Phase Noise and the Radio Amateur

A weak signal disappears in the phase noise of the stronger signal.

The March 1988 QST provides a relatively clear explanation of what phase noise really is:

https://www.robkalmeijer.nl/techniek/electronica/radiotechniek/hambladen/qst/1988/03/page14/index.html

Highlights: 

Phase noise is an undesired variation in the phase of the signal. In this case, an oscilloscope shows that the time between zero crossings of the signal varies over time when compared to the zero crossings of an ideal sine wave. An exaggerated example of phase noise is shown above.

Phase noise on an oscillator signal has exactly the same effect as frequency modulating the oscillator with noise.

Whenever a carrier is passed through a mixer, the phase noise of the oscillator driving that mixer is added to the carrier.

Phase noise on a transmitted signal causes effects identical to phase noise generated in a receiver.

Any signal that reaches a mixer in the receiver is modulated by the phase noise in the local oscillator driving that mixer. As such, the signal appears to have at least as much phase noise as the local oscillator. Thus, sufficiently strong signals off the receiving frequency can degrade receiver sensitivity by raising the noise floor at the receiving frequency. Receiver dynamic range is reduced as the noise floor rises.

With a frequency-shift-keyed or- a phase-shift-keyed signal, the close-in phase noise limits the maximum bit error rate that the system can achieve. Both of these effects can be quantified once the communications system is defined. With an SSB voice signal, the effects are much harder to predict, but excessive phase noise does degrade SSB signal intelligibility to some extent.

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Receiver guru Rob Sherwood provides some very useful historical background on his web site:

http://www.sherweng.com/documents/TermsExplainedSherwoodTableofReceiverPerformance-RevF.pdf

Phase Noise: Old radios (Collins, Drake, Hammarlund, National) used a VFO or PTO and crystal oscillators to tune the bands. Any noise in the local oscillator (LO) chain was minimal. When synthesized radios came along in the 70s, the LO had noise on it. It is caused by phase jitter in the circuit, and puts significant noise sidebands on the LO. This can mix with a strong signal outside the passband of the radio and put noise on top of the weak signal you are trying to copy. This is a significant problem in some cases: You have a neighboring ham close by, during Field Day when there are multiple transmitters at the same site, and certainly in a multi-multi contest station. You would like the number to be better that 130 dBc / Hz at 10 kHz. A non-synthesized radio, such as a Drake or Collins, has so little local oscillator noise the measurements were made closer-in between 2 and 5 kHz.   

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Experimental Methods in RF Design (EMRFD) has this to say about phase noise:

"The local oscillator is a critical part of any communications system. Modern transceiver performance is often compromised by LO systems that suffer from excess phase noise, effectively limiting the receiver dynamic range. While quiet oscillators, those with low phase noise, can be built using traditional methods, these circuits often lack the thermal stability of a synthesizer.... Frequency synthesis is not, however, the answer to all the LO problems presented to the experimenter.  Some PLL synthesizers are burdened by excessive phase noise. Those using DDS, while quieter, emit spurious outputs, often in profusion.  Both use an excess of digital circuitry that can often corrupt a receiver environment."  page 4.1

   

"At first glance, phase noise sounds like an esoteric detail that probably has little impact on practical communications.  This is generally true." page 4.12 

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Hans Summers G0UPL analyzed and measured the phase noise of the Si5351a chip: 

http://qrp-labs.com/qcxp/phasenoise.html

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DC4KU appears to be using the crystal filter method used by Hans: 

https://dc4ku.darc.de/Transmitter-Sideband-Noise_DC4KU.pdf

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Martien PA3AKE has done a lot of great work on this topic.  See: 

https://martein.home.xs4all.nl/pa3ake/hmode/dds_pmnoise_intro.html

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Dean KK4DAS commented on the phase noise video of the IMSAI guy: 

Watching the video I was reminded of Segal's law roughly paraphrased as follows.:

A man with one spectrum analyzer knows his phase noise. A man with two is unsure.

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

Ham Radio Pico Balloons Feared Shot Down by USAF

The Aviation Week article below helped to confirm some of my worst fears about the balloon thing.  For a long I've wanted to launch one of these balloons.  Recently I've been thinking about doing it from SolderSmoke Shack South (in the Dominican Republic -- they are BIG on party balloons down there!). 

https://aviationweek.com/defense-space/aircraft-propulsion/hobby-clubs-missing-balloon-feared-shot-down-usaf?fbclid=IwAR0ra3U4QPlzrNiVDNXz1UzQdDNfFUpccrQIRhVaCKkrZWHIPXQ0hwxEVKI

Check out Hans's site about the circumnavigators: 

http://www.qrp-labs.com/circumnavigators.html

QRP Labs HQ Tour

Really cool to see Hans describe his QRP Labs workshop in Turkey.  Lots of soul in that worshop.  Thanks Hans.  

 And here is a 2022 Turkish media interview with Hans and his team in the workshop:  

Hans Summers G0UPL Wins FDIM 2N2222A Power Out Challenge -- 4.1 Watts from Two 2N2222As

Farhan told me how cool this was.  And he was right.  It looks like a lot of fun.  Congratulations Hans! 

 

SolderSmoke FDIM Interviews: Hans Summers G0UPL Talks about the QDX and His New Balloon Tracker

 

Thanks to Bob Crane W8SX for getting us this wonderful interview with Hans G0UPL.  Its really amazing to hear Hans talk about how many QDX rigs and Baloon Trackers have been sold by QRP Labs, and how quickly they sell.  Really great.  Hans's comments on the realities of the parts shortage was also very interesting. 

Listen here (about 7 minutes):  http://soldersmoke.com/2022 G0UPL.mp3

U4B Balloon Tracker 

Video #3 17/12 Transceiver -- Receiver is Working on 12 and 17 meters (Listen! Video!)

Here is an update on the 1712 transceiver project. The receiver circuitry is done and I can listen on 17 and 12 meters. In this video I was using my 75 meter doublet tuned to 17 meters (reception on 12 was pretty good using this antenna). As you can see, I found a temporary solution to the VFO dial problem -- I am using the cardboard tube from a coat hanger super glued to a knob. The tube fits snuggly over the shaft from the VFO assembly.

Hans Summers' QRP Labs Bandpass Filters:

http://www.qrp-labs.com/bpfkit.html

http://www.qrp-labs.com/images/bpfkit/bpf2.pdf

Thanks Hans!

Farhan's Amazing Knack Story: From a Boyhood SW Receiver to the Design of the sBITX SDR

The presentation starts at about the 4 minute point. 

I think if I were only allowed to watch one YouTube video in the next year, I'd make it this one. 

In this amazing RSGB video, Ashhar Farhan VU2ESE takes us back to his earliest days as a radio amateur.  He tells us about his very early desire to build radios, his early projects, and his personal evolution as a designer and builder,  from a simple DC receiver, to the BITX, the Minima, the uBITX and now the hybrid HDR/SDR sBITX.  

There is a lot of  homebrew wisdom and tribal knowledge in this video. And we learn so many hitherto unknown details about the rigs that have become so important to us:  

-- Farhan had the EMRFD book with him on the famous flight from Sweden to India during which the BITX was designed. 

-- We learn about the origins of the BITX oscillator circuits, and that the VFO and BFO are essentially the same.  

-- I was really pleased that Farhan included a picture of my HB BITX17 rig in his presentation. 

-- Farhan discusses the difficulties he faced in obtaining needed parts in India. 

-- We actually see the nylon washers that Farhan used in the original BITX. 

-- Farhan discusses his early system for measuring coil inductance. 

-- In addition the huge contribution of EMRFD,  Farhan talks about how he was helped by Pat Hawker G3VA's writing, and the ARRL's SSB Handbook. 

-- Farhkan talks about his Tex 465 'scope and his building of a Spectrum Analyzer. 

-- We see his evolution to dual conversion. We see the conceptual birth of the Minima and the birth (thanks Wes!) of the TIA amps.  I didn't know about the HF-1.  Then Farhan designed the uBITX and now the sBITX.  

 -- Farhan talks about his practice of taking the pictures of new rigs with the new rig sitting atop the book that was most important in its design and construction.  FB. 

-- I was really blown away by Farhan's presentation of how the uBITX advertisement was inspired by and in many ways based on the Heathkit ad for an HW-101.  Amazing. 

-- I learned a lot from Farhan's discussion of SDR theory.  I pledge to spend more time with this.  I really like Farhan's hybrid HDR/SDR approach. 

-- But I have a question:  Farhan seems to say that we'd need a big expensive GOOGL computer to do the direct sampling HF SDR.  But doesn't the little RTL-SDR do just that?  Without a GOOGL?  

-- Great to see Wes's AFTIA being used in the sBITX.  

-- Really cool that Farhan has his mind on VHF transverters when designing the sBITX.   I liked use of the TCXO module to free up one of the Si5351 clock outputs.   FB.  And great to include an idea from Hans in this rig. 

Thanks very much to Farhan (who stayed up until 3 am to do this!) and to the RSGB for hosting.

Wisdom from AA0ZZ: NO LIBRARIES! ASSEMBLER CODE ONLY! -- "Digital Crap" -- "No Magic Fruit" What qualifies as a real rig? Si570 vs. Si5351

 

Bill,

Why do you guys make your Soldersmoke podcasts so darn intriguing such that I can’t listen to them in the background while I’m doing something else?   Good grief!  I start listening and before long you make me stop and chase down a rabbit hole to find something new that you mentioned that I had no clue was out there.    Before long I’m doodling out a new sketch or playing with at a new design for something I really need to experiment with or build “next” or something I need to  try.   It is taking too much of my time!!  J

 I’ve been listening to your podcasts for years.   Way back, before I knew you and before I knew you were doing these Soldersmoke blogs with Mike, KL7R, and just before he was so tragically killed, I was collaborating with him on a simple frequency counter project using a PIC microcontroller.  We were making good progress on a neat design.  I later completed the project but always kept his contributions noted as part of the source code. 

 I’ve been making PIC-based VFOs for years – dating back to about 2000 – aiming them at builders who were looking for something to go along with Rick Campbell’s (KK7B) receivers.  Rick is a good friend now, after we met in the Kanga booth at Dayton where we both were demonstrating our stuff.  (Bill Kelsey (N8ET) of Kanga, was the “marketer” for my kits as well as Rick’s for many years.)   My original VFO kits used a DDS (high-end AD9854) that simultaneously  produced I and Q signals which made it perfect for Rick’s phasing gear.  Rick is a big supporter of my work but he still kids me about polluting his beautiful analog world with my “digital crap” (copyright KK7B term).   When I came out with a newer version VFO using a Silicon Labs Si570 PPLL  (I can hear already Pete Juliano groaning) it was a big improvement over the AD9854 in noise/spur reduction.  I documented this all in a QEX article in about 2011 and Rick (and Wes Hayward) were very supportive/appreciative of my work.   

 I have used the Si5351 also and I understand Pete’s point of view.  It’s “plenty good” for most amateur projects.  However, it remains a fact that the Si570 is a better part and produces a cleaner signal.  That’s the reason why the Elecraft KX3 uses a Si570.   Granted, the newer Elecraft KX2 uses a Si5351 but it’s most likely because they wanted to preserve battery life (the Si570 uses more power but not nearly as much as the AD9854) and also to reduce the cost.   I do understand!   I also fully understand the ability of the Si5351 to produce I and Q signals via different channels.  I’ve had extensive conversations about this with Hans Summers, at Dayton and online.  I use a pair of Flip-Flops on the output of the Si570 instead.  My PIC code driving the Si570 is ALL written in ASSEMBLER code.  Yep!   I’m an EE but have had a career mainly in software development and much of it was writing assembler code.   I dare say there aren’t too many gluttons for punishment that do it this way.  I do it because I want to understand every line of code don’t want to be dependent on anyone else’s libraries.  Every line of code in my VFO’s and Signal Generators is MINE so I know I can debug it and it can’t get changed out from under me.   (This problem bit Ashar Farhan hard on the Raduino of his BitX.   Tuning clicks appeared because the Si5351 libraries he used changed between the time he tested it and released it.   I was really appalled when I dug into this and resolved to NEVER use libraries that I didn’t write myself.  Similarly, this also makes me have some distaste for Arduino sketches.  I would rather see ALL of the code including the initialization code, the serial routines, etc, rather than having them hidden and get pulled in from Arduino libraries.  That’s similar to the reason why Hans Summers didn’t use an Arduino in his QCX.  He used the same Atmel microprocessor but developed/debugged it as “C” code with the full Atmel IDE/debugger.                                                                                                            

By the way, Pete  mentioned the Phaser FT8 transceiver by Dave, K1SWL, in a recent podcast.  Dave is a very close friend, even though I haven’t met him in person since about 2000.  We Email at least daily and some of it is even about radio. J   I did the PIC code for the tiny PIC that controls the Si5351 in the Phaser.   Yes, it’s written entirely in Assembler again!   I do know how to do it for a Si5351.  That Si5351 code is not nearly as much “fun”, though.  I know, this will make very little difference to guys who write Arduino “C” code to control it but under the covers it’s a world of difference.   It takes me about 15 serial, sequential, math operations to generate the parameters for the Si5351.  None of them can be table driven and they all have to be performed sequentially.   (This is all hidden in about 5 lines of complex, Arduino “C” code but the operations are all there in the compiled assembler code.)   In contrast, my Si570 code is almost all table driven.   I just have to do one large (48-bit) division operation at the end to generate the parameters.    Yes, that’s a bit of trickery to do in ASM.   There are no libraries do this.

 I will point out one more advantage of the Si570 in comparison to the Si5351.  It has the ability to self-calibrate via software instead of relying on an external frequency standard.  In my Si570 app I can read up the exact parameters for the crystal embedded inside the Si570, run my frequency-generating algorithm “backwards” and determine the exact crystal frequency (within tolerances, of course) for that particular Si570.  Then I update all the internal tables using that crystal frequency and from then on all generated frequencies are “exact”.   I love this!  Frequency often moves by about 6 kHz on 40M.

 Oh yes, I must mention the difference of home solderability of the si570 vs the Si5351.  Those little Si5351 buggers are terribly difficult to solder at home while the Si570 is a breeze.   I know, many folks will just buy the AdaFruit Si5351 board and it’s already soldered on but, again, I like to do it all myself.   No “magic Fruit” for me.

 Now that I retired a couple of years ago and am getting out of the VFO kitting business I can finally build complete rigs instead of just making the next-generation VFO’s for everyone else to use.   I recently build a tiny, Direct Conversion rig with a Si570 signal generator (of course) and a diode ring mixer (ADE-1).  Look at my web page,  www.aa0zz.com  to see it, along with my VFO projects that I’ve been building in the past.   As you well know, Direct Conversion is fun to build and the sound is astounding; however, they are rather a pain to use!  Yes, I did make it qualify as a real rig by making several contacts all over the country.  (Wes Hayward gave me the criteria:  he told me that I must put any new rig on the air and make at least one contact before it qualifies as a real rig.)  

 The new rig that’s on my workbench is my own version of a phasing rig, experimenting with a Quadrature Sampling Detector (QSD, sometimes called a “Tayloe” mixer), using some ideas from Rick’s R2 and R2Pro receivers and many innovations of my own.  At present my new higher-end Signal Generator works great, the QSD receiver works great (extremely quiet and MDS of -130 dB on 40 meters) and the transmitter is putting out about 16 watts with two RD16HHF1’s in push-pull.  You can take away my “QRP-Only-Forever” badge too, not that I’ve ever subscribed to that concept!  Still more tweaking to do with the TX but now I’m also working on the “glue” circuitry and the T/R switch.   The SigGen, RX and TX are all on separate boards that plug into a base board which has the interconnections between boards and the jacks on the back.  I’ve built DOZENS of variations of each of these boards. Fortunately they all fall within the size limit criteria to get them from China at the incredible price of $5 for 10 boards (plus $18 shipping) with about 1 week turnaround.   Cost isn’t really an object at this point but it’s more of getting a hardware education that I sadly missed while I concentrated on software for so many years.  it’s certainly nice to have willing mentors such as Rick, Wes, Dave (K1SWL), Don (W6JL) and many others to bounce my crazy ideas off.  Yes, I’m having a ball!  

 I was licensed in 1964 but out of radio completely from 1975 to 1995.   Do you like the picture of my DX-100 on my web page?  My buddy in the 60’s had a Drake 2B and I drooled over it but couldn’t afford one.

Now I must finish this rig before you guys send me down another rabbit hole.   Too many fascinating things to think about!   I literally have a “priority list” on the my computer’s desktop screen.  Every time I come up with a new project idea – something I really want to play with such as a Raspberry Pi, SDR, etc, I pull out the priority list and decide where it fits and what I want to slide down to accommodate it.  That’s my reality check!

 Take care, Bill.   Thanks for taking the time to give us many inspiring thoughts and ideas.

 73,

-Craig, AA0ZZ

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/

Adam N0ZIB's FB Station (and UGLY Michigan Mighty Mite)

Bill and Pete, 

Thanks for the work you put into your podcast. I’ve been listening to it on my commute and while at work (I’m a welder/fabricator). Fantastic content.  Keep up the great work.  

All your talk about Farhan and the Ubitx convinced me to order one.  I welded an aluminum case for it and upgraded to the Nextion 3.5” screen. Also added a tuning knob from a Heathkit SB-401.  So far I’m really enjoying this rig. Plan to add an audio amp (to drive a larger speaker) and a CW filter to it this weekend.  In the station picture I sent I also show my paddles made from a hacksaw blade and stainless steel hardware. It’ll send 25 WPM before it gets a little sloppy.  My QCX 40 is also pictured.  I have a commercial rig too but find I’m not using it very often. 

Plan to start building the simpleceiver soon and maybe a bitx 17 too. Your podcast played a big part in convincing me to pick up a soldering iron again.  You guys are awesome.  Keep it up.  

73’s

Adam

N0ZIB

(Pete noticed that the main tuning knob on Adam's uBITX was NOT from Heathkit but was instead from a Collins KWM-2 or 32S3.  He advised Adam that the knob would sell quickly on e-bay.  It did, and will finance additional N0ZIB homebrew projects.  We are thinking of adding these knobs to our SolderSmoke Retirement Fund Portfolio.)   

Adam continues: 

I was listening to your older podcasts and heard several discussions about the Michigan Mighty Mite.  So this jumbled up mess probably doesn’t look like much but I built one. I need to order a 40 meter crystal and actually build it again on a board(with the coil rewound for 40) but my “proof of concept” build was a success. Using a variable cap from a Hallicrafters S20-R and the crystal holder from a Heathkit.  

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. 

QSO Today -- Episode 300 -- Panel Discussion

Congratulations to Eric Guth, 4Z1UG for reaching episode #300 on his QSO Today podcast.  To commemorate the event, Eric organized a panel discussion.   It was a real pleasure and honor to participate.   

Listen to it here:  https://www.qsotoday.com/podcasts/300

Thanks again Eric! 

SolderSmoke Podcast #212 HDR, Boatanchors, SDR, Antuinos, Spurs, QSX, Mailbag

Dale Parfitt W4OP's  SBE-33 with modern digi freq counter

SolderSmoke Podcast #212 is available: 

http://soldersmoke.com/soldersmoke212.mp3

22 June 2019

CONGRATULATIONS TO PETE:  Licensed 60 years today

Pete Juliano during Field Day, 1959

Sideband Engineers Models 33 and 34 -- Thanks Pete! 
Hans's QSX SDR Rig at Dayton-Xenia and FDIM
W8SX FDIM interviews

Pete's SDR Projects -- Update

The Peregrino SSB transceiver in the summer SPRAT

Why no rare earth cell phone speakers in ham projects? 

My HDR "waterfall" project

Farhan's Antuino
Cubesat origins
RF Lab in an box
SWR, PWR, SNA
Superhet receiver with ADE-1 at front, and log IC at the output
Adapters (SMA to BNC) help
DON'T BLOW UP THE INPUT RESISTORS (LIKE I DID!) 
My dirty DIGITIA -- Denial, then acceptance
FFT 
Useful programs:  SPURTUNE and ELSIE
A better bandpass filter for the DIGITIA 
The importance of a good test set up with Antuino

Manassas Hamfest: WA1UQO, W4WIN, AI4OT

MAILBAG: 
KG7SSB
WA3EIB
VK4PG
W3BBO
Jeff Tucker -- Who owns Drake 2-B #4215? 
KN4BXI
KC5RT
K3ASW

FDIM Interview with Hans Summers G0UPL on QSX SDR Rig, Probable Price, Features

Wow, our ace correspondent in Dayton/Xenia Ohio, Bob Crane W8SX, did a great interview with homebrew hero Hans Summers G0UPL.  

Hans discusses the success of the QCX CW phasing rig -- more than 7,300 sold.  That's amazing.  I didn't think there were that many solder melters in the world.  

Even more amazing is his description of his QSX SSB SDR rig, which is currently in development.  Click on the link below to listen to Bob's 6 minute interview.  You will be blown away by the features and the price of the QSX.  Go Hans!  

http://soldersmoke.com/G0UPL FDIM 2019.m4a

Thanks Bob! 

SSB on the QCX? Sounds pretty good here (Video)

In SolderSmoke #211 we reported on recent efforts to generate SSB from the QCX CW phasing rig -- we said that we'd heard that the effort wasn't very successful.  But today we got an e-mail from Jim W4JED pointing us to YouTube video from Guido PE1NNZ.  

I must say the signal sounds pretty good to me, and it looks good in the waterfall.  Listen for yourselves via the video above.  His is the signal on the left. 

Guido has a great write up, along with software here: 

https://github.com/threeme3/QCX-SSB 

I hope this all works out -- it would be great to get on phone with Hans Summers' amazing phasing rig. Here is a picture that hints at the potential: 

Go Guido! 

W7RLF Homebrews a Receiver -- FB!

Ryan W7RLF has joined the small and elite group of radio amateurs who have homebrewed a receiver.  And it is a receiver filled with soul, juju and mojo; the project was inspired by Wes Hayward and Farhan, and used components from Hans Summers.   Congratulations Ryan and thanks for all the work you did in documenting your experience. 

Who will be the next intrepid ham to join the homebrew receiver club? 

Hello Sirs!

This month I read Wes Hayward's post on the history and heritage of DC receivers in ham radio and it brought a lingering interest to a head. I had to build one. I run the BITX40 and uBITX group on Facebook, and I posted to the other hams there: Which DC receiver should I build? Farhan recommended his DC40. Mind you, I've never homebrewed a radio before, so this is all new territory for me. 

I did build it, and it does work. It also uses QRP Labs stuff from our friend Hans Summers. This thing has a lot of QRP heritage :) I documented it every step of the way including all of my dumb moves and things I got wrong, and my desire is to inspire others to try homebrewing the way Wes, Farhan, Hans, and you YOU GUYS have inspired me to try it. I am hooked, of course! Here's a link to my blog to Part 1:

https://miscdotgeek.com/building-direct-conversion-receiver-part-1/

It's a four part series (unofficially 5 really) with 8000 words to it, and I hope you guys enjoy it and I'd be ticked pink if was worthy of mention on your show. Here's a video of it too:

https://www.youtube.com/watch?v=ju3kOEyCMYM

73 to you both and I wish you the best!

Ryan Flowers W7RLF

https://miscdotgeek.com

Built-in Spectrum Analyzer in Hans Summers' QSX Rig.

I agree completely with the e-mojis.   Wow!  Cool!  I love it! 

Hans Summers is a genius. 

This is almost enough to make me get with the program and embrace SDR.  

Hans has done what seemed to have been impossible: true homebrew with SDR.