Dale Parfitt, W4OP, Inducted into the QRP Hall of Fame

I was really pleased to confirm that Dale Parfitt, W4OP, was inducted into the QRP Hall of Fame in 2025.  It would have been a travesty to leave him out.  

I met Dale on the internet years ago.  After homebrewing one myself, I had found on the internet a version of Doug DeMaw's Barebones Superhet receiver using a FAR printed circuit board.  Years later, I was having a bit of trouble with it.  I think was probably trying to change the band from 20 meter to 17 meters or something like that.  There was this guy named Dale who was helping me a lot.  After a while, he said something like, "Hey, wait a minute.  That receiver board you have sounds very familiar.  Wait!  That's the receiver that I built!"  It was.  I was working on a receiver that Dale himself  had built. 

It turns out that I have told this story many times on the SolderSmoke blog.  (That's what happens when a story is good, and when the blog is OLD!)  Many other W4OP adventures appear on the blog (including a water-cooled EME anteanna, and reception of Mike Rainey AA1TJ's Vanguard replica transmitter).   Check out the W4OP posts on the SolderSmoke blog here: 

https://soldersmoke.blogspot.com/search?q=W4OP

And be sure to listen to Eric Guth 4Z1UG's interview with Dale:  

https://www.qsotoday.com/podcasts/w4op

Congratulations on the QRP Hall of Fame induction Dale.  It was richly deserved and makes membershop in that group all the more meaningful.  

Notes from an Australian SA612 Enthusiast

One of the first articles that I put on this blog was an NA5N post about the SA-612 -- this was originally posted on December 2, 2006: https://soldersmoke.blogspot.com/2009/06/na5n-on-ne602.html  Today our friend Paul VK3HN today noted the end of production.  The SA-612 is no longer being produced, but it is not forgotten, and there are a lot of them still around.  Thanks Paul.   

One thing I would add:  It took me a while to get my head around the Gilbert Cell mixer that is the heart of the SA-612.  Here is how I came to understand it: 

https://soldersmoke.blogspot.com/2021/11/how-to-understand-ne-602-and-gilbert.html

Paul writes: 

The end of a four decade life, the NXP SA612 (in SOIC8) ceased production and the final delivery date for orders placed by the last-time-buy deadline was August 18, 2023.

The SA612 truly is a remarkable chip. It's as if The Radio Gods got together back in the early 80s and said, 'what integrated circuit can we bring into the radio world that will supercharge homebrew radio and help enthusiasts to build their own rigs?'. And after the wise council settled on a combined oscillator-mixer in a single DIP-8 package, the rest is history
.
The 602/612 launched dozens of DIY radios and even businesses, and the careers of the QRP pioneers, from Doug DeMaw to Wayne Burdick to Dave Benson. I'll bet even Wes Hayward built a few.

SA612 discussions on Groups.io lists such as Qrp-Tech ran for decades and continue to attract attention and raise new insights today.

Even Elecraft with all of their digital radio know-how and resources launched the KH1 hand-held CW rig into production with SA612s in its receiver as late as 2023.

It really is an almost ideal part for simple homebrew receivers and transmitters. A 200MHz mixer with balanced inputs and outputs, an on-chip stable LO that can be used in three ways - a crystal BFO, an LC (or varactor) VFO, or a buffer for an external oscillator or clock such as the si5351 digital PLL/multisynth. Up to 15dB conversion gain which mostly eliminates the need for IF gain. Able to be gain-controlled with a DC AGC applied to its input. And did I mention low current?

Its only weakness is in its mixer dynamic range and strong signal performance but if you put a basic BPF in front, for simple homebrew rigs at home or portable/field rigs, this hasn't really been a problem.

Of course there are other mixers that outperform the 612 but some consume much more current, and none have the built-in oscillator.

Vale the SA612. You served, and continue to support the homebrew community like no other chip. You will not be forgotten.

Fortuitously, eBay is full of $5 a piece NOS parts on tape, which pretty much guarantees they are not fake. And at this price, for all you get, they're still great value!


Paul VK3HN.

Confirmed card-carrying SA612 fan-boy.

SolderSmoke Podcast 261: Travel, AI-Apocalypse, ARRL Award, Amplifiers (with Claude) , Transcoms, Smoke released in DR, QRP, CW, MAILBAG

SolderSmoke Podcast #261 is available for download: 

Audio:  http://soldersmoke.com/soldersmoke261.mp3

Video:  https://www.youtube.com/watch?v=1rzw8lxBzRo

Alaska, Colorado, Dominican Republic

Opening:   Travel notes:    Pete to Denver.  Dean to Alaska.  Bill in the Dominican Republic. 

The future of the podcast.  We will embrace our NIMCEL status and fight on in spite of the AI Apocalypse.   Thanks to Peter VK3TPM, Hamilton KD0FNR, Sam AI7PR, Todd K7TFC  and the WayBackMachine for providing backup and transfer options for the blog. Google could end Blogspot at any time.    

Dean and Bill win the 2025 ARRL Technical Service Award.  Thanks to Bruce KC1FSZ for the nomination. And thanks to Bill Morine N2COP for letting us know.  91 receivers completed so far!  

SolderSmoke East was pleased to host Phil W1PJE, a distinguished MIT radio astronomer AND member of the SolderSmoke Direct Conversion Receiver Hall of Fame.   

Dean:   Amplifier design,  woes, triumphs, tribal knowledge.  And help from Claude. 

KK4DAS 100W MOSFET AMP

Pete:  Project X  -- The Transcom SBT-3,  Crossroads and Decisions. 

Transcom SBT-3

SHAMELESS COMMERCE DIVISION:   FIGHT THE AI-APOCALYPSE -- BECOME A PATREON SPONSOR.

GET BEZOS TO SEND US BEZOS BUCKS!  Use the Amazon link on the upper right.   

BUY PARTS AND STUFF FROM MOSTLY DIY RF. 

Bill: 

-- Smoke released in TWO RD06 finals.  Scrounged IRF-510s to the rescue.   

-- Working VK6 on 20 SSB.  

-- My old HW-101 -- inspired by Pete and by Will N5OLA.   

-- High frequency hearing loss and direct conversion receivers. 

-- Eleven contacts on 40 with the DC RX and a Tuna Tin 2. Mike Bryce WB8VGE came back to my CQ! First ever QSO with SolderSmoke DC receivers on both sides:  K1OA-N2CQR.  

-- Do real hams use ALC? Do we really NEED ALC? 

Mailbag: 

Who is the Project 326 Guy?  A British engineer resident in China for last 20 years. 

Steve EI5DD  Ham Radio Ireland magazine.  Hey -- Why no Irish DC RX builders? 

Paul K9ARF -- Thanks for the very kind e-mail about SolderSmoke. 

Rogier PA1ZZ -- Many nice videos and suggestions on blog backup. 

Grayson KJ7UM on the EF-50 valve (thermatron!) 

Bruce KC1FSZ  Four DC RX builders at the Wellesley Mass radio club. 

Chris KD4PBJ -- Long trip to pick up two directional beacons possibly for 630m or 2200m bands! 

Alan W2AEW did a Minimum Discernible Signal test on the DC RX.  FB! 

Mike WN2A  -- Many great comments on MDS in its various forms. 

Philippe F6GUH is a FB homebrewer.  

Mike EIOCL -- Always great to talk on the air with an old friend. 

Walter KA4KXX -- I checked into the Sunrise net!  With my HW-101!  Thanks Walter. 

Farhan VU2ESE -- Watched our interview with Phil W1PJE

Phil W1PJE was an SWL with an old Halli receiver.  VOA?  Boo!  But Radio Marti is BACK! Also, the hydrogen line from the cosmic dark ages has red shifted to... 7.1 MEGA hertz!  So LISTEN UP! 

Phil W1PJE with a Halli and the Haystack Observatory Dome

My Eleven Contacts using the SolderSmoke Direct Conversion Receiver -- It is NOT a toy!

I have made 11 contacts using the SolderSmoke Direct Conversion receiver.  Ten of the 11 were after June 3, 2025. This was in very casual operation, operating with less than 1 watt with a dipole antenna.

Alan W4AMV

1. The first of course was back in February 2023 with W4AMV.   On this one I was using a simple "10 Minute Transmitter" that I threw together thinking that I would use it to demonstrate the receiver to our high school students.  "Wait a minute," I thought.  I called CQ and W4AMV answered.  I was running about 100 mW. He too was using homebrew gear.  https://soldersmoke.blogspot.com/2023/02/first-qso-with-high-school-receiver-100.html

2, 3, 4.  On June 4, 2025 I again fired up the 10 minute transmitter.  My T/R scheme was VERY simple: I have an MFJ coax switch that I use to select the rigs that will connect to my various antennas.  On the antenna switch I selected my 40 meter dipole.  I ran two pieces of coax from two different positions on the MFJ switch.  One I marked RX, the other TX.  The transmitter and the receiver were working off 9 volt batteries. I quickly worked N2WJW. Gil in New Jersey.  But I noticed that the 10 Minute rig was drifting.  So I pulled out my trusty old Tuna Tin 2 transmitter and used it to heartlessly replace the 10 Minute Transmitter.  Now with SEVERAL HUNDRED milliwatts, I worked W2XS, John in New York on June 5, 2025.  Later that same day I worked N9FGC in Indiana.

 

K1OA's Rig

5. My most amazing contact came on June 7, 2025. Here is my log entry: 40CW K1OA First 2 way contact with station also using a SolderSmoke DC Receiver!At around 0630 EDT on June 7, 2025 I heard K1OA calling CQ on 7030 kHz CW. This was exactly where I had a crystal.  I called him, but he didn't hear me.  I sent him an e-mail.  We tried again -- he heard me calling him and I heard him responding by calling me, but I don't think we succeeded in exchanging signal reports. It was close, but no cigar.  I had to walk the dog. Scott and I agreed to meet on 7030 kHz at 0730 EDT.  Arggh.  There was a QSO there.  I thought we might have to try to change frequency, but this would have been tough because both of us were crystal controlled on transmit.   Fortunately, the contact on 7030 kHz wrapped up.   Scott called me, I responded, and we were able to exchange signal reports.  I was so excited that I almost forgot to hit the record button on my phone.   But I caught the last minute or so.This was really something.  This really goes to prove what Dean and I have been saying all along:  this receiver is not a toy!  It can be used for real ham radio contacts.  And now we have had these receivers on both ends of a contact.  For transmit, Scott was using a KA4KXX transmitter with about 3 watts output.  I was on my Tuna Tin 2 at about half a watt output.

Jim W1PID

6, 7, 8.  Later on June 7, 2025 I worked an old friend, Jim W1PID.  Jim is a friend of Homebrew Hero Mike AA1TJ, and was involved in Mike's effort to cross the Atlantic with a voice-powered rig.  Jim also was one of my contacts with the ET-2 QRPppp rig. I also worked WZ2J  Vin in NJ. I also worked John W2XS again. 

Mike WB8VGE

9.   June 11, 2025  (Really evening of 10 June 2025) Famous homebrewer, Anchorologist, Heatkit authority and fellow member of the QRP Hall of Fame Mike Bryce called me!  40CW 0034 WB8VGE Mike Bryce came back to my CQ! Mike wrote: Nothing like quartz locked frequency control!You know it sounded pretty damn good at 500mW. You were holding your own until QSB would take you out in a deep fade. But all in all, one hell of great QRP QSO.I was running my Ten Tec Scout that I had just put back together a couple of days ago.  Got around to putting the case back on it tonight, and had it cooking in the back ground just listening to the stations come and go. I had worked a few POTA stations near by and found a quite spot. I was working on a project when I heard your CQ through the din of the 40M band. Glad I took a break and worked your QRPp signalbest 73  QRP # 4816 You get a QSL for that QSO!

Here's my post about Mike, WB8VGE:  https://soldersmoke.blogspot.com/2018/09/wb8vge-on-qso-today-qrp-hb-boatanchors.html

10. Around June 11, 2025 I worked W4MY in a contest. 

11.   On June 12, 2925 I worked some DX with the rig.  It was VA3ICC, Ian in Ontario. 

Ian VA3ICC

All of this reinforces something that Dean KK4DAS and I have been saying all through this build process:  this little DC receiver is not a toy.  It can be used as a serious ham radio receiver and it can -- even when paired up with a very low-power crystal-controlled transmitter and a simple antenna -- make some great ham radio contacts. 

Steve WD4CFN's FB Mid-Tennessee SolderSmoke Direct Conversion Receiver

 

Steve WD4CFN has built a FB SolderSmoke Direct Conversion Receiver.  CW reception video appears above. 

From his QRZ page:  "I also enjoy QRP.  A group of us have started a local QRP club this year, MidTN QRP Group. (https://groups.io/g/MidTNQRP). "

Steve writes:  

I finished my SS DCR tonight and connected an antenna. Lots of summer QRN, but also lots of signals. Thank you and Dean for all the work you guys put into this project.  It is so well done and documented.  The whole project has been a great learning experience, especially the mixer part.  I haven't built a diode ring mixer before, just used the SA602/SA612 type mixer.  Testing the mixer pushed me to better understand how to use the FFT function of my scope to make sure the mixer was working correctly.  This was a great project! Thanks to all.

Here is Steve's receiver inhaling SSB:

Congratulations Steve. Welcome to the Hall of Fame.

A FIRST! K1OA Contact with N2CQR -- All Homebrew with SolderSmoke Direct Conversion Receivers on Both Ends

At around 0630 EDT on June 7, 2025 I heard K1OA calling CQ on 7030 kHz CW. This was exactly where I had a crystal.  I called him, but he didn't hear me.  I sent him an e-mail.  We tried again -- he heard me calling him and I heard him responding by calling me, but I don't think we succeeded in exchanging signal reports. It was close, but no cigar.  

I had to walk the dog. Scott and I agreed to meet on 7030 kHz at 0730 EDT.  Arggh.  There was a QSO there.  I thought we might have to try to change frequency, but this would have been tough because both of us were crystal controlled on transmit.   Fortunately, the contact on 7030 kHz wrapped up.   Scott called me, I responded, and we were able to exchange signal reports.  I was so excited that I almost forgot to hit the record button on my phone.   But I caught the last minute or so.  See above.  

This was really something.  This really goes to prove what Dean and I have been saying all along:  this receiver is not a toy!  It can be used for real ham radio contacts.  And now we have had these receivers on both ends of a contact.  For transmit, Scott was using a KA4KXX transmitter with about 3 watts output.  I was on my Tuna Tin 2 at about half a watt output.   

Thanks Scott! And thank you Walter!  

A Tale of "Ten Minute Transmitters" and "Tuna Tin Twos": N2CQR Goes Back to CW QRP!

Inspired by K1OA and KA4KXX, I put the SolderSmoke DC receiver to work on the CW portion of 40 meters. At first I used a very (perhaps overly) simple "Ten Minute" transmitter. On June 4, 2025 I worked N2WJW in New Jersey. But the transmitter drifted as it got hot. So I switched to the more robust Tuna Tin 2 (TWO transistors!) and worked W2XS in NY and N9FGC in Indiana on June 5. With both transmitters I was "rock bound" -- crystal controlled. Power out was always less than 200 milliwatts. Antenna was a low to the ground dipole. The receiver was powered by our beloved 9V battery. The transmitter had a second 9V battery. Some observations: First, even if you CAN hear other signals, the different tones allow your brain to seperate them out (this has long been known to CW operators, but might not be readily apparent to newcomers). So even if the DC receiver is broad in frequency response and even though it IS also receiving the other side of zero beat, you can make CW contacts (unless, of course, another station is on a frequency that produces exactly the same tone as the one you are trying to work), even at very low power . Second, you don't always really have to be right on the other station's frequency. Here's why: If he is looking he can see you in his waterfall! So that SDR waterfall is now a friend to crystal-controlled HDR operators. Who would have thought? Above is a picture of the my station with the Ten Minute transmitter. See the notes I wrote on the QSO with N2WJW.

Ten Minute Transmitter (the gray thing is a CW key)

Direct Conversion Receiver

Tuna Tin 2 that replaced the Ten Minute Transmitter

Note battery and crystal

Not a Toy! K1OA Making Contacts with the SolderSmoke Direct Conversion Receiver and a KA4KXX Transmitter

This goes to prove what we have been saying all along:  this receiver is not a toy!  It is capable of operating as part of a real 2-way ham radio station. Hall of Fame member Scott K1OA has paired his receiver up with a Merry Christmas transmitter designed by Walter KA4KXX and has been making CW contacts with it (see above).  Walter supplied the crystal and many of the needed parts.  Scott has already worked WA9RNE, N4HAY and W3RJ, and has tried making contact with Walter but no luck yet. He has gotten RBN reports from Germany and New Zealand. All that with just 3 watts.

This is not the first time this receiver has been out to use.   I made one contact with it using a "Ten Minute" QRPp transmitter that I had intended only to use for test purposes: 

https://soldersmoke.blogspot.com/2023/02/first-qso-with-high-school-receiver-100.html 

HoF member Aaron ZL1AUN used his receiver with an SSB transmitter to make contact using his receiver:

https://soldersmoke.blogspot.com/2025/02/soldersmoke-direct-conversion-receiver_23.html  We understand Aaron's article about the receiver has been published in "Break-In" magazine -- we hope to get a copy (electronic would be fine!) 

And who can forget HoF member Nate KA1MUQ who turned his "frying pan"  direct conversion receiver into a double sideband transceiver and used it to make phone contact with Idaho from California: 

https://soldersmoke.blogspot.com/2025/03/nate-ka1muq-turns-his-frying-pan-dc.html 

If anyone is aware of other contacts made using this receiver, please let me know.  

Agent Sonya -- Did Soviet Spies Really Homebrew Their Rigs?

Ursula Kuczynski (Agent Sonya), 1936.Credit...via Peter Beurton

My recent blog post about the intrepid Soviet hams who homebrewed versions of the UW3DI SSB transceiver led to a comment about early Soviet era overseas intel officers who -- supposedly -- homebrewed their own transmitters and perhaps receivers.  

Here is a New York Times review of the book that mentions the homebrewing by spies:

https://www.nytimes.com/2020/09/15/books/review/agent-sonya-ben-macintyre.html

Here's the Wiki page on Sonya:

https://en.wikipedia.org/wiki/Ursula_Kuczynski

Tony Percy took a look at the homebrew claims:

https://coldspur.com/signal-sonyas-wireless/

Percy seems quite well informed about radio and about how believable Sonya's claims about her radio activities were.  He uses the Morse acronym QRP, talks about Maximum Useable Frequency, discusses antennas and the relative difficulty of building a receiver.  He also talks about the need for crystal controlled transmitters if the QRP transmitter was to have any hope of reaching Moscow Center.  In sum, he thinks the reports of Sonya's radio derring-do are just nonsense.  

I agree with Tony Percy.  I just think it would be impossible to take a newcomer, show them how to scratch-build a radio, send them to a foreign country, have them buy the needed parts, expect them to build the rig and the antenna... oh and learn to use the Morse Code along the way.  I just don't think that is possible.  

Is Tony Percy a ham?  What do you folks think about the plausibility of the claims about Sonya's radio prowess?  

Ken W4KAC's Wonderful SolderSmoke Direct Conversion Receiver -- with a Leaf Blower Tuning Dial

Ken W4KAC tells me that the tuning knob that he used to minimize hand-capacitance effects on his PTO started out as a gear in a leaf  blower.  I commented that the engineers who designed that gear surely never thought that it would someday be used in a homebrew direct conversion receiver.   

Ken lamented the polemical nature of the SSB discussion captured in the above video, but the clip does give a good demo of the SSB capabilities of Ken's receiver. And the video gives some nice close-ups of the receiver itself.  

Ken is a CW guy, and he has already homebrewed a QRP CW transmitter that he hope to pair-up with the receiver.  Here it is: 

Ken reports 160 mW output with a 377 mile reception report on the Reverse Beacon Network.  I made a contact with something similar: https://soldersmoke.blogspot.com/2023/02/first-qso-with-high-school-receiver-100.html

Ken wrote about the importance of persistence: 

Good morning. Just wanted to say, don't give up if your receiver is not quite right. Mine was working, I even posted a video here. When building the AF amp from the transformer end back, the Q4 stage was fine. I added Q3 and had a "motor-boating" oscillation when I applied a signal. I tore it all off the board and started over. I still had the problem, so being stubborn I continued on and kept adding more filter caps to quiet it down all I could. The receiver worked and sounded pretty good during the day when I copied WA4FAT and others. That evening was a different story when the band was working well and very full of signals. Very strong stations were ok, but I was getting lots of "hash" and noise other than normal band noise. FT8 was breaking through weakly all over the band along with other unidentified stuff. Yesterday morning I grabbed a new piece of copper clad and built and entirely new AF amp. It tested properly all through the build. Instead of installing that board I decided to find the problem with the original. I "thought" I had used new transistors when I rebuilt it the first time. Turns out I had probably put the original Q3 back, because replacing it cured the problem. I had an entirely different receiver last night. A pleasure to listen to. Don't give up like I did at first!!

Ken went the extra mile by building a SECOND Direct Conversion receiver.  So he may soon get TWO Hall of Fame credits.  Here is the second one that Ken built: 

 https://www.youtube.com/watch?v=HUSWKJZdc8E&t=39s

Thanks Ken!  

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

For more information on how you too can build the receiver: 

Join the discussion - SolderSmoke Discord Server:

https://discord.gg/Fu6B7yGxx2

 

Documentation on Hackaday:

https://hackaday.io/project/190327-high-schoolers-build-a-radio-receiver

 

SolderSmoke YouTube channel:

https://www.youtube.com/@soldersmoke 

"QRP Classics" The Book that Got Me Started in Homebrew

https://soldersmoke.blogspot.com/2022/09/fixing-up-old-homebrew-rig-barebones.html

A question this morning from Scott KQ4AOP caused me to Google this old book    On page 59 I found the article about my first transmitter.  Someone has put a copy of the entire book on the interenet.  Here it is: 

https://ham.v4.si/books/QRP%20Classics%20-%20The%20Best%20QRP%20Projects%20from%20QST%20and%20the%20ARRL%20Handbook.pdf

Helge SM/LA6NCA Activates Colorburst Liberation Army in Sweden!

FB Helge.   This is really cool.  I didn't realize until I saw the schematic at the end that he was on 3579 kHz -- that is the old color-burst frequency, and now the frequency of the Color-burst Liberation Army. 

It was challenging to do this without sidetone.  But there appears to be a bit of room left in the matchbox -- could he squeeze in a few more components for a rudimentay sidetone?  Maybe just a piezo buzzer across the key? 

VIVA EL CBLA! 

Chuck Adams' Modification of the MXM Simple Transceiver -- An Early QSO with the MXM Thirty Years Ago

Click for a better view

Esteemed Homebrew Hero Chuck Adams AA7FO saw me struggling with the T/R switch on my hamfest-found MXM SupeRX/TX transceiver. Chuck kindly sent me a modification of the circuit that allowed for automatic T/R.  I see it also envisioned the use of a VFO.  We are not sure if this version of the MXM transceiver ever made it to market, but it certainly would -- in any case -- be of interest to homebrewers.  

Chuck wrote: 

Attached is a schematic I drew for Bruce almost 30 years ago with a program that I wrote.  This is for the Simple Transceiver where Bruce and I worked out the solid state switch to replace the slide switches you have to use to switch between receive and transmit.

BTW.  MXM stand for 1990, the year Bruce started his kit adventures.  I worked Bruce on the first beta build of the transceiver Denton TX to Smithville TX on 40m during the day.

Thanks a lot Chuck.  

KE5HPY Builds a QRP Transmitter

 

FB Chuck, very cool.  Please send us more reports on this rig.  

Chuck has been on the blog many times, with many projects: 

https://soldersmoke.blogspot.com/search?q=KE5HPY

73  Bill 

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

Bill/Pete:

 

Thought you would appreciate a recent project inspired by the fabulous EMRFD.  This started as a test bed W7ZOI universal tx to evaluate my stock of RF BJTs and employ some FT-243s in the shack.  That was interesting by itself but the 16-32 dBm output (choice of device really matters!) did not reach the intended targets using my 40m dipole.  So, add a W7EL RF PA and a nifty, clean 7W emerges after damping output from Q2.  The final is pleasantly efficient and needs only a modest heatsink to survive key down for 60 seconds.  KFS then reported S7-9.  Success.  Time to box it up and go XTO, add a meter output at 30dB down and an RF driven LED indicator.  Left room to add an ATtiny85 CQ keyer but ran out of time.  Had to move house and knock down my 40-6m antennas.  That was the most painful part of moving.  So this rig sits while I find a new place to hang antennas.  Eventually, the TX will get a RX mate when it is possible to box up a 40m DC RX with Si5751 and OLED display. Am still trying to solve how to mount an OLED display cleanly in an aluminum box. First, I have to reconstruct my workbench.

 

Keep up your good work, and that is no April Fool’s joke. 

 

73,

 

Chuck KE5HPY

A QRP Quiz Question

 

I have the answer from an excellent and authoritative source.  

Here is the question:  The rig I bought for one dollar at Winterfest was produced by MXM Industries of Smithville Texas.  What does "MXM Industries" mean?  Why was this the name of the company? 

The Doug DeMaw Article that got me into Homebrew Double-Sideband

Just click on the images for a better view

Pete WB9FLW asked for this.  This was an important article for me -- it paved the way for my entry into homebrew phone gear -- this article was the basis for my first DSB transmitter, built in the Azores. 

I think Doug was a bit optimistic in saying that SSB operation was possible with this rig.  Maybe it was possible for Doug, but for most of us DSB is just a LOT easier to get going than SSB.  (I know that some people don't believe this, but I note that most of these folks have built neither DSB nor SSB rigs.  It always seems easier before you start to melt solder.)  

Be sure to check out the 10 meter DSB rig recently built by Mike WU2D.  He has 6 or 7 good videos on this project, including this one: https://www.youtube.com/watch?v=xThoAMv4zrw

Another CW Contact with the SupeRX/TX 40 (Video)

I changed the crystal in the transmitter.  I got a different rock from Mouser and am now on 7030.  

Wednesday April 3, 2024. On 40 meters in the afternoon with Mike KM4KY in North Carolina.

MXM SupeRX/TX 40 Rig Info

 

My SupeRX/TX 40 -- now on 7030 kHz

Click on schematics for a better view

Details on the receiver: https://archive.org/details/73-magazine-1991-04

Details on the transmiiter: https://archive.org/details/73-magazine-1991-12/page/10/mode/2up

Article on MXM Industries of Smithville,Texas:  

https://www.worldradiohistory.com/Hambrew_Magazine.htm

Click on images for a better view

Click on images for a better view

A QRP CW Contact (Video) with the Winterfest MXM SupeRX/TX 40 (1 Watt, Crystal Controlled Transmitter)

I picked this transceiver up at Winterfest for one dollar. 40 meters. Superhet receiver with 455 kc ceramic filter and 2 NE602s. Crystal controlled one watt transmitter on 7039.5 kc. I emailed Jeff KA2BKG and asked him to slide up a bit to my freq. I am glad he did. Thanks Jeff.

KD0FNR's Amazing San Francisco TouCans Rig -- A Rockmite and a Tuna Topper in a Pineapple Can Mounted on the Dipole in a Shopping Bag

Click on the image for a better look

This post has a definite San Francisco vibe. 

Hamilton KD0FNR appeared on the SolderSmoke blog way back in 2011.  Perhaps he should join forces with N6ASD who lives quite close to him in SF, and seems to share radio interests.  Also in their area is the esteemed Bay Areas blogger and homebrewer Dave AA7EE ; Dave recently sounded the CBLA alarm, alerting us to the presence of an intruder on 3579 kHz.  In the process, Dave mentioned the Pt. Reyes Web SDR, the presence of which came as welcome news to Hamilton. Finally, Dave and Hamilton mention the KPH Web SDR, which brings to mind Dick Dillman W6AWO who has been on the SolderSmoke blog several times.  

Hamilton and his kids have their rig (a Rockmite and a Tuna Topper in a Dole Pineapple can) mounted at the feedpoint of their dipole (in the red shopping bag above).   They link to it via WiFi and Bluetooth. FB.  Thomas Witherspoon has a nice presentation (by KD0FNR) of the TouCans project on his blog: https://qrper.com/2023/12/field-radio-kit-gallery-kd0fnrs-rockmite-20-and-tuna-topper/ 

Hamilton KD0FNR writes: 

At the moment, the kids whose dad I am, better known as the gang—12, 10, and 8 year-old Diaze, Mota, and Tawnse.. all internet aliases—are big into 20 meters QRP CW with Project TouCans, a Rockmite coupled to a Tuna Topper. The radio and the amp that popped us out of QRPp to plain-old QRP are both housed in a Dole Pineapple can with a tuna can as a cover and antenna mount. The whole rig is still very much mounted in our half-wave dipole! 

Project TouCans consists of a Rockmite feeding a 5 Watt Tuna Topper, all of which is housed in our dipole antenna. The Rockmite has a single crystal bandpass filter on it's rx input. That makes it a pretty wide reciever which is fine, but it's particularly sensitive to its tx frequencies, 14075.5 and 14058 kHz AND—for some reason I have yet to understand—10459 kHz. By watching the SDRs that now—thanks Dave—envelope us here at our home QTH in San Francisco, we can see the frequencies of incoming signals. That information keeps me from responding to 14059 kHz signals in vain.

And now, the headphone repeater: TouCans is completely wireless with respect to the ground. That means there's no power line, no feedline, no keyer lines and no headphone line. Keyer controls are handled via wifi to a Raspberry Pi Pico-W on the rig while audio is brought back to my headphones via Bluetooth. Power is provided by a USB-C battery pack that lives in the rig which is mounted above us in the antenna. (Yes, all of this is becuase I thought feedlines matches and baluns were too mystical and hard to understand years ago. Yes, this has probably all been more work than a balun. Yes, I am still totally enamored of my original design decision. :) ) Anyway, the bluetooth range is about 50 feet and the wifi range is shorter than that. The short of it is—pun not intended—that I can't quite use the rig while I'm in my office. But, I can send CQ to the rig every half minute or so via a memory keyer, then turn on the SDR in my office, and then sprint a bit closer to the rig when someone calls back. (It helps that houses in SF are a bit tiny.) So, SDRs are kinda an integral part of our QTH setup and it's awesome to learn about a new—to us—one! Thanks again!