KE5HPY's Altoids Direct-Conversion Receiver for 40 Meters

Click on the image for a much clearer view.

It is a thing of beauty.  You can see all four stages in there.  There is the Bandpass Filter in the upper left.  Below that is the VFO.  In the center you can see the SBL-1 mixer. Off to the right is the audio amplifier.  FB Chuck! 

Chuck KE5HPY writes: 

Allow me to add an endorsement of the joy and practicality of the DC receiver. Whether XTO, VFO or DDS, ring diode mixer, or Polykov, the DC IF concept is a real winner.  They really deliver wonderful audio and clarity that is very satisfying for homebrew builder.

Thought you might enjoy these photos of a 40 m receiver and built 10 or so years ago.  The design is straight out of EMRFD.  At that time, the Altoid tin craze was in full swing and this is one of several projects I stuffed in a tin.  This compact receiver has traveled on lots of camping and kayak trips where it delivered good DX reception using only a 30 foot piece of wire for antenna running back to the tent. It’s fun to hear intercontinental QSOs when you’re in the middle of nowhere. With my 40 m dipole attached at home, I think this little rig can hear anything my Icom hears.  

It’s great that you’re promoting this practical technology. Keep up the good work.

Happy Birthday to Pete Juliano, N6QW

 

Pete Juliano 

Excellent husband and father.

Vietnam veteran who went into harm's way for his country.

Master homebrewer. 

A great cook.

A wonderful friend. 

A great co-host of the SolderSmoke podcast. 

HAPPY BIRTHDAY PETE! 

Popcorn Electronics is BACK! Yea!

 

https://qrp-popcorn.blogspot.com/

Check it out at the URL above.  FB!  Thanks Todd!  And thanks Vasily!  

I never knew that Mike KL7R (the co-creator and first co-host of SolderSmoke) was responsible for the Popcorn nickname.  FB!

SolderSmoke Podcast #255 -- Accept the HB Challenge!, DeMaw SSB, Brilliant TR-3, Tube Talk, Ground Truth, Tales of Woe, SDR RX, Pico Balloons, MAILBAG

Mythbuster II -- 20 meters only

SolderSmoke Podcast #255 is avalable: 

Audio:      http://soldersmoke.com/soldersmoke255.mp3

Video:       https://www.youtube.com/watch?v=c54qiITMxwM

--   First: Happy Holidays!   I have on a Santa Claus hat!  

-- December 18.  Pete completes another orbit.  Happy Birthday Pete.  Please send him birthday greetings. 

 --  Bill was on Ham Radio Workbench: https://soldersmoke.blogspot.com/2024/11/bill-n2cqr-appears-as-guest-on-ham.html  Our challenge to HRWB.  Gauntlet thrown down... OUR CHALLENGE HAS BEEN GRACIOUSLY ACCEPTED!     We now extend the challenge to the entire SolderSmoke community: Build one of these:  https://hackaday.io/project/190327-high-schoolers-build-a-radio-receiver

Homebrewing is not for the faint of heart!  Accept the challenge!  Build stuff! 

Our question:  Did Doug DeMaw ever build an SSB transceiver?  Starting in September 1985 he wrote a five part series on an SSB TRANSMITTER for QST.  But he prefaces it by asking, "Why would anyone build an SSB transmitter today?" He says it would be fun "for the experience and understanding it would provide." But not for use, you see... And it is not a transceiver. 

Bill's theory about DeMaw, SSB,CW and sideband inversion:  He was a CW guy so sideband inversion did not really matter. He could get it wrong and still make it work.  

Pete's Bench: 

Brilliance and the TR3. https://www.youtube.com/watch?v=2C-eYB8yFzg&t=13s

A tale of woe.  Done in by a light bulb.

Thanksgiving dinner and SSB transceivers. https://n6qw.blogspot.com/2024/11/11292024-how-to-homebrew-thanksgiving.html             https://www.pastapete.com/

Hybrid plans:  https://www.youtube.com/watch?v=zKUjHZMf3Fs&t=5s

Dean's Bench:

Travelogue – Falcon 9 Launch

Building a homebrew T Match tuner for the end-fed long wave – sourcing the parts, winding the coil – taps, testing 

VWS Makers Projects

SDR Receiver Project – starting in January

VWS Pico Balloon – Traquito - Traquito - WSPR Pico Balloon

Revisiting the 10M DSB rig

Soldersmoke listener challenge – build a DCR with KK4DAS – overview then one board a week

SHAMELESS COMMERCE DIVISION:  Mostly DIY RF.    Please subscribe to our YouTube Channel.  And use the Amazon link on our blog.  Become a Patron via Patreon (on the blog). SolderSmoke is now on Blue Sky and Threads -- follow us or at least like us there. Please turn on automatic downloads on your podcast app -- most podcast apps will only store a few episodes. This will help bump the numbers, which will improve visibility.  Please give the show five stars and, if possible, a nice review on your podcast service,  That will help with the discovery rate for people looking for new podcasts.

Bill's Bench:

Is "The Ground" a Myth?   ARRL VP says Ground is a Myth: https://www.youtube.com/watch?v=KdX-978tvkY.  Bill disagrees.  Helicopter story.  Refrigerator story.  Original single wire telegraph system. https://en.wikipedia.org/wiki/Single-wire_earth_return

Front Panel and Freq Counter for the Mythbuster II. 

Another Tale of woe:  A mysterious audio problem on the 15-10 II rig.  Done in by.... Duh!   Comparing sideband suppression with Mythbuster I.  Differences in Hfe?  Notes on Mythbuster II build. 

TinySA Ap -- A cure for Fat Finger Syndrome? : http://athome.kaashoek.com/tinySA/Windows/  How to get and load the Ap (you might want to start watching at 1:11) https://www.youtube.com/watch?v=zu4X5dyUlpo&t=2s  General info video on the TinySA Ultra: https://www.youtube.com/watch?v=6C24RnYNOWQ&t=1143s

For the DR shack -- I got a Swan SWR-1A on E-Bay. 

 MAILBAG:   

-- Scott KQ4AOP trying to track down the DeMaw SSB transceiver mystery.  On the DC Receiver: This was my first receiver build and, it was great fun. When you finish the build and prove you are able to tune through the band, you are welcomed into the secret society! The build is the initiation.I am happy to print and ship the PTO if needed. 

-- Bill WA5DSS has built a High School Direct Conversion Receiver! 

-- Grayson KJ7UM liked the 1971 video on old THERMATRON AM radios: https://soldersmoke.blogspot.com/2024/11/basic-radio-circuitry-1971-film.html

-- Chris KD4PBJ sent nice electronic care package. 

-- Walter KA4KXX is honored that Dean named his dog for him (Walter was just kidding) 

-- Thanks to Bob W8SX for FDIM 2024 interviews.

-- Tony G4WIF insomnia driving him to podcasts.  Amazed by quantity of food eaten on Thanksgiving. 

-- Nice comment from Trigger about the podcast.

-- Clint says "valves" when he means THERMATRONS.   Kindly asks about "Oooo Thats Awesome"

-- Eric 4Z1UG faced with a new challenge.  Get well soon OM.

-- Sam WN5C and his Chat GPT AI Elmer. 

-- Paul VK3HN on using AI for electronic design.  I dunno... Apocalypse Now in the DR?

-- Tommy SA2CLC FB old military gear on QRZ site. Helps with HP8640B repair. 

-- Mike WN2A nice comments on Chappy Happy's FB Tezukuri DC RX https://soldersmoke.blogspot.com/2024/11/tezukuri-and-chappy-happy-amazing.html 

-- Allison KB1GMX.  Good info on ground truth. 

-- Phil W1PJE Had to throw out 15 test leads.  Fake wire!  

--Todd K7TFC Thoughtful comments on AI and ChatGPT, Help with TinySA Ap 

-- Steve KW4H Boatanchor guy.  Likes that we often scratch our heads trying to understand. 

-- Nick M0NTV built a 40 meter DC receiver: https://soldersmoke.blogspot.com/2024/12/a-40-meter-direct-conversion-receiver.html

-- Dave AA0KU asks about CCI amp (AN762)  Also woking on Drakes. 

-- Jack (Dhaka Jack!) F4WEF/AI4SV  Good thoughts on how to bolster SolderSmoke's ratings.

--Tobias thinks the decline IS ALL HIS FAULT!   

-- Tony VE7JUL building a TJ DC RX.  Go Canada! Dean says: 3D print PTO former at 110%

-- Jim KI4THC getting his uBITX on the air. 

10S November 23, 2024 1517Z SV1AER Kostas in Athens.  Said a very sincere “Oh my goodness! Congratulations!  That is not a very common thing!” when I told him rig was homebrewed.  Nice fellow.  Great response. 

An Evening Bandscan on 40 Meters using the High-School Direct-Conversion Receiver

This video shows how useful this receiver really is.  Build one of these!

Mike WU2D's Video on the SimpleX Super Receiver -- Part II

 Another FB video from Mike WU2D.   

But you know,  I too find myself kind of opposed to front panel on-off switches.  I power my rigs with small DC supplies.  I just turn on the supply when I want to use one of the rigs.  I don't have or need a switch on the front panel of the rig.  

I especially liked Mike's use of the gate dip meter and, of course, the Q meter.  FB OM. 

I must say I have a preference for the first version, but only because I dislike the regenerative circuit in the second version.  I do like the newer-style coils -- I have one in the BFO of the Mate for the Mighty Midget receiver.   

Thanks Mike for the sideband inversion factoid in Part 1!   The Hallas Rule -- words to live by. 

One word of caution.  I used 6U8s on my Mate for the Mighty Midget receiver.  I had good results, but WA9WFA had a lot of trouble.  We eventually concluded that the 6U8s didn't age well.  And they were quite long in the tooth.  We found (from the tube guys) that 6EA8s aged better and were a good and easy sub for the venerable (perhaps TOO venerable) 6U8s.  I switched tubes in my rig and it did seem to work better.  BTW, this is the receiver that I use to listen to the Old Military Radio Net on Saturday mornings.  

Here is the story of our switch from 6U8s to 6EA8s: 

https://soldersmoke.blogspot.com/2022/02/6ea8s-in-mate-for-mighty-midget-and.html

Listening to 40 meters on the DC Receiver -- And I Heard a Distinguished Homebrewer!

I made the video above to show postential builders how useful our Direct Conversion receiver really is.  Late in the video (starting at 11:17), I heard a station calling CQ.  It was N4QR.  A check of QRZ.com shows it was Bob Null.  Here is picture from Bob's QRZ page: 

Check out the old general coverage receiver and -- wait for it -- the homebrew thermatron transmitter.  TRGHS. 

Google led me to this amazing video by Stever N4LQ that describes a book that N4QR put together on how to build thermatron transmitters from Junkbox/Hamfest parts: 

Steve N4LQ is in contact with Bob N4QR and asked him which transmitter he was using when I heard him.  Bob said he thinks it was his 30 watt 807 final transmitter. 

Thanks Bob. and thanks Steve!

"The Build Is the Initiation" -- KQ4AOP Offers Encouragement and a PTO Coil Form for Receiver Builders

Scott KQ4AOP put a comment on a recent SolderSmoke Blog post that I found especially encouraging and apprportiate. He was writing about his experience building the High School Direct Conversion receiver.  

Scott wrote:

"This was my first receiver build and, it was great fun. When you finish the build and prove you are able to tune through the band, you are welcomed into the secret society! The build is the initiation. I am happy to print and ship the PTO if needed." 

The 3d printed form for the tuning inductor is often a show-stopper for prospective builders.  Scott offers to print out a form for you, and send it to you. 

Scott's mailing address is on his QRZ page.  His e-mail address is: streez55@gmail.com

 Thanks Scott! 

Here is a post I did early this year on Scott's receiver: 

https://soldersmoke.blogspot.com/2024/02/scott-kq4aop-successfully-builds.html 

Here are the SolderSmoke Posts about this project  (keep scrolling -- there are 41 posts!):

https://soldersmoke.blogspot.com/search/label/TJ%20DC%20RX 

My Receiver Doesn't Work Right! What Should I Do?

An early version of our DC receiver.  Note the tuning guide under the grey tuning knob. 

We prepared this for use by the high school students who were building direct conversion receivers. Unfortunately none of them got to the point where they would use this little article, but given the fact that a number of people are now engaged in direct conversion receiver projects, I thought it would be a good idea to post this here. Also, much of this applies more generally to receiver problems. 

My receiver doesn’t work right!

What should I do?

First, relax.  You will be able to get it to work.  The design is good, people around the world have built this receiver, and you will be able to get it to work.  But homebrew radio is not plug-and-play radio.  Sometimes a new receiver needs some tweaking, peaking, and coaxing. 

Realize that the 40 meter band has its ups and downs.  The downs usually come at mid-day.  The sun’s position high in the sky causes a build up of the D layer of the ionosphere.  This tends to absorb radio waves. So signals are often weak at mid-day.  Signals will be much stronger in the morning, and in the evening.

Can you hear the “band noise” when you connect your antenna?   This sounds like hiss or static.  Some of this is the result of thunderstorms in Brazil.  Some of it is from events far away in the cosmos. Some of it comes from the weed whacker down the block!  But if you can hear this noise, that is a very good sign that your receiver is working.  The signals you are looking for will be stronger than this band noise.

Where are you tuning?  Your receiver tunes from about 6.8 MHz (with the screw all the way our) to about 7.8 MHz (screw all the way in).  But we are only really interested in the ham frequency band between 7.0 MHz and 7.3 MHz.  Try to tune your receiver near the middle of the tuning range (with the screw about half-way in).  You should hear morse code from about 7.0 to 7.06 MHz.  Then you should hear strong digital signals at 7.074 MHz.  Tuning further up (screw going in) you should start to hear hams speaking to each other using Single Sideband.   At first they will sound like Donald Duck.

 Don’t worry about the Donald Duck speech!  Just carefully tune through the signal until you hit the spot where the speech sounds normal.  You may have to tune up and down a bit until you find the right spot.  Now you can listen. 

 If you tune further up you will hear Shortwave Broadcast band AM signals.  You will be able to tune them in.  Sort of.  But they will sound distorted.  This is unavoidable with this kind of receiver.  But you will be able to hear the hams on Single Sideband with no distortion.

Sometimes you will only hear one side of the conversation.  That is normal.  The other station may be either too far away from you, or too close to you.  You may be outside his or her skip zone.

One very obvious thing to check:  How is your battery?  Is it drained, or is it still at about 9 volts?   You may need to change it.

How is your antenna?   It doesn’t have to be fancy or elaborate.   33 feet of wire will do.  But it does need to be up in the air a bit.  And you need to have the 33 foot counterpoise wire connected to the ground (on the PC board).  With many pieces of consumer electronics antennas are kind of optional – the devices will often work without them.  Not so with ham gear.  Antennas are important.  If you are not receiving signals,  it may be because of your antenna.

SimpleX Super Superhet Receiver -- A Great Video from Mike WU2D

Here is another great video (and project) from Mike WU2D.  I'm a big fan of homebrew superhets.  And wow, Mike presents a band-imaging superhet!  Two bands for (almost) the price of one!  I have FIVE homebrew dual-band band-imaging transceivers around me.  Believe me, once you have the experience needed to build an SSB transceiver, a dual-bander is the way to go.  Five bands seems like a bit too much.  But two seems to be at the sweet spot.  

I wrote to Mike reminding him to talk about the sideband inversion problem.  This rig will invert the 75 meter signals,  but this is easily resolved by just shifting the BFO frequency.  I also pointed out that many of today's builders will be detered by the need to scrounge for parts.  Where oh where is the BOM OM? 

Thanks Mike! 

Challenge Accepted! Why we Designed the High-School Direct-Conversion Receiver the Way we Did

Dean KK4DAS's Beautiful DC Receiver

The folks over at Ham Radio Workbench have graciously accepted the challenge issued in our last podcast: that they scratch-build homebrew the 40 meter Direct Conversion receiver that Dean KK4DAS and I designed for local high school students.  We want to help our brothers over at HRWB.  For example, we may be able to supply a few of the 3D printed PTO coil forms.  Here is some background information on the project. 

Details on the project can be found here: 

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

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

Design Decisions in the Direct Conversion Receiver

Why did we do it this way?

In thinking about how to design this receiver, we had to make early design decisions on almost every stage.  Here are some of our key considerations.

VARIABLE FREQUENCY OSCILLATOR:

Normally we might have used a variable capacitor to change the frequency of this oscillator.  But variable capacitors are now expensive and hard-to-source.  Our friend Farhan in Hyderabad used a simple variable inductor for this purpose in his “Daylight Again” transceiver. The coil form for this part could be 3D printed.  A metallic screw would vary the inductance as it is screwed in and out of the coil.  

We also decided to use the same simple Colpitts oscillator circuit used by Farhan in his own high school direct conversion receiver.  This circuit is unusual in that the feedback capacitors are also the frequency determining elements (along with the variable inductor).  This simplified the circuit and reduced the parts count, and proved to be remarkably stable.

For the VFO buffer we used the simple JFET buffer from Farhan’s Daylight Again design.  

Based on suggestions from other radio amateurs, we developed a simple frequency readout based on the position of the end of the tuning screw  (how far in or out?).

We selected the 40 Meter band for this receiver because we thought it would be easier to get the VFO stable on this frequency, and because Farhan had built his receiver for 40 meters.

MIXER:

At first we hoped to use a simple singly-balanced mixer using two diodes and a single trifilar transformer.   But we found unacceptably high levels of AM breakthrough (mostly from Radio Marti on 7335 kHz) when using this circuit.  So we switched to a diode ring.  This required two more diodes and an additional trifilar transformer.   We believed the students would have great difficulty building and installing two trifilar transformers so early in their building experience.  So we used transformers that had been wound in Hyderabad by a women’s collective employed by Farhan, and developed a scheme for fool-proof installation of these transformers.

We also found that the mixer needed a diplexer at its output – this would provide a 50 ohm termination at all frequencies and would result in much cleaner action by the mixer and greatly reduced AM breakthrough from Radio Marti.   We used the same circuit used by Roy Lewellen W7EL in his Optimized Transceiver circuit.

BANDPASS FILTER: 

This was the simplest board in the project but it required the students to wind two coils on toroidal cores.  A simple dual-tuned circuit design would be sufficient.  We used component values from the QRP Labs website.  We showed them how to wind the coils, and made a video about the technique.  Students used a simple Vector Network Analyzer (Nano VNA)  to tune the filter.

 

AUDIO AMPLIFIER: 

We had to make several design decisions here.  First, we rejected the idea of using an IC amplifier like the ubiquitous LM-386. We wanted this to be a completely analog and discrete component experience. Then we rejected the idea of using a push-pull output circuit.  While this would have eliminated the need for an audio output transformer, it would have resulted in a more complicated circuit.  In the end we opted for three simple RC-coupled common-emitter amplifiers with an audio output transformer.  There was no feedback in these circuits.  We found there is a lot of gain (hFe) variation in the 2N3904 transistors that we used.  Care needs to be exercised in making sure that transistors of moderate (but not too high) gain are used.  

This AF amplifier chain probably presented a 1500 ohm impedance to the mixer (instead of the desired 50 ohms), but we think this problem may have largely been taken care of by the diplexer.  

We found some very small (one square inch) speakers that could be easily used in this circuit.

ANTENNA:

While the students could use a wide variety of antennas, we recommended a simple ¼ wave antenna with a ¼ wave counterpoise.  We thought that this antenna – of only 33 feet in length would provide good performance with low complexity, and would be well suited to the “upper floor bedrooms” from  which many of the students would be listening.  Also, this antenna would not require the use of coaxial cable or an impedance matching transformer. We made a video on how to build and use this antenna. 

POWER SUPPLY:

We opted for the use of 9 volt batteries.  This proved to be a safer and wiser choice that limited the kind of mayhem that could occur should a variable voltage supply be used.

Details on the receiver can be found here: 

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

May 29, 2023

Pil Joo's Homebrew Superheterodyne Ham-Radio Receiver

It is just very cool to see someone build a superhet and get it to work.  For so many years amateurs were told that "homebrew receivers are too hard."  Even simple regens or direct conversion rigs were sometimes seen as beyond the abilities of amateurs.  But here we see another reminder of this not being true.  Even a superhet -- which is a lot more difficult than a direct conversion receiver -- can be homebrewed by an amateur builder.  Three cheers for Pil Joo! 

He wrote on the SolderSmoke Facebook page: 

I finished my first super het receiver. It's for the 40m band. It consists of: bandpass filter, tuned amp, diode ring mixer, wide band amp, crystal ladder filter, wide band amp, then SA602 + LM386 combo. I learned tons as i put all the components. First two amps are my design. The third amp is bga2866. The bandpass filter is what i posted a few days ago. I planned to make another one but with 2.5db insertion loss i thought it was good enough.

The result is actually quite good. I can hear everything a local kiwisdr can hear. Now, I have lots of ideas about how i can improve, but that will be another radio.

Pil Joo

A 40 Meter Direct Conversion Receiver from M0NTV -- With some SolderSmoke Comments

Nick's video appears above. 

First, let me say FB Nick.   It is nice to see you making use of the AGC amp designed by Wes and Bob,  using the board from Todd's Mostly DIY RF, using a mix of homebrew pads and Me-Squares  from Rex, and finally the Franklin Oscillator that we spent so much time talking about on SolderSmoke.  

But here are some comments:  

-- I still don't think you need that RF amplifier in front of the mixer. And I suspect you would be better off without it.  We did not use one in our high school 40 meter project, and never missed it.  In fact, on one version of the high school receiver I even put in a simple 10k pot as an attenuator (no RF amp).  Even up on 20 meters, I do not have an RF amplifier ahead of the diode ring mixer on either of the Mythbuster rigs I have built.  Nick,  maybe experiment a bit more and try the receiver just going from the BP filter into the mixer and see what happens.  

Note that Wes W7ZOI DID NOT have an REF amp ahead of the diode ring mixer in his original 1968 40 meter Direct Conversion receiver (the one that launched the solid-state DC recevier revolution): 

-- The Franklin oscillator is an interesting, but complicated circuit.  The gimmick is, well, gimmicky.  Here is the thing:  You can achieve similar levels of stability using simple conventional, single transistor oscillators.  We dispensed with the variable capacitors, and used PTO--style variable inductors. They worked fine.  This Franklin oscillator still does seem to drift a bit, right?   I would ground the board to the inside of the metal box.    

I would also try putting all the stages on a single ground plane.  This might help.  

Charlie "Red" NJ7V Builds an Oscillator -- Manhattan Style

https://www.youtube.com/shorts/7t_E5N4CQxg

Red did a nice job building, then explaining, this 18 MHz crystal oscillator.   I especially liked his use of Manhattan techniques, and the way he explained his effort to make the new circuit work.  Too often builders expect a circuit to work right away.   This often doesn't happen, and the new circuit requires some troubleshooting.  Red did this with this circuit and got it working.  

Red has a nice YouTube channel: https://www.youtube.com/@RedSummitRF.  It is focused on POTA, but we hope it has more and more homebrew stuff like this.  

Thanks to Rogier PA1ZZ for sending me this. 

The Importance to Bell Labs of Lunch or Breakfast with Harry Nyquist -- "The Communicator" -- Bimonthly Publication of the Surrey (British Columbia) ARC.

This is a good sample (!) of the great content to be found in "The Communicator." This is the bimonthly publication of the Surrey (British Columbia) Amateur Radio Club.  You can find the publication and digital back issues here: https://ve7sar.blogspot.com/ 

There is a lot of great material in this publication. 

Pete N6QW Has Hybrid Rig On-The-Air

 

A thing of beauty on a wooden board.  Pete's post: 

https://n6qw.blogspot.com/2024/11/11252024-1st-dx-with-40m-hybrid-rig.html

"Them that know can make it go!"  Indeed.  

Pete talked about the history of this rig, and especially of the Thermatron portion of it, in the most recent episode of the SolderSmoke podcast: 

https://soldersmoke.blogspot.com/2024/11/soldersmoke-254-audi-and-video-versions.html

Thanks Pete! 

Oscar 7... and Oscar 11 (aka UoSat-2)? Did Oscar 11 do much the same thing as Oscar 7?

Above is a pretty good video by Retro Rockets.  Some will quibble about the technical details presented, especially about early radio, but I think the video does a pretty good job of describing the early production of ham radio satellites.  

As I watched this video however, I started to wonder if OSCAR 7 was in fact unique in coming back from the dead.  Back in 2018, I watched signals from OSCAR 11 (aka UoSat -2) as it tumbled through space with its battery dead, powered by a direct connection to its solar  panels: 

https://soldersmoke.blogspot.com/2018/12/ghost-ship-oscar-11-tumbles-through.html  

This was what Retro Rocket said was Oscar 7's claim to fame, right?  

In both cases, what happened was pretty cool, but did OSCAR 11 sort of repeat the supposedly miraculous rebirth of OSCAR 7?   

Sam WN5C uses ChatGPT as an Emergency Elmer

Sam WN5C has been on the blog before.  Last year we covered his heroic use of a Michigan Mighty Mite at Thunderbird State Park:  https://soldersmoke.blogspot.com/2023/06/sam-wn5c-builds-michigan-mighty-mite.html

This time, Sam writes about a good  ham radio use for ChatGPT: 

Hope you’re doing well. Just a quick note: ChatGPT is turning out to be a great homebrewing tool for me.

My elmer has been swamped with family issues, so my basic questions (“can you explain this circuit for me”) and hard questions (“why doesn’t this circuit I built work?!”) that he usually responds to right away has been a bit delayed. I’m in the process of designing a 5-band QRP CW transceiver with a superhet receiver and SSB receive so I’m learning a bunch of new circuits.

 

I’ve hated the idea of AI as someone who writes a lot (it cheapens what I’ve spent my career trying to perfect!), but man it is smart. I can ask it all kinds of questions. For example, it helped me design a little IF amp last night and ensured I got my impedance matching right (it’s great for mashing up lots of circuits and ensuring they work together). I can ask it for suggestions on part types and values. It helps with Arduino code if you’re into that. You can use plain language but it does well with heavy jargon. And, which I find really cool, it will step you through troubleshooting. It teaches the math, too.

 

Anyway, you or your readers might find this helpful. Especially when one is building at 3 AM and needs an answer immediately.

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

Thanks Sam! 

 

Tezukuri and Chappy Happy -- Amazing Videos on Homebrew Radio (from Japan?) - Another 40 Meter Direct Conversion Receiver

So around the time we were building 40 meter direct conversion receivers, someone else was doing something similar.  His product (above) is a lot nicer than ours.  He has an S-meter and a digital frequency readout.  But like ours, his is built on a wooden board.  FB OM.  

If you want to see what a direct conversion receiver can do, watch his video (above). 

I was really amazed to see him use a modified VFO from a Kenwood TS-820.  Not long ago Pete N6QW spotted one of these on e-bay and recommended that I buy it.  As with the Yaesu FT-101 VFOs, we bought it for the gears and reduction drives but ended up with the entire VFO circuit.  I now have one on my shelf, ready to go.  TRGHS. 

We are not sure who Chappy Happy is, but "Tezukuri" means "hand-made" in Japanese. The writing in the video descriptions are in Japanese, then Chinese. 

Here is the YouTube channel.  Amazing stuff here:  https://www.youtube.com/@chappyhappy3675  He is clearly a ham.  He even works on an old S-38.  Who is this guy? 

Basic Radio Circuitry -- a 1971 film

This 1971 training film is pretty good.  I like how they break the RF circuitry into just four components, then describe the AM receiver stage by stage.  The way they handle diode (envelope) detection is exactly right.  But their description of how mixing moves the incoming signal from the broadcast band to the IF is overly simple, and sort of just repeats the hetrodyne story from music. Real mixing is, of course, more complicated than that, but too complicated for a 15 minute film. 

Bill N2CQR Appears as a Guest on the Ham Radio Workbench Podcast

https://www.hamradioworkbench.com/podcast/hrwb-223-a-conversation-with-bill-meara-n2cqr-from-the-soldersmoke-podcast 

Partly in an effort to make ammends for some overly harsh comments I made about the podcast's approach to the "rejuvenation" of old radios (it turned out to be overly digital for me) I appeared earlier this month on the Ham Radio Workbench podcast.  It was a lot of fun. They are a great  bunch of guys.  And I think we had a great discussion of homebrewing and HDR in the modern era. We talked about Jean Shepherd, Farhan, G-QRP, kits vs. homebrew, homebrew vs. commercial, SDR rigs, the sBITX, the NORCAL 40, the Gilbert Cell Mixer, our experience (bad) trying to get high school kids to build a DC receiver, and many other topics. 

Thanks George!  And thanks to the entire Ham Radio Workbench crew!

Remember, SolderSmoke has issued a challenge to the HRWB team:  We challenge them to build the 40 meter Direct Conversion receiver that we designed for our local high school.  We urged them to build it the way we designed it -- avoid the temptation to substitute stages, or use pre-fab circuit boards.  Build the four stages Manhattan style and get the receiver working on 40.  Here are the details on how we did it.  Here are our building documents:

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

The challenge has been issued.  The gauntlet is on the ground.  Go for it HRWB!  Put those workbenches to use! 

Video -- Mythbuster II Rig Gets a Front Panel -- Circuit Build Almost Done

Yesterday I built a front panel for my Mythbuster II 20 meter SSB transceiver. 

I used 1/8 inch plywood available from Amazon. 

I cut holes for the main tuning knob and dial, for the AF gain control, for the mic plug and for a 6 figure PLJ PIC frequency counter.   This gives me 100 Hz read capability, but I can hit the lower button on the counter to get 10 Hz reolution.  This may help when the other guy complains bitterly that I am 40 Hz off frequency.  The counter added noise to the receiver, but I was able to knock this down completely with a resistor and a cap on the power line to the counter. 

I put copper tape on the inside of the panel. 

I added a reverse polarity protection circuit.  I now sleep more soundly. 

I increased the size of the heat sink on my RD06 final.  This decrease the danger of blowing up this device. 

I added a jack for the connector that will switch the outboard .1 kW linear from R to T.  

Video above. Comments welcome.  

 

FDIM 2024 Interview with Farhan VU2ESE

Thanks to Bob Crane W8SX we have some great interviews with those who made presentations at the Four Days in May event (FDIM 2024).  Sorry for the long delay -- it is all my fault, but I have excuses.  Our thanks to Bob W8SX, our correspondent at the FDIM event.  

Here is the interview with our friend Farhan, VU2ESE, the ham who has brought so much homebrew goodness to the hobby, starting years ago with the BITX 20 schematic. 

http://soldersmoke.com/FarhanVU2ESE.mp3

Thanks Bob!  Thanks Farhan! 

SolderSmoke #254 (Audio and Video Versions): Australian Hex Beam Eaters, Fake Wires, Hybrid Rig, Antennas, Mythbuster II Transceiver, Mailbag

Hex Beam Eater

November 13, 2024

SolderSmoke Podcast #254 is available: 

Audio Version here:  http://soldersmoke.com/soldersmoke254.mp3

Video Version here:  https://www.youtube.com/watch?v=ZiZwWY1CQgI

Opening:  Disturbing news from Australia!  VK5RS reports that his Hex beam was EATEN by Cockatoos!  So stop whining about your HOA problems, OK?  It could be much worse! 

FAKE WIRES FROM CHINA!  Oh no!  Even the wires?  There is a good video from Mattias.  I have it on the SolderSmoke blog.  https://soldersmoke.blogspot.com/2024/11/clip-leads-made-with-fake-wire-buy-good.html  Important to note that Parts Candy doen't have this problem.  Buy your test clip leads from our sponsor, Parts Candy.  Link in the column on the right or go to partscandy (that's one word).com

Bill's appearance on the Ham Radio Workbench.  (Bill made some overly harsh comments about radio rejuvenation, and was trying to make amends.)  But now we throw down the gauntlet.  WE CHALLENGE the HRWB guys to build -- to homebrew - our TJ DC RX.  They will experience JOO, JVO and the elite status that comes with having built their own ham radio receiver.  And if they go on to build a 10 minute transmitter, they can use it for CW contacts.  Like on POTA (Thomas!) 

Anniversary approaching:  In August 2025 we will mark 20 years of the SolderSmoke podcast.  And we have already passed TEN YEARS OF JULIANISMO!  Pete joined the podcast on May 26, 2013.  Thanks Pete! 

Question for the group:   Which SSB transceivers did Doug DeMaw build?  

Pete's Bench:  Thermatron-Transistor Hybrid Goodness.  https://n6qw.blogspot.com/2024/10/blog-post_20.html

Dean's Bench:  The new Hex Beam (watch out for Cockatoos!)  Now that Dean and I both have Hex Beams, we plan on pointing them at Southern California in an effort to talk to an elusive RADIO GENIUS. Stay tuned! 

Dean's Hex Beam -- A Thing of Beauty

Also homebrew random wire with T match tuner for attic.  RF Burns!  

SHAMELESS COMMERCE:   Please link to our blog and podcast!   Please become a Patreon supporter (I have been posting special content there).  Be sure to make use of the great boards, parts and kits available at Mostly DIY RF.   Still use the Amazon link on the SolderSmoke blog page. 

Bill's Bench: The new Mythbuster II (20 meters only).  Built in about 3 weeks. On-the-air, while still on the bench!  Worked Euope and South Africa QRP.   https://www.youtube.com/watch?v=6o9QerQ7jzg

Getting another CCI amp for the Dominican Republic. 

MAILBAG: 

-- Paul VK3HN,  talks about the nice sound of the Mythbuster II's receiver, and a new QRP rig from Dave Benson K1SWL. 

-- Rick N3FJZ sent some very kind words in support of the SolderSmoke podcast. Thanks Rick. 

-- Chris KD4PBJ sent us a very nice message.  Thanks Chris. 

-- Kevin from Belgium sent a nice blog post in support of SolderSmoke. 

-- John WB4BTL spotted his old call (from 1974) in my Novice Log.  

-- Dave KD2E spotted his Novice call in  my Novice log:  WN2TBB. He also  saw a good friend WN2EHE. 

-- Mehmet who has the awesome and useful WEBSDR of NA5B helped me with a Facebook problem.  Thanks Mehmet! 

-- Mike WN2A asked about the Yaesu FT-101 9 MHz VFOs. 

-- Phil W1PJE (from MIT!) writes about old broadcast radio shows. And some really nice words of encouragement. 

-- Grayson KJ7UM sent kind words of encouragement, and great background on hybrid rigs. 

-- Peter VK3TPM writes about the decline of blogging, but notes that blogs are useful repositories. 

-- Todd K7TFC sent me some additional Mostly DIY RF boards.  Thanks Todd! 

-- Ed DD5LP/G8GLM  Kind words on SolderSmoke, nice info on the G-QRP 50th edition. 

-- Bill AH6FC  Encouraging words and good info on solar.  Mahalo Bill!  

-- Michael AG5VG Building LC VFOs for 7 MHz.  FB OM!

-- Bob K7ZB An EE who likes the treatment of mixers in the SolderSmoke book.  

Two Satellites Spotted Pre-Dawn

 

I was out with Guapo the dog at 5:28 am EST on November 12, 2024.  I looked up and first saw one satellite moving from South to North.  Then another moving in the opposite direction.  Heavens Above provided details --see above.  

Clip Leads Made with FAKE WIRE! Buy Good Ones from PARTS CANDY!

We don't see many videos about clip leads,  but this one fits in well with our esoteric subject matter. 

Carlos of Parts Candy (our sponsor) responds: 

Interesting video. Yes the clips we make are nickel plated steel but the wire is tinned copper. When I was making custom orders I made some custom clip lead sets using 100% copper clips for a few people who really needed the low resistance. In most applications the steel clips should be fine. The resistance for 12” clips is about 12mOhms and the 32” clips are around 24mOhms, iirc.

The bottom lines:  1)  Don't scrimp with a crimp -- get a good solid soldered clip-wire connection from Parts Candy. 2) Parts Candy wires are not fake.  They are tinned copper 3) The metallic composition of Parts Candy clips does not degrade performance. 4) But if a customer really needs copper clips, Carlos can make them too. 

Parts Candy web site:  https://www.partscandy.com/

Video Update on the Mythbuster II 20 meter SSB Transceiver

I have added the transmit circuitry. I described building practices. We listen to the receiver again. I talk about plans for transmit/receive switching. After this I will build another CCI 100 watt RF amplifier for use in the Dominican Republic.

For the first look at this rig see:

https://soldersmoke.blogspot.com/2024/10/bill-n2cqr-builds-yet-another.html

 We will discuss this further in an upcoming Ham Radio Workbench Podcast, and in SolderSmoke Podcast #254 (mid-November 2024) 

Using a Photomultiplier THERMATRON to Detect Single Photons

I've been a fan of Jeroen's YouTube channel for a while now.  He has a very nice approach, combining theoretical knowlege with practical experiments and equipment builds.  Here we see him using a photomultiplier tube and a board acquired in flea market to build his photon detector.  

This video has a lot to offer us.  First, there is a single thermatron.  There is a tube socket.  There is a (really small!) high-voltage power supply.  He uses an oscilloscope. There is a laser.  There are photons.  And at one point, a single photon.  

Having recently built a simple Wilson Cloud Chamber, my attraction to this device is easy to explain.  I suspect our friend Grayson will be interested in it for Thermatronic reasons.   There is a Part II.   Check out the YouTube channel: 

https://www.youtube.com/@HuygensOptics  

Here is more info on the channel and it's creator: 

Hi, my name is Jeroen and on the Huygens Optics channel I publish videos on personal projects. My main fields of interest are optics, mechanics and photolithography. The videos aren't targeted towards a general audience but for people with a passion for science and technology (e.g. my fellow nerds). The channel is named after the famous Dutch mathematician, astronomer and inventor Christiaan Huygens (1629-1695). He was the first to publish a mathematical description of the wave properties of light, and also discovered Saturn's rings.

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

Thanks Jeroen

On the Election

This time around, in an effort to keep this blog focused on radio and electronics, I have decided to move my election recommendations to my other blog site.  So check it out there: 

https://tahplu.blogspot.com/2024/11/election-2024-vote-against-trump.html

More Background on the Mythbuster II Rig (and a short video)

Above is a short clip of me hearing an old friend on the new receiver.  TRGHS. 

A couple of guys on Facebook asked for a schematic for this rig.  I don't really have one -- as you will see it is a collection of different circuits from lots of different sources.  I was also thinking that if you need a schematic for a rig like this, you probably shouldn't try to build a rig like this.  But in an effort to be nice, I supply here some background info on some of the circuitry and parts sources.  And no, I don't have BOMs nor Gerber files.   

More info on the Yaesu VFO is here:

https://soldersmoke.blogspot.com/2021/07/mythbuster-video-3-using-vfo-from-yaesu.html

The VFO is kind of high in frequency. But it is very stable. I can't really take credit for this -- the credit goes to Yaesu. But I like the circuit because it is all analog and all discrete component. It even has a split stator temperature compensation variable cap! At Pete's recommendation, I originally bought these boxes thinking that I'd just get the anti-backlash gears and the reduction drives. But the sellers always sent the entire VFO boxes. They even come with a "clarifier" circuit which I now use as an "up 5-10" feature that lets me work the DX-peditions on 20.

As for the tape, I got mine from Amazon. It has conductive adhesive:
https://www.amazon.com/gp/product/B07QQJ4MX1/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

The boards for the IF Termination Insensitive Amplifiers come from Todd K7 TFC at Mostly DIY RF:  https://mostlydiyrf.com/tia/

The little LM386 boards that I have been using are available here: https://www.amazon.com/dp/B00LNACGTY?ref=ppx_yo2ov_dt_b_fed_asin_title  I precede it with one stage of AF amplification from the original BITX 20 sechematic.  I put a 10K pot between this stage and the LM386 board. 

Here is the Amazon source for the 1/8 inch plywood that I will use for the case (I have used up all the pandemic treadmill packing material):  

https://www.amazon.com/dp/B0D5VCBBP4?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1