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DC RX Example by KK4DAS
SolderSmoke Podcast #245 is available for download:
Audio Podcast: http://soldersmoke.com/soldersmoke245.mp3
Video: (68) SolderSmoke #245: Cuban DSB, DC Receiver?, AI, Winterfest Loot, Gina's Podcast, 6BA6 buy, MAILBAG - YouTube
Travelogue: Cuba DSB and AM. Jose CO6EC and the Islander. We need more info, especially on the solid state Jaguey rig.
Bill’s bench:
Will the High School DC receivers get finished? Future uncertain. But the project was technically interesting. Great working with Dean KK4DAS. Battling AM breakthrough from Radio Marti. We joked that Dean has been listening to Radio Marti so much that even though he doesn’t speak Spanish, he has noticed an increased urge to liberate Havana.
Audio amps: Harder than we thought. Lots of variation in Hfe of 2n3904s. Oscillations.
Not using feedback amps nor LM386s, nor push-pull. Simplicity is a design goal.
Fixing the tuning (bandspread) problem on the VFO was fun.
Antennas? A quarter wave with ground or counterpoise works well. We tried it. (59) An Antenna for the TJ 40 Direct Conversion Receiver - YouTube
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Back to work on the uBITX. I chickened out on replacing the predriver with a BFR-106, but then – Just in time Todd K7TFC and his Mostly DIYRF came out with BFR106 boards! TRGHS. I will do the mods on two uBITX transceivers. I even bought a solder-sucking iron for the second job.
Winterfest Hamfest. Big success. Thanks VWS. HERRING AID FIVE! Simpson 260! QF-1, Another Radio Shack DMM, Eamon Skelton’s Homebrew Cookbook, Knobs, SWR meter.
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Travelogue: Cuba DSB and AM. Jose CO6EC and the Islander. We need more info, especially on the solid state Jaguey rig.
Bill’s bench:
Will the High School DC receivers get finished? Future uncertain. But the project was technically interesting. Great working with Dean KK4DAS. Battling AM breakthrough from Radio Marti. We joked that Dean has been listening to Radio Marti so much that even though he doesn’t speak Spanish, he has noticed an increased urge to liberate Havana.
Audio amps: Harder than we thought. Lots of variation in Hfe of 2n3904s. Oscillations.
Not using feedback amps nor LM386s, nor push-pull. Simplicity is a design goal.
Fixing the tuning (bandspread) problem on the VFO was fun.
Antennas? A quarter wave with ground or counterpoise works well. We tried it. (59) An Antenna for the TJ 40 Direct Conversion Receiver - YouTube
----
Back to work on the uBITX. I chickened out on replacing the predriver with a BFR-106, but then – Just in time Todd K7TFC and his Mostly DIYRF came out with BFR106 boards! TRGHS. I will do the mods on two uBITX transceivers. I even bought a solder-sucking iron for the second job.
Winterfest Hamfest. Big success. Thanks VWS. HERRING AID FIVE! Simpson 260! QF-1, Another Radio Shack DMM, Eamon Skelton’s Homebrew Cookbook, Knobs, SWR meter.
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SHAMELESS COMMERCE:
-- Todd’s Mostly DIY RF and the BFR106 boards, and much more: https://mostlydiyrf.com/
-- Become a Patreon sponsor of SolderSmoke: https://www.patreon.com/join/4785634/checkout?ru=undefined
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Pete's Bench:
Technical Note: Skype problems. Pete's Skype kept dropping out. Bad in the last podcast (#244). Three minute gap. I was ready to scrap the whole podcast when Dean KK4DAS offered to help. And he is obviously well qualified: https://potomacofficersclub.com/speakers/dean-souleles/ Dean went to work with AI. And he was able to fill the audio and the video gaps. Can you spot the three minutes of AI? Send me an e-mail with the time segment of the AI/Deep Fake portion of SolderSmoke 244. The first one with the correct answer will win a prize.
SolderSmoke #244:
Thanks Dean!
----Interview on his Pete's daughter’s podcast. https://soldersmoke.blogspot.com/2023/03/listen-to-pete-juliano-on-his-daughter.html
-- 6BA6 e-bay buy. Will we see an all 6BA6 rig from Pete?
-- The NCX-5 on e-bay
PETE’S NEW BLOG: https://hamradiogenius.blogspot.com/
Mailbag:
-- A New SPRAT arrived in the mail. PH2LB’s Gluestick on the cover.
-- Will KI4POV – Awesome homebrew – on the blog.
-- Sands, VK9WX listening to SolderSmoke on Willis Island! Wow.
-- Andreas DL1AJG in Germany continues with the Electronics for Biologists DC RX build.
-- Dean KK4DAS and his homebrew 10 meter DSB rig.
-- Jim W2UO built a Michigan Mighty Mite and made a contact.
-- Dave K8WPE and the E in IBEW. We need new stickers.
-- Bob KC4LB – Surface Mount is SMALL.
-- Bruce KK0S on the Herring Aid 5 Board.
-- Chuck WB9KZY on Nuclear Monopole Resonance very cool video – on the blog.
-- Alan WA9IRS wants a CW editor for his phone. Really.
-- Vic WA4THR also working on uBITX power out improvement.
-- Tobias weighs in on Kludge. As in Fudge.
-- Tony G4WIF notes that when he changes his oil he often removes sludge, not slooge.
-- Consultations with Lexicographer Steve KB3SII.
-- Walt AJ6T says CW operating declined after FCC ruling in 1970s about callsigns.
-- Ramakrishnan VU3RDD now VU2JXN has joined the VWS. An old friend of SolderSmoke. Urged us to launch a blog back in 2008. We announced his daughter’s birth - - now Ram is getting ready to build a DC receiver with her.
Don't lose hope on the DC RX! I mentioned it to my wife who organizes girl scout activities, and this time of year is always rough for keeping school kids involved, no matter how interested they are in it. They have trouble booking rooms at the school, the schools are trying to wrap up their obligations before spring break, and compared to Jan/Feb, kids have more activities going on (ESPECIALLY kids at TJ), so they're getting pulled in a lot of directions right now. Thank you for spreading the tribal knowledge! -73, Dan KC0ZIR
ReplyDeleteThis comment has been removed by a blog administrator.
ReplyDeleteGreat podcast! On the high-school issue, I don't think it's necessarily true that the students might think "rusty spoon" technology is not worth bothering with. In his book, _The Revenge of Analog_, David Sax found that younger people are the ones really driving the return of vinyl records, film photography, paper notebooks, and even fountain pens. He doesn't think it's just a kitsch or retro interest ("That's old and funny and therefore cool") but rather an appreciation for the characteristics of analog technology (mostly) lost by digital. In the end, he thinks, they're embracing both as valuable.
ReplyDeleteAnd to address points-of-view not yet expressed by the "kids these days" lamenters , I haven't found those of my own (Baby Boom) generation any more prone to finish what they started (including me) than those of Generation X, Millennials, or GenZ. In some ways, I find those generations more impressive than my own.
Hey Bill, Pete - great podcast. Happy to help out with the Pete challenge - but not sure even I can get PeteGPT to promote analog VFOs. That's a stretch.
ReplyDeleteAs far as the high school DCR project, I think we have a core group of about 20 students who would like to finish the project - which is 4-5 teams. Our experience working with the students has been really positive on the whole. When they completed the oscillator, they were delighted to hear it squeal on shortwave receiver that Bill brought in. We actually had to carry the receiver across the room to prove to them there were no hidden wires.
Mark - I think your comments are dead-on - our challenge has been less the student's interest and more scheduling and coordination along with competing activities. It is an afterschool club, so the students that show up are pretty motivated, but they clearly have a lot going on.
And Bill - you and I have learned a lot through the process - and smashed a few ham radio myths to smithereens - never again will I believe you need a hermetically sealed box and glacially stable mechanical components for an analog VFO. Long live the PTO and simple Colpitts oscillator!
73,
Dean
KK4DAS
This comment has been removed by a blog administrator.
ReplyDeleteDear Bill: I am offering a $500 cash prize to the first of your licensed high school students who builds my "Merry Christmas Rig" CW transmitter and uses it to successfully check-in to the Sunrise Net.
ReplyDeleteWow, very nice of you Walter. 73 Bill
DeleteBut can they use machine-generated and machine decoded CW?
DeleteDear Bill: Some people (15%?) are born without a good sense of rhythm and are unable to learn Morse Code, so if that is the case, my feeling is certainly yes. However, I will leave final judgement on this issue to you.
ReplyDeleteBill, the Herring Aid 5 should sound good through the QF-1, I've got one and it's great!!
ReplyDeleteThanks OM! EXCELLENT idea. We will probably try this out and will report back next year at around this time. 73 Bill
DeleteGreat podcast again. Re the comment by Pete about the Adafruit SI5351 crystal replacement, are you aware of the ProgRock2 sold by Hans Summers? That board is so small you can fit it into a HC6 crystal can. See https://qrp-labs.com/progrock2.html
ReplyDelete73 Paul