Nick M0NTV's Really Useful SDR Transceiver (video)

Even though I am more of an HDR guy, I really liked Nick's SDR rig.  I like the modular approach, with all the modules inside a transparent plastic box (see below).  Don't worry about the shielding Nick -- I had the same concern about my BITXs in wooden boxes, but they worked fine. 

Nick really did a great job on the video.  The bloc diagram was especially useful, both on the hardware and on the software.  Very cool.   It is nice to use this phasing approach,  with the digital magic happening at audio frequencies.   I fear that soon FPGAs and direct digital sampling will take the hardware fun out of these rigs.  We already have a bit of that with the RTL-SDR dongles. 

Very cool how the Teensy takes care of the 90 degree audio shift.   I had to do that with chips in my phasing receiver. When I first saw Nick's bloc diagram, I was looking for the audio phase shift network -- then he explained that that was in software, in the Teensy. 

Nicks arrangement for switching the filters is very nice.  

Thanks Nick!  

 

A Wizard Near Blackpool: M6AGC's Wonderful Homebrew Rigs

https://www.qrz.com/db/M6AGC

Alan's YouTube Channel:  https://www.youtube.com/channel/UCISxWaAc5xW6oFElxGN4xWg

One of Alan's recent projects (spotted on Facebook): 

Pete N6QW and Steve G0FUW Talk to RSGB About Homebrew (Video)

Wow, what an unexpected treat!  Here we can watch Pete N6QW and Steve G0FUW talk to the Radio Society of Great Britain about homebrew radio.  Steve talks about kits and scratch-built rigs.  I really liked seeing his early rigs and his description of how building these rigs helped him become a more advanced homebrewer.  I also liked his mention of George Dobbs as a guiding light in the QRP and homebrew world. 

Pete focuses on SDR and provides a really great description of this approach to homebrew.  I was struck with how great it is that, after a lifetime of HDR building, Pete is willing to embrace this new technology. He talks about it as part of "a learning journey."  As always, he sets the example for us all.   

Thanks to Pete, Steve, and RSGB. 

The Amazing Rigs of WA3TFS

There are a lot of great ideas and circuits on WA3TFS's page.   He spans the SDR-HDR divide.   He makes great use of simple SDR dongles.  Check out his QRZ page and the web site that describes his projects in more detail: 

https://www.qrz.com/db/WA3TFS

https://044640f.netsolhost.com/

An End to the HDR - SDR Conflict? Kevin AA7YQ Combines the Best of Both Worlds

We've had some pretty amazing contact with Kevin AA7YQ over the years.  Kevin and I originally bonded due to our common experience with parachutes  (he was smoke-jumper, I jumped while in the army).  Kevin once used a parachute to insulate a QRSS beacon.   And one day, while thinking about SolderSmoke during a drive through Montana, Kevin turned on his rig only to hear... ME!  He caught one of my infrequent CW contacts. TRGHS.  

Now we hear that OM Kevin may be poised to end the HDR-SDR civil war that has for so long been dividing our great podcast.  Can Kevin's new rig heal our wounds and allow us to enjoy the beauty of SDR waterfalls while not forsaking the joy of hardware defined rigs?   Kevin will soon launch a blog describing his effort at rig-building. See below for a preview.  Stay tuned.  

Kevin wrote: 

I am currently working on a new rig design.  It is a hybrid HDR(Hardware defined)/SDR radio that incorporates some classic superhet design along with some of the more useful features of SDR.  I have found that pure SDR is really not that enjoyable for me.  I love using GNU radio to mock up and test design concepts, but SDR basically dilutes the “magic” of radio to nothing more than software and touchscreens, stuff we use every day all day.  Its not the Ham Radio I grew up with as a kid and was fascinated by.  On the other hand, I have always fought temperature drift, large variable capacitors minimal tuning range, and associated with classic VFO and VXO designs.  In fact, in 1997, for my senior capstone design in EE at Montana State University, I designed a 20m superhet that used a DDS LO.  At the time DDS was cutting edge technology I used an AD7008JP50.  I had to beg and plead with ADI to get a couple samples for my design, since they exceeded my self-funded college student project budget. 😊  But that’s another story.  SDR has made me grow extremely fond of the waterfall display.  I love having the visual “situational awareness”  of what is going on in a moderate bandwidth outside of the spot I am tuned to. I also am a big fan of digital filtering and modification-ability that comes with boot-loadable microcontroller designs.  So this design includes most of the real highlights of SDR but does not take the fun out of designing,  building, and operating a HDR.

Anyhow, this design is a big goal of mine to complete and build in 2021.  I am not retired yet so I still have to balance, work, family, and tinkering time, but I am very excited about this project.  I have “noodled” this design to the point of what I have achieved full-on “analysis paralysis”.  That is, I keep designing and redesigning, optimizing, and figuring to the point where after months of thought, I have nothing to show for it 😊.  So my New Years goal for 2021 is to make “good enough” rather than “perfect” design decisions and move forward.  I will keep you posted on the design and possibly start a blog so I can get some peer review input from the greater RF Design/Homebrew community on my project.  I’ll keep you informed on my progress.

SolderSmoke Podcast #227: Solar System, SDR, Simple SSB, HA-600A, BITX17, Nesting Moxons? Mailbag

SolderSmoke Podcast #227 is available: 

http://soldersmoke.com/soldersmoke227.mp3

Travelogue

Mars is moving away.  Jupiter and Saturn close in the sky.  And the Sun is back in action – Cycle 25 is underway.  Also, the earliest sunset is behind us.  Brighter days are ahead.

Book Review:  “Conquering the Electron”   With a quote from Nikola Tesla. 

No real travel for us:   Hunkered down.  Lots of COVID cases around us.  Friends, relatives, neighbors.  Be careful.  You don’t want to be make it through 10 months of pandemic only to get sick at the very end.  SITS: Stay In The Shack. 

Pete's Bench and Tech Adventures:  

 Backpack SDR  keithsdr@groups.io

 Hermes Lite 2

 Coaching SSB builders

 G-QRP talk  

 A new source for 9 MHz crystal filters

 Bill's Bench: 

Fixing the HA-600A Product Detector.  Sherwood article advice. Diode Ring wins the day.  Fixing a scratchy variable capacitor.  Studying simple two diode singly balanced detectors.  Polyakov.  Getting San Jian frequency counter for it.

 

Fixing up the 17 meter BITX.  Expanding the VXO coverage.  Using it with NA5B's KiwiSDR. 

Resurrecting the 17 meter Moxon.  But WHY can't I nest the 17 meter Moxon inside a 20 meter Moxon?  They do it with Hex beams.  Why so hard with Moxons? DK7ZB has a design, but I've often heard that this combo is problematic.  Any thoughts?   I could just buy a 20/17 Hex-beam but this seems kind of heretical for a HB station.

Suddenly getting RFI on 40 meters.  Every 50-60 Hz. Please tell me what you think this is (I played a recording).  

MAILBAG:  

Dean KK4DAS’s Furlough 40/20

Adam N0ZIB HB DC TCVR

Tony G4WIF  G-QRP Vids.  Video of George Dobbs. 

Grayson KJ7UM Collecting Radioactive OA2s. Why?

Pete found W6BLZ Articles

Rogier KJ6ETL PA1ZZ lost his dog.  And we lost ours. 

Steve Silverman KB3SII -- a nice old variable capacitor from Chelsea Radio Company. 

Dave K8WPE thinks we already have a cult following.

Dan W4ERF paralleling amps to improve SNR. 

Jim W8NSA -- An old friend. 

Pete Eaton   WB9FLW    The Arecibo collapse 

John WB4GTW old friend... friend of: 

Taylor N4TD HB2HB  

And finally, we got lots of mail about our editorial.   No surprise: Half supportive, half opposed.  Obviously everyone is entitled to their opinion.  And we are free to express ours.  It’s a free country, and we want it to stay that way. That is why we spoke out.

Yesterday the Electoral College voted, finalizing the results.  All Americans should be proud that the U.S. was able to carry out a free and fair national election with record turn out under difficult circumstances. And all loyal Americans should accept the results. That’s just the way it works in a democracy.

We are glad we said what we said. It would have been easier and more pleasant to just bury our heads in the sand and say nothing.  But this was a critically important election and we felt obligated as Americans to speak out.  We'd do it again. And in fact we reserve the right to speak out again if a similarly important issue arises.  

Adding 10 kHz of Coverage to My BITX 17

 

Solar Cycle 25 is underway.  The Solar Flux Index and Sunspot numbers are up considerably.  I have dusted off my old BITX17 transceiver.  This time around I am using it in conjunction with a waterfall display provided online by NA5B's KiwiSDR receiver, which is located about 9 miles east of me. This SDR receiver allows me to see the entire 17 meter band.   It was this panoramic display that made me pay more attention to the fact that the Variable Crystal Oscillator (VXO) that I am using in this rig prevented me from tuning the lower 10 kHz of the 17 meter phone band (18.110 -- 18.120 MHz). 

I use two crystals switched by a relay to cover the band. One is at 23.149 MHz, the other at 23.166 MHz.  The crystal filter is at 5MHz.  With a coil and some caps I could move the frequencies of the oscillator enough to cover 18.120 to 18.168 MHz (top of the band). 

When I first built this thing, I kind of wrote off the lower 10 kHz of the phone band.  I couldn't get the oscillator to work that low, and I was already satisfied with the top 48 kHz.  But the NA5B waterfall often showed SSB stations in that lower part of the band.  I wanted to talk to them.  So I started thinking about how to do this.       

Looking at my schematic (above) I remembered that most of the frequency lowering was done by L1, a 3.2uH toroid.  I figured that to go a bit lower, I would just have to add inductance.  But I didn't want to lower the frequency provided by BOTH crystals -- I just wanted to bring the frequency with the lower crystal down a bit.  

In my junkbox I found a 1 uH coil.  I disconnected the lower lead of the 23.149 MHz crystal from its connection to the relay.  I soldered the 1 uH coil between the crystal and the relay (see picture above).  This moved the lower limit down to 18.087 MHz. 

Now crystal one provides 18.087 - 18.144 MHz 

         crystal two provides 18.137 - 18.167 MHz

So now I have the whole phone band.  Bob is my uncle. TRGHS. 

This was a very quick and satisfying little fix. As Pete says WYKSYCDS: when you know stuff you can do stuff.  Indeed.  And as I re-build and repair gear that I built years ago, I am often reminded that as time goes by, we learn more. We end up knowing more and being able to do more.   

I am also planning on rebuilding my 17 meter Moxon;  this time I will make it better and stronger.         

SolderSmoke Podcast #226 The U.S. Election, Solar Cycle, uSDX, Hermes, HP8640B, SGC 600 Sig Gen, HA-600A, Mailbag

SolderSmoke Podcast # 226  

http://soldersmoke.com/soldersmoke226.mp3

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

About the U.S. election

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

Mars:  Setting early, will have to shift to evening observation.  Weather has been poor. 

Sunspot Cycle 25 is underway -- SFI 78, SN 32  

The Gliessberg cycle

Pete's Bench:  #49,  #50,  uSDX,  Hermes Lite

Bill's Bench: HP8640B,  Global Specialties Corp 6000 counter, Lafayette HA600A.

MAILBAG:

Peter VK2EMU Sent me copy of 1947 Handbook.  Thanks Peter

Brad W1BCC Spotted 10 S-38s for 80 bucks on Craig’s list.  What’s going on here? 

Dale K9NN sent both Pete and I care packages with very cool part, including DG Mosfets

Stuart ZL2TW sent me Les Moxon’s Antenna Book.  TRGHS. Moxon will be back! 

Alvin N5VZH got his receive converter with a little Tribal Knowledge from SS. 

GM4OOU The Bitsy DSB rig from Scotland

Peter VK3YE DSBto DC incompatibility SOLVED

Paul VK3HN's Digital SWR and Power Meter and Low band AM TX VFO/Controller FB Videos. 

VK2BLQ alerts us to article about Jac Holzman of Elektra Records. 

AA0ZZ great message on assembler language and writing software the hard way. 

SolderSmoke Podcast #225: Mars, uSDX, G-QRP, HP8640B, DX-390, Rotary Tools, Walla Walla SDR, MAILBAG

SolderSmoke Podcast #225 is available

http://soldersmoke.com/soldersmoke225.mp3

Mars,  West Coast smoke.

Pete's Activities: 

-- DC receivers.

-- CW offset

-- GQRP talk

-- The uSDX project

Bill's Bench

-- Sliding into the Vintage Test Gear Cult:  HP8640B . 

-- Fixing up and figuring out Radio Shack DX-390 receivers.  

-- 220 to 110 on a few remaining devices.     

-- Got myself a Dremel-like rotary device.  

Tech News: 

-- ARRL/TAPR Convention:  SDR project from Walla Walla University students.   Intuitive explanation for why desired and image freqs in a mixer come out with very useful phase differences.  

-- Chuck Adams' Amazing Lab Notebook.   Includes a simple circuit to measure resistance and Q in crystals.  FB. 

MAILBAG: 

-- Dino KL0S  SITSing in his shack, homebrewing 9 MHz filters  FB Dino.  Airborne! 

-- Dave NT1U sent us the famous 1968 QST Article by W7ZOI re DC RX.  

-- Ron K0EIA listening to SWBC staions with uBITX.  

-- Ted AJ8T  Korguntubes making a 12AX7 equivalent.  

-- Joel N6ALT sent me a nice DX-390 manual.  Thanks Joel

-- Bob KD8CGH alerted us to the uSDX project -- story on the blog. 

-- Craig AA0ZZ Sent a great message with insights on computer code -- I will put up on the blog. 

--Tracy KN4FHX reports on optimistic prognosis for SolarCycle 25.  Some chickens may have to be sacrificed.   

-- Stephen M0OMO Thanks SolderSmoke for rekindling interest in this hobby. 

-- Paul VK3HN  has a cool new rig -- The Prowler -- check it out

-- Steve N8NM working on his Sunbeam car -- Pete already knew about the carburetor synch problem.  N6QW knows everything. 

Mixer Insights using Propellers and Cameras -- From Walla Walla University. And SDR Design Info.

 

Pete Eaton sent us this video from the 2020 ARRL/TAPR Communications Conference.   I have the portion of interest cued up (above).  (The portion of interest begins at 6:59:46.)

There is a lot of really cool SDR design info in this video and in the associated paper  (the TAPR site says you have to pay the ARRL $9 for the paper, but in the comments someone says the papers will be available free after the conference).  

What caught my attention was the students' discussion of mixer action.   They use an analogy with a spinning propeller (the incoming RF) and a camera (triggered by the local oscillator) that samples the incoming signal at a specific rate. This is analogous to a Quadrature Sampling Detector. 

The really interesting part for me was how this analogy allows us to see how phase differences between the desired signal and the image signal arise.   These phase differences permit an SDR receiver (or indeed an old fashioned phasing Direct Conversion receiver) to reject the image while allowing the desired signal to pass.  

This is a key point in understanding mixers, and is really quite amazing. Before I saw this video, I had just come to accept (without understanding WHY) that the desired signal and the image signal would have phase differences, EVEN IF THEY WERE COMING OUT OF THE MIXER AT THE SAME FREQUENCY.  It is this phase difference that allows us to knock one down while allowing the other to pass. The propellers and cameras of Walla Walla University gave me insight as to how and why these phase differences exist.  

In their paper, the Walla Wall group mention uSDX, the project that is currently generating so much excitement around the world: 

Low-cost is not the only reason SDRs have become more popular among the amateur radio

community. More recently, Guido Ten Dolle’s μSDX open source transceiver has generated

increasing interest in quadrature sampling down-conversion SDRs in the homebrew QRP

community. Guido, PE1NNZ, was able to modify the QCX, QRP transceiver for SSB operation

with an efficient class-E amplifier, using only an ATMEGA328 and Arduino code to run the QSD

SDR. This groundbreaking work in this type of SDR has inspired various renditions of Guido’s

radio, fostering a lively groups.io group that can be followed at https://groups.io/g/ucx.

Kudos to Caleb Froelich, Dr. Rob Frohne KL7NA,  Konrad McClure, Joshua Silver, and 

Jordyn Watkins KN6FFS,  all of Walla Walla University,  for some really impressive work.  (BTW:  Rob tells me that back in the mid-90s he too built one of Rick Campbell's phasing receivers and wrote a QST article about it  (probably the first SDR article published by QST).  Details on the project are here: http://fweb.wallawalla.edu/~frohro/R2_DSP/R2-DSP.html

Global Collaboration: The uSDX -- A Multi-Mode QCX

Bill:

There is a new open source, home brew, multi band, multi mode QRP transceiver that grew out of the QRP Labs QCX. Through some serious magic it retains an efficient class E RF amplifier for sideband and digital modes. It crams impressive SDR capabilities into an Arduino. More info at https://groups.io/g/ucx/topics

The basic work appears to have been accomplished by Guido Ten Dolle PE1NNZ. It uses pulse width modulation of the PA supply voltage to transmit  modes other than CW while retaining class E efficiency and uses a direct conversion SDR receiver.

 https://github.com/threeme3/QCX-SSB .

There are several variants by different developers. I built a variant designed by Barbaros Asuroglu WB2CBA  

https://antrak.org.tr/blog/projeler/usdx-an-arduino-based-sdr-all-mode-hf-transceiver-pcb-iteration-v1-02/ that uses through hole components (mostly) and I'm pleased with it's performance. I also designed and 3D printed a case.

This has an interesting development process with contributions by many, including the usual gang of suspects: Hans Summers, Ashhar Farhan, Manuel DL2MAN, Kees K2BCQ, Allison KB1GMX and Miguel Angelo Bartie PY2OHH. I apologize to the many others whose names I didn't list.

The band switch multiband version by DL2MAN is even smaller, but with SMD components which I wasn't ready to tackle yet.

BTW - your podcast encouraged me to go in this direction. I built a BITX 40, a uBITX (sent you a pix of it in an old Heathkit Twoer case), U3S, QCX and now my first step from kits to built from plans.

73

Bob   KD8CGH

https://antrak.org.tr/blog/projeler/usdx-an-arduino-based-sdr-all-mode-hf-transceiver-pcb-iteration-v1-02/

Using SDR without SDR Hardware -- N2CQR Adjusts Analog BITX20 using Web SDR

I know what you are thinking:  Software Defined radio with the TOTAL elimination of hardware? WHERE IS BILL AND WHAT HAVE THEY DONE WITH HIM?  

Relax my friends.  All is well at SolderSmoke's East Coast HQ.  In fact, just yesterday I was making use of one of the systems described in this video.  Here's how: 

I was on 20 meters with my BITX 20 Hardware Defined (HDR) homebrew transceiver. Everything was going smoothly.  We have some sunspots now, so DX is once again possible.  I heard a loud U.S. station (that will remain anonymous) calling CQ, so I gave him a call.  

The trouble started right after he looked at my QRZ page. You see,  I have pictures of my homebrew rigs there.  These images sometimes trigger hostile reactions, especially from guys who have almost their entire stations INSIDE their computer boxes.  I also admit to occasionally making things worse by pointing out that it is possible to build a BITX20 for about five dollars U.S.   Some guys apparently don't like hearing about this. 

Anyway, the fellow I was talking to proceeded to give me a very blunt and harsh signal report:  "Well, I suppose your signal is strong enough, but your audio is TERRIBLE!"  Interpersonal relations pointer:  This is NOT a good way to alert a fellow ham to possible technical problems in the rig that he has built by hand, from scratch, in his home workshop.  Especially when the person delivering the harsh signal report is using a "rig" that was built by credit card in a robotic factory on the other side of the planet. 

So that QSO ended rather quickly. But I did want to follow-up in the comment about the audio.  And here is where I turned to Web SDR.   Mehmet NA5B has a really nice WEB SDR receive system in Washington DC, just about 8 miles east of me.  Before 20 meters opened, I called up Mehmet's SDR on my computer, tuned it to the frequency of my transceiver and watched the screen as I asked if the frequency was in use.  I then issued a couple of hopeless CQs, again watching the screen.    I could see in NA5B's waterfall that my signal was indeed seriously lacking in low frequency audio. 

Now it was time to turn to hardware.  Rig on the bench, 'scope and sig generators fired up,   I quickly determined that the problem most likely resulted from my placement of the  carrier oscillator frequency in relation to the homebrew USB crystal filter.  I had placed it about 300 Hz too low.  This resulted in a low AF frequency roll off not at the desired 300 HZ, but instead at around 600 Hz.  That would make the audio sound "tinny." So I moved the carrier oscillator up 300 Hz and went back to Mehmet's SDR receiver.  I could see that the lows were now at the right level.  Thanks Mehmet. 

One note about the audio coming out of the many SDR radios on the air:  When you look at the passbands in the Web SDR receivers you can see audio going almost all the way down to the frequency of the suppressed carrier.  With non-SDR rigs  you usually see a gap of around  300 Hz between the carrier freq and the start of the SSB signal.  This is often the result of our filter rigs having IF filter skirts -- you would place the carrier oscillator frequency a bit down the skirt -- this would help with opposite sideband suppression and all you would be losing would be the lows below 300 cycles, which weren't really necessary anyway.  I had placed the carrier oscillator too far down on the skirt.  

Of course, sometimes SDR rigs will also have a gap between the carrier freq an the start of the audio if the operator has set the passband this way, or if the microphone attenuates below 300 Hz.  But you see a lot of signals with audio filling almost the entire passband --some of the "Enhanced SSB" guys are running audio passbands that go as low as 50 Hz.  

Has anyone else noticed this "full passband" effect when looking at the waterfalls?  
Any other tips for using Web SDR for troubleshooting?  

SolderSmoke Podcast #223 Field Day, Club Talks, Patreon, NanoVNA, Farhan Video, SPRAT, BIG MAILBAG

SolderSmoke Podcast 223 is available: 

http://soldersmoke.com/soldersmoke223.mp3

27 June 2020

Quarantine Field Day!   

Ironically, THIS YEAR we are both participating

Pete's FD Plan, Bill's FD plan 

Talking to Clubs: 

Pete's talk to the Cedar Valley Iowa Club

Bill's talk to the Vienna Wireless Society

Pete's Bench

DDC SDR

Ideas from the Summer SPRAT

Mean Well Voltage Regulator

SHAMELESS COMMERCE DIVISION: PATREON.   SS is an  SV DELOS WANA-BE!

We got our very first Patreon Patron!  Jonathan Magee from the UK!  Upper Left on the blog.

Continue to use our site for your Amazon purchases. 

Bill's Bench

NanoVNA

Understanding L Networks

+/- 6kHz Ceramic filter for Q-31

Lobes, Nulls and WSPR

Miscellaneous: 

Farhan's feedback Amplifier Video

British Antarctic Broadcast heard (sort of)

MAILBAG:

Mauro VA6BRO liked the SolderSmoke book.  Thanks Mauro

Tryg in Galway Ireland is listening.  Hope to get you the signed books Tryg. 

Michael N4MJR suggested that I use N2 Corona Quarantine Radio as my phonetics.  I dunno... 

Ed DD5LP has been helping us get SS rebroadcast on a German SW broadcast station. Stay tuned! 

Rogier PA1ZZ in California sent an e-mail about the Don Lee Broadcast System.  Thanks Rogier!

Rick KE3IJ  Silver Skirt on his 2B also. W3GOO did it.  Rick traded his Commodore 64 for the 2B.  Yea! 

Walter KA4KXX has a simplified circuit for the MMM!  From UK

Peter VE1BZI thank us for the tribal knowledge.  Dipolo Crilolo

Peter VK2EMU Wee need someone to make the Constructor Crusader badge. 

Scott KA9P sent us the Amateur Wireless cover from 1934 with the Constructor Crusader thing. 

John GM4OOU Built lockdown rig.  we want pictures! 

Jerry KI4IO  His version of the Sproutie by AA7EE   FB 

Adam N0ZIB built a MMM

Wouter ZS1KE in South Africa -- comparing notes on Drake 2-Bs

Randall KD5RC wants to get started in HB. 

Pete Juliano's Presentation to the Cedar Valley, Iowa Amateur Radio Club (Slides)

Earlier this month Pete N6QW spoke via Zoom to the Cedar Valley,  Iowa Amateur Radio Club.  This was an especially appropriate venue for Pete, the creator of the KWM-4;  Cedar Rapids was the long-time home of Collins Radio.  Many of those in the club used to work for Collins. 

Here is Pete's PowerPoint presentation: http://soldersmoke.com/N6QWslides.pptx

Some notes on the event: 

For the Zoom connection, Peter used his Linux Mint computer. 

  

Pete mentioned that Gene Senti,  while tinkering in his basement,  developed the KWM-1.  One of the guys in the audience confirmed Pete's account, but added something: Collins employees could buy ham gear at a discount. Senti bought a brand new 75A4 receiver (commercial price in late 50s was about $900) and he modified it from being just a receiver into a transceiver.  Imagine taking a new radio and doing that!  But when he got it working,  Art Collins came over to his home to see the invention. The rest is history.

Pete got grilled a bit on why he was still using “analog’ front ends on his several SDR builds -- why not Direct Digital Conversion?   Pete says he may now try to build a DDC rig. 

There was also a lot of very nice feedback on the SS Podcasts – there were many regular listener’s in that group. 

You can see Pete's slides here:  

http://soldersmoke.com/N6QWslides.pptx

Lightning Strike on the Washington Monument

Here in the DC area, the monument is very frequently in view.  I have been up to the observation deck.  We were here for the earthquake that damaged the structure.   On Thursday night someone made a good video of lightning hitting the monument.  

This particular storm was flashing through my window, and was visible during a Zoom class through the windows of persons elsewhere in the area.  

This lightning storm took out one of NA5B's amazing Web SDR receivers.  I think it was only the LF receiver.  I am sure Mehmet will have it back on-line soon.  

Here is an article on the topic: 

https://www.popularmechanics.com/science/a32781804/watch-lightning-strike-washington-monument/

QCX SSB -- But How Much QCX Remains?

Hack-A-Day carried a very nice video describing recent efforts to turn Hans Summers' amazing QCX CW monoband transceiver into a multi-mode, multi-mode (including SSB) rig (see above).   This is project will greatly interest QCX and SDR fans.  

But I wondered how much of the old QCX is still there after the modification.  Not much, it turns out.  

Here is the bloc diagram of the QCX.  It is essentially a phasing rig, using the same principles as my venerable HT-37 transmitter and my version of KK7B's R2 receiver: 

Yesterday Paul VK3HN sent me the schematic of the new multi-mode, multi-band version:  

Notice how different it is.   I thought that perhaps the new rig would keep something of the I-Q circuitry of the QCX, but it does not.  This is not a criticism, just an observation.  

But here is something that harks back to a topic we've been debating on the blog and podcast.  Notice that the top diagram is a bloc diagram.  There is a lot of circuitry in most of those boxes -- lots of resistors, capacitors, inductors, and transistors.   There is a schematic diagram under that bloc diagram.  But look at the second diagram.  While it looks like one, that one is NOT a bloc diagram. That IS the schematic diagram.  Most of the circuity has been sucked into the chips.  

While many will prefer the rig described by the second diagram, I remain an HDR guy, and don't really like seeing the circuitry disappear into the ICs.  But, to each his own.  This is all for fun.  Congratulations to the guys working on the new rig. 

ZL2CTM Charlie Morris on "QSO Today" with Eric Guth 4Z1UG

Eric Guth 4Z1UG had a really nice interview with our friend Charlie Morris ZL2CTM.  Charlie shared with Eric a lot of wisdom about how to homebrew radio gear.  I especially liked Charlie's comments on keeping most of his rigs on the wooden prototype boards.  He said something important when he talked about the benefits of taking a break from a difficult problem, then coming back to it with a rested and refreshed mind. I noted, however,  that he said most of these frustrating problems have to do with software.  

I got got several chuckles out of Charlie's comments on the difficulty of building stable analog LC VFOs (here he seemed to be channeling our good friend Pete Juliano).  I chuckled because as I listened I was happily building the analog LC VFO for my Q-31 Quarantine receiver.  The centerpiece of this project is a variable capacitor that Pete gave me;   Pete took it out of an old  Galaxy V transceiver.   Believe me guys, no rotary encoder could possibly look as nice or have as much soul as that capacitor from Pete, with all its gears, reduction drives, and anti-backlash mechanisms.  It even smells of machine oil.  Call me a Luddite, but I will stick with the coils and capacitors.  

Listen to the interview here: 

https://www.qsotoday.com/podcasts/zl2ctm

Thanks to Charlie and Eric. 

SolderSmoke Podcast #220 -- S-38Es, AD9833s, Pete's Phasing Rig, FT-8

Java on the S-38E Tuning Dial

SolderSmoke Podcast #220 is available

http://soldersmoke.com/soldersmoke220.mp3

Hunkered Down.  StayInTheShack:  SITS!  Flatten the Curve!  It is working.

Teaching English again – via Zoom.  Kids completing the school year remotely.  

BILL'S BENCH

-- Finishing up on the S-38Es.

  

-- I wrote up my alignment, isolation and dial string experiences.

-- SWL  WRMI Radio Miami International on 39 meters 9.4-9.9 MHz.  Rock and Roll.

-- S-38E work is causing me some serious legal problems.  They are threatening to take down our sites and our podcast.   Google has put a CEASE AND DESIST ORDER on my blog:   Check it out http://soldersmoke.com/CEASEANDDESIST.JPG

--S-38E caused me to want to get my HRO dial receiver on the SW broadcast bands with a good AM detector.  

-- Next up: Hayseed Hamfest cap for my Drake 2-B.  And I have an idea on how to easily broaden it for AM:  Tap the 455 kc output on the Q multiplier jack.  455 AM detector to audio amp. 

SHAMELESS COMMERCE DIVISION

PETE’S BENCH

AD9833

Phasing Rig Project

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DEAN’S PROJECT – Step by step.  Trouble shooting.  Understanding.  Receiver triumph.  FB.

MAILBAG

Jack 5B/AI4SV doing well in Cyprus

Daniel SA7DER listens during commute in Sweeden.

Peter VK2EMU building a 6 meter amp.  With Tubes

Jim WA8ZHN  says there are still 7751 Novices on the books.   FB.

Mike WB2BLJ modding his BITX – having a lot of fun.

Fred KC5RT – Great idea on isolation transformer in my S-38E.  

Jerry Palsson: S-38C's curves vs. S-38E's exotic places.  Java. 

Krakatoa East of Java

The Year of Living Dangerously

Anonymous mail:  FT-8 DX -- Are these contacts legitimate? See below. 

Dear Bill and Pete: 

I've been meaning to share with you something that has come to my attention by a rather circuitous route. 

As you guys know, I've been involved in the software/IT side of ham radio for many years. I've watched many digital modes come and go.  I've always enjoyed my work, but lately I've seen something that makes me uneasy. 

I'm sure you guys have heard of the fantastic DX that is being worked by many guys using FT-8.  It seems like all they need to work Jakarta is a couple of watts to a wet noodle. Shazam!  Contact! 

Well, I learned something that calls into some question the legitimacy of many of these contacts....  

As i understand it, certain manufacturers, in cahoots with a major American ham radio organization (that happens to be very dependent on ad revenue from that manufacturer), have secretly set up a system that combines the internet and ham radio. 

Here is how it works:  Suppose Joe Ham gets on FT-8 on 40 meters.  He puts out a call using his QRP transmitter and the aforementioned wet noodle.  No way that signal is going to Jakarta, right?  Well, it will with a bit of help.  

The system has SDR transceivers  and great antennas set up at strategic points around the world -- these are really great locations -- think mountain tops near the coastlines, always with high speed internet T5 connections. I think this is part of the whole “contest superstation for on-line lease” business model.  

One of these stations picks up Joe Ham's FT-8 call. Sometimes it will just re-transmit it, sometimes is will send it to a counterpart station on the other side of the globe.  Bingo, Joe Ham's signal is suddenly in Jakarta.  A station there enthusiastically responds, and that signal goes back with the same kind of repeater/ internet assist.  This is all done out of the reach of the FCC.  They are usig overseas locations,  some of them in Mexico.

Of course they have to be careful not to "facilitate" these kinds of contacts during times in which the bands are obviously dead,  That's why 40 is so useful for this system.  Obviously they can't keep this kind of thing secret forever -- they just want to get guys hooked on FT-8, then they can reveal the system, selling it as nothing unusual, you know, sort of akin to Echolink.  

Of course, this hasn't been made public (for obvious reasons!) but I can tell you the name of the system:   They tried to make it sound like something familiar (in this case like APRS): They call it  "Automatic Private Radio Internet Link 1."  My understanding is that when they do their “roll out” they will offer the new service to those willing to pay a subscription.

Obviously as an old-school, traditional ham, I'm troubled by all this.  What do you guys think?  I wonder what your listeners would think. 

Please don't mention my name..  But here is a site that describes the new system: 

http://www.automaticprivateradiointernetlink1.com/

Thanks and 73... 

Please let us know if you have any information on this, or have observed any unusual and suspicious success with FT-8.