CuriousMarc Looks at Phase-Locked Loops (PLL)

I really like Marc's (AL6JV) videos. It is great fun and very educational to watch him and his team troubleshoot some of the old gear they work on.  There is also a lot of humor. 

In this video Marc delves into the circuitry of the Phase-Locked Loop.  I didn't know that the PLL circuitry has its origins in the space program.  NASA needed a circuit that would permit very narrow band reception of a signal that was undergoing the kind of Doppler shift that spacecraft produce.   Viola! Enter the PLL.  Far beyond Apollo, PLL circuits started to show up in ordinary radio gear.  The General Electric (and JC Penny!) CB transceivers that we rescued from 11 meter infamy used PLL as the frequency determining circuit. 

Marc gives a really good explanation of how the PLL circuit works.  Thanks Marc. 

However, Marc gives an incorrect pronuniation of "kludge" (it should sound like fudge).  But he is a computer guy and is originally from France, so all is forgiven.  He also redeems himself by making fun of the inaccuracies that appear in what he calls "data shites." 

A NETFLIX Series with Boatanchors and Direction-Finding -- All the Light We Cannot See

Looks good.  November 2, 2023. 

Spy Rigs, Para Sets, Bugs, and Enigma Machines -- Dr. Tom Perera W1TP (video)

This is a really amazing presentation by Tom Perera W1TP to the Fairlawn (NJ) Amateur Radio Club. 

There is so much great info in this presentation.  Some of the highlights for me: 

-- The U.S. Civil War telegraphic (wired) spy set was just mind blowing.  I had never heard of this.  

-- The way the Nazis transmitted a signal 1 kc off the BBC frequency, so that Germans who tuned their Nazi-issued receivers to the BBC could be detected by neighbors (from the resulting 1 kc tone!) and turned in to the Gestapo.  

-- "Things don't land gently when dropped by parachute." Indeed.  This was a reminder of the courage of the young women who parachuted into Nazi-held territory during WWII.  Like Paulette.  It was great to see her with her Paratrooper wings on.  AIRBORNE!  And the picture of the operator with the bicycle generator was of Virginia Hall.  See: https://www.npr.org/2019/04/18/711356336/a-woman-of-no-importance-finally-gets-her-due  That portrait hangs in the hallway of the National War College. 

-- How they put the schematic of the PRC-5 right into the box.  Great idea.  But it had a terrible receiver.  One of the schematics showed a 455 kc IF and a BFO.  So they sent in superhets, not just regens. 

N2CQR operating the Para Set of G3ROO around 2009

This video makes me want to build a Para Set. 

Thanks a lot to Tom W1TP and the Fairlawn ARC. 

F6CRP's FB Homebrew Receiver

I like F6CRP's homebrew receiver.  I like the way he presents it (block by block) and I like the inclusion of the W7ZOI IF board. The JF3HZB VFO is quite cool (even though it is digital),   We have posted about this VFO several times: 

 https://soldersmoke.blogspot.com/2022/05/who-is-jf3hzb-creator-of-that-nice.html

Denis has a very nice station and workbench: https://www.qrz.com/db/F6CRP

He also has some very nice videos on his YouTube channel: 

https://www.youtube.com/@radiorider8249/featured

Thanks Denis! 

Antoine's Home Lab in Paris

Another very interestng lab brought to us by CuriousMarc.  

 

Dhaka Jack Moves to France

Jack Welch AI4SV has been an important member of the SolderSmoke community for many years.  I remember fondly our Straight Key Night CW contact in which he told me that my HT-37 had "presence" even on CW.  His thoughtful (!) piece on time crystals was also quite memorable.  Jack has finally settled down (a bit) after a string of foreign assignments.  He has landed happily in France, in a villa, on a vineyard, surrounded by wild boar and hunters.  FB OM. 

Hi Bill & Pete,

I've packed up the shack and moved from Cyprus to France, so no more 5B4APL. To obtain a French callsign, you have to submit proof that you've lived in France for three months, so I'm F/AI4SV until December and then we'll see. 

I'm not sure how long we will be here, but probably a few years at least. Since we know next to nothing about French real estate, we are renting for the first couple years -- a château on the outskirts of Bordeaux. Before you think that I've come down with delusions of grandeur, I should point out that in that area, château means an old, stone house that is hard to heat in the winter -- and particularly difficult to run wiring around. Antennas and grounding are going to be particularly challenging. The selling point for the house was not so much my hobby as its location in wine country. In fact, there is a Sauterne my house's name on it (although I have nothing to do with production of the wine, that's in professional hands).

Back in the early days of Soldersmoke, Bill used to occasionally mention the dreaded Italian wild boar, the cinghiale. I didn't think that would ever be terribly relevant to me, but it is. A couple days after arriving in the Bordeaux suburbs, a sanglier (French cousin of the cinghiale) strolled across a road as I came around a bend. We almost had a month-long supply of bacon, but I managed to steer around him.

Since it will be a while before all our belongings arrive and even longer to set up a proper station, I have focused on operating QRP in the field and activating SOTA summits. That has gone well, but I aborted my most recent attempt when I ran into a bunch of orange-clad rifle-toting hunters who were combing the mountain in search of sanglier. Apparently it's a big thing here. I decided to survive to activate the peak on another day.

Finally, I have attached a journal article, which at first glance doesn't seem to have a lot to do with radio, but kind of does. It turns out that both the human ear and violins have non-linear characteristics that cause them to function as audio frequency mixers. Looking through the article, you'll find some familiar looking formulas about mixing products, harmonics and resonance. If Bill wants to get away from ICs, perhaps his next rig could include a 17th Century Italian violin as a mixing stage.

Cheers & 73,

Jack
F/AI4SV

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

Hello Jack:  

Great to hear from you.  Wow, France!  You are rivaling my string of nice-to-go assignments.  FB OM.  Have fun.  

Yes, the Cingales.   Hunting season was always a bit of an uneasy time.  We used to dress the kids up in reflective vests.   One time we found a very drunk Italian hunter wandering around with a shotgun (that was kind of scary).  We would know when hunting season started by the sound of gunfire in the morning.    Kind of reminded me of other places!  

In retirement I have gotten back into VWS.  We are having a lot of fun.  Just yesterday 30 students at the Thomas Jefferson High School got their Technician licenses. They will soon build Direct Conversion receivers. 

As for mixing, what you sent reminded me of my early confusion on this subject.  In the SS book I describe the "Terzo Suono"  -- it is really just an additive heterodyne.  I confused it 

with a true mixing product.  But it was an educational confusion. 

Please keep in touch and let us know how things are going at the Villa!  

73  Bill 

A Double Sideband Transmitter from France -- F4IET's "Master Robert"

The Radio Gods seem to be steering us toward Double Sideband.  A few days ago I got an e-mail from Alain F4IET.   We had him on the SolderSmoke blog two years ago, talking about his French backyard pandemic Field Day.  His recent e-mail reminded me of his very fine homebrew DSB transmitter, which is his only rig and with which he has worked the world. 

The rig is named for the fellow -- Robert F6EUZ -- who is Alain's teacher from the local radio club. 

Alain's rig was shown to the world in the G-QRP club's Winter 2020 issue of SPRAT (SPRAT 185).  Once again, let me note:  If you are not subscribing to SPRAT, you are just WRONG.  Join G-QRP and start receiving SPRAT:  http://www.gqrp.com/join.htm

Alain gives some nice shout-outs to Pete N6QW,  Charlie ZL2CTM, and Basanta VU2NIL, all of whom provided advice and counsel on this project.  So think about it:  the Master Robert rig was built in France under the guidance of a French Elmer, with advice from hams in the U.S., New Zealand, and India, and was featured in journal of the British QRP club.  That, my friends is the International Brotherhood at its best. 

As I read about Alain's rig, I found myself thinking about the Direct Conversion receiver projects underway around the world.   The Vienna Wireless Society's Maker Group, is, for example, building a simple DC receiver.   It would be relatively easy to pair up a rig like the Master Robert with a DC receiver (the VFO could be the only stage common to both transmit and receive) to make a simple phone transceiver.  That kind of rig was my first phone transceiver.  Alain reports that he is currently working on a second version of the Master Robert.  It will be a transmitter-receiver (TRX) and will be used in SOTA operations. 

Alain's description of his transmitter is a lot of fun: http://www.f4iet.fr/mdwiki/#!master_robert.md

I especially liked his comment about how the other phone stations never knew he was on DSB: http://www.f4iet.fr/mdwiki/#!dsb.md I had similar experiences out in the Azores with my DSB rigs.  

Here is Alain's main page: http://www.f4iet.fr/mdwiki/#!index.md

Alain's QRZ.com page:  https://www.qrz.com/db/F4IET

Here is the Master Robert schematic from GQRP: http://www.gqrp.com/Maestro_Robert_Cct.pdf

 

Here is a link to the 76 DSB posts on the SolderSmoke blog (keep scrolling down!): 

https://soldersmoke.blogspot.com/search/label/DSB

A Nice Christmas Gift Out of French Guiana -- The Launch of the James Webb Space Telescope

 

A nice Christmas present from NASA and ESA on the screen early on Christmas morning.  

Track Webb Telescope's progress here: 

https://www.jwst.nasa.gov/content/webbLaunch/whereIsWebb.html

Video: E. Howard Armstrong and Early Radio

This is a really wonderful video. It might seem slow to those accustomed to faster-paced YouTube videos, but the information content is very high -- it contains a lot of pictures I hadn't seen before and audio of Howard Armstrong.  

I never knew that the name of the radio company Zenith was derived from the early callsign "9ZN." 

As a Northern Virginian, I like the reference to NAA Arlington.  

I used to live near Yonkers, N.Y.  I remember Warburton Ave.  What a fine shack young Howard had up in that cupola attic.  

The photo of Armstrong's breadboard was very nice.  My Mythbuster is in good company.

QRPers will get a kick out of the newspaper headline "New Radio Marvel Revealed!"  (They cut the power out from 20kW to 5 watts!) 

Thanks again to Dave Bamford W2DAB for sending me the book about Armstrong, "Man of High Fidelity" by Lawrence Lessing.  

Finally, I remember talking to Bruce Kelley W2ICE at hamfests.   He was a great radio amateur: 

https://www.qcwa.org/w2ice-01351-sk.htm

http://www.arrl.org/w1aw-bulletins-archive/ARLX020/1997

Be sure to check out the Antique Wireless Museum's YouTube Channel.  Lots of good stuff there: 

https://www.youtube.com/channel/UCX55peBhzeX1qps_VYXdLBA

We have the famous photo of Major Armstrong,

 but this is the first one I've seen of a slightly younger Captain E. Howard Armstrong. 

Parasets, Parachutes, and Tubes in "A French Village" Season 3

https://en.wikipedia.org/wiki/Un_village_fran%C3%A7ais

In season 3, Episodes 7 and 8, resistance members parachute in from London.  They are equipped with what looks a lot like a paraset.  One of their tubes develops an open filament.  The Germans engage in radio direction finding.  The Morse code is fairly good (but not great).  All in all, there is quite a bit of radio-related material. 

"A French Village" is a very well-done series.  But it is (of course) quite dark. 

A Parachute that Flies Home Autonomously

 

Too often ham radio bloggers and podcasters tend to focus their efforts on the projects of, well, older guys like us.  I think it is a good idea to direct attention toward young innovators, the next generations of people who are working on interesting new projects using new technology.  

Yohan Hadji is definitely one of these young innovators.  He is 16 years-old and is working to develop a system that would guide the parachutes of descending balloon payloads to designated safe landing areas.  Having spent a lot of time chasing the parachutes of Estes rockets, and after having to PERSONALLY guide my own parachute to a safe landing area (sometimes without success),  Yohan's project caught my attention.  

The videos above describe the project.  

A Hack-A-Day article provides good background: 

https://hackaday.com/2021/01/07/gps-guided-parachutes-for-high-altitude-balloons/#more-454705

And finally, if you want to support Yohan's work, he has a GoFundMe site: 

https://gofund.me/c0ae8d1f

Marc Verdiell Has The Knack

Here is Marc Verdiell, the "Curious Marc" who repaired the Soyuz Clock (shown in yesterday's blog post).  

Really cool.  Many SolderSmoke fans will completely understand Marc and his passion for 
electronics. 

A Backyard Pandemic Field Day in France (Smoke Released!)

Thank you Alain! 

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

Hello Pete and Bill,

As you know I am a great fan of your blogs. The fields days are not usual here but because our both countries have been hard hit by the Covid I felt good to participate in this kind of (solo) activity.

My wife Patricia shot 2 pictures for you.

I did some QSO with my callsign followed by FD, but in my enthusiasm I pushed a bit the pressure on my small TX and the PA Mosfet went promptly to the sky...

As you will see, even my dog Guerlain (no callsign) participated...

Hope that you enjoyed a great FD.

Take care my friends.

73 Alain F4IET

DIY Waterfall -- A Quick and Easy Panadaptor Using a Sig Gen and O'scope (video)

I've been getting waterfall envy.  The panoramic frequency display is the one thing that could lure me to the dark side (SDR).   Heck, they now have 3D waterfalls!  What next?  Holographic waterfalls? Virtual reality waterfalls?  This is almost too much. 

Anyway, in an effort to counteract all of this waterfall seduction and to show that us analog HDR guys can go panoramic too, I decided to try to create my own panoramic display without resort to SDR.  

Of course, this is a very old technique.  It was invented in the 1930s by Marcel Wallace, F3HM.  He was the inventor of the Panadaptor which was the forerunner of today's waterfall.  Panoramic reception was used by the armed forces during WWII.  In 1946 Hallicrafters marketed a Panadaptor for its ham radio receivers (see below). 

In figuring out how to do this, I thought back to my use of my Feeltech signal generator to scan the response of a crystal filter.  The Feeltech has a very handy sweep feature.  

In this case I set up the Feeltech to sweep from 4.85 MHz to 4.75 MHz in one second.   With the 12 MHz IF of the BITX40 module, this would result in a sweep from 7.150 to 7.250 MHz. 

The sweeping Feeltech just replaced the VFO on my BITX.   I hooked up the Rigol oscilloscope to the audio output of the BITX.  I set the horizontal scan rate at 100 ms per cm.  This would have the trace go across the whole screen in 1.2 seconds. 

After a bit of fiddling, I could see signals on the 40 meter phone band.  But my display would kind of drift along the screen making it hard to know the frequency of the signals I was seeing. 

Alan Wolke W2AEW provided the solution.   He advised me to put a big stable signal at 7.150 MHz near the input of the BITX, then use this strong signal to trigger the 'scope scan.  The HP8640B signal generator that Steve Silverman gave me (and that Dave W2DAB picked up for me in NYC) provided the triggering signal.  

I put a piece of tape across the bottom of the scope display to calibrate the display.  See video above. 

It works!   It is not as cool as the SDR waterfalls, and it does not convey nearly as much information, but it was a fun project. 

More here: https://en.wikipedia.org/wiki/Radio_spectrum_scope

http://www.astrosurf.com/luxorion/qsl-ham-history7.htm

"Want one!" F6DMQ's Remote Rig

I talked to Yves F6DMQ last night on 20 meters.  I was on my all-analog BITX20.   Yves was up in Toulouse, operating his station near Cannes via this EXTREMELY COOL remote rig.   He connects to the home station via 4G.   Check out the rest of his station here: 

https://www.qrz.com/db/F6DMQ

HNY (Happy New Year), SKN (Straight Key Night) 2019, and an HT-37 with "presence" -- even on CW

I got the HT-37 working just a few days before the New Year's Eve/New Year's Day Straight Key Night event.  Looking at my older blog posts, I now see that the problems first surfaced in LAST YEAR's SKN.  Wow, it took me a long time to get to that problem. But I'm glad I fixed it in time for SKN.  

For SKN I used the VU3XVR straight key from India that Farhan gave to me.   See the picture above.  

I started out on 80 meters on New Year's eve.  I rarely operate on that band -- I thought it would be a good change of pace. Here is who I contacted on 80 CW: 

In the warm-up period before the official start of SKN I worked John KU4AF.  John was running a homebrew tube transmitter and a REGEN receiver.  Respect, my friends.  RESPECT! 

N9EP Ed near Chicago was on a K3. 

VE9XX Don was on a KX3. 

NJ8D Tom in Ohio. 

K4IA, Buck, down the road in Fredricksburg Va.  Buck was running a Drake TR4C with a Begali key.  FB Buck.  He mentioned that he had had a Drake 2B -- he said he regrets selling it.  Indeed. 

VE9WW Bill in Moncton NB.  On a straight key. 

AA8MI Gene (gosh, that name really sings in CW -- try it!) in Ohio.  Gene was running 5 watts from a K3.  This added a needed QRP element to the festivities.  Thanks Gene. 

AI4SV Jack in Rockville Md. OH MY GOD!   NOW I REALIZE WHO THIS WAS!  Jack!  Jack of Antanarivo Madagsascar!  And now I understand what he said to me.  He said in CW that my HT-37 has "Lots of presence." Huh?  What?  I couldn't figure out what he was talking about, but now I realize that he was joking about all our discussions mocking the poor audiophiles.  Well, thanks Jack. I'm glad the rig has presence, EVEN ON CW!  THIS QSO GETS MY VOTE FOR BEST SKN QSO. 

I also listened for a while to W3GMS.  His signal had a lot of character and personality.  He was telling the other fellow that he suspected this was the result of a soft voltage regulator tube in his DX-60.  I think he was also using a Drake 2-B.  I didn't get a chance to talk to Howard, but I'm sure it would have been fun. 

 On New Year's morning I switched bands.  First to 40 where I worked Greg NM2L near Atlanta. He said he fingers and wrist were out of condition, but I told him his fist was FB. 

Then I went to 20 CW where I worked a bit of DX.  First David F8CRS then Bert F6HKA.  The contact with Bert reminded me of the charms of DX contacts using CW. "VY GM DR OM."  It was nice.  

N7AQQ Mike in Montana.  

So it was a good SKN for me. Working the French stations reminded me of the allure of listening to CW coming in from far away, and from a foreign culture.   And it was great to hear from AI4SV that my HT-37 has "presence" even on CW. 

73 and HNY to all. 

F5LVG's Nail Board Receiver -- Names for the Technique

Pete WB9FLW reminds us that Olivier F5LVG has LONG been using copper nails and wood boards to build amazing rigs.  See above for one magnificent example.  That, my friends, is a superhet receiver.  Inspirational! 

http://oernst.f5lvg.free.fr/rx/Super2016/RXSuper2016.html

http://oernst.f5lvg.free.fr/rx/Super2016/RXsuper2016En.html

http://www.stormwise.com/ampage1.htm

A few posts back we asked for nominations for the official name of this technique.   We still have to consult with Steve Silverman on this, but the nominations are: 

Armand WA1UQO (perhaps reflecting his proximity to Washingotn DC)  "Wire-Tapping" 

Gary Hinson:  "Coffin Dodging"  (sounds a bit dodgy to me). 

And the front runner so far, from Melbourne, Australia -- drum roll please: 

Peter Parker:  "NAILBOARDING."  (Peter thinks he nailed it with that one.  I tend to agree.)  

Understanding Switching Mixers (as in the Ceramic DC RX)

W3JDR's Comment on my post about the DC RX mixer got me thinking.   He was right -- my explanation of the mixer action wasn't quite complete, especially as far as switching mixers are concerned.  I remembered that I had written about this in the SolderSmoke book.  Below you can see the part of the book in which I discuss switching mixers.  Realize that the two diodes in F5LVG's mixer play the same role as the two gates in Leon's circuit.  It will be worth your while to sit down with Leon's circuit diagram, his frequency chart,  and a ruler and really go through this so you can SEE and really understand how the two gates (or switching diodes) generate sum and difference frequencies.  

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

I guess I still yearned for clarity and intuitive understanding...  Time and time again, as I dug into old textbooks and ARRL Handbooks and promising web sites served up by Google, I was disappointed. 

Then I found it.

It was in the Summer 1999 issue of SPRAT, the quarterly journal of the G-QRP Club.  Leon Williams, VK2DOB, of Australia had written an article entitled “CMOS Mixer Experiments.”  In it he wrote, “Generally, mixer theory is explained with the use of complicated maths, but with switching type mixers it can be very intuitive to study them with simple waveform diagrams.” 

Eureka!  Finally I had found someone else who was dissatisfied with trigonometry, someone else who yearned for the clarity of diagrams.  Leon’s article had waveform diagrams that showed, clearly, BOTH sum and difference output frequencies.

Switching mixers apply the same principles used in other kinds of mixers. As the name implies, they switch the mixing device on and off.  This is non-linearity in the extreme.

Not all mixers operate this way.  In non-switching mixers the device is not switched on and off, instead one of the signals varies the amount of gain or attenuation that the other signal will face. And (as we will see) it does this in a non-linear way.  But the basic principles are the same in both switching and non-switching mixers, and as Leon points out, the switching circuits provide an opportunity for an intuitive understanding of how mixers work. 

Let’s take a look at Leon’s circuit.  On the left we have a signal coming in from the antenna.  It goes through a transformer and is then applied to two gate devices.  Pins 5 and 13 of these gates determine whether the signals at pins 4 and 1 will be passed on to pins 3 and 2 respectively. Whenever there is a positive signal on gate 5 or on gate 13, signals on those gaps can pass through the device.  If there is no positive signal on these gates, no signals pass.  Don’t worry about pins 6-12.

RF A is the signal going to pin 4, RF B is the “flip side” of the same signal going to pin 1.  VFO A is a square wave Variable Frequency Oscillator signal at Pin 5. It is going from zero to some positive voltage.  VFO B is the flip side.  It too goes from zero to some positive voltage. 

Look at the schematic.  Imagine pins 5 and 13 descending to bridge the gaps whenever they are given a positive voltage.  That square wave signal from the VFO is going to chop up that signal coming in from the antenna.  It is the result of this chopping that gives us the sum and difference frequencies.  Take a ruler, place it vertically across the waveforms, and follow the progress of the VFO and RF signals as they mix in the gates.  You will see that whenever pin 5 is positive, the RF signal that is on pin 4 at that moment will be passed to the output.  The same process takes place on the lower gate.  The results show up on the bottom “AUDIO OUTPUT” curve. 

Now, count up the number of cycles in the RF, and the number of cycles in the VFO.  Take a look at the output. You will find that that long lazy curve traces the overall rise and fall of the output signal.  You will notice that its frequency equals RF frequency minus VFO frequency.  Count up the number of peaks in the choppy wave form contained within that lazy curve.  You will find that that equals RF frequency plus VFO frequency. 

Thanks Leon!  

F5LVG's Glue-Built Mixer Transformer

One thing I forgot to mention:  In Olivier F5LVG's DC receiver article back in SPRAT 100, he casually mentioned building a transformer for his mixer by taking two inductors of the appropriate values and GLUING THEM TOGETHER.   What a great idea!  I had to try it.  I did.  Picture above.  It worked in my Ceramic DC receiver, but the trifilar transformer from Farhan in India worked better.  Perhaps the coupling was tighter.  But hey, it worked.  Three cheers for Olivier.    

Amazing Homebrew/Boatanchors QSOs on 40 --Six solder melters in a row!

Al W8VR

After a day of happy tinkering with the Direct Conversion receiver I've been working on, I turned off the soldering iron and got on 40 meter SSB with my BITX Digi-Tia. 

First -- Steve W4IJ came back to my CQ.  Steve is a boatanchor enthusiast and has written for Electric Radio magazine.  FB. 

W4IJ Boatanchors

When Steve signed off, I got into a contact with Pete W8NBO.  We had spoken before and he had told me of a homebrew transmitter he'd built as a kid.  This time I asked for details: It was a 6AG7 oscillator to a 6L6 amplifier.  He ran it with an S38 (brave man!).  He described what must have been a very painful effort to hack (literally) the needed holes in the transmitter chassis using just a spike, a hammer and a file.  I told him this brought back my memories of similarly painful chassis work (mine was for a power supply for a Heath HW-32A).

At this point we were joined by Arnie, W2HDI.   Arnie's rig is in Stowe Vermont, but he was running it remote from the South of France where he and his wife were celebrating their 50th wedding anniversary.  Arnie shared with us memories of similar chassis pain -- his were related to an external modulator that he built for a DX-40. I think he said that all he had was a hole punch and a file.  Oh, the humanity! 

Then Al W8VR joined the conversation.  Al said that he's been in the game so long that his early rigs were built using cigar boxes as chassis.  I pointed to a connection:  I noted that my BITX rigs are enclosed in what could be considered cigar boxes.  Al's QRZ page picture has a magnificent AM rack rig that he said was actually built twice.  There is also an HRO-60 in the picture.  FB. Check it all out at Al's web site.  Click on the mic for the write ups, the key for the pictures.  http://www.w8vr.org/

Then Dennis K0EOO called in.  Holy Cow!   Dennis and I spoke not long ago.  You may recall my enthusiastic write up of his beautiful 1974 SSB rig: 

http://soldersmoke.blogspot.com/2017/08/k0eoo-homebrew-ssb-in-1974.html

and

http://soldersmoke.blogspot.com/2017/08/more-on-k0eoos-amazing-homebrew-ssb-rig.html

This was almost too much.  Rarely will you spontaneously come across so many hams who have melted so much solder.  FB. 

Icing on the cake:   When I returned to the bench, I fired up the DC receiver and heard Mike KN4EAR talking about his BITX40.  I switched to the Digi-Tia and gave Mike a call.  He reports making many contacts with his rig. FB. 

TRGHS.