Mike WU2D POTA CCC Camp Activation (21 October 2024) with 1930s-era Station -- See If You Can Contact Mike!

Frank Jones lives!  See if you can work Mike on Monday.  Let us know if you do! 

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

Bill,

 

I’m scheduled to tour the Civilian Conservation Corps. Camp at Bear Brook State Park here in NH on Monday. This is the largest totally intact camp in the country.

I will be activating POTA with the 1930s portable Station. The POTA CCC Camp event is scheduled for Monday around 2:30 ET (if I get everything setup after the camp tour). Primary 7057 kHz Sec 7054 kHz.

 

The station is an internal battery powered, push-pull Jones Oscillator Transmitter at around 3 Watts out, and a two-tube regenerative receiver that is a period ham artifact. So, four type 30 battery tubes in total.

The antenna is a single wire feed Windom with suspended counterpoise so basically an Off Center Fed Hertz (OCFH).

 

Between the weather, running the station, logging, and doing camera work, and of course, MURPHY - this should be nuts.

1930s Regen with Transmitter – Fully Self-Contained Portable. Note Charger that is attached to top off the internal battery on transmitter. I did not buy the proscribed 25 9V Batteries and make a TX HV pack up! I used a DC-DC converter and a LiPO drone battery! The Receiver is 100% Dry Cells However.

 

73’s Mike WU2D

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More info here: https://www.youtube.com/watch?v=N2Pdprx0ItY

And many other great videos on Mike's YouTube channel: https://www.youtube.com/@MIKROWAVE1

Helge LA6NCA's Altoids Tin Receiver

Here's another great video from Helge LA6NCA.  This is a follow-up to his Altoids Spy Transmitter project.   Really well done.   Hack-A-Day called this receiver "regenerative" so naturally I was disappointed, but when I watched I realized that it is NOT a regen but is instead a direct conversion receiver.  TRGHS.  All is right with the world.  Thanks Helge!  73 

VK2BLQ's Two-Tube Regen with a SolderSmoke Dial

 

Thanks to Peter Marks VK3TPM ("a bloke with too many hobbies") for alerting us to this magnificent homebrew receiver with the especially magnificent tuning dial.   

http://blog.marxy.org/2022/03/a-two-valve-regenerative-receiver-for.html 

We have used old CDs as dials for many years.  I have one on my Q-31 Quarantine SW receiver.  But never have we seen one with SolderSmoke emblazoned on it. FB OM. 

Stephen VK2BLQ should make sure that those 6U8s haven't gone old on him.  I recently replaced the 6U8s in my Mate for the Mighty Midget with 6EA8s.  This seemed to rejuvenate the receiver.  

Also, it is shame that Stephen doesn't keep that rig at 12 volts.  250 V?  Yikes.  As I often say, you CAN hurt yourself with 12 volts, but you really have to work at it.  Not so with 250 V.   One hand behind your back Stephen! 

Thanks to Peter and Stephen. 

A Christmas Story: Mike AA1TJ Builds Receiver for 486 kHz, Listens to Fessenden Commemoration (Audio)

Mike's 486 kHz receiver

As if being able to get home on Christmas Eve 2021 and then catching the Webb Telescope launch was not enough, Santa had another gift for us:  Michael Rainey, AA1TJ, the Homebrew Hero of the Hobbit Hole, was back at it, melting solder. Mike threw together a regen receiver that allowed him to receive a transmission commemorating Reginald Fessenden's historic first transmission of phone signals.  I was really pleased to once again be able to read about an AA1TJ radio adventure.  Thanks Mike!  Here is what Mike heard: http://soldersmoke.com/AA1TJ 920km.mp3

Mike wrote: 

My chum, Peter/DL3PB, recently told me that Brian/WA1ZMS would broadcast a commemoration of Reginald Fessenden's mythical (operative word) 1906 Christmas Eve AM transmission. Doesn't that sound like fun?

True to form, I began scratch-assembling my receiver yesterday afternoon just as Brian went on the air. Then again, a two-transistor regenerative radio for 486kHz isn't exactly rocket science. In any case, I was up and listening inside of a half hour.

 
What did I hear? Static. Just static. As a sanity test I quickly tuned down to 371KHz to find my favorite non-directional beacon, "GW," beaming in loud and clear from Kuujjuarakip.

 
Kuujjuarakip?

Kuujjuarakip is a tiny settlement of mostly Inuit and Cree inhabitants located up on Hudson Bay. The villages are primarily accessible by air and water so a robust radio beacon is an obvious necessity.

 
Satisfied that my receiver was working properly, I re-tuned to 486kHz. Back to static. On the bright side, at least there were no commercials. I continued listening intently until Vic called me to dinner. After the dishes were done I slipped back down to my underground radio shack for one last try.

I heard it right away. Beneath the static I heard a weak, out-of-tune, solo violin playing, "Oh, Holy Night." The signal strength varied wildly with ionospheric propagation. When the signal finally climbed high enough above the noise I ripped out the bipolar transistor audio amplifier stage, connecting my headphones directly to the junction field effect transistor detector output terminals. Of course the audio was far weaker now, yet I could easily follow the tune until it eventually faded away. Not bad for an estimated 15 watt ERP AM signal from a distance of 920km. And on 486kHz, no less, just a hop-skip-and a jump from the old 500kHz Maritime CW band; where countless ship radio operators went to send their last SOS.

 
Returning to the house, I emailed my reception report and included a short recording that I had made of it. Brian replied just after midnight; apparently, equally as stoked

"Yours’ is the best DX ever given your regen RX! Way to go! I just love it."

He went on to tell me that he was born and raised in Vermont, but he'd been working as a radio scientist down in Virginia since 1990. Told me his heart was still here in the Green Mountains and he was touched to learn his meager signal had found its way back there on Christmas Eve. All in all, a night to remember.

 
If you're still with me I hope you'll listen to the short NPR story in the provided link. It originally aired on the supposed 100th anniversary of this event. It's not just about radio history. It's about belief, memory and the myths we lug around in our heads. I thought it was well done.

 
Cheers,
Mike

Listen to what Mike heard. He says he "merely connected the mic input line of my computer across the headphone terminals. Some of the noise in the recording, - certainly the higher frequency stuff - is a byproduct of the computer. The headphone audio with the computer switched off was much more pleasant."  Here it is: http://soldersmoke.com/AA1TJ 920km.mp3

NPR story (audio and text)

https://www.npr.org/2006/12/22/6665738/christmas-eve-and-the-birth-of-talk-radio?fbclid=IwAR1G3ZchgTCc2EDnkS5BCxGARwsa87bvf0LO9nd5hfLQDvb96fR6w0dBzw4

Scott WA9WFA's Beautiful HBR-13 Receiver (3 videos)

This is Scott WA9WFA's first homebrew construction project.  He did an amazing job on a very complex project:  a 13 tube superhet receiver.  It features plug-in coils for multi-band coverage, dual conversion with IFs at 1600 kHz and 100 kHz, and several regenerative stages.  Scott's construction is top notch. He tells us that he had been working on this receiver for several years, so long in fact that some of his friends began to wonder if it really existed.  Well wonder no more.  Retirement has provided Scott with the time to finish this project. 

I like the way Scott talks about the project in these videos.  He puts it in the context of his long-standing goal of building his own high quality ham station.  With the HBR-13 done, he is more than halfway there.  We all know that the receiver is the hard part.   

I agree with those who say that Scott should keep the plexiglass front panel.  I think it looks very cool.  

In the third video, Scott takes us on a cruise through the 40 meter band.  The receiver sounds great.  Lou EA3JE's booming voice came through quite nicely from far-off Barcelona. 

Congratulations Scott on building a truly outstanding receiver. And on making some great videos. 

There is some additional background info on the HBR-13 in this blog post from back in September: 

https://soldersmoke.blogspot.com/2021/09/the-hbr-13c-homebrew-receiver.html

Super-Regeneration is Super-Strange

Farhan VU2ESE is largely responsible for this.  He has recently been talking about VHF.  (More about this in due course.).  This started me thinking about my failed effort in London to get on 2 meter AM.   My plan was to use the transmit portion of this HW-30 (above) with a 2-to-10 downconverter and my trusty Drake 2-B for receive.  

Tony G4WIF also bears some responsibility:  When I expressed interest in Farhan's VHF work, Tony sent me two articles from SPRAT.  Both of them were about super-regenerative receivers.  

Farhan's comments caused me to pull the HW-30 out of storage.  I started poking around the transmitter.  But then I noticed something:  On receive, the AF amplifier was obviously working.  Then, when I tuned through the 2 meter band, the rest of the receiver seemed to be working too.  I fired up the HP-8640B sig gen on 2 meters and turned on the AM modulation.  Indeed, the old receiver was inhaling!  

This launched me into an effort to understand how super-regenerative receivers work.  There are a lot of really weak explanations out there. You get the distinct impression that the person explaining the circuit does not understand it himself.  This makes explaining it very difficult.  I am not the only one to notice this phenomenon:  Mike WU2D commented on this in one of his excellent super-regen videos.  This one:  

https://www.youtube.com/watch?v=QOhNPLT8R10

Mike very kindly said the operation of this circuit seems like "magic."  I was thinking more in terms of Voodoo.  

Howard Armstrong discovered super-regeneration years after he invented plain old regeneration.  The new discovery came around 1921.

It looks like VHF guru Frank Jones had very early misgivings about super-regeneration.  In his 1934 classic 5 Meter Radio Telephony, Jones seems unenthusiastic about the circuit and about our ability to understand it:  "To explain, simply, exactly how this form of detection takes place is not a simple matter, but some of its characteristics are easy to visualize."  In this book, Jones goes on to predict that super-regens will be superseded (!) by superhets.  Indeed, in his 1961 book VHF for the Radio Amateur there are no super-regen circuits; all the receive systems are down-converters to HF receivers. 

Still, with that HW-30 hissing away right next to me, I feel I need to understand how the super-regen works.  I'm not there yet, but I'm trying.  Here are some good resources: 

A good article from Wireless World 1946:  

http://www.r-type.org/articles/art-285.htm  

A student's write up of his effort to understand: 

https://folio.brighton.ac.uk/artefact/file/download.php?file=597679&view=111191

But the best so far (for me) is from Frederick Terman (one of the founders of Silicon Valley) in  his 1943 classic Radio Engineer's Handbook.  Click on the images for a clearer view. 

I will definitely try to get the HW-30's 5 watt AM transmitter going.  I am not so sure I'll do anything with the receiver.  I think this is a matter of picking your battles and "finding joy."   I didn't find joy in FT-8, so I stopped working with it.  Same with my HA-600A, DX-40 Novice rig.  Same with CW in general.  And the same with SDR.  I suspect that super-regen receivers may also fall into this category.  I mean, let's face it, if you are not fond of ordinary regens, is there any real chance that you will like SUPER-regens?  Even Frank Jones seems to have disliked them.  And there is a reason Howard Armstrong moved on to superhets -- they are better! But still, that receiver is hissing away at me...  Stay tuned. 

1BCG -- 1921 Transatlantic Test and the Upcoming 100th Anniversary

In December 2021 we will reach the 100th Anniversary of the famous Transatlantic Test that marked the first crossing of the Atlantic by radio amateurs.  The video above provides a really excellent description of the momentous event. A few things struck me: 

-- Even then they struggled with amplifiers that wanted to oscillate. 

-- Armstrong should have gotten more credit for the transmitter design.  After all, it was his regenerative system that gave rise to the kind of oscillators that allowed for CW (vice spark) and that formed the basis of the MOPA transmitter that these fellows used. 

-- The info on the Superhet receiver used by Paul Godley in Scotland was really interesting:  It used   "resistance-coupled amplifiers without transformers," similar to what we have today in Farhan's BITX transceivers. 

-- Wow, Harold Beverage himself! And his antenna was used at the Scotland receiving station. 

-- "It was a miracle that no one got mixed up with the high voltage."  Indeed.  

The Antique Wireless Association has built a replica of the 1921 transmitter.  The video below shows it being tested. 

 

The 1BCG website announces that: 

On December 11, 2021 the American Radio Relay League, The Radio Club of America and the Antique Wireless Association will recreate these historic transmissions on 160 meters near the same location that was used in 1921, using a replica transmitter constructed by volunteers at the Antique Wireless Association. This special event is your opportunity to relive a historic moment in amateur radio history.

The operating schedule and frequency for the 1BCG Transatlantic Tests Special Event has not been established.

Additional details will be posted here when they are available.

http://1bcg.org/1BCG/

Technical Manual 11-455 -- Radio Fundamentals -- July 17, 1941

This is an illuminating little book.  It was published by the U.S. War Department on July 17, 1941, less than five months before Pearl Harbor.   Far from being dated, this book contains a lot of  great explanations of -- as the title indicates -- the fundamentals of radio.   I turned to it this morning for a little refresher on the physics of regenerative feedback.  

You can get your own paper copy here:  

https://www.amazon.com/Technical-Manual-Radio-Fundamentals-11-455/dp/B000HI6306

Or here: 

https://www.ebay.com/itm/War-Department-TM-11-455-Radio-Fundamentals-WWII-1941-/141763081079

Or you can read a slightly more recent edition (1944!) online (free) here: 

https://archive.org/details/Tm11-455/mode/2up

Please let me know if you find this book useful. 

Notes and Video on Doug N0WVA's Amazing Single Transistor Regenerative Receiver

When I had trouble getting the regen receiver in W2UW's ET-1 circuit to work, I turned to the internet and -- through AA7EE's site -- found the circuit of Doug N0WVA.   This circuit has completely changed my attitude toward regen receivers.   I have been exchanging e-mails with Doug -- below is a compilation of the info and regen-wisdom that he has shared.  More to follow... Thanks Doug. 

From Doug N0WVA: 

I came up with the diode after exploring ways to ditch the source r/c combo. The thinking was the closer I could get the source to ground the less voltage/capacitance fluctuations the gate would see.  Also I hated seeing everyone using .01 bypass to avoid audio oscillations and also losing audio gain. 

 The green LED works good but even better is directly grounding the source. Then feed a small negative bias through the gate leak resistor , adjustable via a potentiometer.  

On video, the audio is taken straight from the radio shack headphones that are connected to the audio transformer. The headphones are held directly to the phones case ( no hole for the microphone seen on the phone)  

The variometer is  made with I think a 1.25 inch pill bottle and the tickler inside is around an inch in diameter pill bottle. I used a pharmaceutical syringe's outside tube for a shaft. The tickler form has a couple holes cut for the shaft to pass through, it is a friction fit, more like slits cut and the rod pushed through. I used the soldering iron to melt round holes on the actual outside coil form for the shaft to turn on. On the back of the shaft is a small screw that goes through the outside coil form and screws into the syringe center hole that holds it in place. The tickler is one turn, I think, and routed through the inside of the shaft via small holes melted with the soldering iron.

A couple tweeks to mention is instead of a resistor in the gate, use a choke for less noise, makes a big difference, especially if you listen to AM.  Also I have been using a gimmick for the gate cap.  Just maybe a #36 enamel wire wrapped around  the hot tank lead 5 or 6 times and then I remove turns till the thing stops oscillating, then add a turn. This helps cut down even more on strong signal pulling. 

I have always been on a quest for more performance out of the least parts. This design was about as far as it could go, I think....

I have never done any real sensitivity tests on the regen, so you have gone farther than me already. One thing was noticed though is the gate resistor does add a lot of noise, especially noticeable just under oscillation in AM detection mode.  So I took a one meg 1/4 watt resistor and wound as many turns of #38 wire on as I could, probably around 80 turns, then subbed it out for the gate leak.  This dramatically improved the noise level just under oscillation. This was with a simple antenna band noise test. I think it also improved the noise under oscillating conditions. 

Adding extra antenna coupling will probably help a lot, but, there is a point where we start getting too much strong signal pulling.  The strong external bias battery trick will also improve this, although at the cost of extra parts.

Book Review: "Man of High Fidelity: Edwin Howard Armstrong" (Free Download)

Dave W2DAB sent me this wonderful book.  He picked up a copy at a recent Columbia University lecture on E. Howard Armstrong.  Written by the notable science writer Lawrence Lessing, the book was first published in 1956.  The paperback copy that Dave sent me came out in 1969; while 50 years old, my copy is in remarkably good shape. 

I really liked the book.  The author captures the technical achievements of  Armstrong, while also describing vividly the world in which Armstrong lived.  Being from the area, I especially liked Lessing's description of New York City and the Hudson Valley in the early years of the 20th century. This was the world of my grandparents; Lessing's book helped me understand it better. 

For the radio amateur, I think the most gripping part of the book is the way Lessing describes  the excitement of early radio.  Armstrong was a true enthusiast for the new technology, and he was -- even as a teenager -- at the cutting edge.  He was constantly striving to improve the technology, especially the receivers.  Like us, he often became obsessed with his radio work, often forgoing sleep and missing family meals as he toiled away in his workshop. Lessing tells us of Armstrong's astonishment and joy, when, upon inventing the regenerative receiver, he was suddenly able to clearly receive signals from distant stations that previously had been barely discernible.  Realize that when he was doing that, he was the only person on the planet who was doing it.  He was the inventor. He was the first. 

Lessing gives us a lot of great information about Armstrong's work as an officer in the U.S. Army Signal Corps in Paris during World War I.  We learn more about how his desire to be able to detect noise from the electrical systems of enemy airplanes led him to the invention of our beloved superhet receivers.   But my favorite Armstrong in WWI story involves his visit to the radio shack of the ship that was carrying him to the war.   In the radio shack he found a conventional station.  But he asked the operator if he happened to have one of the then new audion tubes.  On the spot, Armstrong took the tube and rigged up a regenerative receiver.  He and the ship's radioman then delighted in hearing stations that had never before been audible.   Amazing.     

I was less interested in the sad tale of Armstrong's legal patent battles, so I kind of skimmed through that.  I'm also not much of an FM guy, so I'll save those portions of the book for a later date.  

I think this is an important book about a significant part of radio history.  It is well written.  It gets almost all of the technical details right (but sorry Mr. Lessing,  radio waves are not composed of electrons).  The book deserves a place on the shelf of all radio history libraries.   If you can't get a print copy, an online version can be downloaded here: 

 https://archive.org/details/in.ernet.dli.2015.189098

Thanks again to Dave W2DAB.   

VE3BOF's Regens and DC Receivers

VE3BOF BENCH

Hi Bill:

This is Clark, VE3BOF, in Hensall, Ontario, Canada.

Hensall is located in southwestern Ontario, north of London and a 2  

hour drive west of Toronto.

Last Sunday night, 2017-10-01, I tuned in to 7277 kHz to listen to  

the BitX40 net. I heard you and 2 or 3 others.

Your signal was 5-7, perfectly readable.

The receiver I was using is a modified version of the WBR receiver.

It is still on the piece of chipboard that I mounted all the modules  

onto.  It's an excellent little regenerative receiver.

In the same state of incompleteness, is a modified version of the  

Easy Receiver (QRP Kits) direct-conversion receiver,

I use this receiver for the CW end of the 40M band.

Both receivers have been fitted with 10-turn pots for easy tuning,  

and also lcd frequency counters for displays.

I'm a former Motorola Communications tech, and used to maintain the  

radio systems of District 6 of the Ontario Provincial Police and our Ministry 

of Health emergency services radio system.

Being retired now, I have more time to check Soldersmoke every day  

and listen to your

conversations with Pete, N6QW.

Thank you for very interesting and worthwhile QRP information and  

programming.

Clark Forrest, VE3BOF

Colin M1BUU's New Receiver Project

Hi Pete,

Just checking in :-)

I have actually been melting solder recently. I decided to build a little CW receiver. I love my regenerative RX that I built as a teenager, but after all these years, I'm tired of constantly tweaking the controls!

My project is a 20m CW only superhet receiver with a 9MHz home brew filter. I'm using the SI5351 for the oscillators. I originally thought I would cover multiple  bands, but for now I have the parts for 20m coverage. I might tinker with other bands at a later point.

I'm using your LBS code on the Arduino, the one for 20m with 9MHz IF. I haven't applied power to the rig yet but it's not far off fully built. I tweaked the Arduino sketch using my Uno and tonight I have successfully transferred the code to a Pro Mini. (Code went into Pro Mini on first attempt - amazing!).

73 for now,

Colin M1BUU

Haunted by the Gong (Ooooo that's Awesome!) Donald's Knack Story

Bill:

 

First off thanks for the wonderful podcast. I only just discovered it and I have loaded as far back as I can go on my Phone. I have been listening to it every waking moment. Though I fear that even at one or 2 a month no amount of commuting, dishwashing or bathroom cleaning will allow me to catch up with you. 

  I so identify with your idea of the Knack. I was forever taking things apart, my mom had to remove anything that could be used as a tool from her home for my first few years as even at age 2 I was into clocks, cabinets and basically anything that wasn't nailed down. Until your podcast I hadn't even heard of the International Geophysical Year, but discovered I missed it by only 3 months being born in March of 59. I do think though that those of us that were even a little knackish were encouraged on our way by the Space program. 

  Even though I grew up in Canada, I was riveted to the TV for every space launch, touch down or space walk. Many of my first memories are watching grainy broadcasts from Gemini and then on to Apollo. Even now I stayed up to watch the Mars rover land those few years ago. 

  Radio was always a special interest for me from the First Short wave radio I got from my grand father. I remember discovering WWV, BBC VOA and the Netherlands english language programming. This of course launched me into a frenzy of stringing wires higher and higher much to the chagrin of my parents. My poor dad that was an arts major didn't know what to think of me. 

  I'd always wanted to get in to ham radio but the code requirement held me back. My dyslexia kicked me really bad. I had the little tapes from radio shack and I'd work and work but got no where. So i resolved myself to just shortwave listening. 

  I was laughing when you talked about your relationship with Regenerative Radios as one of the first radio projects I built was the "Science Fair Globe Parol Regenerative Radio" From radio shack. Here is a link to the thing http://www.ohio.edu/people/postr/bapix/rsglobep.htm I still have it at my mom's house. The last time I put batteries in it it would at least get WWV. Which is no small feet when you realize I built it with one of those Weller Soldering Guns that you could reseal canned goods with. I'm sure if I opened it up now there'd be blobs of solder the size of Cicada's in there.  

  I was just listening to Episode 147 where you were talking about the All American 5 tube radio. I must have tore down 20 of those things as a kid. Your Right they were dangerous as anything you could get. Most of them the chassis was hot if the plug was in wrong and there wasn't like a fuse or any safety equipment in there to stop you from hurting yourself. Yes they were cheep and made so without a transformer, and all the tube heaters in series with the panel bulb for a bit of protection to prevent a surge on power up. But one other feature they had was that when they were originally produced there was still some DC mains power around and they would run if you put in the Plug the right way. My old electronics teacher claimed that you could run them off 3 45 volt batters on the Farm in a pinch. Though 19 40's battery technology I'm not sure if that was a practical solution. Though In High School that's what we had to learn. Learned to tune, debug and repair those puppies. 

  After high School I went into the phone company and later made my way as a lot of us Knackish people in to the computer/software industry. And low and behold after about 30 years they dropped the Code requirement and now living in the States I went out and finally got a license. 

  I just wish I had found your podcast sooner as I would have done things a little differently. However I have managed to do some serious kit building. I have built two TNC's, one for the beaglebone and one for the Pie. I have built one softrock receiver and another Softrock emsamble  RXTX that I'm just trying to figure out how to make work. I also built though it's not really a kit a Kx3 that is my main HF rig. 

  I thought I was really interested in the computer radio connection but wow when I see what you have done with the BITX and the manhattan build I'm thinking I want to build a rig that maybe I can run some JT65 or PSK31 on. I know what you mean about the Phone and SSB but right now stuck in the city of Chicago my antenna space is limited and i'm surrounded by power poles so I have a lot of noise no matter what I do. 

  One thing I need to talk to your buddy Pete as in the left over spare time I have, between work family and radio I'm trying to complete the BSC that I never did during my misspent youth. But I'm stuck at the final project. I need something that needs some code and could be written up as a research paper I keep thinking there has to be a radio project here somewhere. 

  Anyhow that's enough I'm sure you get lots of people with their stories but I thought a little of what I encountered might be interesting. I really appreciate the podcast love all the personal stories combined with the tech talk. Keep up the good work. I'm looking forward to getting current. 

   Donald L. Gover KC9ZMY

P.S. I have woken up twice as of late thinking I heard a Gong followed by "Oooo That's Awesome" Maybe I'm listening a little to much :) 

 

P.P.S  Again catching up on the podcasts though my podcast listening time is a little reduced as I bought your darn book that's very interesting! But I wanted to make sure that I did inform the Knackers Union, whom I believe that Steve Snort Solder Smith is the enforcement officer that I had already constructed my 40m low pass from 4 state QRP. I have provided photographic evidence of it's construction and promise not to QRP on 40M without it. 

 

 

Drake Dongle Derring-Do -- 2B goes SDR (video)

Here I take my Drake 2B  -- arguably the quintessential Hardware Defined Radio -- and connect its first Intermediate Frequency circuitry to an RTL-SDR Dongle, allowing me to digitally process, filter, and display (panoramically!) the signals being inhaled by the ancient receiver.  Another cool tech twist:   To get at the 455 kHz IF signal I use the "Q-Multiplier" jack on the back of the receiver.  This connector was put there to allow for the use of a selectivity enhancing regenerative stage.  So I'm using that connector for a similar purpose, but using technology that wasn't even being dreamed about when that Drake 2-B was being designed in 1961.  


Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

When Your Local Oscillator Could Sink Your Ship!

Thomas KK6AHT is the intrepid radio amateur from France who moved to California and successfully built a Minima as his first homebrew project.  Yesterday we got additional evidence that Thomas definitely has THE KNACK.  It seems that he has been looking through really old radio magazines (clearly a symptom).  He sent us this add from 1942.  Yikes!  Imagine getting your ship sunk because your Local Oscillator is not quite local enough!  

.....................

Hey!

I thought you would get a kick out of this 1942 ad. Sounds like those guys had a some good reasons to fight QRM ... Who knew the important role played by the FCC during the war?

Now tell me: why were the receivers so noisy at the beginning of the war? What did they change? Happy new year to you both! May the gods of radio (and digital) bring you much fun on the air.

73, Thomas  

..............................

Good to hear from you Thomas.  Long time no hear -- I was beginning to fear that you had grown disillusioned with homebrewing and had switched to stamp collecting or something else less frustrating.

As for the ship radios, two things come to mind.  Some of them may still have been using regens at the start of the war.  If so, that was kind of suicidal -- regens radiate!  The detector moves in and out of oscillation (sometimes staying in oscillation) at the receive freq.  The Germans were quite good at detecting and direction-finding these signals, on land and at sea.   So the regens would have to go.

Superhets are not quite as bad, but they too can radiate.  My Bitx spills out a bit of signal at 23 MHz (VFO) and at 5 MHz (BFO).  Without adequate shielding, these sigs could also be detected and triangulated.   Looks like the radio in the picture had lots of shielding. 

We watched a French movie last night:  The French Minister.  A comedy about life in the French Foreign Ministry.   It was kind of fun.

What are you working on?   I am listening to 17 meters using an OLD superhet in which I have replaced the VFO with an Arduino/DDS generator.   Works great but the display is making lots of noise. 

73  Bill 

..................................

Hi Thomas,

Well Thomas, I will dip my toe into some very deep water and attempt an answer for you which also is an important clue about QRP operations.

1. Today we have many many signals co-existing in the radio spectrum. During the war there was much less radio garbage and the military lit up the ether with transmissions very sparingly. But that is on the transmit side. That said the local oscillators (much like you have with the Si-570 on your Minima) used in receivers also produce RF that unless is minimized in some fashion is passed right through to the antenna and can be detected. Regenerative receivers are especially prone to this. Yes some military equipment used regenerative receivers. In fact the famous Paraset had to be constantly moved so it would not be detected.
2. This receiver generated RF into the antenna was addressed by companies like Scott by shielding everything. That receiver in the photo probably weighed about a 100 pounds or more. Much attention was paid to RF bypassing and grounding. The cheap table top radios were RF generators par excellence.
3. There was another approach developed in WWII to solve that problem and forms the basis of what makes work that little device sitting in your pocket. The odd part it was invented by a famous movie star. Look up Heddy Lamar in wikipedia. She and a co-inventor came up with the concept of frequency hopping and spread spectrum technology. By jumping frequencies it would be hard to pinpoint a transmitting station. That concept forms the backbone of our cellphone system
4. Now the QRP part – if the RF output from a receiver local oscillator (milliwatts) can be detected from afar – then it follows QRP works!

Have fun. 

Pete

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Colin Finishes His BITX

Wow, that is one beautiful BITX.  Nicely done Colin.  But I must say that you are exhibiting an almost inhuman degree of patience!  Who needs a case?  Fire that thing up and make the traditional "still-on-the-workbench" initial contact. 

Hi Guys,

I loved the last SolderSmoke, it was another great episode. It really does amaze me, that a few years ago, hams were saying that it was too difficult to build your own gear that would be anywhere near to the commercial stuff, but here we are with Arduinos etc bringing powerful functionality to the masses. I couldn't have imagined building an SSB rig with a pretty and functional LCD screen when I started in ham radio.

Bill, first regens, now SDRs? Amazing! I exchanged a few words with George Dobbs about your change of heart towards regenerative receivers, he seemed genuinely pleased. :)

Pete, your Si5351 work with the pretty displays is cool, I can see me getting pretty hooked! I have the Si5351 board, Paul M0XPD advised me to buy it. I'd love to build another SSB rig in a smaller box for regular SOTA activating. I must look into the pretty little displays and have a play with the Si5351. I notice that Hans Summers has now put out a cheap Si5351 based kit, handy for us guys in Eu. http://www.hanssummers.com/synth.html

I finished building my BITX board yesterday but wanted to have a sleep before applying power! Today I carefully checked the circuit for errors and found none, phew! I fired the rig up gently, watching the current carefully. I wound up the TX bias to 50mA as stated in the MKARS80 instructions, all went well. I plugged in the mic and spoke - BANG! - Everything went off. Oops - I had used a 500mA fuse for initial safety and forgot to swap it for the bigger one! I fitted a 1.6A fuse and hey presto, all was fine. I was absolutely amazed and to be honest, rather proud of myself. I think the TX is a little bit too hot, my meter is showing about 6W on voice peaks- eek! The rig seems to be perfectly behaved though, no wierd effects seem to be happening. I can just turn the bias down a bit, right?

Anyway, I was happy with my progress so I finished for the day. I still need to investigate and probably tweak the carrier suppression.

I spent a short while talking into a dummy load, using my FT817 to monitor the transmission. My 2yr old son was interested in my voice coming out of the 817'sspeaker!

Thanks for all the guidance and help along the way, I'm elated that I've built a voice rig that works! I've attached a pic of my finished board, I only just squeezed the circuit on, but isn't she pretty? :-)

Can't wait to get the rig built into it's case and score that first QSO.

73, Colin, M1BUU

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Regen Receivers in Cuba

Hola amigo Bill:

I was able to pick up the podcast with excellent audio quality.
It is quite true that regenerative receivers are very much in use
even today... for example many if not all of the automobile RF
keys opening and closing the cars doors rely on a superregenerative
receiver circuit !!!

The radio that you copied at the blog works very well indeed
but it would be  good idea to include a 5 kilo ohms volume
control.... Very easy to do indeed.

But let me tell you that my favorite regenerative receivers are
the classic ones, using vacuum tubes, and operating them
at voltages not higher than 50 volts... As a matter of fact many
tubes work very well at the 24 volts DC voltage level.
Using the classic Hartley circuit , there is no need for a hard to
find throttle capacitor required by the Armstrong circuit, because
the regeneration control works very well by using a potentiometer
to change the screen grid voltage of the detector.

I agree that using an RF stage ahead of the detector is always
a very good idea.... In my tubes regenerative I use a triode connected
6AK5 clone.... as a grounded grid stage....another 6AK5 clone ( the
6ZHE1P Russian tube ) is the detector and I use another 6AK5 clone
as the first audio amplifier then feeding an audio output pentode
all provided from a very simple basic 70 volts DC power supply.
BTW, using regulated DC on the filaments of the detector stage,
although a luxury by my standards is very helpful to reduce
hum .... 7805 regulator recycled from a bad motherboard, with
one 1N4007 from broken Compact Fluorescent Lightbulb inserted
in series with the regulator ground pin, produces a nice 5.7 volts
regulated DC that with a brand new tube is more than enough... with old
6ZHE1P recycled from Russian TV sets, you add another 1N4007 to obtain
6.4 volts regulated DC....

As said in the podcast, it is very important to do a very good
mechanical engineering job, place the main and bandspread tuning capacitors
away from the front panel, use isolated shafts between the capacitors
and the dial mechanism and make the front panel of a a thick steel
plate if possible.

There is a Dutch Cascode Regenerative radio that several Cuban radio
amateurs have built... it was designed with the amateur bands in mind so
the information about the tuning coils and capacitors lets you
obtain a very excellent bandspread on the ham bands.
I can send you that circuit that uses very common 12AT7-ECC81
and Russian equivalent double triodes.

Keep up the good work amigo and always tell us when the next
podcast is available. BTW it lasted for almost an hour !!!

73 and DX

Your amigo en La Habana, Cuba
Arnie Coro
CO2KK
Host of Dxers Unlimited radio hobby program
Radio Havana Cuba


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"Off the Shelf" Regenerative Receiver

I call it the "Off the Shelf" Regen because the base on which it is built is scrap lumber from a recent shelf building project.  Also, all the parts came out of the junk box.  

6-10 MHz, AM, CW, SSB, Data.   4 transistors, no chips.   


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SolderSmoke Podcast #164 Ancient Tribal Knowledge: Tube and Tube-like Radios

SolderSmoke Podcast #164 is available:

August 16, 2014

http://soldersmoke.com/soldersmoke164.mp3

ANCIENT TRIBAL KNOWLEDGE -- TUBE AND TUBE-LIKE RADIOS

Workbench Updates: 
-- Pete's Arduino Keyer Project
-- Bill Builds (and LIKES!)  a REGENERATIVE RECEIVER
-- The Joys of Regen Shortwave Listening
-- Grayson Evan's Tube (Thermatron) Book
-- Book review:  "The Joy of X"  (It's about math).
-- Shameless Commerce:   A Plug for Bill's Book
-- Pete discusses tube projects
-- Making your own enclosures from Home Depot flashing
-- Amplitude Modulation
-- Compactrons, Nuvistors and other unusual tubes
-- BANDSWEEP:   Radio Havana on Bill's new regen 


Bill's Mate for the Mighty Midget Receiver
3 6U8 Tubes on a Benton Harbor Lunch Box Chassis


Nuvistor 2 meter down converter


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Jim, WB5UDE's Knack Story

Hi Bill! ...

Of all the Amateur Radio related podcasts I've sampled, SolderSmoke has

been my favorite.  The reason is because of the passion you (and Mike,

too, in the beginning) bring to us each and every episode.  I've been

passionate about radio since I was 10 years old, and electronics in

general since I was about 8.  Many of the other podcasts seem to lack

this quality, or worse, try to have a "how to do things in Amateur Radio

the right way" focus.  I suppose their thinking is that hams listen to

podcasts to learn, so they assume their job is to tell someone how to

get started doing this or that.  However, the result often comes off

being preachy-- that there is a Right Way to do things, and that it's

important to do things that way, so they'll work out best.  That's not

what Amateur Radio is about!  Amateur Radio is about doing something

because you're passionate about it.  Even where your own passions are

concerned (e.g. individual analog components, no chips!) you acknowledge

that the other approaches are equally valid, and that we should all

do what we enjoy.  You're not shy about branching off into your other

technological passions, about space, RC aircraft, etc., which as you

rightly observe, so many of us have in common.

We share a passion for learning and understanding about radio/electronics.

Where we differ is in the depth of understanding we crave.  Actually,

I have experienced enough of that desire for total understanding to know

exactly what you're talking about, but I'm usually content without it.

I realized back when I was a teenager that some things would click for me

right away, and some others, I'd always struggle with.  I made peace with

that very early.  Still, I have wondered more than I could find ultimately

adequate explanations for about things like, OK...exactly what ARE these

radio waves?  More often, though, I am content to gain a sufficient depth

of understanding that I feel comfortable knowing how I might achieve a

particular thing.  I have great sympathy for your struggle with "holes" in

transistor theory.  That actually clicked for me, but not immediately--I

had to chew on it just a bit, but then it did gel.  If that "?" floating

over my head had refused to disappear, I might have found that a little

frustrating.  But to me, the really frustrating thing is that books so

often begin by talking about electrons and holes and depletion zones and

so forth.  I have found that a much simpler explanation is sufficient

for my tastes--I'm content to understand that there are N-doped and

P-doped sections, and that this allows the silicon to control current

in a certain way.  Knowing how we arrange the electronics around a

transistor to get it to behave in its own useful way in a circuit is

really all I've ever cared to know.  And furthermore!... I'd rather

have the whole presentation be top-down...I'd rather start with what a

transmitter and receiver are, and what their stages are, and what kind of

circuits go into those stages, then eventually, down to what components

make up those circuits.  It's all a natural progression, for me, of, "OK,

I understand that--now, how exactly does that part work?  Give me more

details, please."  The whole thing of just learn all these fundamentals,

and we promise we'll eventually tie them together into something useful

doesn't work well for me as a way to learn.  Worse than that, it doesn't

thrill me to the core the way gaining a gradually deeper and deeper

understanding does, as I drill down into more and more detail about

things I've caught an interest in, and remain content with a shallower,

surface knowledge of things I just want to know well enough to use,

when I need them.  So, I don't have the same burning desire to get down

to the bottom foundation in first principles all around that you do,

but I do love to learn, and understand.

I got my start in electronics when I was eight years old, and read a

book my parents had bought me about electricity.  I suddenly realized

that things like flashlights and motors didn't have to be a strange

mystery, but were things I could understand, and even try for myself.

I began reading everything I could find at school about electricity.

Meanwhile, over the next couple of years, I began appreciating music.

Reproducing music was something very special that electronics could do.

Even more special, radio electronics could bring you this music from

far away.  That whole combination, bringing communication from far away,

including things I found enjoyable, and doing it with this wonderful

magic of electricity, which it was possible to actually understand, was

(and still is to this day) quite thrilling.

When I was ten years old, I realized that, lo and behold, it would

actually be feasible for the amount of money my parents would be able

to spend for a Christmas present, to buy a pair of toy walkie- talkies.

I set a new level of obnoxiousness leaving the catalog open to the

page with the walkie-talkies, and finally, just flat out telling them

that's what I wanted.  I then exceeded that level of obnoxiousness when,

I'm ashamed to say, I absolutely chewed them out when they didn't take

the hint.  Instead, I got a tape recorder.  I actually enjoyed that, too,

but continued to campaign for the walkie-talkies, and when I still wanted

them a year later, my parents decided I meant it, and bought them for me.

(My dad knew a thing or two about radio himself, and my mother later

told me that my dad had been concerned that the walkie-talkies would be

fragile, would perform poorly, would chew up batteries like you couldn't

imagine, and would have a very disappointingly limited range.  He was

right about all those things, but it turned out I was right, too--in spite

of all that, I loved those walkie-talkies as much as I'd known I would.)

Meanwhile, I got a 100-in-1 electronics set for my birthday.  My parents

had wanted to find one that was about individual components, but all

they could find was one that was based on projects using a pre-built

audio amplifier, radio receiver, speakers, and battery holders.  Its only

component-based aspect was an apparent afterthought, an AM BCB transmitter

built on a cardboard circuit board.  This was really a bit too "appliancy"

for me--I would rather have been learning how to make components work--but

I still learned a lot from that.  I also bought an AM clock radio for

less than a dollar at a garage sale.  It didn't work very well, but this

was really good, because I learned that I could make it work much better

by wrapping a few turns of wire around its built-in loop antenna, and

attach that to various antennas I got to experiment with.  Months later,

I found a very nice tube-type AM/FM Zenith table radio at another garage

sale, and bought it for $5.  That radio went home with me strapped to

the back of my bicycle, then went on the bookshelf on the headboard of

my bed.  I learned to work its knobs backwards, reaching behind my head.

I listened to AM radio stations from all over the US until all hours of

the night, and my addiction to radio grew even deeper roots.

Then, when I was 13, I found a Zenith Transoceanic portable at a

garage sale, for $15.  I raced my bicycle home as fast as I could.

(This radio was a little too big for the bicycle.)  I got my mother to

drive me back there (urging her to hurry!  before someone else bought it),

and brought that one home....  then spent that whole evening driving my

parents nuts by running into the room where they were every few minutes,

excitedly exclaiming something like, "and NOW I'm getting a station from

GERMANY!" and then running back to see what I could get next.  Of course,

I had even more fun with it after I put a decent outdoor antenna up.

When I was 16, I finally met an Amateur Radio operator.  I'd read an

ARRL book about becoming a ham, and building one's own station, but the

books were a little expensive, and I wasn't sure how to go about it all.

Pat Barge, WB5OEB, about one year older than me, had earned his license

about a year before, and was eager to pass along the favor of showing

the ropes.  I got to listen as he operated his station, and he told

me which books would give me the specific knowledge I'd need to pass

the tests.  I was 17 when I got my first license.

While I was learning what I'd need to get my first license, I got my

next great receiver--this time, an RAL-7 regenerative receiver.  You and

I very much see regenerative receivers differently, but then, I had

the pleasure of learning on the best regenerative receiver ever made.

Back in those early days, I'd sometimes hear the opinion that the RAL-7

was not merely the best regenerative receiver ever, but the best receiver

ever, period.  I think all those old-timers have died off, though.

I've enjoyed building a bit over the years, too.  I haven't found nearly

as much time for it in my adult years, so I think to this day, about

half of my building was done as a teenager.  I haven't done anything

impressive, but I have made contacts using things I've built myself, and

what a thrill that is!  I've built more than a dozen projects (but fewer

than two dozen).  The most fun I've had was several years ago, following

the advice of a post to the Glowbugs list, I began experimenting with

crystal radios, then slowly began to ramp the circuits up, adding tube

amplifiers, tuned circuits, etc.  My favorite successful project was

a SWL converter to feed a car radio.  I built a doubly balanced diode

ring mixer and a crystal oscillator.  I used a 3-gang air variable

as the foundation for a 3-stage front end filter.  I had an 8.x MHz

crystal that put signals from (depending on where I tuned that 3-gang

air variable) either the 49 m or 31 m shortwave broadcast bands in the

tunable IF provided by the AM car radio, which fed a nice 3-way speaker

from a stereo, for the most beautiful sounding SWL listening of my life.

Like all my projects at that phase, it never left the breadboard stage,

but it stayed on the breadboard for a long time, while I paused in my

building to enjoy listening for a while.

I serve as one of the net control stations for a local two meter FM net

that meets weekly to discuss technical topics.  We got our start back

before most folks had Internet access, and served a very useful role as

the place where hams who had a problem to solve or wanted to ask how to

get started in a new phase of Amateur Radio could come and get answers to

their questions and ideas about how to do things.  In these days where

it's easier to Google for answers, we've morphed into more of a general

discussion session among a small, dedicated group, but it's still a lot

of fun.  It gives me a chance to do what I enjoy the most consistently

in Amateur Radio, which is to understand, talk about and explain things.

In fact, that's often all I find time for.  Other than the weekly net,

I sometimes go a long time without actually getting on the air.

When I do get on the air on HF, it's almost always CW.  I've always

struggled with Morse, which has never come easy to me, but I enjoy it.

Every time I return to HF after having been away for a while, I think,

"This time, I'm going to do some SSB" but every time I actually sit down,

I think, "But tonight, I'm going to do CW."  I can't explain why I like

it better, but it just seems to me to be a particularly special part of

the magic of radio.

Before closing, I'd like to finish by responding to something you

mentioned in episode 162.  You told about a member of the audience at a

talk you gave, who was asking about how much time it had taken you to

build a particular radio, seeming to suggest there was a price to pay

by investing all that time.  I love to explain to people that there is

a whole different economics to Amateur Radio.  In my professional life

in IT, I'm always promoting the idea that we should deploy and install

systems so that we will expect them to work trouble free throughout

their anticipated lifespan.  People balk at the expense of doing it

that way, but it's my job to remind them that the cost of having it

fail, in lost productivity, is far greater than the expense of doing

it right in the first place, not to mention the fact that coming along

later and remediating an inadequate deployment usually costs more than

it cost to do it wrong the first time, let alone the incremental cost of

doing it right.  Similar ideas prevail with radio.  We see professional

radio installations where many thousands of dollars are spent doing

things that we hams rarely even consider.  For many of us [raises hand]

we must do Amateur Radio out of a meager budget for entertainment,

or not at all.  But even more importantly, if we enjoy doing these

things, then the time spent laboring at our projects--transmitters,

receivers, antennas, etc.--is not a liability at all; it is an asset!

If assembling a kit, or planning and building some unique project, or

putting up a different antenna every six months, is something we truly

enjoy--even LOVE doing--then that time spent is no hardship at all.

Thanks, Bill, for the time and effort you put into providing us with

an episode of SolderSmoke from time to time.  All my life, I'd wished

for TV and radio shows about Amateur Radio, and now, they're finally at

my fingertips.  Your gift to the hobby is deeply appreciated.

73,

Jim  WB5UDE