Pil Joo's Homebrew Superheterodyne Ham-Radio Receiver

It is just very cool to see someone build a superhet and get it to work.  For so many years amateurs were told that "homebrew receivers are too hard."  Even simple regens or direct conversion rigs were sometimes seen as beyond the abilities of amateurs.  But here we see another reminder of this not being true.  Even a superhet -- which is a lot more difficult than a direct conversion receiver -- can be homebrewed by an amateur builder.  Three cheers for Pil Joo! 

He wrote on the SolderSmoke Facebook page: 

I finished my first super het receiver. It's for the 40m band. It consists of: bandpass filter, tuned amp, diode ring mixer, wide band amp, crystal ladder filter, wide band amp, then SA602 + LM386 combo. I learned tons as i put all the components. First two amps are my design. The third amp is bga2866. The bandpass filter is what i posted a few days ago. I planned to make another one but with 2.5db insertion loss i thought it was good enough.

The result is actually quite good. I can hear everything a local kiwisdr can hear. Now, I have lots of ideas about how i can improve, but that will be another radio.

Pil Joo

AG5VG's Homebrew 20 meter Superhet (with a CW rig Coming) (Video)

 Michael AG5VG finished this receiver last weekend.  He hopes to build a CW transmitter using an output of the Si5351.  Obviously I defer to Pete on that one.  Good going Michael.  I think it sounds great and looks even better.  

Amazing Homebrew from Japan -- 7L4WVU's All Homebrew Station

Thanks to Roy WN3F for alerting me to this.  Tadashi-san has really built some beautiful stuff.  Especially impressive to me is his use of the spectrum analyser and two-tone audio tests to look at IMD of the entire transceiver.  See video above. FB OM.  

Be sure to check out 7L4WVU's YouTube channel: 

https://www.youtube.com/@7L4WVU

And his QRZ page heralding his all-homebrew station covering 1.8 to 430 MHz: https://www.qrz.com/db/7L4WVU

SolderSmoke Podcast #250 Dean KK4DAS joins Pete N6QW and Bill N2CQR

SolderSmoke Podcast # 250 is ready for download: 

http://soldersmoke.com/soldersmoke250.mp3

VIDEO VERSION: (1707) SolderSmoke Podcast #250 -- With Pete N6QW, Dean KK4DAS, and Bill N2CQR - YouTube

Intro:   Welcome to Dean KK4DAS.  For 2024 Pete and I hope to jazz things up a bit by bringing in fellow homebrewers to talk about their projects.  Dean is our first victim.  Welcome Dean. 

Some good news:  Several new homebrew receivers are inhaling:  Armand WA1UQO in Richmond has an amazing looking regen.  Scott KQ4AOP in Tennessee got his DC RX working.  Mike AG5VG in Texas has been homebrewing BITX 20s and BITX 40s.  All are on the blog.  

Pete's report: 

-- Recent blog entries on filters,  SSB rig architecture, and of course digital VFOs. 

-- Phasing measurements, quadrature, and the Seeed Xiao RP2040

-- Error in QST article on early SSB transceiver.  ANOTHER ERROR!

--LC VFO on blog!  FB Pete!  

Dean's report:  

-- Tales of woe on the homebrew sBITX

-- Help from Farhan.  

-- Ground Bounce.  FFT Hallucinations.   Wisdom files.

SHAMELESS COMMERCE DIVISION:   

-- Whenever you are tempted to buy something from AMAZON, just start at the Amazon symbol on the right side of the page.  We get a cut from Bezos, and it doesn't cost you anything.  

-- You can try to do the same thing with E-bay.  We are finding a lot of great parts there. 

-- If you see a SolderSmoke post on Facebook,  please Like and forward. 

-- Become a patron!  Go to the Patreon page.  We put the money to good SolderSmoke use. 

-- Visit Mostly DIY RF and buy a PSSST kit!  

Bill's bench:  

-- Building yet another BITX dual bander.  15-10 again. Tried to use a 25 MHz filter left over from the earlier project, but I had to build another.  Built a new VFO using the variable cap and anti-backlash gear recommended by Pete.  Was a bit tough to get the receiver sounding good.   Had a diode ring as the second mixer, but went back to a singly balanced mixer. 

-- 10 meter AM -- Thanks to Jerry Coffman K5JC for mod. 

Other topics: 

--Counterfeit chips.  Why? 

MAILBAG: 

Wes W7ZOI 

Jim Cook W8NSA  Transoceanic BFO

Grayson KJ7UM -- Vintage Computer Museum

Chuck Adams --Glad to hear that Chuck is doing well.  

Frank Harris  K0IYE --  NO CHIPS!!!! 

ED DD5LP  Antenna software

Eldon KC5U  10 AM We  made a contact

Joh DL6ID  10 AM   

Phil   W1PJE of MIT   10AM   Where is L5? 

Bob WP4BQV now in UK 

Dino Papas KL0S in Wilmington   Reverse Polarity protection. 

AA7EE Dave Richards  Liked Armand's receiver

Rogier PA1ZZ  

Jonathan-san W0XO  Listened to my ET-2 CW Whoop,whoop

Nick M0NTV  Great videos from Nick the Vic

Will KI4POV  Working on his own SSB rigs.  

John West -- Who is the South American ham who made his capacitors and heat sinks? 

Ed KC8SBV  Working on DC receiver, experimenting with FETs 

Mike WN2A great contributions.  Si5351 sole source danger! 

Nick N3FJZ -- watch out for dead bands when testing receivers! 

Don KM4UDX encouragement from new Prez of VWS

Dave K8WPE Likes QF1 Cap backlash.  Says I'm getting soft! 

Dave WA1LBP My fellow Hambassador, from Okinawa USMC Sergeant with a workshop. 

Going Down the Phase Noise Rabbit Hole with the IMSAI Guy (VIDEO) -- Is there a better way?

Chimera:  2.

a thing that is hoped or wished for but in fact is illusory or impossible to achieve.

(from the Oxford English Language Dictionary). 

Phase Noise.  We know what it is, but how do you measure it?  Pete N6QW and I went through this back when people were casting phase noise aspersions at (Pete's!) beloved Si5351.   More recently phase noise hate  has been focused on (my?) beloved Franklin oscillator.  When I asked a very technically proficient and guy at the VWS club if he could measure phase noise, I was surprised when he honestly said that he could not. 

And now we have the IMSAI guy saying, essentially, the same thing.  Wow, if the VWS guy and the IMSAI guy -- with all the spectrum analyzers at their disposal -- have trouble measuring phase noise, what hope do we ordinary hams have?  I mean, at best most of us have just an oscilloscope, a NanoVNA,  and a TinySA.  

Look, I know that phase noise is real and in certain circumstances, it is important.   But sometimes I suspect that its measurement is also a bit of a technical chimera:  If,  for whatever reason,  there is a circuit that you don't like, you can claim that the phase noise of that circuit is bad.  Or horrible. I think we see this sometimes with the Franklin oscillator.  Very few hams will be able to measure it and dispute the assertion that the phase noise is bad.    

For a perhaps painful walk down SoldeSmoke's "Phase Noise Memory Lane"  go here: 

https://soldersmoke.blogspot.com/search?q=Phase+Noise

Thanks to the IMSAI guy for a great video.   But let me ask:   Is there a better, simpler way to measure phase noise?  One that will avoid chimerical results and that could be used by hams with sort of standard ('scope, sig gen, NanoVNA, TinySA) test gear? 

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

SolderSmoke Podcast #246: PeteGPT! DC RX, Si5351, Franklin osc, Cuban DSB, Hex beams, uBITX mods, DX, 10 meters, MAILBAG

 

SolderSmoke Podcast #246 is available: 

AUDIO PODCAST: http://soldersmoke.com/soldersmoke246.mp3

YouTube VIDEO: (247) SolderSmoke Podcast #246: uBITX, Hex Beam, DX, High School DC RX, 10 meter SSB Rig, MAILBAG - YouTube

The AI Deep Fake Threat!  PeteGPT!

Hearing Aid info:  I can hear the cymbals in my audiogram adjusted Airpods.

Update on the TJ DC RX project – Several receivers working! https://hackaday.io/project/190327-high-schoolers-build-a-radio-receiver

Sunil’s company provides Nano/Si5351 combos.  With the KD8CEC software. Very cool.  http://amateurradiokits.in They have a new SSB dual band transceiver – the Airpal.

Mark AJ6CU helping me. Sent me Nanos with KD8CEC software. His uBITX Settings Editor seems very cool. https://github.com/AJ6CU/uBITX-Settings-Editor/releases/tag/V2-beta-1  Thanks Mark.  

Franklin Oscillators. 

Cuban Islander and Jaguey info.  Send more!

Fixing up uBITX 2   How Bill blew up TWO Raduino Nanos. My results with the KB1GMX mods. (see below)

Hex Beam work:  Adding 10 and 15 meter elements.  But now I can hear AM breakthrough from WFAX 1220 AM  (5 kW during the day),  So I made a high pass filter.

Made first contacts on 15 and 10:  Argentina, Brazil, Dominican Republic.

First contacts with both India VU3TPW and China BA4TB.  SSB homebrew.

sBITX news. Taking orders!

Pete’s 10 Meter SSB Project

Mailbag:

--Wes W7ZOI provided great info and analysis on the Franklin oscillator. And lots of great tech info on other topics: http://w7zoi.net/oldtech/ponder.html Thanks Wes!
--Lex PH2LB. uBITX mods. TO-18 Heatsinks. New stickers (see above).
--Kostos SV3ORA and Hans G0UPL about the Franklin Oscillator.
--Listening to HRWB 178: Great stuff, many old friends: George KJ6VU moved to Oregon. Thomas K4SWL on the show.  Ben, an old friend of Pete’s,  mentions John Zaruba K2ZA – the guy who gave me the DX-100. Wonderful connections.
--Thanks to Todd VE7BPO for sending me another AADE LC meter. I need it for the SSSS.
--Nick MONTV planning a 15/10 meter dualband SSB rig. Me too! See video.
--Trevor Woods in W. Australia – The portrait in Artie Moore’s shack. Chuck WB9KZY – Willam Ramsay
--LA6NCA Helge three tube RX. Regen or DC? Mike Masterson WN2A and I discuss.
--Mike WU2D video on Retro QRP rigs – Steve G0FUW discusses Severn rig long in the works –started 1983 and nearly finished!
--Tim Hunkin of Secret Life fame did video with speaker made from potato ship bag. Discussed with Tony G4WIF and others. Also, Tim has an amazing video on cutting holes in metal. On the SolderSmoke blog.
--Bob Crane W8SX will be covering FDIM for SolderSmoke!
--Glen VE3DNL working on a more sophisticated DC RX.
--Craig KC2LFI from the beach on Grand Cayman. FB.
--Steve EI5DD reports We have changed our name - The May Issue of the HAM RADIO IRELAND Magazine, Ireland’s only independent magazine for the Radio Experimenter: https://docdro.id/SHH0VEy
--Mike EI0CL on 15 meters with Dean KK4DAS. FB
--Howard N3FEL of the Penn Wireless Association wants to do a group build of a DC RX.
--Martin LW9DTR in Buenos Aires looking for help with the code for an AD9850
--Todd K7TFC – always helping other homebrewers.
--Really thoughtful message from Kevin WN7Z

uBITX 2

My KB1GMX mods to uBITX 2

The Awesome Homebrew of Will KI4POV

 

Will's homebrew station is really something.  The rig (it truly qualifies for this term of praise) is amazing all by itself  (see below), but a look at Will's QRZ page reveals other ingenious inventions and techniques:  There is the clock made from panel meters.  And the method he uses for making aluminum project boxes.  He even made an N0WVA regen receiver.  That's the one I used in my ET-2.   Fantastic.  

Will really needs to share his homebrew skills with others.   I hope he is soon in a local high school teaching students how to build things.  Thanks Will!  

Bill and Pete,

Just wanted to send a note to update you on the latest projects here. The last time I emailed, I mentioned wanting to build a superhet, which you (rightfully) discouraged, pushing for a DC receiver.

Well, I finished the superhet at the end of last year. I had most of the receiver working long before then, but got bogged down in an AGC system. The final receiver is a 5 band si5351a controlled single conversion superhet loosely based on Todd, VE7BPO's design with several modifications. I used a 9 Mhz IF instead of 4, I used a digitally controlled LO and BFO, and as mentioned, I added an AGC system, which ended up being the most challenging (and most interesting) part. The final AGC system I ended up with used the detector and amplifier side of Wes Hayward's "full hang" AGC from SSDRA, but I didn't have the IC IF amplifiers with variable gain, so instead, it fed a PIN diode attenuator circuit to control the IF gain. The final result worked great, but I nearly pulled my hair out getting it to work. I originally intended to build the receiver for 40 and 20 meters, but it ended up covering 80, 40, 30, 20, and 15 since I used the filter relay board from QRP Labs which had 5 slots.

After I got the receiver running, I decided I needed a matching transmitter, so I  built up a simple CW transmitter to match. It uses an si5351a VFO driving a 74HC04 hex inverter as the buffer amplifier. The trick here is that by driving all the inverter gates in parallel, the output impedance is ~14 ohms broadband, suitable for driving a BJT PA without any need for matching transformers. The PA is 3 2N2222s in parallel with heat syncs putting out about 2 watts from 80 - 15.

The part I'm most proud of is that I have the arduino for the receiver connected to the arduino for the transmitter through a serial line. The receiver sends it's current frequency to the transmitter so that the transmitter can track the receiver's frequency as you tune (like a transceiver). I'll attach a few pictures of my homebrew station below. The transmitter is on the left, receiver is on the right. The box on top of the transmitter is my homebrew keyer. Next up on my build list is a solid state T/R switch.

Bill, I've enjoyed following the updates on the school DC receiver build. My local club is wanting to do some youth outreach, and I'd love to get them involved in building. I'm the only builder in the club though, so I don't know if I personally have the manpower to make it happen. Also, thanks for the recent info and pictures of Cuban homebrew rigs. I grew up listening to Arnie Corro, so I love seeing their resourcefulness and ingenuity. Makes me want to take apart some old electronics.

Pete, I'm enjoying following the 10M SSB project. With the uptick in propagation, I've been bitten by the 10M bug, and I'm thinking a 10M rig may have to be on my project list for this year.

73,

Will - KI4POV

KI4POV's Clock

KI4POV's N0WVA Regen

Cargo Culting, Appliances, and Homebrewing

Hack-A-Day had an interesting short piece on cargo culting and computer coding:

https://hackaday.com/2022/12/03/cargo-culting-and-buried-treasure/  

Obviously there is a lot here that it applicable to ham radio.  Feynman admonished us to try to deeply understand what we are doing.   Do we risk cargo culting when we make use of gear that we really don't know anything about?  Or when we use a chip that we don't really understand?  (I'm looking at you, Si5351.)

I guess we can't really understand some of this stuff as deeply as Feynman would like -- can anyone describe the signal flow in a CPU chip?  I don't think so.  And Feynman would be the first to admit that no one really understands quantum mechanics. Still, as the author notes, we should be cognizant of the gaps in our understanding.  For there dragons lie.  Or opportunities to learn. The comments on the Hack-A-Day post are mostly pretty good. 

SDR Direct Sampling: The End of Homebrewing (as we know it)

I sometimes hear hams claim that our efforts to build simple direct conversion receivers are "very relevant" to modern technology and are "directly applicable" to today's communications techniques.  These hams will say that direct conversion receivers are at the heart of modern rigs. 

That's a nice thought, and it might have been true in the past, but I don't think it is true anymore.  

I think the future is what you see written on the black box (!) that encloses the receiver in the above video: "DIRECT SAMPLING RECEIVER."   In the recent past we did have two direct conversion receivers in the front end of SDR receiving systems.  These receivers produced I and Q signals that were fed into the computer (often via the sound card).  That was nice.  

But the writing has been on the wall for a long time.  There is no longer a need for all that direct conversion and I and Q.  Just put a fast Analog-to-Digital converter chip at the front end, convert the entire HF spectrum to a digital stream, and send that stream to your computer.  Or to another part of your "rig."  As in the ubiquitous 7300. 

I don't mean to be a Luddite here.  That big waterfall is very nice.  The receiver sounds great.  But I am a homebrewer and I prefer to build my own gear.  Ordering this black box on my phone,  having it delivered by Bezos to my front step, and then updating the driver, is not what I consider homebrew radio.  

A couple of things I spotted:  The Si5351 chip in the box -- at least one part was recognizable.  And the completely vertical skirts on all the SSB signals -- lots of 7300s out there.  

Hey, to each his own, YMMV, whatever floats your boat.  Just don't kid yourself into thinking that our beloved DC receivers are still somehow being used in these modern black boxes. 

Farhan Takes us Back into the Daylight -- An Analog Rig with a Homebrew Crystal Filter and an LC VFO

 

There is so much radio goodness in this rig and in the blog post that describes it.  Farhan's blog post will keep us busy for a long time.  There is much to learn there.  But perhaps even more important is his larger view of the role of analog circuitry in ham radio.  Here are a couple of excerpts from his introduction: 

 Here is the memo : The analog never died. The world is analog all the way, until you descend into Quantum madness. The antennas are analog, Maxwell died a content, analog man. Our radios, ultimately, are analog machines and we are all analog beasts too. Amateur Radio technology has evolved into the digital domain. However,  it has only made it easier for us to do analog with computers to simulate and print our circuits.  So, it’s time to bid good bye to our Arduinos and Raspberry Pis and build an Analog Radio for ourselves. So let’s see what we can achieve in hindsight, a return to our native land and a rethink of our approaches. The radio is called Daylight Again, a nod to being back at the FDIM in 2022 after a gap of two years. It is named after the Crosby, Stills, Nash and Young’s song that had been humming all the time while put this radio together, emerging after 2 years of lockdown.  This radio that took two days to come together, no actually two years! That’s: parts of it got built and stowed away, thoughts were struck in the shower, questions popped up during early morning cycle rides and notes and circuits were scribbled in the notebook.  I must take the first of many diversion here: I hope you all maintain a notebook. Write down the date and whatever you thought or did on the bench and the result. Nothing is trivial enough to leave out. Wisdom comes to those who write notes.  I started to build this on Saturday the 14th May and I checked into the local SSB net on Monday morning, the 16th May 2022.

AND

Having clean VFO  is the most important way of increasing the dynamic range of your radio. A free running JEFT VFO that has sufficient power and a good Q components, will be unmatched by any synthesized or direct sampling radios. The math is all on the side of the free running VFO. We are talking -150 db/Hz at 10 KHz spacing, by comparison the Si5351 is -125 db/Hz, it is 300 times worse.

That is just part of the intro.  We should all study the rest of Farhan's blog post very carefully and incorporate the wisdom into our new rigs: 

Here is the blog site: 

https://www.vu2ese.com/index.php/2022/08/04/daylight-an-all-analog-radio/

Enough of the darkness.  Step into the daylight my friends. 

Phase Noise and all that

Our friend Dave K8WPE has been listening to old podcasts.  He recently came across those in which Pete and I were talking about phase noise.   He asked for some resources on this topic.  Here is what I sent him: 

 Receiver performance expert Robert Sherwood explains it this way: 

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. 

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

Rhode and Schwarz have a good oversight video with great graphs that explain the fundamentals,  See above or here:  https://www.youtube.com/watch?v=hfgaEjf1154 

I think a lot of the fretting about advanced receiver performance measurements are really kind of over-the-top, and mostly of interest to advanced builders who want the very best performance from their receivers.  Most of the rest of us are happy if we can hear the band noise and separate the desired signals from the QRM.  But I must admit that as time goes on, I find myself getting more and more finicky.  I start to worry about gain distribution and dynamic range.  But I don't worry so much about phase noise because I am more of an LC oscillator guy and don't make much use of the PLL devices (like the Si5351) that do produce more phase noise. 

I've had many articles on the blog about about phase noise.  Here they are: 

https://soldersmoke.blogspot.com/search?q=%22phase+noise%22

Who is JF3HZB? (The Creator of that Nice Digital VFO Dial) -- Some Links

Many of these sites are in Japanese.   Just look for the translate button on your browsers. 

 YouTube channel: https://www.youtube.com/user/uebo0222/videos

Web site:https://tj-lab.org/

Twitter: https://twitter.com/t_uebo

Blog: https://tj-lab.org/%e3%83%96%e3%83%ad%e3%82%b0/

Upgrades of the JF3HZB VFO: https://github.com/WA2FZW/It-s-Not-Just-Another-Digital-VFO-by-WA2FZW-VK3PE-and-G3ZQC

Discussion on Japan's "QRP Plaza."http://bbs7.sekkaku.net/bbs/?id=qrp&mode=sort&check=now&type=letter&open=1&view=1&reverse=off&inputform=1&search=JF3HZB

The JF3HZB Digital VFO Dial in the DJ7OO Direct Conversion Receiver (Who is JF3HZB?)

Pete was talking about this beautiful Digital VFO dial in the latest podcast.  In response, Klaus sent me an e-mail with links and the video above,  describing how he used the VFO dial in a very cool Direct Conversion receiver project.  TRGHS. 

Here is the web site (you can easily get the English translation by clicking on the UK flag link): 

http://www.kh-gps.de/uni-rx.htm

Thank you Klaus!  And thanks to JF3HZB!  (Does anyone have more information on him?) 

Level UP EE Lab Builds a Superhet Receiver

I was really glad to have stumbled across Darren's YouTube channel: 

(46) Level UP EE Lab - YouTube

Heck, he has an S-38E on the shelf above his bench.  He is clearly one of us.  What is his callsign?  

This morning I watched the first and last of his 10 videos on his superhet receiver project.  Very cool.  Lots of good info in there.  And there is something for everyone:  Arduinos and Si5351s, along with a lot of standard analog circuitry.  The first episode appears above. 

The variable bandwidth filter looks very interesting. And there was a nice shout-out to Charlie Morris and one to Hans Summers. 

I really like his effort in episode 10 to measure Minimum Discernible Signal using commonly available test gear.  This helped me in my effort to get more rigorous and serious about receiver performance measurement.    

Darren has many other excellent projects on his YouTube channel.  My Hammarlund HQ-100 receiver started giving me trouble this week, and I was debating whether or not to fix the old thing.  Darren's channel provided the inspiration I needed.  It will be fixed!   

Please subscribe to Darren's channel.  And spread the word about his videos.  We definitely want him to make a lot more.  

Thanks Darren! 

Dennis WC8C's FB Homebrew 6 Meter Rig -- Any Ideas or Suggestions?

 

Dennis WC8C is the event coordinator for the radio club in Michigan that I recently spoke with.  He mentioned to me that he was working on a homebrew 6 meter rig.  FB Dennis.  I see lots of tribal wisdom in your approach, especially in your decision to do this in a stage-by-stage modular form. 

Dennis's rig is obviously a work in progress, so if anyone out there has any helpful hints (especially on the carrier suppression and on the testing for spurs and splatter) please share them with him via e-mail or blog post.  

The files on Dennis's rig are on GITHUB: https://github.com/soligen2010/6_Meter_Transceiver

Thanks Dennis!  

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

This is my 6 Meter homebrew transceiver, currently work in progress.  It is a single conversion super –heterodyne design.  I constructed each stage independently with SMA connectors.  This is so I can re-make sections as needed, and will allow me in the future to swap sections to experiment with alternate designs.  The VFO and BFO are controlled using a SI5351 with an Arduino micro controller.  I currently have separate SI5351 modules for VFO and BFO because I suspected issues with cross-talk.  These issues may not actually be real, so once I am happy with the performance, I will test again with just one module to see if it is OK.  The Power Amp is still on the to-do list, so output is well under 0 DBm

The Blue boards were designed by me and ordered on-line.  The other boards I etched myself.  Construction is mostly surface mount because I find it easier than drilling all the holes.  SMD components are mostly 805 and 1206 size. Transistors are SOT23.

The Band Pass filter is a 5 coil design made with air-core inductors.

3 bi-directional termination insensitive (TIA) amps are used (blue boards).  Total RX gain is about 44db.  Total TX gain is about 16db.  Each board has its own independent RX/TX switching circuitry (mosfet based) and is fed with +12.5, GND, and RX/TX logic signal from the Arduino (3V logic and up will work)

The Mixer and modulator are both Diode Ring mixers.

The 12 MHz SSB filter is a crystal ladder filter similar to the one used in the uBitx.

The Mic and audio pre-amp (also a blue board) is made on a modified TIA amp board.  I had 10 of these boards made, and the needed circuitry was largely the same, so I modified the board with a rotary tool and jumpers.

The Audio amp is a PAM8403 module and drives a headset.  I did make some modifications to the module so it runs in-spec and to eliminate the power on audio pop.

The challenges I have been having are mostly related to spurs, splatter, carrier suppression and TX audio quality.  I have been gradually tweaking these things to improve operation before I start on a power amp.  My IF is 12 MHZ, and I was using the LSB side of the crystal filter because it is sharper (VFO 62 – 66 MHz) but have recently changed over to the USB side of the filter (VFO 38 – 42 MHz).  This eliminated the spurs I was seeing near the pass band.  I still need to make some adjustments to the crystal filter as it is too broad.

I still have some splatter and audio quality seems low, but I am starting to doubt my test setup.  I see the splatter on the RTL SDR, but I don’t see it on the Tiny SA.  The spatter happens at ~160 KHz intervals.  I am hoping to find someone local with a better spectrum analyzer to help me verify if it is the rig or my SDR dongle/test setup.

The modules to the side of the picture are my rejects/experiments.  The one covered in copper shows how I eventually will shield all the modules.  I 3D printed a cover for the board, when wrapped it with copper tape, soldered to the bottom ground plane.  The one shown is a diode ring modulator.  For some unknown reason the carrier suppression is rather poor.  I had previously made a junk-box modulator that had much better carrier suppression.  I don’t know why it is better than the one I more carefully made for the radio, but until I figure it out, I am using the junk box version.  The junk box modulator uses unmatched schottkey diodes, whereas the “final” one uses a 4 diode SMD package because I wanted them matched – I thought this would be better, but maybe not.

LA6NCA Designs and Builds a Very Hybrid 80 Meter Transmitter (Si5351 and a 12A6 Tube) (Video)

Helge LA6NCA put out a really nice video explaining how he designed and built an 80 meter transmitter. 

I like how he put the Si5351 and the Arduino chip in what looks like a slightly expanded FT-241 crystal box.  Nice.  

I like the box and the chassis.  

I like his testing/tuning technique.  

The homebrew capacitor was a very nice touch.  

Where can I get some of those coil forms?  

And of course, the R-390 receiver adds a lot of mojo to the shack. 

Helge's web sites document an enormous number of great projects:  

Helge's page on the 12A6/Si5351 transmitter: https://www.la6nca.net/homebrew/tx_12a6/index.htm

Helge's main site:  http://www.laud.no/fykse/index.htm

Thank you Helge! And thanks to Hack-A-Day for alerting us to this. 

My Kind of Chip: A Homebrew Discrete 555 Timer Built on Wooden Boards (video)

This is really beautiful. Radraksha Vegad (Pargrahi) from India built a discrete component version of the venerable 555 timer chip.  He built it on wooden blocks.  This leads to the kind of understanding that even Jean Shepherd would have admired.  No longer is the 555 a little mysterious black box.  No, Pargrahi shows us how it works.   

 I know we could do something similar with the NE602 or the LM386.  But probably not with an Arduino microcontroller or an Si5351.  And that says something about understanding and complexity. 

Thanks Radraksha.  And thanks to Hack-A-Day for alerting us to this: https://hackaday.com/2021/12/20/all-hail-your-new-giant-555-timer-overlord/#more-512230 

Hack-a-Day: Has DIY become Click-and-Buy?

https://hackaday.com/2021/12/11/has-diy-become-click-and-buy/

Hack-A-Day today asks about the boundaries between DIY construction and the use of purchased, completed electronic components.   This is closely related to our long-standing discussion of what really constitutes "homebrew." 

Is it really homebrew if you buy a bunch of  already-stuffed PC boards and connect them together?  

Is it really a homebrew receiver if 90% of the components are inside one chip? 

Is it really homebrew if most of the signal processing is done in your computer (that you definitely did not build)? 

The comments below the article are interesting.  There we see some of the same arguments used by ham radio operators who are more inclined toward click-and-buy. They argue that since none of us are making our own resistors and transistors, we are ALL therefore click-and-buy people, so we should just get over it and pull out the credit cards. Some commenters carry this to extremes and ask if the real homebrewers are out there mining the copper for their wires.  

The debate seems to spill over into the software area:  One person asks if it is really DIY if you are using software libraries that contain code written by someone else.  Or to be truly DIY should you write all of your own code in assembly language?    

There is one very insightful comment about hams who are inclined to disparage the homebrewing that they did in their youth.  We often hear this:  "Oh, I used to build my own gear, but now-a-days I just buy commercial transceivers -- they are so much better."  As if homebrewing was a folly of youth, something that they grew out of (and up from) as they became able to afford the latest ham radio appliances.  As if homebreweing were a regrettable thing that was done only out of necessity.   This is, I think, sad.  

I think I'm a lot closer to the traditional concept of DIY than I am to click-and-buy.  I still prefer LC oscillators to Si5351/Arduino combos.  I prefer traditional filter rigs to SDR rigs.  And I prefer to make my own crystal filters.  I don't like to use ICs unless I really understand what is going on inside them (so I can be comfortable with an NE602 or an LM386, but I'm not comfortable with a CPU chip that may have millions of transistors in it).  But I am not homebrewing my own transistors nor am I mining copper. 

What do you folks think about this? 

https://hackaday.com/2021/12/11/has-diy-become-click-and-buy/

KG7TR's Magnificent 75S-2B Receiver -- Tubes, an Si5351, an Arduino, a Bit of Collins, and a Bit of a Drake 2-B

 

Oh man, I share this with much trepidation because the last time I posted something about the work of Mike KG7TR,  Pete N6QW said he felt like putting all of his own work in the dumpster, so much better was the artistry of KG7TR.  This receiver is so cool and so well-done that we now  might have to post a guard outside the N6QW shack -- heck Mike even has an Arduino Uno and an Si5351 in there!  Don't do it Pete!

I was led to this magnificent receiver by the very humble 6U8 tube.  Scott  WA9WFA and I have been learning (mostly from Grayson KJ7UM) that the much used and sometimes loved 6U8s (three of them in our "Mates for the Mighty Midget")  might be a bit long in the tooth, old even by Thermatron standards.  I was worried when I remembered that my Drake 2-B has a 6U8 in it -- V2, the first mixer.   So I Googled for more info and was led to this amazing receiver, a 2018 creation by KG7TR.  How did we NOT see this for almost four years?

Here is more info and pictures: 

http://www.kg7tr.com/75s-2b-receiver.html

Here is Mike's write-up of the project: 

http://nebula.wsimg.com/c2281e9bdf3b54da42ca4b0b541b4ec9?AccessKeyId=D18ED10DA019A4588B7B&disposition=0&alloworigin=1

Mike KG7TR's web site:

http://www.kg7tr.com/ 

As for the 6U8s, well Grayson says the tube has been getting something of a bum rap.  And  KG7TR has two of them in this receiver, so I will obviously have to give the 6U8 another chance.  

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

I didn't know that Lew McCoy had his own crystal and crystal filter company: 

http://www.kg7tr.com/the-real-mccoy.html