Category: direct conversion

FLASHBACK: The Herring Aid 5 Direct Conversion Receiver and Frank Jones (Video)

The Radio Gods seem to be pushing me towards Direct Conversion receivers. This week I was speaking via Zoom with the very FB L’Anse Creuse Amateur Radio Club in Michigan. My Herring Aid 5 tale of woe came up (see video above). Then Dean KK4DAS was sharing video of the amazing fidelity of the Pete Juliano Direct Conversion Receiver. Then I started thinking about Frank Jones W6AJF, and the story (fictional) of his build of the Herring Aid 5 by Michael Hopkins AB5L:

———————-

I gave Frank a board for the Herring Aid Five redux from the April 1998 QRP Quarterly and challenged him to build one up. It took maybe two hours and that includes his own touches which included refusing to buy any parts.

For the transformers, he calculated the turns ratios from the impedances and tested a bunch of TV set pulls ’till he found something close. But he made the output 1:1 because his Brandes phones are close to 1000K Ohms as it is.

He was willing to use toroids, but not to buy one, so I gave him an Amidon circular and he calculated the values of the 18 specified units. Then he wound them on unidentified cores from my junk box after learning the permeability of each with his homebrew dip meter.

A store bought Zener was out of the question so he mixed and matched regular diodes with transistors hooked up as diodes until he got close enough to 10 volts. The mosfets came out of a TV tuner and Frank will use any plastic bipolar that says “C” or “D” on it for a 2N2222.

Of course it worked the first time. He rigged up a patch to a pair of Class A push-pull 6L6s so Christie could hear it and she said it was “Also cute but bigger than the other one.”

Now a real QRPer would cry at that, but not Frank who sees no advantage in miniaturization at all. In fact, he mounted the whole thing in an old case from a Collins 6 and 2M transceiving attachment he junked out for the parts and no two knobs matched as Frank thinks matching knobs slow you down in a pileup. He wanted to take it back to his own shack and try it out with his breadboard MOPA and pair of 100THs because he does not run QRP, saying it “transfers the burden to the other guy.”
—————–
Frank Jones was one HARD CORE HOMEBREWER. No store-bought Zener diodes or toroidal cores for him!

All of the SolderSmoke Herring Aid 5 articles can be found here:

A New Michigan Mighty Mite Oscillates in Northern Virginia

We are pleased to report that OM Jack, NG2E, has successfully built a Michigan Mighty Mite transmitter, and has experienced JOO (the joy of oscillation). You can see Jack’s prototype in the video below:

Jack has his eye on more ambitious homebrew projects, but is wisely taking a step-by-step approach. He described his plans this way:
  1. Capture this MMM into a semi-permanent design: ie, perf board.
  2. Measure performance. What does the carrier wave look like on a scope?
  3. Build a low-pass filter.
  4. Can I amplify the signal? Maybe add an amplifier stage or two. Transistor?
  5. Next, let’s look at receivers. Pete & Bill recommend that I build a Direct Conversion receiver. I know Peter Parker (VK3YE) has a simplified version.

AA7EE Casually Kills a Direct Conversion Receiver, then Coldly Discards a Diode Ring Mixer

I was really glad to see that Dave AA7EE has — after a long absence — posted another article on his blog. The article has some great personal reminiscences about his involvement with direct conversion receivers. Here is one passage:

I spent many happy hours tuning around and listening on 80M with the DSB80. It was this first experience that cemented my affinity for direct conversion receivers built with commercially available diode ring mixer packages. It just seemed so simple – you squirt RF into one port, a VFO into the other, and (after passing the result through a diplexer) amplify the heck out of the result. The seeming simplicity of the process of converting RF directly to baseband audio has held great appeal for me ever since. Unfortunately, that project didn’t survive. One day, in later adulthood, in my apartment in Hollywood, I reversed the polarity of the 12V DC supply and, discouraged at it’s subsequent refusal to work, tossed the whole thing away. Now, I cannot quite believe that I did that, but it was during a long period of inactivity on the ham bands, and complete lack of interest. If only I could go back, and not have thrown it into the dumpster of my apartment building! Hollywood is ridden with recent notable history. My little double sideband transceiver met it’s unfortunate end just 100 feet from the spot where Bobby Fuller, of The Bobby Fuller Four, was found dead in his car, in 1966, the subject of a still unsolved mystery to this day. The death of my little DSB rig was a lot less mysterious. To think that I heartlessly tossed an SBL-1 mixer into a dumpster, is a mark of how far I had strayed from my homebrewing roots, forged in a little village in England. Now, a few years later, in a city known for it’s sin and excess, I had cruelly ended the life of a stout and honest diode ring mixer. I suppose I should spare a thought for the polyvaricon but, well, you know – it was a polyvaricon!

https://aa7ee.wordpress.com/2021/03/04/the-ve7bpo-direct-conversion-receiver-mainframe/

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.

Adam N0ZIB’s Direct Conversion Transceiver

This is obviously very cool, but looking ahead I think Adam should think about adding one more mixer, changing the bias on the TX amps, and adding a mic amp. Boom: A Double Sideband Transceiver.

Pete wrote: When I was in the US Navy and a particular unit did something outstanding – the Command ship would raise the Bravo Zulu Flag for a job well. Don’t know if you can see it there in MO but I have raised the BZ flag to you. Outstanding and congratulations.

Bill and Pete:

Just finished a DC transceiver using Arduino nano, SI5351 (my sincerest apologies, Bill), diode ring mixer and lm386 audio amp. The transmit portion is a two-stage class AB pre-amp (from EMRFD page 2.32), which is driving an IRF510 final (biased at 2.08 volts) from Pete’s design. Output is about 5watts into a CWAZ low pass filter, based on the design from here: https://www.arrl.org/files/file/Technology/tis/info/pdf/9902044.pdf

I’m using a manual TX/RX switch which is doing multiple things. It brings the Nano A1 LOW, offsetting the transmit frequency 600 Hz for CW, grounds the audio input to prevent deafness (learned that one the hard way), and it engages a relay that switches the antenna from the receiver to the transmit, and also turns on the transmitter stages. Keying is through the first stage of the pre-amp.

I still have some tidying up to do, and I’m not sure the LPF works so well using two component inductors instead of all toroids, but I finished it today and made my first QSO into Ontario almost 1000 miles away. It’s been great fun!

73,
Adam
N0ZIB
Missouri

VK3YE’s Super Simple Phasing Receiver

Really simple, really nice. I like the innovative way they achieved the RF quadrature: they did it by splitting and phase-shifting the RF signal, not the VFO signal. I also like Peter’s use of the AM broadcast signal to demonstrate the sideband suppression. Then, SSTV for icing on the cake.

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.



Presence (Absence?) and Direct Conversion Receivers (with wise comments from Farhan)

Hello Bill,
I was reading an online article by Wes Hayward, W7ZO from 1968 about the history of direct conversion receivers (http://w7zoi.net/dcrx68a.pdf) . It was linked in an email in qrptech. It recounts how he had first build a dc receiver with a single diode for the detector, and how microphonic it was, and dissatisfying an experience. This was in the early days of solid state devices, and so they were hard to come by. He describes meeting another ham engineer at work Dick Bingham, W7WKR who immediately recognized that what he needed was a diode ring mixer. The story goes on to describe their experiments, and success at this design.

They decided to write up the design for QST. I won’t bore you with the details…the article is well worth reading about how Wes mailed the radio and the design to ARRL, and how it ended up in the hands of a new person on their staff there, Doug DeMaw, W1CER (later W1FB.). Here is an excerpt from the article describing Doug’s reaction to the receiver:

“This was the epiphany, the moment when Doug realized that solid-state technology had produce a new way to build a simple receiver. Doug tuned the receiver higher in the band and found some SSB. Again it was like nothing he had ever heard. It was as if the voice came from the same room. Doug used the term presence in his description.”

Here I present the earliest use, that I know of, of presence being used to describe a receiver. I have to say when I read it, I immediately thought of you guys, and decided to share.

Thanks for all you guys do.
dave /nt1u
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Bill replied:

Thanks Dave. Yea, that’s the 1968 article that launched the use of DC receivers. I had forgotten about DeMaw’s early use of “presence.”

Just to cause trouble, perhaps we should start commenting on “absence” i.e. “I dunno OM, I think your rig lacks a bit of absence in the mid-range… turn menu item 63b to ELEVEN!”
🙂
73 Bill
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Farhan wrote:

Mon, Aug 3 at 3:22 PM

When I got my license, my friend Anil SM0MFC was living in Hyderabad. He lent me his HW-8. I stringed up a 40 meter dipole with a lamp cord and worked with it. Somehow, the combination of the lamp cord length and the 40 meter inverted V made it resonate on 20 m as well. The HW-8 had a nominal antenna tuner and I worked pretty good DX.

Till date, it remains the best receiver that I have used for regular contacts. The only trouble it had was the the MC1496 was a nominal detector, it overloaded heavily with shortwave broadcast stations. There was an unnecessary RF amplifier in the front-end that they could have done without.

I made several direct conversion receivers, but never managed to hang on to any. This makes me want to build one, one of these evenings. I even have a KK7B R1 kit. but real men solder on without any PCBs or even circuit diagram!

A 7/14/21 direct conversion radio that puts out 3 watts of power is what my ideal setup would be. I am not too bothered with the images on CW. I just tune them out in my head. Real soon now, at the moment, i am trying to finish a radio that has been in the works for years. Finally, I am making some headway.
-f
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Farhan of course is no slouch in the DC receiver area. Years ago he wrote a wonderful post about building a DC receiver with his cousin for her class project:

Included in this post was a passage that I included in my book SolderSmoke — Global Adventures in Wireless Electonics:
————————–
Why build a receiver?
Why do you want to build it? These are available at the Dubai Duty Free asked Harish, an old friend, when he spotted us struggling over the DC40 one evening. I didn’t have an answer to this question and considering the amount of work piled this quarter, it appeared to be a sensible thing to ask.

I think this question is answered by us all in different ways. My personal answer would be because we human beings are fundamentally tool builders. We have an opposable thumb that allows us to grip the soldering iron.
For an engineer (by the word ‘engineer’, I don’t just mean those who have a degree, but anyone who applies technical knowledge to build things) the act of building a receiver is a fundamental proof of her competence and capability. It is much easier to put out 1 watt signal than it is to receive a 1 watt signal.
A simple definition of a good receiver is that a good receiver consistently, clearly receives only the intended signal, such a definition hides a wide range of requirements. The receiver has to be sensitive enough to pick up the weakest signal imaginable (note: clearly), it has to be selective enough to eliminate other signals (only), it has to be stable enough (consistently).
For a ham or an engineer, building a usable receiver is a personal landmark. It establishes a personal competency to be able to understand the very fundamental operation of the radio and mastery over it.

——————–
Bill: OM Ryan Flowers did a 5 part series on building the DC40. If you are want to build one, I suggest you use the schematics on Ryan’s site. There was an error in Farhan’s original schematic — Farhan corrected it but some of the incorrect schematics are still floating around the internet. Here is part one of Ryan’s series:

Farhan’s DC40

10 Meter Quarantine QSOs near Boston — KC1FSZ’s Peppermint 10

Hi Guys:

I hope all is well. Thanks for the more frequent episodes!

I’ve not submitted anything lately but I’m still doing a lot of building. Over the last few weeks I’ve been working to get myself on 10 meters. There is some good local activity up here in the Boston suburbs on 10. The result of this effort is the next in the Peppermint Line of high-performance radio products for the discerning operator: The Peppermint 10. This rig uses digital VFOs and puts out about 12 watts on a good day. It works in conjunction with a direct-conversion receiver that has been modified for 10 meters. The details are described in the write-up (see link):

https://mackinnon-public-web.s3.amazonaws.com/peppermint-10/index.html

73s,

Bruce KC1FSZ

Direct Conversion (videos)

Here are a couple of videos from 2017 (never posted before). I built a little 40 meter Direct Conversion receiver for my nephew John Henry.

Whenever we work on circuitry like this, we should be be grateful for Wes Hayward W7ZOI who, in a 1968 QST article, reminded us of this important but until-then forgotten technique.

More information on this project appears in these links:

https://soldersmoke.blogspot.com/2017/10/a-direct-conversion-iphone.html

 https://soldersmoke.blogspot.com/2017/11/iphone-direct-conversion-receiver-with.html

A Frequency Readout for the Fish Soup 10 (with cool BLUE numerals)

Note the cool BLUE numerals. They represent 7040, 7050, 7060, 7070. The little black “pointer” is from a power cord wall fastener. My tuning cap has a nice reduction drive — the pointer follows the movement of the capacitor blades. The VFO is very stable.

Simplicity is a virtue. CW is, I think, outmoded and kind of absurd (one letter at a time? really?), but it does allow for extreme simplicity. Using a rig with just 10 transistors, putting out half a watt of RF, I am regularly communicating with people. This is what I like about CW.

I’ve had about 12 solid contacts with this rig since putting it on the air earlier this month. The VFO was a huge improvement over being crystal controlled. Crystal control was OK back when receivers were broad and hams tuned around for replies, but those days are gone. Getting the transmit offset set correctly was another huge improvement.

FDIM Interview with KI4IO — Homebrew Direct Conversion Transceiver

I‘ve been a big fan of Jerry’s for several years. He is the homebrew wizard of Warrenton, Va. Warrention is just about 25 miles west of us. Cappuccio the wonder-dog was born on a farm in Warrenton.

I’m really glad that our ace correspondent Bob Crane W8SX caught up with Jerry at FDIM. I liked his description of the joy of using a homebrew rig, and of the advantages of direct conversion. Inspiring stuff! Listen to the interview here:

http://soldersmoke.com/KI4IO FDIM 2019.m4a

Be sure to check out the KI4IO page on QRZ.com

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:


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:


73 to you both and I wish you the best!

Ryan Flowers W7RLF

SolderSmoke Podcast #208

SolderSmoke Podcast #208 is available:

http://soldersmoke.com/soldersmoke208.mp3

 15 December 2018

 Pete and the California fires
Bill goes to Brooklyn
2 meter simplex
A return of the trivial electric motor
Audio from Mars
HF Conditions — a real mixed bag

 Pete looks back at 2018 — The Year of the SSB Transceiver — Lessons Learned

 Hans Summers, the QSX and the virtues of SDR
W7ZOI’s DC Receiver Retrospective
The 1972 Solar Flare and the Vietnam War

 SHAMELESS COMMERCE: Buy your gifts through the Amazon link to the upper right.
Consider SolderSmoke the book as a gift. Visit Pasta Pete’s for cooking ideas.

Don’t Build It! Sage — but unexpected — advice from Pete.

Straight Key Night approaches.

Book Reviews:
–“What is Real?” (Quantum Physics)
— RHdb by K6LHA.

 Movies
“Bohemian Rhapsody”
“First Man” (Not yet!)

 MAILBAG:
Steve G0FUW
Ed KC8SBV




W7ZOI: Direct Conversion Receivers — Some Amateur Radio History

http://w7zoi.net/dcrx68.pdf

 Farhan and Pete WB9FLW alerted me to this wonderful article by Wes Hayward, W7ZOI. I guess my interest in DC receivers must have been noticed by the Google algorithm because I am bombarded by ads extolling the virtues of “Zero IF.” Hey Google — I’m already a believer! I was converted by W7ZOI’s 1968 article in QST. And my belief in the technique has been greatly reinforced by his November 2018 50th anniversary article.

There is so much good stuff in Wes’s look-back piece. The travails of trying to write for QST are presented very well. And we learn that none-other-than Doug DeMaw himself is responsible for the use of the word “presence” in describing amateur radio audio.

This article has inspired me to take a new look at the DC receiver I built last winter. Mine needs some work. I think it is kind of deaf. It could probably benefit from a diode ring detector. But it already has presence.

http://w7zoi.net/dcrx68.pdf

 Thanks Wes. And thanks to Farhan and Pete for the heads up.

KD4PBJ’s PTO “Turtle” Receiver

Gents,

Here’s my newest creation.
It’s a PTO tuned receiver for 40 meters and uses the WA6OTP PTO circuit I built a couple years back. I believe I had sent you a picture of it then. I bought the tuning assembly from him which is the aluminum bracket, acrylic tube fitted with Pem nut, and brass screw. The circuit uses a J310 as oscillator transistor and several bipolar transistors for amplification and buffering.

This feeds a ADE-1 mixer, mounted on a little breakout board I bought from RfBay.
Years ago I had good luck building the Rock Bending Receiver from the ARRL handbook, so I took the audio chain from it and incorporated it. It uses a TL072 and a LM 386.
As of now I haven’t needed any kind of front end filter, but am working on a 40 meter bandpass filter from Hans Summers that I will put on the input just in case it’s ever needed.
I had been looking for an easy enclosure and found this in one of the break rooms at work. An empty Christmas nut tin.
The PTO screw goes in and out like a turtle sticking its head out of the shell, plus my 13 year old son Alex’s favorite animal is a turtle. So it goes.

Chris
KD4PBJ


Ralph AB1OP — A New Receiver (with Mojo) and A New Acronym (with Attitude)

Bill and Pete,


😀 Completed the wiring the LBS Part I (pics attached)
I’ve said wiring completed but, it’s not really done. lt will need some peakin’ & tweakin’ and I already have made design changes to the power board.

My Summer Project took ALL Summer, had the usual excuses with Summer activities, family obligations, interruptions and days of just plain goldbricking.

At last all the LBS Part I boards were laid out, etched, populated, soldered and installed. As a novice Toroid winder it took a while to get the toroids done. (I had to do THREE DBM Transformers to get two to match.)

Some features of note:
1. Extensive use of the recycle bin for front / rear panels and feet. (Tin can and bottle caps) Go Green!
2. Extra Mojo was induced with using the 10K pot Farhan supplied with my first Bitx40 Kit that I did not use, (I replaced it because I could not find knobs for 4mm shafts back then)

3. Junk box speaker (8 Ohm – 0.5 W) from a cheap radio alarm clock my Mom threw away after it stopped working.

4. Use of the RG405 coax for interstage RF connections. (No Murphy’s Whiskers)

😞 My tale of woe. Apparently after connecting the LBS Part I stages together I put the AD9850 module back in it’s socket upside down — then applied power, Awaiting the replacement. HIHI

😜 SITB or Stick-It-To-Bezos. Again this month my Ham stuff budget was blown on an Amazon order (replacement AD9850 modules being not cheap anymore). I started at the soldersmoke blog web page search bar so there should be a little something heading to your North Virginia QTH from Jeff.

73,
AB1OP_Ralph

KE4MIQ’s Repurposed Raduino Receiver


FB James — Really glad you are listening, and that you are having fun with a Direct Conversion receiver — souped up with a Raduino!


Bill, Pete
Just listened to #204. (New Listener)

You talked about using the Raduino with other radios.

I bought one of Mike Hagen’s RaduinoXs to use with my Bitx40. So, I have repurposed my original Raduino as a VFO for my 4SQRP ZZRX-40 DC receiver. I used Allards’s v1.26 with a few code changes to tune 7.000 to 7.300. It’s currently al fresco on a piece of Hobby Lobby foam board. I may “cabinetize” at some future date.

Attached is a pic of the ZZRX-40, Raduino, and Goodwill Sony speaker with Jameco stereo amp, all running off of Harbor Freight 9v Nimh rechargables.

So far I have heard over 40 states and 20 countries with a 65ft piece of wire in the rafters.

73s

James

KE4MIQ

WA1UQO’s Discrete Ceramic DC Receiver

Armand writes:

The attached picture is your DC receiver. A little tweaking left to do as the range right now is ~ 7.44Mhz to 7.032Mhz. I used one of Farhan’s trifillars and a couple of air coils that you gave me last year. Listening to the Wisconsin QSO party as I type.

FB Armand! The receiver looks great. I hope others will follow your lead and build this simple little receiver for 40.