A Very Early Radio-Controlled Device -- Using Spark and a Coherer, in Spain

Click on the picture for a better view -- check out the coherer and the tapper 

Hack-A-Day has an interesting story about Leonardo Torres Quevedo and his very early automated chess machine.  Torres Quevedo was a Spanish inventor active in the early years of the 20th century. 

The chess device was really interesting, but two things caught my eye about this fellow: 1) he lived and conducted some of his experiments in my old home of Bilbao, Spain and 2) he built a very early radio-control system that used -- in the receiver -- a coherer as the detector.  

There is a lot material on Torres Quevedo.  Here is just a sample of what is out there  

His book:  https://www.torresquevedo.org/revistas/index.php/BIB/issue/view/12/1.  Discussion of the Telekino device is on pages 109-127. 

The Branly Tube or Coherer: https://en.wikipedia.org/wiki/Coherer

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

https://www.researchgate.net/publication/2998424_Early_Developments_of_Wireless_Remote_Control_The_Telekino_of_Torres-Quevedo

https://cyberneticzoo.com/wp-content/uploads/2010/12/Telekine-Yuste.pdf

1903 article in Electron (Spain) about the Telekino and Coherers. https://hemerotecadigital.bne.es/hd/viewer?oid=0028654330&page=6

https://alpoma.net/tecob/?p=13766   This article contains the diagram of the device (see above).  You can see the coherer with its tapper.  

Here we see the Telekino installed in a boat in Bilbao harbor.

SolderSmoke Podcast #247 -- Hating on the IC-7300, Pete Goes FT-8 with a KWM-1, Bill's 15-10 Rig, MAILBAG

Bill's 15-10 Rig -- Click on image 

SolderSmoke Podcast #247 is available: 

Audio Podcast:  http://soldersmoke.com/soldersmoke247.mp3

Video:  (482) SolderSmoke 247 -- Hating on the IC-7300, Pete goes FT8 (with a KWM-1), Bill's 15-10 rig, Mailbag - YouTube

Bill’s Bench:

The 15-10 Dual Bander.

n  10 pole crystal filter at 25 MHz.

n  G3UUR, Dishal, AADE and all that..

n  Testing woes.  Looked bad.  But it was a bad test cable. Duh.

n  VFO (Colpitts) at around 3.5 MHz.

n  Buffer blues:  Bad J-310s.  Beware!  

n  Variable cap from a Heath Q Multiplier

n  A bit of a black art – competing goals. Freq coverage, etc.

n  BFO needed an amp to turn on the diodes in the balanced modulator

n  TIA amps.   SIX dual direction TIAs.  18 transistors.

n  On a pine board (like Frank Jones)

n  Will use the N6QW all discrete AF amp.

n  Maybe an RD16 in the final?

n  Will build a second one for the DR.

 Shameless Commerce:  Mostly DIY RF and the PSSST kit.  Todd K7TFC reports:  “The P3ST is on track for Lee Deforest's birthday release (August 26th). I'm going to send out another newsletter on July 4th, and I'll give some details on P3ST development.” Results of Todd’s Survey.

Pete’s Bench

n  FT-8 on the KWM-1!

n  Presentation to the ham club.

n  Why the Icom 7300 is the anti-thesis of homebrew.

MMAILBAG:

-- SPRAT 195  Summer 2023, in the mailbox.  A happy day at N2CQR

-- Armand WA1UQO sent a wonderful book about Faraday and Maxwell… And told me Jim K8OI was heading to our area.  I met Jim at the VWS Field Day event.  FB.  Thanks Armand.

-- Tony G4WIF sent Father’s Day greetings.

-- Alvin N5VZH asking about electrolytics for his 2-B.  Hayseed Hamfest!

-- John AC2RL replacements for the IBEW.  We need to start over!

-- Steve “Snort Rosin” Smith WB6TNL was in the area.  Sorry I missed him.

-- Joh DL6ID helping us to track down origins of a homebrew receiver Grayson saw in Berlin.

-- Grayson KJ7UM was in Europe visiting his wife’s relatives.  But I think he is back in the USA.

-- Walter KA4KXX sent a QRP HB family portrait. 

-- Wouter ZS1KE sent info on surface mount soldering.

-- George Zaff KJ6VU Ham Radio Workbench – re-runs! Recommended audio processor.  Let me know how it sounds. 

-- Michael AA1TJ   Great to hear from him. 

-- Alan Wolke W2AEW on the toroids  he used in Diode Ring video.  Thanks Alan!

-- Dean KK4DAS, AI and SWR meter project  And new lexicon word:  Hamsplaining. 

-- Bob N7SUR --  Let me know we are semifinalists in the Hack-A-Day prize!  

The 15 - 10 rig from above -- Click on image

Australia and Apollo 11 -- Honeysuckle Creek

Trevor reminded me that Parkes ("The Dish") was not the only Australian antenna at work during Apollo 11.  This very nice video gives a more complete description of what happened.  

I saw one piece of Collins gear.  And some of Curious Marc's HP frequency counters.  

More on the Honeysuckle Creek Tracking Station here: https://honeysucklecreek.net/

The Carrington Event and the Current Solar Cycle (Solar Max "Sooner and Stronger")

 

From the article: 

"Sunspot activity has increased dramatically in early 2023, with sunspot numbers far exceeding NASA's predictions each month — though nothing as big as Carrington’s sunspots have been seen yet. Still, the profusion of sunspots and other solar weather suggests that the next solar maximum will arrive sooner and stronger than NASA previously predicted. Whether the incoming maximum brings with it a Carrington-level storm is a matter of pure chance — but scientists will keep watching for spotty signs on the sun, just in case."

https://www.yahoo.com/lifestyle/see-monster-sunspot-launched-carrington-120000667.html

Part III: Curious Marc Repairs an All-Discrete Freq Counter: DO NOT ATTEMPT REPAIR OF CAVITY RESONATOR

I love all the "DO NOT ATTEMPT" warnings.  Wow, even HP got so skittish about this stuff.  Marc has a great sense of humor and notes that, "no cavity resonators were harmed in the production of this video."   I like the description of the mixers and the photo of the mixer antennas. 

Another Podcast -- "Lamp Talk"

 

This is a blast (!) from the past.   A SolderSmoke listener sent this to us in 2006.   

So hey,  be careful with the high voltage!  

Another Model Rocket that Lands like SpaceX -- With a Great Description of the Flight Computer, Software, and Design

Wow, I have to give the devil his due:  this is NOT something that could be accomplished with my beloved discrete (not discreet!) transistors. 

As someone who spent a lot of time as a kid shooting Estes model rockets into the sky, this project really caught my attention.   (My simple rockets used parachutes, "streamers,"  or nothing at all to land.)  This guy uses onboard computers, software, and retractable landing gear.  Very cool.  

Thanks to Jenny List and Hack-A-Day for alerting us to this.  

Part 2: CuriousMarc Fixes an All-Discrete Counter -- "Like an IC, but in discrete form."

Marc nicely sums up this project with this line:  "It's an IC but in discrete form!"  On the same theme, he later says, "Who needs a logic analyzer when you can do a visual debug with neon bulbs?" 

Very cool.  Lots of troubleshooting and repair lessons in this video: 

-- Again we see the benefits of paper manuals.  (Todd K7TFC commented astutely on this under yesterday's post.)

-- 2N2222s to the rescue.  

-- A surprisingly large number of bad transistors (6?) found.  Why did they go bad? 

-- Marc repeatedly says, "Let me poke around."  Poking around is often important.  Mark fixes the reset line after poking around.  He is not sure HOW he has fixed it, but he has... by poking around.  Sometimes this happens.  Thank God for small favors. 

-- Marc has some fancy HP board extenders.  I am jealous.  

-- He also has a cool de-soldering tool.  More jealousy.  Want one. 

-- Marc's understanding of how the HP engineers had to put one of the flip-flops "on the edge of stability," and how his 'scope probe was capable of disturbing this stability. 

-- Remember that those Nixies are TUBES with enough voltage on them to really zap you.  So be careful in there.  This is an especially dangerous mix of transistor tech and tube tech.  With transistors you can work on them with the rig fired up.  With tubes, well, you have to be careful.

Part III tomorrow. 

CuriousMarc Repairs an old DISCRETE COMPONENT HP Frequency Counter

I really liked this repair video from CuriousMarc (aka AJ6JV).  This counter pre-dates the use of integrated circuits -- it is all discrete transistors.  Near the end, Marc mentions how this made this repair "like debugging a big integrated circuit, but with access to each transistor -- this made it quite satisfying."  I hear ya Marc -- with big ICs maybe all you would get to do would be to swap out a single IC.  There would not be much of a challenge there.  

With the older, discrete circuitry you get a good view of how Marc troubleshoots -- how he finds the precise points where the device is failing.  Note his use of the old HP paper manuals. I know this is an old guy thing, but I think the paper manuals (as opposed to the online versions)  just make the process easier.  Note too that Marc at one point had to go back to microfiche. 

The transistor tester Mark used was very cool. 

The whole physical structure of the HP device is very similar to my NYC HP8640B.  Thanks again Steve Silverman and Dave Bamford. 

I will look at Parts II and III of this series soon.  

Sam WN5C Builds a Michigan Mighty Mite and Takes it to Lake Thunderbird

 

Sam WN5C built a Michigan Mighty Mite and then went the extra mile by putting it on the air from a field location.  And what a great name this location has for a QRP operation:  Lake Thunderbird. 

Sam wrote up his experiences for K4SWL's QRPer blog: 

https://qrper.com/2023/05/guest-post-lake-thunderbird-k-2792-with-a-homebrew-transmitter/  

Below is a picture of the rig.  NOTE THE LOW-PASS FILTER.  FB OM. We wouldn't want that rig tearing up the electromagnetic spectrum. 

Looking ahead, Sam writes: 

Next step is a DC receiver (maybe the high school receiver?) and then a more substantial transmitter married together, I think. This is all incredibly fun.

Thanks Sam! 

Nine Homebrew Transceivers by Walter KA4KXX (and some QRP and QRO RC planes)

 

Our friend Walter KA4KXX in Orlando recently sent us this really cool "family photo" of his homebrew rigs.  Be sure to see the key that explains the photo (below) FB Walter.  Thanks too for the model airplane pictures. (Click on the images for better viewing.) 

Walter wrote: 

I recently realized that I am now operating nine homebrew transceivers, which would fit nicely in an “aerial” photograph, so I grabbed my stepladder and everything did fit well in the frame.  Six of them come from the BITX side of the family, with #1 and #7 direct conversion and #9 a single conversion superhet but using the NE602.  More basic information is included in the sketch.

I tried a Si5351 VFO once in the dual-band rig #4, but by the time I built the QRP Labs kit with so much closely-spaced soldering, and then added sufficient filtering and amplification to properly drive a 50 ohm load, I was exhausted!

These nine were created during the past eight years, and were preceded by eight more transceivers that I can document, but those have all been disassembled, with many of the parts being used in these later rigs.  I build my transceivers to be operated often, and since 20 Meters has been hot lately, for example, my POTA Hunter log shows over 300 CW and SSB contacts in 2023 alone, so rig numbers 7 - 9 have been earning their keep lately.

In summary I have created a lifetime total of seventeen transceivers so far, and although I am nowhere near the fifty-plus tally of Pete N6QW, I did spend a lot of years instead homebrewing many radio-controlled model airplanes of my own design.  Two photos show one example that I flew in the 2011 Blue Max Scale R/C Contest at the Fantasy of Flight Museum in Polk City, Florida against some stiff QRO competition.

—Walter KA4KXX

How they Make Raspberry Pi 4 Single Board Computers

So, if the Raspberry Pi is a key part of your new "homebrew" rig, how much of the rig did YOU actually build? 

Germany: Direct Conversion Receiver Success!

Dear Bill,

Please my apologies for my late update on our DCR project. We started with the course in the semester break and once the semester started only a handful of students were able to finish their receiver. A long shelf of shame .... 

Here is what we've got so far (those were finished at the end of April already). 3 nice DCRs completely sufficient to copy CW indoors without additional antennas starting from late afternoon. Strong stations can be heard all day. I found that coupling some 6m of wire with one or two windings to the ferrite core can boost the signal dramatically but can also increase noise. 

The PTO is based on your design (Bill Meara N26QR &  Dean KK4DAS) which was sparked by Farhan  (VU2ESE) , except that I've swapped the FET for a NPN. The input amplifier and antenna is from the JUMA active ferrite antenna by Matti Hohtola (OH7SV), the band pass filter is from Hans Summers (G0UPL), the mixer and the headphone amplifier is inspired by Pete Juliano (N6QW), you told me that the diplexer (as well as the whole DCR idea) is attributed to Wes Hayward (W7ZOI) and the perfect schematics of Rick Scott (N3FJZ) where crucial to get me started in the first place. I enjoy keeping track of original sources, as I would do in science. This shows that even little achievements are based on the ideas of many other great people -  and this is nothing to be ashamed of. 

This was a lot of fun! Thank You!

Best and yours sincerely,

Andreas

Wow, the direct conversion re-engineering of education continues, this time at graduate-school level with biologists in Munich!  Amazing.  

Andreas points out that his group was also plagued by semester-related problems that caused many additions to the German shelf of shame.  Let's hope that someday soon these builders will come to their senses and join the ranks of those who have finished their homebrew projects.  

Looking at the schematic (below) of Andreas's project, there are a couple of significant differences from ours:   

-- Their AF amp used a transformer-less push-pull design.  We had considered this but abandoned it thinking that it would be too complicated to explain the workings of this circuit to our students.

-- Most significant, is Andreas's use of a ferrite rod antenna and an RF amplifier.   I think a simple 33 foot quarter wave antenna (with a ground or a counterpoise) might work better.  But hey,  to  each his own!   The important thing is that a number of these receivers were successfully built.  They look beautiful.  

Congratulations to Andreas and the successful Munich homebrewers!  

 

Canadian Build of the Direct Conversion Receiver -- Do This in Your Town! (Video)

This is so cool.  We have been getting reports from Daniel VE5DLD up in Regina, Saskatchewan, Canada.  Daniel is a teacher and he has been building the receiver with a group of students.  

They have been doing very well.  They may end up having more success than we have had here.  

This morning Daniel fired up his build of the receiver and it was inhaling 40 meter signals.  You can hear the CW and the FT8 and you can also hear shortwave broadcast signals just above the 40 meter frequencies.  Congratulations to Daniel!  He is now one of very few radio amateurs who has homebrewed a receiver.  I think his students will soon do the same.  

Daniel's students have built several of the boards and appear to be on the brink of full success.  

Their PTOs look very nice. 

The AF amps were the most challenging of the boards.  Theirs look great.  Excellent soldering. 

We want the receiver project that we carried out at our local high school to serve has a model for others.  After all, we got our inspiration from Farhan in Hyderabad.  We want to see this kind of homebrewing continue.  All of the information on this receiver is on our Hack-A-Day.io page: 

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

We strongly encourage others around the world to find ways to use this project to teach analog electronics.   We think the circuit strikes the right balance between simplicity and usefulness -- when they are done, the students will have a useful receiver capable of worldwide reception.  

Please let us know if you are building this receiver; we are especially interested in the use of this receiver in student-focused group-build projects.  

"Ham Radio Ireland" June 2023 edition (and Free Propagation Guide)

 

Get the latest edition here: 

 https://www.docdroid.net/VlSXkrD/crnews0623-pdf

Thanks to Steve Wright EI5DD.  I had the great good fortune of running into my friend Michael EI0CL on the 17 meter band recently.  Mike mentioned that he had been talking to Steve.  So Steve is in good company.   

Steve also sent me a useful Solar Indices Data Card, suitable for lamination.  You can download it here: 

http://soldersmoke.com/Solar Indices Data Card.pdf

Can you ID this Receiver? Grayson Finds a Homebrew Receiver in Germany. From the GDR. Circuit? Schematic? Thermatrons?

 

Grayson Evans KJ7UM (the author of  Hollow State Design) was recently in Germany where he spotted this museum display of a homebrew receiver built in the GDR (the old East Germany) around 1983 by a 13 year-old.   Very cool. 

Here is today's task for SolderSmoke:  Can you provide any more info on this receiver? The card indicates 0-V-1 which would be a regen with no RF amplifier, right?  Maybe something like this: 

https://www.qsl.net/pa2ohh/15tuberx.htm

 Look carefully at the pictures and try to gather any additional information on the receiver or its builder.  

Thanks Grayson! 

George Heron N2APB talks about Coherent CW at FDIM: Interview #7 by Bob Crane W8SX

It was great to hear George's voice again.  I was a big fan of his "Chat with the Designers" podcast. And it was great to see that Pete Eaton WB9FLW (an old friend of SolderSmoke) was also involved in this presentation.  

At FDIM George was talking about Coherent CW.  Now, my views on CW have been made quite clear, but I am going to deliberately avoid snide comments about how Coherent CW might be a contradiction in terms.  Thank you.   I think this is something that Pete N6QW and I can agree on. 

Nevertheless, this is all technically interesting.  This reminds me of what happens with WSPR.  But I wasn't quite sure what George was getting at with his discussion of the phase of the incoming signal -- I can see the need to get the receivers' narrow filter exactly on the transmitting station's frequency, but why the phase?  

Here is Bob Crane's interview with George: 

http://soldersmoke.com/N2APB23.mp3

And here are a couple of things with background info on CCW. 

https://www.sigidwiki.com/wiki/Coherent_CW

http://www.arrl.org/files/file/Technology/tis/info/pdf/7509026.pdf

Thanks George, thanks Pete, and thanks Bob. 

Farhan VU2ESE FDIM Interview (#6) by Bob Crane W8SX: VHF Rig, sBITX, and Good News on Raspberry Pi 4

It was great that Bob was able to catch up with Farhan and talk to him about his VHF rig and about the sBITX. 

    

Farhan said that the VHF rig (the BITX23) was presented at the homebrew show-and-tell as a project.  The idea was to encourage others to get into VHF homebrewing.  Farhan points out that many of us are reluctant to go into VHF building, thinking that we need special or exotic test gear. No true says Farhan.   He is trying, with this rig, to bust this myth.  FB.

    

On the sBITX, Farhan points out that he too -- coming as he does from the homebrew tradition -- finds some of the modern rigs quite intimidating.  So he designed the sBITX to be less intimidating.  It is, he says, a tinkerable rig that could be homebrewed. It is all open source.  

    

Farhan points out that the rig is built around the Raspberry Pi 4, a device that has recently been hard to obtain.  This has driven up the price of the sBITX a bit.   But good news:  Farhan says that the word on the street is that the Raspberry Pi 4 will be available in quantity starting at the end of June.  

Here us Bob's interview with Farhan: 

http://soldersmoke.com/VU2ESE23.mp3

BITX23 VHF Rig

And here is a video of Farhan describing the BITX23: 

https://soldersmoke.blogspot.com/2023/05/farhan-describes-his-new-2-meter

Thanks Fathan!  Thanks Bob! 

Rick Campbell KK7B at FDIM: Interview #5 by Bob Crane W8SX

/KH6

Having recently been involved in an effort to teach students about radio electronics, I found Rick's comments especially interesting.  

At FDIM,  he and his daughter were presenting a hidden transmitter hunt using rigs and Yagis at 432 MHz.  This was in part the result of his students having wanted to do something new with ham radio.  It was very impressive that the students had done this all with gear that they had built themselves.  Rick also made sure that they all learned how to solder.   

Rick ended the interview with a nice shout-out to SolderSmoke. 

Here is the interview: 

http://soldersmoke.com/KK7B23.mp3

And here is a paper Rick did on VHF.  It is a bit old, but it is good.  

 http://www.pnwvhfs.org/conference/2009/Introduction-to-VHF-Experiments.pdf

 Thanks Rick!  Thanks Bob! 

Eric Schwartz WA6HHQ of Elecraft -- FDIM Interview #4 by Bob Crane W8SX (audio)

 

It was really cool that our correspondent at FDIM caught up with Eric Schwartz WA6HHQ of Elecraft.  Some highlights from the interview: 

-- Eric met Wayne Burdick through the NORCAL 40 (Wayne had designed it, and Eric was writing articles about it).  That was a very influential rig -- it was the basis for a book and a CALTECH course by David Rutledge. 

-- Elecraft has a strong QRP element in its DNA. 

-- The K2 is "Heathkit style" and offers the builder the opportunity to understand the rig at the component level. 

-- Eric says that using something you built yourself is worth at least 10db. 

Here is Bob's interview with Eric:  

http://soldersmoke.com/WA6HHQ23.mp3

Thanks Eric and thanks Bob.  

Jerry KI4IO (Wizard of Warrenton) Describes His ALL ANALOG Phasing Transceiver -- Bob Crane FDIM interview #3 (audio)

Wow, this one really resonated with me.  Jerry had me won over when, early in the interview, he described his decision to dispense with the Si5351/Arduino combo:  "I said the hell with this digital stuff!"  I hear you Jerry.  I feel your pain OM.  

Jerry then goes on to describe a rig with bits of circuitry from some legendary sources:  The Ugly Weekender transmitter.  SSDRA and EMRFD.  W7ZOI's 1968 Direct Conversion receiver.  

Jerry discusses the "presence" of the direct conversion receiver.  And he decries the pernicious effects of AGC.  (Indeed, real hams MANUALLY control the gain.) 

The Wizard of Warrenton then shares some important tribal wisdom:  After building that new piece of gear, leave it on the bench for a couple of weeks.  Beware of "radio infatuation" (what a great term -- we will have to include this in the lexicon).    Jerry points out that while at first, the new rig will seem just perfect, with time time the need for improvements and modifications will become apparent. 

Jerry also has connections to India and Nepal (where he helped Father Moran).  See: https://www.qrz.com/db/KI4IO

Here is W8SX's interview with Jerry: 

http://soldersmoke.com/KI4IO23.mp3

Thanks Jerry!  Thanks Bob! 

Greg Latta AA8V on Making Aluminum Chassis -- FDIM Interview by Bob Crane W8SX #2 (audio)

Our correspondent Bob Crane W8SX caught up with prolific builder Greg Latta AA8V.  Greg gave an FDIM talk on how to make aluminum chassis without having a machine shop.  I guess I am now going to have to buy a belt sander from Amazon.   

I was really glad that Greg mentioned his real passion: retro building.  FB Greg.  I have talked to Greg several times on the ham bands -- it is always an inspirational experience.  

Here is Bob's interview with Greg: 

http://soldersmoke.com/AA8V23.mp3 

Here is Greg's pdf file on his aluminum chassis construction technique.

https://www.frostburg.edu/personal/latta/ee/chassis/aluminumchassisconstructionnomovies.pdf 

And here is Greg's amazing web site: 

https://www.frostburg.edu/personal/latta/index.html

Thanks Greg!  Thanks Bob! 

Hans Summers G0UPL and his new QMX: The Bob Crane W8SX FDIM Interviews Part 1 (audio)

http://qrp-labs.com/qmx.html

We are very pleased and grateful to present this year's series of Four Days in May interviews by our FDIM correspondent Bob Crane W8SX.   Once again Bob did an outstanding job interviewing the FDIM participants. 

In this interview, the amazing Hans Summers talks about his latest QRP Labs kit, the QMX.  It is a combination of the QCX Mini and the QDX.  

Hans explains the M:  QMX. The M is for Marriage. Magnificent. Merger. Marvelous, many things like that. It’s what you get when you marry the mechanical and conceptual design of QCX-mini, with the SDR, multi-band digital implementation of QDX. Simply: QDX + QCX-mini = QMX. 

It has a very clever switching power supply that automatically adjust to prevent spurs and harmonics from the power supply from appearing in the band of interest. 

I was especially interested in his plans to implement an SSB option in future software updates.  Hans will use the same very complicated SSB generation scheme used in the trueSDX rig, but hopes to achieve higher performance and  improved signal quality due to the much more robust hardware of the QMX. 

Here is the interview: 

http://soldersmoke.com/G0UPL23.mp3

Here is the QRP Labs site about the QMX:  http://qrp-labs.com/qmx.html

Here is the QRP Labs web site: http://qrp-labs.com/

And here is a really wonderful and very current article by Hans on the evolution of QRP Labs and its rigs from 2010 right on up through 2023 and the QMX.  It is really interesting: 

http://qrp-labs.com/images/qmx/docs/fdim2023.pdf

Thanks to Bob Crane W8SX, Hans Summers G0UPL, and all of the FDIM organizers. 

Hans G0UPL-- Homebrew Hero

Coffee with Farhan VU2ESE (video)

Early morning in the N2CQR shack, May 16, 2023

-- Propagation

-- Web sites (RBN, PSK Reporter, others)

-- CW

-- Homebrew rigs

-- VFOs

PSSST! MostlyDIYRF Will Sell a Kit of Pete's Rig!

 

From the wizard of Newbury Park! The Pssst Transceiver Kit

Sometimes you just want to put something together and have it work, you know? No futzing with isolation pads, superglue, and blank copper-clad, no dead-bug make-shifts, no ugly, ugly, ugly component acrobatics. Sometimes, a nice and orderly printed-circuit board that's just like uptown, along with sorted and clearly-labeled components and step-by-step instructions, can provide respite from the terrors and risks of scratch-built homebrewing. Just once in a while, mind you. Here's a dandy kit that can get you on 15, 17, or 20 meters pretty quickly, is fairly simple to put together (only eight transistors), and is small enough to take on a trip. At the same time, its modular architecture makes it also an experimenter's platform. It's not a single PCB and a mess of components. Each circuit block is its-own module which you can swap out for a different one you scratch build later on.

Why would you want to do that? Suppose, for instance, you want a narrower passband for the SSB filter (maybe even narrow enough for CW use). Likewise, you might want a wider or narrower front-end bandpass filter, or a different frequency response for the mic amp. Or, how about an active or triple-balanced diode-ring mixer for the product detector, or maybe higher gain in the RF amplifier on receive? Because the circuit modules in the Pssst just plug into a motherboard, you can unplug one and put another one in. Of course, you can do this to change bands as well. All you need to do is to swap out the front-end band-pass filter and you can put the rig on 15 or 17 or 20 meters (along with changing a jumper on the digital VFO/BFO board). The Pssst was designed and originally built by Pete Juliano, N6QW (Pete's Simple Single-Sideband Transceiver). Rather than use bidirectional circuits for many of the blocks, he relies on inexpensive relays to "steer" the modules from receive to transmit modes. Each active module uses a single transistor for gain (except for the final amp which uses three), and in that way the Pssst is a minimal design that, because of its modular architecture, can be made as complex and as elaborate as the experimenter wishes. The Pssst is designed for a nominal output of 5 Watts on 20M when fed with 12VDC. By feeding the final amp with a higher voltage and providing some active cooling (from a three-dollar "pancake" fan), output can be increased to beyond 15 Watts. In addition to complete and detailed kit instructions, the Pssst design has an existing Groups.io "reflector" forum for the exchange of ideas and questions. The kit will be available in two basic versions: with or without enclosure panels and hardware. Available on the 150th birthday of Lee DeForest, the inventor of the Triode (August 26th)

This was in the latest newsletter from MostlyDIYRF.  

Thanks to Pete Eaton for alerting us. 

FB Todd!  

https://mostlydiyrf.com/

Farhan Speaks to Students about Satellites and Direct Conversion Homebrew Receivers (audio)

In our talks at the local high school we have frequently mentioned Ashhar Farhan, his Cubesat experience, and his use of a direct conversion receivers teach electronics to students in Hyderabad, India.  So we were really please to have the opportunity to bring Farhan himself in to speak to the students we have been working with.  

Here is the audio of Farhan's talk: 

http://soldersmoke.com/FarhanTJ.mp3

The acoustics in the room are not great, so you may have to listen carefully, but it is worth it.  Farhan dispenses a lot of tribal knowledge and wisdom about satellites and about the value of homebrewing simple radio equipment. 

Farhan and Bill Fire up the sBITX and (at the other end of the tech spectrum) a Direct Conversion Receiver (video)

At the high tech end: the sBITX.  At the low tech end: The high-school direct conversion receiver. 

Check out the frequency readout on the DC receiver!  

Farhan Describes his New 2 Meter SSB Transceiver (Video)

On May 16, 2023 Farhan gave us a look at his new BITX23 2 Meter Transceiver. Two days later he made a presentation on this rig at the Four Days in May event. Highlights: -- Use (and non-use) of the Cascade tool -- Cascade and the original BITXs -- ADE-1 -- SI570 -- Raspberry Pico -- Diplexer -- Different Grounds to get rid of digital noise -- Gimmick Capacitors (and gimmicks made from coax) -- Ugly SMD Capacitor Soldering -- Tombstoning! -- Melting RG-174 Coax -- No need to learn Arduino programming -- Dilbert! -- Bill and Pete -- Techie Tatts! Thanks Farhan!

Two days later, Farhan presenting the rig at FDIM

Two Videos from Farhan's Visit (more to follow)

 

Farhan Visits Northern Virginia En Route to FDIM (Videos to Follow)

Mike KD4MM, Farhan VU2ESE and Dean KK4DAS

Farhan VU2ESE was in Northern Virginia this week, on his way to the Four Days in May Event at the Dayton Hamvention.   We had a great visit with Farhan.  We took him out to the Thomas Jefferson High School for Science and Technology where he shared with the students tribal wisdom about building CubeSats and about building simple direct conversion receivers.  Farhan's use of direct conversion receivers to teach homebrewing to students in Hyderabad inspired our efforts in Northern Virginia.  We often referred to Farhan when speaking to the students here, so it was really great to give them a chance to talk to him directly. 

From the high school we went to the local restaurant at which Vienna Wireless has its weekly lunch. Many of the people at this lunch are also members of the VWS makers group.  This was a lot of fun. 

Don KM4UDX even brought in his somewhat eccentric build of the uBITX transceiver designed by Farhan.  Don's rig is labeled "The uBITX of Life."  It has also been called "The Franken-uBITX." Whatever the name, Farhan was clearly pleased to see Don's handiwork. 

I shot a lot of video during Farhan's visit (last time I failed to do this and regretted it).  I will put these videos up on the SolderSmoke YouTube channel during the days ahead. 

Thanks Farhan!