SolderSmoke Direct Conversion Challenge: 139 Receivers Built

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 

 

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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?

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

But... I think this show 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

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

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:

1. 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.

2. 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.

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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!

 

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.

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