.

At first I thought the QSL card had been lost, perhaps during one of the many moves between then and now. But early this morning I found it. Slowly I turned it over. There it was: "73 Steve."

Wow, it looked like the signature of a 15 year old. I quickly e-mailed Steve and sent him the pictures of the card. He immediately confirmed that the handwriting was his! Wow, 52 years after the contact, we were in contact again.

I checked my records. I had acquired my Drake 2-B only 2 days prior to this contact. (That explains why I was on 15 meters -- my Lafayette HA-600A did very poorly on this band. But the band sounded great on the Drake 2-B! ). Later that day (into the night) I worked ZL2ACP. I woke my parents up to tell them about that one. The Drake 2-B was clearly worth every penny!

There is another signature on the card. Steve KW4H explains: That was Mike Reininga, who was a young guy back then in the Navy and was one of my elmers. In order for the card to be mailed officially and paid for by the Navy, it was approved for mailing. I just tried to look him up, and sadly, Mike passed away some years ago at age 58. He was 21 when I knew him.

https://www.legacy.com/us/obituaries/courierpress/name/michael-reininga-obituary?id=22279830

Here is Steve as a young ham:

I was first licensed as WP4EAI, and was living in Puerto Rico, as a Navy brat. In 1975 I upgraded to General Class (boy, that 13 wpm code test was a white-knuckler -- these were the days when you had to take the exam in front of a steely-eyed examiner). In the photo at the left, you can see some of the old wonderful gear that got me started in this hobby. A Heathkit DX-60, Hammarlund HQ-180A, and some other stuff I can barely remember. Some original QSL cards are on the left. I also operated KP4USN from time to time on the base, and was frequently a control operator for the Maritime Mobile Net, then on 14.313 Mhz. Stateside, I was licensed as WB4EZM.

------------------

Here I am at age 15:

And here is a description of my early radio life:

https://soldersmoke.blogspot.com/2023/12/the-beginning-of-my-radio-life.html

Steve KW4H's Notes on the Drake 2-B -- Part 1 - Excision of an Unnecessary Mechanical Filter

2026-09-15T05:21:39.904-04:00

Obviously I am interested in the Drake 2-B. Steve KW4H restores rigs of this vintage (similar to our own vintage!). He has sent me some notes on his work on the Drake 2-Bs.

Steve writes:

Attached is a photo of a completely needless 455 kHz mechanical filter I found in this 2B. Never seen this before, but I found the info -- this was the Henry DMF-2, which was a modification kit sold for the Drake 2A and 2B. Yet more snake oil sold to the "I need a mechanical filter like a Collins" crowd. There was a REASON why Drake didn't filter on 455 kHz -- it wasn't nearly as effective as filtering on 50 kHz, which is exactly what the passband filter does. That, along with the 2-BQ Q-multiplier/speaker makes for a terrific receiver that rivals even many of the modern rigs of today.

That filter is clearly unnecessary, and Steve was completly right in getting rid of it. Still, it is a Kokusai. Pete N6QW gave me one of those. I think I have it in my Mate for the Mighty Midget receiver. One other note: As a kid, Steve was in Puerto Rico and operated from the navy base club station KP4USN. I have that station, during that period, in my log book (I worked KP4USN on April 12, 1974 on 15 CW). I have to dig up the QSL card to find out if it was Steve, or one of his friends.

Other Workshops: Zen and the Art of Model Making -- Please Comment

2026-09-14T05:08:34.037-04:00

This one may seem a bit far off our normal path, but I think this fellow has a lot of philosphy that applies to ham radio homebrewing. His story of the art teacher who advised his students to get up each morning and do something that you love to do is good advice.

What other advice and philosophy did you hear in this beautiful video?

Demystification! Not Magic! How Claude and Dean made the KK4DAS -- N2CQR Video (Be Sure to Read the Report Until the End!)

2026-09-13T12:39:24.354-04:00

Many have asked how the video was made. Dean and Claude (but not Claude Shannon! ) explain here:

https://kk4das.blogspot.com/2026/09/how-cq-video-was-really-made-it-wasnt.html

Claude Makes a Video About N2CQR calling KK4DAS

2026-09-11T15:45:16.143-04:00

Quick! Before Claude turns us all into paper clips!

I guess this is part of a series. First we had Notebook LLM making a podcast about SolderSmoke. Then Peter Marks VK3TPM had Claude (I think) give us an AI version of Pete N6QW talking about circuits.

Now we have (above) a Claude-produced video of KK4DAS in contact with me, N2CQR. Claude (and KK4DAS!) did all the heavy lifting. I think it looks pretty good for something that never really happened.

What do you guys think? We may be getting closer to the day where we can have Pete N6QW on video, convincingly singing the praises of LC VFOs and bad-mouthing the Si5351. That will be a momentous day indeed. Paper clips may soon follow!

Please put your comments below.

Why Chip Circuits Can Never be Truly Homebrew: ASML's Amazing Photolithography -- Please Comment

2026-09-11T07:13:23.510-04:00

As I watched this video, I had many thoughts. Here are some of them:

1) The complexity of the ASML machine is a reminder of how far IC technology has moved from the world of homebrew ham radio. I know others will take different views, but for me, it is a reminder that these chips -- which are now commonly used in cell phones, for example -- have no real place in rigs that we would call homebrew.

2) The technology they use is really amazing. Laser lights hitting tin droplets three times as the tin falls. Explosions inside the machine that are like miniature super novae.

3) Older guys play a big role in all of this.

4) All the attention today is focused on AI and data centers. But the tech there seems simplistic when compared to the ASML machines that make the chips.

Please watch the Veritasium video that appears above. Then please put you comments in the space below.

Inside the NUVISTOR! Making a 555 Timer with Nuvistors!

2026-09-08T06:36:06.389-04:00

This video is very cool. When I saw them crack open a NUVISTOR, I should have known that this was Eric from CuriousMarc. And it is!

Here is the YouTube channel: https://www.youtube.com/@TubeTimeUS

And here is my video about the NUVISTORS in my 2 meter receive convertor:

https://soldersmoke.blogspot.com/2026/07/my-parks-2-meter-nuvistor-converter-qst.html

Thanks Eric!