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Wednesday, January 22, 2025

SolderSmoke Direct Conversion Receiver Challenge -- Soldering!

The DCR challenge is going well, and we have several builders making good progress.  We noticed that some first-time builders are having a little trouble with soldering. Cold or weak solder joints are the bane of the of the homebrew builder’s existence.   It happens to all of us.  A board that was working fine suddenly is not working – you poke around and touch some part and the board springs to life – you just found a cold solder joint.  Dean, KK4DAS put together a short bonus video just on soldering.  He covers the tools you need for a basic soldering station, and step-by-step instructions for reliable soldering Manhattan Style.

No Bunching Up! It is Possible to Achieve Dial Linearity (and Stability) with an LC VFO


One of the major complaints about LC VFOs is that they allegedly cause "non-linear tuning."  Essentially, this complaint claims that you will inevitably end up with your frequencies all "bunched up" at one end of the tuning range, with frequencies greatly "spread out" at the other end. BUT WE HAVE FOUND THAT THIS IS NOT NECESARILY TRUE.  With a bit of careful design work, you can avoid the dreaded "bunching up."  I have used the calculator in Bob's Electron Bunker to DESIGN VFOs that do not "bunch up" the frequencies.  

Recently, Mike WU2D built a version of the Simple X Super receiver.  It has a VFO in the 5 - 6 MHz range.  And guess what?  There is NO bunching up of frequencies. As proof, I present the tuning dial that Mike made for his completed receiver.  See above.  Note the nice linear tuning.   

So you see, success in this area is possible -- all it takes is some careful design work. 

Similar results are possible with the other major allegation about LC VFOs:  That they are inherently and irreparbly unstable.  Proponents of this theory would have you believe that only by the use of an Si5351 (or something similarly digital) is stability possible.  Again, NOT TRUE!  It is possible to make LC oscillators that are stable.  All it takes is careful design and good construction practices. 

Monday, January 20, 2025

SolderSmoke Direct Conversion Receiver Project -- Video #2 -- Building the PTO/VFO

The response to the SolderSmoke DCR challenge has been terrific -with nearly 7,000 views of the first episode!  Thanks so much for checking it out.  The goal is to convince you that you can build your own receiver and then go get you started on Homebrew ham radio.  We already have confirmation that it can be done!  Congratulations to Peter, VK3PTM and Matthew, KY4EOD who have both completed the receiver.  The boards look good and, even better, they sound great.   Videos and descriptions are here on the blog and on the SolderSmoke Discord sever.   Speaking of the Discord server, we already have a very robust conversation going,  It’s a great place to give feedback and to get your questions answered. Builders are helping builders and we at SolderSmoke are trying to answer as many of your questions as we can.  This is a beginner’s project, so all are welcome.

 

In episode 2 of the SolderSmoke Direct Conversion Receiver challenge we tackle the PTO.  We discuss a bit of the theory, walk through the schematic, and take you step-by-step through building and testing the oscillator and buffert.  By the time we are done we will have achieved JOO!  (the Joy of Oscillation).  And when you build it you will be 1/4th of the way to having build your own 40 meter receiver.

 

 

Links:

 

Join the discussion - SolderSmoke Discord Server

https://discord.gg/Fu6B7yGxx2

 

Documentation on Hackaday

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

 

SolderSmoke YouTube channel

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

 

SolderSmoke blog

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

SolderSmoke Direct Conversion Receiver Project: The Input to the Mixer from the VFO -- How Much Is Enough?


I was asked to post some pictures of how the input from the VFO (from the J-310) to the diode ring mixer looks.  The picture above is the VFO output across a 47 ohm resistor to ground through the .1 uf cap to the drain of the J-310.  The mixer is NOT connected.   The question is: Is this enough VFO signal?   

Realize that the VFO is just turning the diodes on and off at the VFO rate.  See this page for more details: 
Look carefully at the scope pattern and at the diagram.  Also look at Alan Wolke W2AEW's excellent video (URL in the above post).  You will see the importance of the VFO turning on and off the diodes.  This is how the diode ring multiplies by 1 and -1.  This is how mixing happens.  This is how audio is produced.  

Now, back to the question:  Is the output we see above "enough."   We can check to see if the VFO is turning on and off the diodes by reconnecting the mixer to the VFO and looking again at the mixer's VFO input port (with no resistor connected).  This is what I see when I do this: 


Here you can see the diodes being switched on and off on the peaks of the VFO voltage.  That is the flat topping you see.  It looks to me as if this is enough. And indeed I have no problem hearing down to the band noise (I can hear an increase in the hiss when I connect the antenna) and I can hear plenty of CW, FT-8 and LSB signals.  I am using ordinary 1N4148 silicon diodes.  

Often we hear manufacturers say that their mixer (like the SBL-1) needs 7 dbm (about 1.4519 V peak to peak across 50 ohms) input from the VFO.  But I think that is just for the SBL-1.  Ours is a homebrew diode ring.  It is, I think, different. So it might not NEED 7 dbm.  In fact, look at the voltage level differences:  Across the 50 ohm resistor we see 504 mV p-p.  But with the diode ring connected we see 1.5 V p-p.  This implies that the LO port input impedance is not 50 ohm, but is probably around 150 ohms.  Indeed when I put a 150 ohm resistor across the output of the VFO (no mixer connected) I measured aroung 1.4 V p-p 

Bottom line:  Just make sure your VFO is turning the diodes on and off. 

Saturday, January 18, 2025

Looking for Contacts on 10 meter AM from the Dominican Republic -- 29.005 MHz AM


I was listening to the Old Military Radio Net this morning and I heard Tim WA1HLR talking about some contacts that he had made on 10 meters, near 29 MHz.  So I pulled my modified CB rig off the shelf, connected a power supply and my 10 meter vertical, and began to listen.  Soon I heard CQs!  One from G4ITR and then one from  G4VZR.  I now have high hopes for at least one QSO.  So please, point those ten meter beams at the Dominican Republic and give me a call.  I am on 29.005 Mhz.  

73  Bill HI7/N2CQR

Wednesday, January 15, 2025

Ugly and Manhattan Construction from Popcorn Electronics


Todd (oops, I mean Vasily) has a really nice video on Ugly and Manhattan construction techniques on his re-born Popcorn Electronics site.  See above for the video.  The site's URL is https://qrp-popcorn.blogspot.com/

Some people apparently dislike these techniques.  To each his own, but I like the Manhattan method.  In fact, in the SolderSmoke Direct Conversion project, we are recommending the use of Manhattan circuit board tecniques.  With Manhattan, you get a lot flexibility.  At one  point, for example, the High School students told us that they had forgotten to put a needed pad on the board.  No problem!  Just glue in a new one.  Or if you put in one too many, just take one off.  

You also keep all the circuitry and all the connections on one side of the board.  This facilitates repair or modification.  This kind of thing is not so easy when you have components on one side of the board and the connections on the other side.  You spend a lot of time flipping boards over, breaking wires,  trying to remember what goes where.  Also, because the pads push the connections a couple of millimeters above the ground plane, I find that Manhattan technique actually reduces the chances for an accidental short to ground. 

There has been some discussion of where the term "Manhattan style" comes from.  Having been born on Manhattan island, I too wonder about the origin of the term.  Some see it as the result of the grid pattern (like Manhatten's street grid) that results from the rectangular or square pads that are often used.  Others point to the vertical parts placement that we see when looking at a board from the side -- the parts look like the skyline of Manhattan.   Either explanation, I think, works.  

Here is a Manhattan-style board I recently built in the Dominican Republic for my homebrew 15-10 meter SSB transceiver. I couldn't find any Gorilla glue here, so I went with Loctite Coqui. Same stuff.   Latin American super glue! 

The 10 meter Beacon at HI7/N2CQR (and reception reports)

Above is the 10 Meter beacon at HI7/N2CQR.

The first one to hear the beacon was Dean KK4DAS in Northern Virginia, within hours of it going on the air. Here is Dean's recording of what he saw and heard:

Later, Mike WN2A heard it. Pete N6QW in California may have heard it too. A number of stations are reporting reception via the Reverse Beacon Network (RBN): It is being picked up almost daily (gray-line?) by Rico DF2CK who has an amazing station in Germany. K1RA in Warrenton Virginia (also an amazing receive set-up) is also picking up the station. W3OA in North Carolina is also hearing it and reporting by RBN. TI7W in Costa Rica has also heard it. Sadly, RBN is kind of clunky with beacons -- it seems to obstinately insist that I am in Northern Virginia.

Rico DF2CK writes:

Hi Bill,

thanks for info. 3 Watt can be loud on 10 if condx are good :)

The west direction skimmer setup on 10 m is a 6 el Yagi into a SDR with
AD9255 adc and XC7Z020 fpga.
A design by Pavel Demin which I am testing for a while now.

Enjoy the Caribean, here its minus 2 C and boot high snow.

73, Rico
DF2CK

Check out Rico's amazing station here: http://df2ck.de/

Andy K1RA wrote from Warrenton (Northern Virginia): 

Hi Bill
  Cool on spotting your beacon.  With good conditions I'm surprised you're not being heard elsewhere.

  I'm running a multi-band, multi-mode skimmer for CW, FT8, FT4, WSPR & JS8CALL continuously and simultaneously covering 160m-6m, 24x7 with Redpitaya SDRs and KiwiSDR/RaspSDRs


15 minute map view through PSKreporter here:


73 & good DX'ing!

andyz - K1RA

Tuesday, January 14, 2025

Shock and Awe: The Story of Electricity --- Wonderful Video by Jim Al-Khalili (sent to us by Ashish N6ASD)

From Ashish N6ASD -- Oil Lamps and Electronics

Here is the link to the video: 


First, thanks to Ashish Derhwagen N6ASD for alerting me to this video.  You should all check out his blog

This is a really important video.  It is the best I have seen about the history of electricity and electronics.  It is from 2011, but it is still very good. Jim Al-Khalili travels through the world and displays the actual devices developed by the likes of Heinrick Herz,  Guglielmo Marconi, and Jagadish Chandra Bose.  There is great discussion of Benjamin Franklin, Volta and Galvani.  The role of electricity in The Enlightment is discussed.
  

Jim talks about the early transatlantic cables, and why some of them didn't work. 

We see Jagadish Chandra Bose developing early point-contact semiconductors (because the iron filings of coherers tended to rust in the humid climate of Calcutta!) 

There is a video of Oliver Lodge making a speech.   There is a flip card video of William Crookes (one of the inventors of the cathode ray tube and the originator of the Crooke's cross).  

We see actual coherers.  

There is simply too much in this video for me to adequately summarize here.  Watch the series.  Watch it in chunks if you must.  But watch it.  It is really great.  

Thanks Ashish.  And thanks to Jim Al-Khalili.  

https://www.youtube.com/watch?v=Gtp51eZkwoI

Monday, January 13, 2025

SolderSmoke Direct Conversion Challenge -- Video #1

This is the first in a series of videos and postings on the SolderSmoke Direct Conversion Receiver challenge.  Dean, KK4DAS takes us through an overview of the project.  He covers the architecture of the receiver, construction techniques, component sourcing and selection and generally sets the stage for the build.  Future videos will cover each board in detail.

 

We are very excited invite you to join the SolderSmoke Discord server.  This is an experiment to see if Discord is a good forum for SolderSmoke listeners to interact with us and each other on topics of interest.  For now, we will be used Discord exclusively for discussion of the DCR challenge.   To join the SolderSmoke Discord server click on the link below.

 

Links and references:

 

     Join the discussion - SolderSmoke Discord Server

     https://discord.gg/Fu6B7yGxx2

     Documentation on Hackaday

      High Schoolers Build a Radio Receiver | Hackaday.io

     SolderSmoke YouTube channel

      SolderSmoke -- Homebrew Ham Radio - YouTube

     SolderSmoke blog

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

SolderSmoke Podcast #256: HNY SKN, LA Fires, Barkhausen! Southern Cross, Homebrew vs. Kits, AN762 Kit, Woe, Beacon, ARRL Kids, SDR Build, DC RX videos, Pete Hacked! Power alternatives, KWM4, Mailbag

A Tale of Woe! 

SolderSmoke Podcast #256 is available: 



Travelouge
:  From the DR.  

Happy New Year! 

Fires in LA.  

Dean:  Breaking the Barkhausen criteria.  

Seeing the Southern Cross for the first time in 30 years. 

For all three of us:  The SolderSmoke Homebrew Challenge.  And assembling a kit. https://soldersmoke.blogspot.com/2025/01/some-history-of-homebrew-ham-radio-from.html

https://soldersmoke.blogspot.com/2025/01/the-magic-that-only-comes-from-radio.html

https://soldersmoke.blogspot.com/2025/01/steve-g0fuw-talks-homebrew-and-kits.html

________________________________

Bill's (Southern) Bench: 

-- SKN with QCX given to me by Bob.  Thanks Bob! 

-- Finishing up the AN762 .1kW amplifier.  Socketry and relays.  Working well.  

-- A tale of woe:  Some difficult troubleshooting on the 15-10 rig. Intermittent oscillation.   Naturally I blamed the TJ DC RX AF amp.  Spent a lot of time working on that amplifier.  But problem always returned.  Started looking at output from carrier osc/BFO.  Waveform weird. Then weirdness disappeared and so did the whooping.  So I rebuilt the entire carrier osc/BFO/ mixer board.  Went back to singly balanced 2 diode mixer.  Used LTSpice for the oscillator amp.. No more whooping.  Turning the diodes on and off  but not quite 7 dbm...  Should I be concerned? 

-- A 10 meter beacon!  28.233   Please listen. Send e-mail reports.   Thanks to WN2A.   

-- Antenna thoughts.  Getting a tripod.  

The HI7/N2CQR 10 meter Beacon

_______________________________

SHAMELESS COMMERCE!   Mostly DIY RF!  Lots of useful kits and boards there.  I have used their TIA boards.  Todd K7TFC is one of us.  FB store. 

Become a SolderSmoke patron.  We need the help.  Homebrew is under seige!  We are one of the few sites, blogs, podcasts that are promoting it!  Help us!  

Buy stuff from Amazon and E-bay using the links on our sites. 

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

Dean's Bench: 

-- ARRL kids day -- Exhausting.

-- VWS Makers SDR receiver build.  

-- High School DC RX Build news. How to watch the videos.  

_______________________________

Pete's Bench:  

-- Hacked! 

-- Power Alternatives. 

-- Thermatron Finals

-- KWM-4. 

__________________________

Mailbag

Dave Newkirk W9BRD (son of Rod).  Great comments on homebrew radio. And a great picture. 

Derek N9TD built the DC Receiver.  FB Derek! 

Peter VK2EMU at 39C in Australia.  HOT! 

Drew N7DA -- Some great comments on kits vs. homebrew. 

Tommy SA2CLC has a nice video about fixing the cavity resonator in his HP8640.  Respect! 

Ben KC9DLM sent good presentation from India: https://github.com/kholia/talks/blob/master/Dhiru_My_RF_Homebrew_Adventures.pdf

Scott KQ4AOP and Derek N9TD offering to 3D Print PTO coil forms.  FB!  

Donnie WA9TGT on the beautiful signals from DC receivers. 

Chuck KE5HPY's FB Altoids DC receiver

Todd VE7BPO:  POPCORN ELECTRONICS IS BACK!  Thanks Todd.  And thanks Vasily! 

Jim KA4THC has his uBITX on the air and is making contacts!  

Farhan VU2ESE fond memories of homebrew dinner with Wes and other HB Heroes (on the blog). 

Charlie ZL2CTM -- About his new Pelican Case SSB rig. 

Walter KA4KXX.  All new hams should build a transmitter. 

Buzz W3EMD  A nice QSO on 10 and then a shout out to the Old Military Radio Net

Stations that heard my beacon and reported to RBN

Sunday, January 12, 2025

Some History of Homebrew Ham Radio -- From Wikipedia and from K0IYE

Frank Harris K0IYE's Homebrew Station

From Wikipedia:  https://en.wikipedia.org/wiki/Amateur_radio_homebrew 

In the early years of amateur radio, long before factory-built gear was easily available, hams built their own transmitting and receiving equipment, known as homebrewing.[2] In the 1930s, 40s, and 50s, hams handcrafted reasonable-quality vacuum tube-based transmitters and receivers which were often housed in their basements, and it was common for a well-built "homebrew rig" to cover all the high frequency bands (1.8 to 30 MHz). After WWII ended, surplus material (transmitters/receivers, etc.), was readily available, providing previously unavailable material at costs low enough for amateur experimental use.[3]

Homebrewing was often encouraged by amateur radio publications. In 1950, CQ Amateur Radio Magazine announced a ‘‘$1000 Cash Prize ‘Home Brew’ Contest’’ and called independently-built equipment ‘‘the type of gear which has helped to make amateur radio our greatest reservoir of technical proficiency.’’ The magazine tried to steer hams back into building by sponsoring such competitions and by publishing more construction plans, saying that homebrewing imparted a powerful technical mastery to hams. In 1958, a CQ editorial opined that if ham radio lost status as a technical activity, it might also lose the privilege of operating on the public airwaves, saying, ‘‘As our ranks of home constructors thin we also fall to a lower technical level as a group’’.[4]

In the 1950s and 60s, some hams turned to constructing their stations from kits sold by HeathkitEicoEF JohnsonAllied Radio's Knight-KitWorld Radio Laboratories and other suppliers.[5]

From "From Crystal Sets to Sideband" by Frank Harris K0IYE https://www.qsl.net/k0iye/

Dear Radio Amateur,

 I began writing this book when I realized that my homebuilt station seemed to be almost unique on the air. For me, the education and fun of building radios is one of the best parts of ham radio. It appeared to me that homebrewing was rapidly disappearing, so I wrote articles about it for my local radio club newsletter. My ham friends liked the articles, but they rarely built anything. I realized that most modern hams lack the basic skills and knowledge to build radios usable on the air today. My articles were too brief to help them, but perhaps a detailed guide might help revive homebuilding. I have tried to write the book that I wish had been available when I was a novice operator back in 1957. I knew that rejuvenating homebuilding was probably unrealistic, but I enjoy writing. This project has been satisfying and extremely educational for me. I hope you'll find the book useful...

...My personal definition of “homebuilding” is that I build my own equipment starting from simple components that (I hope) I understand. I try not to buy equipment or subassemblies specifically designed for amateur radio. I am proud to be the bane of most of the advertisers in ham radio magazines. I still buy individual electrical components, of course. I just pretend that the electronics industry never got around to inventing radio communications. 

An irony of our hobby is that, when the few remaining homebrewers retire from their day jobs, they often build and sell ham radio equipment. These industrious guys manufacture and sell every imaginable ham gizmo. I doubt any of them have noticed that, by making everything readily available, they have discouraged homebuilding.

Designer: Douglas Bowman | Dimodifikasi oleh Abdul Munir Original Posting Rounders 3 Column