VK3ACU Builds a Transmitter for 3.579 MHz

Colorburst, my friends.  CBLA stuff from OZ.  A chip in the mix.  Thanks to Paul VK3HN for sending us this.  

Comments on the SolderSmoke Direct Conversion Receiver from Andri in Bandung, West Java, Indonesia

Congratualtions to Andri, of Bandung, West Java, Indonesia.   Andri successfully built the SolderSmoke Direct Conversion receiver.  (See the the Short below for a video of his receiver in operation.)  Like many, he had some trouble getting the AF transformer -- so he took one out of an old Japanese transistor radio.  He needed the FET for the PTO, so he made due with a surface mount part.  All this by someone who does not have a ham license.  I think he deserves a license, solely based on his successful build of this receiver.  He has done something that most hams will never do:  He has homebrewed a receiver.    Thanks Andri!

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Comments from Andri: 

I am just a newbie and not a ham radio operator, so I don't have a callsign. I do enjoy building electronic things though even though I have no background in electrical engineering.

It was a nice rewarding experience building this receiver. The challenging part was sourcing some parts which are hard to come by here in Indonesia such as the toroid cores, JFET and audio transformer. So I substituted FT50-6 with FT50-2, T50-43 with ferrite core for SMPS, and I use an SMD JFET instead.

Thank you very much for the detailed instructions on how to build this radio. Without them I would be lost. Ham radio has always been intriguing to me, but I never got into it because it is a prohibitive hobby.

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Bandung Wiki: https://en.wikipedia.org/wiki/Bandung

137 Direct Conversion Receivers -- Recently Built in Bandung, Indonesia. But none in Japan, None in China, None in Africa, and only 1 in all of Latin America!

RX built in Bandung Indonesia -- Andri used an AF transtormer from an old Japanese receiver. 

Why have NO receivers been built in Japan?   And none in China.  Only one in all of Latin America. Not one in all of Africa.     

Please let us know if you spot any errors, or if we have inadvertently missed anyone.  Don't worry about being late to the game -- the challenge continues.  All of the info is still available. 

As of July 21,  2026 0930Z:

So far, total receivers built: 137 (129 plus 8 honorable mentions).  Total Count:  137.  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)

Scott               K6AUS  

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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

Why is AM on 3885 kHz?

It is Saturday morning, 0500 EDT.  I am tuned to 3885 kHz, listening to the Old Military Radio Net.  It is on 3885 kHz.  Why this frequency? 

Wikipedia: https://en.wikipedia.org/wiki/SCR-536

Gemini explains: 

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.

How Were 3.579 MHz Crystals Used in Color Television Sets?

Gemini explains: 

In NTSC analog color television, the 3.579545 MHz crystal was the heartbeat of the entire color decoding system. Its primary job was to act as the ultra-precise frequency and phase reference needed to recreate the colors you saw on the screen.

To understand why it was used, you have to look at how color television was engineered to be backward-compatible with older black-and-white sets.

1. The Challenge of "Squished" Color

When the NTSC standard was developed in 1953, engineers had to squeeze color information into the existing, crowded black-and-white television channels without causing interference.

To do this, they decided to transmit color using a color subcarrier centered precisely at 3.579545 MHz.

• Luminance (the black-and-white brightness detail) was sent normally.

• Chrominance (the actual color information) was modulated onto this 3.579 MHz subcarrier.

The color signal used Quadrature Amplitude Modulation (QAM). In QAM, the amplitude of the 3.579 MHz wave determined the saturation (how vivid the color was), and the phase angle of the wave determined the hue (whether the color was red, green, blue, or yellow).

2. Restoring the "Suppressed" Carrier

To prevent the 3.579 MHz color signal from creating distracting, wavy line patterns on older black-and-white TV screens, the carrier wave itself was suppressed (removed) before transmission. Only the "sidebands" (the actual color data) were sent over the air.

Because the carrier was suppressed, the TV receiver had to completely recreate that 3.579545 MHz wave locally to decode the color.

If the TV's locally generated wave was off by even a tiny fraction of a degree in phase, the colors would shift wildly—faces would turn green, and skies would turn purple. This is where the 3.579545 MHz crystal came in.

3. Locking to the "Color Burst"

Because the transmitter and the television set had to be perfectly synchronized, the TV station sent a tiny, brief reference sample of the original carrier wave at the start of every single horizontal line on the screen. This was called the color burst.

• The color burst was a short packet of just 8 to 9 cycles of the 3.579545 MHz wave.

• It was placed on the "back porch" of the horizontal blanking pulse, immediately after the horizontal sync pulse.

Inside the television, the 3.579545 MHz quartz crystal was the heart of a local crystal oscillator circuit. When those 8 to 9 cycles of the color burst arrived at the beginning of a line, a Phase-Locked Loop (PLL) or injection-locking circuit compared the incoming burst to the TV's local crystal oscillator. It adjusted the local oscillator's phase to match the burst perfectly.

Once locked, the crystal oscillator kept ringing cleanly and steadily across the rest of the 63.5-microsecond horizontal scan line, giving the TV a flawless phase reference to demodulate the red, green, and blue color components from the video signal.

The Legacy of the "Color Burst" Crystal

Because millions of color TV sets were manufactured every year, factories produced these highly precise 3.579545 MHz crystals in astronomical quantities.

This mass production made them the cheapest, most widely available crystals on the surplus market. Consequently, generations of engineers and radio amateurs adopted them for unrelated projects—such as building QRP transmitters (often on the 80-meter band, where the second harmonic of 3.579 MHz sits nicely at 7.159 MHz), clocking early microprocessors, or generating telephone DTMF touch-tones.

The 43.333 MHz Crystal in my Nuvistor Converter was Bad. But WHY did I Find Another One in my Junkbox?

Gemini explains why: 

As a radio amateur, you have likely run across these crystals in countless parts bins, swap meets, and vintage schematics. The reason 43.333 MHz crystals are so common comes down to a classic, elegant piece of frequency math that bridged the gap between early VHF operation and standard HF rigs: the 2-meter to 20-meter transverter/converter.

The 2-Meter to 20-Meter Magic Number

Historically, amateur radio operators wanted a way to receive and transmit on the 2-meter band (144–146 MHz) using their highly sensitive, existing 20-meter HF receivers (14 MHz) as a tunable Intermediate Frequency (IF).

To mix a 144 MHz signal down to a 14 MHz IF, you need a highly stable 130 MHz local oscillator (LO):

144 MHz (RF) - 130 MHz (LO) = 14 MHz (IF)

Creating a stable, fundamental-frequency quartz crystal at 130 MHz was physically impossible for decades because the quartz wafer would have to be sliced microscopically thin and would easily shatter.

Instead, designers utilized a robust, lower-frequency third-overtone crystal operating at 43.333 MHz. When you multiply 43.333 MHz by three in a simple tripler stage, you get exactly the 130 MHz LO signal needed:

43.333 MHz times 3 = 130 MHz

Why They Flooded the Market

Because the 2m-to-20m conversion was the gold standard for VHF operation in the 1960s, 70s, and 80s, these crystals were mass-produced. They were the heart of legendary gear like the Drake SC-2 receiver converter and dozens of homebrew transverter designs featured in the ARRL Handbook and 73 Magazine.

If a ham wanted to monitor the popular 146.94 MHz repeater frequency of the era, they would use a 2-meter converter with this exact crystal, allowing them to tune their HF dial to precisely 16.94 MHz.

Other Multiplier Matches

Additionally, 43.333 MHz has convenient harmonics for other bands. For instance, multiplying it by 10 yields 433.33 MHz, which sits perfectly inside the 70-centimeter amateur band and the widely used 433 MHz ISM band (common for low-power key fobs, weather stations, and remote controls).

Whenever you see a strangely specific, non-integer crystal frequency like 43.333 MHz, 38.667 MHz (used for 2m to 10m conversions), or the famous 3.579545 MHz color burst crystal, there is almost always a legacy of mass-production and clever math behind it! 

The Smith Chart -- Veritasium Explains its Origins and How it Works

This is really interesting and represents one of the best explanations of the Smith Chart that I have seen.  

One quibble:  In the beginning, they make it sound like all refelcted power in a transmission line is lost.  That is not really true.  Much depends on the frequency, the type of line used and the length of the line. The video presents this "SWR loss" as being very significant, and many hams seem to think that any SWR worse than 1:1 will kill their signal.   

Look at the question that I put to Gemini: 

I am a radio amateur. My SWR meter shows an SWR of 2:1. I am using 50 feet of RG-58 coax to a dipole antenna. The dipole is cut for 40 meters and I am operating on 40 meters. My rig is putting out 100 watts. How many watts are being reflected? How many watts are being radiated? 

Gemini calculated:  

Assuming your SWR meter is located at the transmitter and shows exactly 100 watts of forward power, 11.1 watts are being reflected at the meter, and approximately 76.1 watts are actually being radiated by your 40-meter dipole.

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That means that in this scenario, I am putting into the transmission line 100 watts and 76.1 watts are being radiated.  That means that the loss resulting from this SWR of 2:1 will be about 1.186 db.  With one S unit equaling about 6 db, this is clearly not enough to worry about.  

Also, lets remember that we could put a 50 ohm dummy load at the far end of our transmission line and achieve an SWR of 1:1.  But that dummy load would not radiate.   

Three cheers for Veritasium for doing this Smith chart video. 

Thanks to Rogier PA1ZZ and to Mike WN2A for sending this video to me. 

Please put below your comments on the video and my observations. 

A Nice Workshop (With The Logical Song)

 

How to Build a MODERN Electronics Workshop (and How Much it Might Cost) (PLEASE COMMENT)

First, kudos to this fellow for pronouncing "solder" correctly.  The L is silent (sorry to our British readers).  He does have an accent, but he is in Texas, and has picked up the CORRECT pronunciation.  So kudos. 

I really liked the video.  It represents a movement into the modern age of electronics.  I know that we usually talk about HDR, and homebrew rigs that -- while solid state -- are from the early 1970s.  There  has been a lot of progress since that time.  This video is a reminder of that, and talks about what we can do to participate in this modernity. 

Some observations: 

-- The microscope.  Looks cool, but it is kind of scary... 

-- The tiny digital rechargeable soldering iron looks like a great idea. 

-- I agree on the mechanical (non chemical) soldering tip cleaner idea. 

-- The 3D printer info is very useful.

-- Enclosures?  I am still in the 1/8 inch plywood era.  I have a ways to go. 

-- We could use more info on CNCs. 

-- I didn't know that you could get a pick-and-place machine for the home.  Probably just as well! 

-- I like the thermal camera.  I also like his suggestion that you could just burn your fingers! 

-- I think an oscilloscpe is a must, even early on.  I agree on the need for a multimeter.  

-- Indeed, a good PC is a must.  

What were your reactions to this video? 

My Parks 2 meter Nuvistor Converter, a QST review, and Bio Info on the Tektronix Hams who Designed It (Who is W7UHF now?)

 

Denton E. Nelson (amateur radio callsign W7UHF) was an electronics engineer and a notable figure in mid-century amateur radio history, best known for co-founding Parks Electronics alongside fellow operator Loren Parks (K7AAD) [3.1.3].

Tektronix Background

Nelson spent part of his career in the 1950s working at Tektronix in Oregon, where he moved through various roles from assembly into test and production engineering [1.2.2, 3.2.3]. During his time there, he was also an active member of the Tektronix Employees Radio Amateur Club [3.1.2].

Parks Electronics and VHF Converters

In the 1960s, Nelson (W7UHF) and Parks (K7AAD) partnered to build high-performance VHF (Very High Frequency) converters, initially starting their production in Parks's garage [3.1.3]. At the time, amateur radio operators who wanted to operate on the VHF or UHF bands often relied on outboard converters to shift those higher frequencies down so they could be tuned on standard shortwave communication receivers.

Leveraging their rigorous professional backgrounds at Tektronix, Nelson and Parks applied strict commercial test-equipment standards to their amateur gear [3.1.3]. Parks Electronics quickly became famous for its superior "little black boxes" [3.1.3]. Unlike much of the consumer equipment of the era, every converter Nelson and Parks produced was individually tested for precise gain, bandwidth, and low noise figure before it was shipped [3.1.3]. This commitment to quality made their equipment highly sought after by VHF and UHF enthusiasts worldwide [3.1.3, 4.1.6].

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One question about W7UHF:  If you go to QRZ.com, you will see that there is still a listing for W7UHF, under the name of Denton E. Nelson.  But it is for a Technician license.  And it lists a previous call as KD6EFF.  Who is that?  Could that be OM Nelson's son?  The holder is in Silicon Valley, and the license seems like it is about to expire. 

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Loren Parks (1926–2023), who operated under the amateur radio callsign K7AAD, was a man of three distinct legacies: he was a skilled electronics engineer who built highly respected amateur radio gear, and a pioneering manufacturer who made millions in the medical device industry. [3.1.1, 3.1.6].

Tektronix and Amateur Radio (K7AAD)

After serving in the U.S. Navy and earning a degree in psychology, Parks moved to Oregon and took a job in the 1950s with Tektronix, the pioneering test equipment manufacturer [3.1.1, 3.1.6]. He was heavily involved in the local amateur radio scene and the company's ham radio club [3.2.1].

Recognizing that operators needed better ways to tune into the VHF and UHF bands, Parks partnered with his Tektronix colleague Denton Nelson (W7UHF) to build outboard receiving equipment [3.2.2]. What started as a garage project became Parks Electronics [3.2.2]. By applying rigorous commercial test-equipment standards to their amateur gear, their VHF converters became famous for their high performance and exceptionally low noise figures. Parks was also a dedicated supporter of the wider ham community, at one point stepping in to purchase and run the VHF'er magazine to ensure the publication survived [2.3.2, 3.2.2].

The Medical Device Fortune

While his amateur radio converters were a critical success among hobbyists, Parks found his vast fortune in the medical field. In 1961, he founded Parks Medical Electronics in Aloha, Oregon [3.1.1, 3.1.7].

Pivoting his electronics expertise, Parks designed some of the world's first impedance plethysmographs and Doppler ultrasound systems [3.1.1, 3.1.7]. These devices are used by doctors to measure blood flow in vascular studies, detect faint pulses, and monitor patients during surgery [3.1.1, 3.1.5]. His company became a global pioneer in vascular diagnostics—making Parks a multi-millionaire in the process—and it remains one of the oldest manufacturers of Doppler systems in the world today [3.1.5, 3.1.7].

The Nuvistor, Thermatrons, RCA, Patents, the Rise of Asian Competitors (and my Parks Electronics 2 Meter Converter)

Asianometry always does a great job with this stuff, although I find myself grimacing when he speaks positively about Sarnoff.  Nevertheless the tube history is good (although he fails to mention that De Forest never figured out how his tubes worked).  

I have four Nuvistors!  They are in a 2 meter converter from Parks Electronics of BEAVERTON, OREGON. I may have this wrong, but I think the video said the Nuvistors were very expensive.  This can't be right.  Gemini AI says the 6CW4s in my Parks device sold for $1.50 to $2.50 in 1961. 

Three cheers for the Nuvistor!   I may try to see if they still work.  

A Very Nice Audio Workbench -- With Lots of Great Ideas

We covered Ben Hase's workbench earlier this week, focusing on his findings about glue, fusible resistors, and relays.  

This is a more complete look at his workshop.  

-- Very useful were his descriptions of his "daily driver" 'scopes and sig gens.  

-- I like the fingers for the patch cords. 

-- It was nice that he has one analog 'scope. 

-- WOW, HE HAS A KLH RECEIVER.  SO DO I!  ROGIER SENT IT TO ME! 

-- His use of Scan-Snap is potenially useful for us. 

-- I like his organization of parts bins. 

-- His use of the "tray truck" is ingenious. 

-- He has a good chair.  I note that he has a physical therapy T-shirt. 

-- His obvious devotion to HAKKO soldering tools is understandable. 

-- He has the obligatory drawer full of Fluke meters. 

We covered Ben's workshop when he was in Manhattan:  https://soldersmoke.blogspot.com/2024/06/another-great-workshop.html

It is great to see that he has more room now.  His acknowledgment of his wife's support was very nice.  

In this video, Ben visits Matt in the Pacific Northwest and swaps ideas on workbench construction: https://www.youtube.com/watch?v=GZ0rupOQKvE

And in this one we see Ben's work on a badly mangled Sansui receiver: https://www.youtube.com/watch?v=3w-wH4CGeT0

With a workshop like that,  Ben should be a ham.  A homebrewer.