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Saturday, July 3, 2021
M0NTV's Latest Breadbox Rig -- The Radio Gods Have Spoken (TRGHS)!
Thursday, December 31, 2020
So Many Wonderful Things on W7ZOI's Site
There he is. Wes Hayward, W7ZOI in 1957. I had never seen this picture before. I found it on Wes's recently updated "shackviews" web page: http://w7zoi.net/shackviews.html .
There are so many treasures on that page, and on all the other portions of Wes's site.
Some highlights for me:
-- Wes's description of the station in the above picture.
-- On his page about Doug DeMaw, Wes mentions that after Doug edited Wes's 1968 article about direct conversion receivers, Doug built some himself, experimenting with different product detector circuits. Having used Doug's mixer circuit in many of my rigs, and having recently experimented with different product detectors for my HA-600A, I kind of felt like Doug was watching over my shoulder, guiding me along as I experimented.
-- Wes's use of a digital Rigol oscilloscope. Makes me feel better about giving up on my Tek 465.
-- The page about Farhan's visit to Wes, and the awesome gathering of homebrew Titans that ensued...
-- Wes's meeting with Chuck Adams.
Thanks Wes. Happy New Year and best of luck in 2021!
Sunday, November 22, 2020
Wrapping up the HA-600A Product Detector Project -- Let's Call Them "Crossed Diode Mixers" NOT "Diode Rings"
This has been a lot of fun and very educational. The problem I discovered in the Lafayette HA-600A product detector caused me to take a new look at how diode detectors really work. It also spurred me to make more use of LTSpice.
In the end, I went with a diode ring mixer. Part of this decision was just my amazement at how four diodes and a couple of transformers can manage to multiply an incoming signal by 1 and -1, and how this multiplication allows us to pull audio out of the mess.
But another part of the decision was port isolation: the diode ring mixer with four diodes and two transformers does keep the BFO signal from making its way back to into the IF chain. This helps prevent the BFO signal from activating the AGC circuitry, and from messing up the S-meter readings. LTSpice helped me confirm that this improvement was happening: in LTSpice I could look at how much BFO energy was making its way back to the IF input port on the diode ring mixer. LTSpice predicted very little, and this was confirmed in the real world circuit. (I will do another post on port isolation in simpler, singly balanced diode mixers.)
At first I did have to overcome some problems with the diode ring circuit. Mine seemed to perform poorly with strong signals: I'd hear some of the "simultaneous envelope and product detection" that started me down this path. I also noticed that with the diode ring, in the AM mode the receiver seemed to be less sensitive -- it was as if the product detector circuit was loading down the AM detector.
One of the commenters -- Christian -- suggested putting some resistance into the input of the diode ring circuit. I put a 150 ohm pot across the input, after the blocking capacitor. The top of the pot goes to the capacitor, the bottom to ground and the wiper to the input of L1 in the diode ring circuit (you can see the circuit in the diagram above). With this pot I could set the input level such that even the strongest input signals did not cause the envelope detection that I'd heard earlier. Watching these input signals on the 'scope, I think these problems arose when the IF signals rose above .7 volts and started turning on the diodes. Only the BFO signal should have been doing that. The pot eliminated this problem. The pot also seemed to solve the problem of the loading down of the AM detector.
With the pot, signals sounded much better, but I thought there was still room for improvement. I thought I could hear a bit of RF in the audio output. Perhaps some of the 455 kHz signal was making it into the AF amplifiers. I looked at the circuit that Wes Hayward had used after the SBL-1 that he used as product detector in his Progressive Receiver. It was very simple: a .01 uF cap and 50 ohm resistor to ground followed by an RF choke. I can't be sure, but this seemed to help, and the SSB now sounds great.
A BETTER NAME?
One suggestion: We should stop calling the diode ring a diode ring. I think "crossed diode mixer" or something like that is more descriptive. This circuit works not because the diodes are in a ring, but because two of them are "crossed." From now on I intend to BUILD this circuit with this crossed parts placement -- this makes it easier to see how the circuit works, how it manages to multiply by -1, and to avoid putting any of the diodes in backwards.
The Wizard of Horseshoe Bend: VK2FC's Wonderful Projects
http://www.vk2fc.com/progressive_receiver.php
Glen's site has many other projects. Check them out:
http://www.vk2fc.com/index.php
And here he is, the Wizard of Horseshoe Bend:
Wednesday, September 23, 2020
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
Monday, August 24, 2020
Experimental Methods Book on Clearance sale -- $20
And it includes a .pdf copy of Solid State Design for the Radio Amateur.
Sunday, August 9, 2020
Presence (Absence?) and Direct Conversion Receivers (with wise comments from Farhan)
Farhan's DC40 |
Sunday, June 14, 2020
Dilbert, Shep, Dex, Pete, Farhan, and Wes! N2CQR Presentation on Homebrewing to Local Radio Club
Dean KK4DAS asked me to speak to our local radio club, the Vienna Wireless Society. It was a lot of fun. I talked about my evolution as a homebrewer, some of the rigs I made, the moments of joy, and the tales of woe. You can watch the presentation in the video above.
I was really glad to be able to explain in the presentation the importance of people like Pete, Dex, Farhan, Wes, Shep and even Dilbert.
I was also pleased to get into the presentation the N2CQR sign that Peter VK2EMU made for me. Thanks Peter!
Here is the URL to the YouTube video (also above):
https://www.youtube.com/watch?time_continue=3414&v=VHSr-v4QO7Q&feature=emb_logo
And here are the PowerPoint slides I used:
https://viennawireless.net/wp/wp-content/uploads/2020/06/VWS-presentation-Rig-here-is-homebrew.pdf
Saturday, April 4, 2020
Quarantine Project: An AM Receiver for the 31 Meter Band. The Q-31.
73 Bill
Friday, November 1, 2019
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
Saturday, December 29, 2018
KC1FSZ's Peppermint III Homebrew BITX with Mods
Bruce KC1FSZ
Thursday, December 27, 2018
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!
Wednesday, November 14, 2018
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.
Monday, October 8, 2018
VU3XVR's EMRFD TIA HB TRANSCEIVER
Ram did a beautiful job on this 40 meter rig. You can read about this project here:
https://vu3xvr.blogspot.com/2018/10/homebrew-5-watts-cw-transceiver-using.html
Monday, January 1, 2018
Jeff Damm WA7MLH on QSO Today
Happy New Year!
There was so much wisdom and tribal knowledge in Eric Guth's interview with Jeff Damm WA7MLH. It was almost overwhelming.
https://www.qsotoday.com/podcasts/WA7MLH
My notes:
-- I sympathize with Jeff's decision to go solid state and give up on high voltage after an encounter with an undischarged 600 volt capacitor.
-- I really like the 1700 kHz IF with a 5 MHz VFO for an 80 and 40 meter receiver.
-- Interesting that EE degree didn't help much in his efforts to understand ham gear. Better to read Wes's books and Doug's.
-- Tek Spectrum Analyzers were specially made to fit down a submarine hatch.
-- Building and measuring just as important as studying the theory. Inked-up text books.
-- Learned ugly from Wes as a teenager.
--Searched for old commercial gear to gut and use as homes for homebrew solid state gear. The enclosures, panels and controls are very useful. Great way to avoid metal work. These rigs are no longer boatanchors! Again, I sympathize. I've sacrificed many Heath Lunchboxes and QF-1s.
-- Jeff Builds the VFO first. My preference too. But he understands Pete's AF-first approach.
-- Finger on the input of the AF amp! Buzz! Yea! Step your way back to the front end.
-- ALWAYS one stage at a time.
-- Osh Park Boards for standard circuit modules. Like Legos.
-- Cubic Feet of air variables. Jeff has a lifetime stash.
--Thinking about what was and should have been his section of EMRFD. Go for it Jeff. PLEASE!
-- Hesistant about chips. Analog guy. Would have been a huge time sink. Analog guy.
-- Buying parts on e-bay. Fewer and fewer RF parts at hamfests.
-- People reading QST Tech Articles for entertainment. Editor apprach: "Nobody will build it anyway." Handbooks giving priority to entertainment and less to information and education.
Monday, October 2, 2017
TRGHS: I Can Hear the Roosters of Boa Vista
At the instigation of Bob N7SUR I've been working on a simple, easy-to-reproduce Direct Conversion receiver for 40 meters. I'm building this for my nephew John Henry, and I'm hoping this will be a circuit that others can use to break into the ELITE corp of successful ham receiver builders. Coincidentally Joh in Freiburg Germany is working on a very similar project -- we have been comparing notes.
At first I used an FET detector described by Miguel PY2OHH. It worked, but at night the AM detection of powerful shortwave broadcast stations drowned out the amateur signals. So Joh and I started to explore detectors that would eliminate this problem. I went with a version of one described in SPRAT by F5LVG ( "The RX-20 Receiver"- see below). Very simple: A transformer to two back-to-back diodes with a 1K pot to balance the signal from the VFO. OM Olivier used a very, very cool transformer: he took two small, molded chokes and simply glued them together! 22uH choke as the primary, 100uH choke as the secondary. I went with one of the toroidal transformers that Farhan left me when he visited in May.
I'm using a varactor-controlled ceramic resonator VXO (no Si5351 in this one!) and a non-IC AF amp designed for use with ear buds (the world is awash in ear buds). It is a "singly balanced" design with the incoming RF signal being the one "balanced out" in the detector.
Last night the receiver passed the AM breakthrough test. The SW broadcast monsters were balanced out and kept at bay.
This morning the receiver passed The Boa Vista Rooster Detection Test. I fired up the receiver and heard an operator speaking Spanish with a Brazilian accent. When I heard the rooster crowing in the background I knew it was Helio PV8AL from Boa Vista Brazil. TRGHS -- this little receiver is a winner.
I'll try to post a schematic soon.
And hey -- look at what wonderful IBEW (International Brotherhood of Electronic Wizards) project this is: Instigation and inspiration from Oregon. Some design ideas from Brazil. A French detector circuit described in a British QRP magazine. A transformer from India. A collaborator in Germany. And finally, the rooster of Boa Vista.
Thursday, August 24, 2017
The Return of Pete's Simple-ceiver Plus (and a possible analog option)
Winter is approaching ladies and gentlemen, and it is time to think about radio projects. Bob N7SUR suggested a direct conversion receiver project. I think this is a great idea. As a kid, I had fallen victim to the idea that building receivers was "too hard" for radio amateurs. Not true! DC receivers to the rescue! Carry on with the DC revolution first launched by Wes W7ZOI in 1968.
Pete N6QW is providing guidance and tribal knowledge via his blog. For those of you who want to join the ranks of those who have defied the conventional wisdom and have broken through the "receivers are too hard" barrier. I say build yourself a DC receiver. Build it from scratch. Many of you already got your feet wet in homebrewing with the Michigan Mighty Mite project. Now it is time to jump into a DC receiver project.
You folks already know what kind of VFO Pete will prefer: It will be an Si5351. That's fine. But I will try to keep the banner of discrete component analog ludite-ism flying high. This morning I ordered a batch of 7.37 MHz ceramic resonators. I hope to pull them down into a significant portion of the 40 meter phone band. If this works, I will share the batch with anyone who wants to joining my Analog Army (remember the CBLA?). Note (above) that Pete has magnanimously left open the possibility of using a non-digital VFO. What a guy!
Check out Pete's project here:
http://n6qw.blogspot.com/2017/08/a-new-line-of-transceivers-difx_19.html
Saturday, June 17, 2017
SolderSmoke Podcast #197: Farhan, Fame, 'Fest, Testgear, SSB History, Dishal Dystopia, QRP CW, MAILBAG
AI4OT and N2CQR |
N2CQR AND W2DAB |
Monday, May 22, 2017
Video: Farhan in the SolderSmoke Shack! BITX, JBOTS, McDonald Straw Sig Gen, uBITX, Sweperino and more!
Thanks again to Farhan for visiting us. It was great to see his reaction to my humble implementations of his great designs. I got him to sign my BITX17. This was really a fantastic day for me and for my family.