Just go to http://soldersmoke.com. On that archive page, just click on the blue hyperlinks and your audio player should play that episode.
http://soldersmoke.com
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.
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?
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
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.
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!
Above you can see what I picked up at the Vienna Wireless Society's 2024 Winterfest Hamfest.
-- On the left in the blue box is an MXM Industries SuperRX/TX 40 transceiver. It is a kit from a Texas company. Superhet receiver with IF at 455 kHz. Crystal controlled CW transmitter on 7040 kHz. The oscillator works, but so far no receive signals. I will have to troubleshoot. Does anyone have a schematic?
-- Behind the MXM there is a nice box marked "Diode Detector" I opened it up and there is just a solid state diode and a 50 ohm resistor to ground. Box may be useful.
-- I got a couple of books: "Weekend Projects" 1979 from ARRL, and "A History of QST -- Volume 1 Amateur Radio Technology 1915 - 2013" 2013 from ARRL.
-- On top of the Weekend Projects book you see a "Crystal Holder" from Gross Radio of New York City. W1UJR has some good history on this company: https://w1ujr.com/written-word/gross-radio-company-circa-1931/ This device seem to be intended to hold in place a raw piece of quartz! Cool.
-- To the right of the books there is a serious-looking VFO. One dollar! Deal! It is a CB VFO, but the markings say it puts out 5.44 to 5.99 MHz. So it should be useful. The dual speed dial is very nice.
-- Above the VFO is a nice step attenuator from the "Arrow Antenna" company of Loveland Colorado.
-- Further to the right are some Electric Radio and Antique Wireless Association magazines that Armand WA1UQO gave me. Really nice. The AWA mags have a very thoughtful piece (warts and all) on Jean Shepherd. And the ER pile has an article by Scott WA9WFA that mentions my work on the Mate for the Mighty Midget receiver. Thanks again Armand!
-- I also got some ADE6+ surface mount mixers. The price was right!
Listener Tobias was laid up yesterday, following the extraction of wisdom teeth. (This seems like an appropriate follow-up to our talk in SolderSmoke Podcast #250 of sBITX "wisdom files" to correct FFT "hallucinations.") Tobias does not appear to have been hallucinating, but he was having trouble seeing what he thought to be a "red poster" in my shack.
In fact, what he was seeing was a red tapestry from Ecuador that was sent to me by Galo Constante HC1GC way back in 1993. I was in the Dominican Republic, running my first ever real homebrew transmitter. Here is an article about this project: https://www.gadgeteer.us/TXHB.HTM I think Galo was also QRP homebrew. My log shows that I worked him eight times from the DR.
Mitad del Mundo = Middle of the World (a reference to the equator).
Here is the QSL I got from Galo:
Here's a 2022 blog post about a resurrection of this old rig:
I have just built an tested a 20 meter “Sputnik” transmitter. It uses two Soviet era “rod” tubes and is fixed tuned to 14.060 MHz. I was able to compress the design to fit in an Altoids tin. The plate tuning capacitor was replaced with a fixed capacitor value closest to the variable for peak power out. Plate voltage is 90 volts and I key both the oscillator and PA via the B+ line. Power output is around 200mW and my first test transmission from the Chicago area was picked up 864 miles away on the east coast via the Reverse Beacon Network. It was definitely Joy of Oscillation and Joy of Transmission!
73, Mike
AA9IL
EN52
----------------
Mike's rig has been heard by many Reverse Beacon Network stations:
------------------
November 29, 2023
Bill:
I started a QSO with AC2C in Ellicott, MD who responded to my CQ but the band dropped (20m)
But that’s a good start and I’ll keep at it! So, yay!
73 Mike
-------------------
Here are some earlier blog post on rigs using Soviet rod tubes:
A recent comment on the blog put me back in contact with an old friend of SolderSmoke: Paul VK3HN. Paul is an amazing homebrewer -- it was great to hear from him. He sent along this video of a portable Summit on the Air activation from the Melbourne Australia area. Paul managed to contact Ignacio EA2BD in Spain. Ignacio was also running low power with a portable set up. The remarkable thing is that we have video from both sides of the contact. FB! Thanks to Paul and Ignacio.
Here we have a Michigan Mighty Mite being modified for AM in Romania, with input from Hungary, and inspiration from Melbourne, Australia (Peter Parker VK3YE). With a very nice shout-out to SolderSmoke.
I really like Ciprian's emphasis on having fun with the electronics.
Sam WN5C built a Michigan Mighty Mite and then went the extra mile by putting it on the air from a field location. And what a great name this location has for a QRP operation: Lake Thunderbird.
Sam wrote up his experiences for K4SWL's QRPer blog:
Below is a picture of the rig. NOTE THE LOW-PASS FILTER. FB OM. We wouldn't want that rig tearing up the electromagnetic spectrum.
Looking ahead, Sam writes:
Next step is a DC receiver (maybe the high school receiver?) and then a more substantial transmitter married together, I think. This is all incredibly fun.
It was great to hear George's voice again. I was a big fan of his "Chat with the Designers" podcast. And it was great to see that Pete Eaton WB9FLW (an old friend of SolderSmoke) was also involved in this presentation.
At FDIM George was talking about Coherent CW. Now, my views on CW have been made quite clear, but I am going to deliberately avoid snide comments about how Coherent CW might be a contradiction in terms. Thank you. I think this is something that Pete N6QW and I can agree on.
Nevertheless, this is all technically interesting. This reminds me of what happens with WSPR. But I wasn't quite sure what George was getting at with his discussion of the phase of the incoming signal -- I can see the need to get the receivers' narrow filter exactly on the transmitting station's frequency, but why the phase?
It was really cool that our correspondent at FDIM caught up with Eric Schwartz WA6HHQ of Elecraft. Some highlights from the interview:
-- Eric met Wayne Burdick through the NORCAL 40 (Wayne had designed it, and Eric was writing articles about it). That was a very influential rig -- it was the basis for a book and a CALTECH course by David Rutledge.
-- Elecraft has a strong QRP element in its DNA.
-- The K2 is "Heathkit style" and offers the builder the opportunity to understand the rig at the component level.
-- Eric says that using something you built yourself is worth at least 10db.
It is time to put aside (again!) all of the heated ideological arguments about the power level that defines "low power." Just sit back and enjoy this wonderful trip down QRP memory lane.
40673! TT2! And G3RJV's PW Severn - indeed, bow your heads!
Wow, the Ten Tec Power Mite (or Might!) -- I still want one. Same for the Argonaut -- what a great name (sounds like a "magic carpet), and with SSB to boot! I want to join the Argonaut cult!
I have both the HW-7 and HW-8 (the HW-8 is heading to the Dominican Republic). This video makes me want to fire up the HW-7. Maybe on 40.
Continuing our search for information the Cuban "Jaguey" DSB rig, Trevor Woods pointed me to Dick Pascoe's QRP column in the (below) July 1998 issue of Ham Radio Today. I think the first SPRAT article about Eric Sears' ZL2BMI DSB rig was in SPRAT 83 in the summer of 1995. This fits well with the sequence described below by Arnie Coro CO2KK.
I am still looking for a schematic and pictures of the Jaguey rig: If you can help in this, please let me know.
We've been giving out prizes for the first team to complete each stage. I wanted to give one of the teams a little oscillator that could b heard with their receiver. So this morning, using a 7040 crystal from the AF4K (SK) company, I threw together a one transistor oscillator. It has just 8 parts, including the key:
I had a low pass filter in the antenna tuner. The antenna was a low-to-the-ground 40 meter dipole. The transmitter was putting out around 100 milliwatts.
N2CQR's Ten Minute Transmitter
The Reverse Beacon Network showed that I was getting out quite well:
Then I thought, wait a second, let's make a contact with the prototype high-school direct conversion receiver.
With the receiver hooked up, I again called CQ on 40 CW. BOOM! Very quickly Alan W4AMV in Raleigh NC came back to my call. Wow! That's 222 miles. And a quick check of QRZ.com revealed that Alan is a homebrewer. Then Google reminded me that his work has been featured on the SolderSmoke blog. TRGHS.
I was so excited during this contact that I almost forgot to film it. But I did manage to get some short clips of the QSO in progress. You have to listen carefully, but you can hear our calls in there while Alan is transmitting (listen for the lower tone):
UPDATE (Feb 27 2023): I asked Alan about the rig he was using: "A PLL EXCITER DRIVING A PAIR OF FETS PUSH PULL ABT 50 w to an inverted L at 55 feet. The Rx a single conversion 9 MHz IF and it is connected to an active antenna in the trees out in the woods abt 25 feet up. Uses an automotive whip antenna about 3 feet long. "
Alan's Rig
This little contact is a reminder of the fun that can come from using simple, homebrew, QRP gear. It is really amazing that the very first contact with this receiver was with another homebrew station. This all reminds Dean and me of something we have been telling the students: the little DC receiver they are building is not a toy -- it is capable of being used in real, long-distance contacts.
Walter KA4KXX in Orlando has been a prolific builder of rigs for many years, and has been a great friend of SolderSmoke: Here are some of the SolderSmoke podcasts and blog posts in which Walter's solder melting was mentioned: https://soldersmoke.blogspot.com/search?q=KA4KXX
As we approach the end of our current stay in the Dominican Republic, I could not miss out on the chance to work Walter with his homebrew rigs. Even though the space weather was stormy, and my dipole was droopy, we arranged to meet up on the high end of the 20 meter CW band this morning. See the results in the video above. A solid QSO with Walter. He says it is HB2HB, but truth be told I was on a uBITX that was built more by Farhan than by me. But this was a great contact. Walter started with a 50W rig, then switched to his 3 watt rig with a DC receiver. FB
Here is the e-mail I received from Walter after the QSO:
Dear Bill:
Many thanks for the great video, and when
you return to Virginia look for your mailman
to bring a postcard from me!
Just after your phone call this morning I scanned
the band from 14.025 to 14.300 and heard only one
SSB QSO at 14.347, and even now I only hear
a half dozen SSB signals, so that makes what
we did even more amazing.
The first photo below is my 3.5 watt NE602 direct conversion
rig which is about 2 years old. The transmit signal is created
by putting a 3 MHz VFO signal into an NE602 mixer with an
11 MHz crystal, so the rig can receive CW and SSB from
14.025 to 14.300 and can transmit CW anywhere in that range
with good frequency stability.
The bottom photo is my new full break-in CW 50W rig which
I just put on the air about a week ago and is still in the finalization stage.
I am not yet happy with it, but then again I am more particular
now than I used to be. It is really a trans-receiver with a single
conversion superhet receiver at the bottom of the board using
an NE602 pair with a 3-crystal 4 MHz 900 Hz bandwidth filter,
and a single 10.080 crystal VFO which is tuned with a polyvaricon
for operating between 14.061 and 14.068 MHz.
At the top is the VXO transmit section using a pair of 14.070
crystals pulled down into the operating range. This signal
is buffered and amplified to about 500 mW which is all that
the MRF101 RF Power Amplifier needs. Visible behind the
board is an AC-powered 24 VDC switching power supply which
is connected in series with the 12 VDC battery to
power the final stage with about 36 VDC. The main 12 VDC is
provided by a bench power supply which is not in the photo.
In both rigs the morse code key is the microswitch
at the lower right corner. (Way more handy and elegant
than your key, I might say?)
This morning each of these rigs was connected to its own
end fed half wave antenna, one in my backyard
and the other on the side of my house. My antenna analyzer
shows them to be essentially equal, but my 50W rig does
not like one of them at all.
Making our international homebrew-to-homebrew contact
today was a terrific ham radio experience, so thanks for all
"SolderSmoke -- Global Adventures in Wireless Electronics" is now available as an e-book for Amazon's Kindle.
Here's the site:
http://www.amazon.com/dp/B004V9FIVW
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