Save $2970! Build this $30 DIY Microphone!

There are a number of good ideas in this video.  We've known for a long time that many expensive mics are really simple, cheap mic capsules in fancy packaging.  This video takes a $12 mic capsule (which looks a bit like the ones we are using for the podcast), adds come amplification, a USB interface, and some really cool looking bronze packaging to come up with a very nice microphone. 

I liked his use of solder wick as a shield for the DIY mic cable.  Who knew the wick was hollow!  I also like the cooking torch for use in soldering the brass.  I need one of those. The little Murata DC voltage booster with positive and negative output seems useful. 

It seems that anyone working on this kind of project quickly gets pulled into the use of "audio speak." Late in the video Matt says his mic has nice low-end "presence."   A quick look at the comments section shows one person saying that one or the other of the mics sounds a bit "moist."   

There are many other similarly interesting projects on Matt's YouTube channel:

https://www.youtube.com/c/DIYPerks/featured

JPL, Mars Helicopter, Cube Sats, Ham Radio and more: N5BF talks to Eric Guth 4Z1UG

This morning Eric Guth has a really interesting interview on his QSO Today podcast.  

Courtney Duncan N5BF had a full career at JPL and is the current president of the San Bernardino Microwave Society.  There is a lot of interesting stuff in this interview, much of it about space exploration.  Courtney tells us about how experience with re-purposing radio gear came in handy at JPL.  For example, the helicopter that they have been flying on Mars has a very cheap and light off-the-shelf Zigbee transceiver.  He also talks about the origins of the Cube Sats.   

Here is Eric's page on this interview, with useful show notes: 

https://www.qsotoday.com/podcasts/n5bf

I like to listen to Eric's shows on YouTube -- here is the YouTube recording of the N5BF interview: 

https://www.youtube.com/watch?v=Fbr4jE11vfg

Here is N5BF's ham radio web site: 

http://cbduncan.duncanheights.com/HamRadio/HamRadio.html

Here is the club page of the San Bernardino Microwave Society:

http://www.ham-radio.com/sbms/

Thanks to Eric and Courtney! 

M0NTV's "Crystal Filters for the Fearful" (video)

I really liked Nick M0NTV's approach to making a crystal filter (see video above).  He really simplifies a process that desperately needs simplification. I remember when I was building my first superhet receiver,  I came across Doug DeMaw's schematic for a crystal tester that would allow me to properly build the filter.  But the piece of test gear was far more complicated than the receiver I was building.  I never built Doug's device. 

Nick's technique is simpler even than the G3UUR method that many of us have been using for years.  Nick dispenses -- wisely I think -- with the need to calculate motional parameters, Q,  and equivalent series resistance.  This also eliminates the need to fidget around with the design software such as Dishal or AADE.  

Nick uses the Cohn topology (good choice) and uses kind of an "informed cut-and-try" technique to come up with the capacitor values.  

Filter impedance is determined with series trimmer resistors and the NanoVNA to watch the resulting passband.  Nick says this is a Charlie Morris ZL2CTM suggestion.  It obviously works very well -- the ripple that would result from impedance mismatch is eliminated.  

Nick's determination of the best turns ratio for the impedance matching transformers is brilliant.

Nick apologizes for what he says is a long video.  But it is only 30 minutes or so long, and if you are going to build your own superhet or SSB filter rig, it is well worth watching.   

Three cheers for Nick and for Charlie!  Thanks guys!   

The Importance of Keeping the Noise FLAT

 

A few days ago I put up a blog post about using a noise generator (in my case my cheap FeelTech sig generator) and my TinySA spectrum analyzer to look at the passband of a crystal filter.  I was using the 9 MHz filter used by Dean KK4DAS and the Vienna Wireless Makers Group.  The idea is simple: insert broadband noise into the input. The filter should pass more of the noise that falls within its passband.  The TinySA should let you see this.  At first, I was pleased that I could clearly see the passband.   I thought I had succeeded.  See above. 

But I was bothered by something.  Look at that bump in the passband.  It should be close to flat across the top.  

I decided to take a look at the same filter with my NanoVNA.  Here I was not using a noise generator.  The NanoVNA sweeps the filter using and looks at output in the Log-Mag mode.  Here is what it looked like (below): 

That was much better.  But why the difference?   Tony Fishpool G4WIF suggested that my noise source might not be putting out noise at the same level on all frequencies.  I took at look at the noise output of the FeelTech sig gen in the range of the filter passband (with some above and below frequencies for reference) and I found that the flatness of this noise depended a lot on what frequency I had the sig gen set to.  I tuned it around a bit until I found a setting that produced a flat noise output in the desired frequency range.  Then I went back and swept the filter with the noise and the TinySA again.  Here is what it looked like with the "flat" noise: 

Better,  I think.  Closer to the passband displayed by the NanoVNA.   

Tony points out that these Chinese sig gens don't really put out random noise -- they give us predictable noise.  Dean said "Predictable Noise" would be a good name for a rock group.   I said they could open for my favorite: "The Ceramic Spurs." 

Juliano

 

https://n6qw.blogspot.com/2021/11/a-scratch-built-minimalist-ssb.html

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

The presentation starts at about the 4 minute point. 

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Buy a Real Sputnik Satellite! Let's Put Sputnik Back in Orbit!

Only 85,000 Euros (that's the opening bid).  But hey, it comes with the receiver pictured on the right.  I guess that's so you can listen to the beeps. 

Here's the description: 

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

Laboratory Test Model of "Sputnik 1 EMC/EMI", 1957
1:1 scale test model of the satellite "Sputnik-1", serial no. "0K6-1/004/1957", with built-in transmitter (including modern 12-volt power supply), polished stainless-steel sphere, consisting of two threaded hemispheres of approx. 23 in. diameter with two pairs of antennae of 95 in. and 105 in. at an angle of 35 degrees to the axis, on stand with O-ring, stand approx. 59 in. high, stand and model together approx. 79 in. high, accompanied by a Tesla Maj 620A radio receiver, manufactured in Prague c. 1956, restored working condition, including replacement of the silver-zinc battery with a modern alternative and a new metal casing for the electronic transmitter. Note: Built at the Experimental Design Bureau-1 (OK?-1/OKB-1) factory, also known as S.P. Korolev Rocket and Space Corporation Energia, Koroljow, Soviet Union, in 1957, shortly before the launch of Sputnik-1. - An impressive artefact from the dawn of the space age, of which few models are known. - Provenance: From the collection of Dr. Frank Malina, USA/CSSR.

Start Price: EUR 85.000

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

I'm a bit suspicious of the "modern 12-volt power supply,"  the "modern alternative" battery and the "new metal casing for the electronic transmitter."

Here's the link to the auction: 

https://www.the-saleroom.com/en-gb/auction-catalogues/auction-team-breker/catalogue-id-breker10030/lot-9c87007d-f0ff-4414-9663-adc200690819

Here's my suggestion:  Musk or Bezos or Branson should buy this thing, fix it up a bit, and put it back in orbit.  So we can listen to it again. I know a version of this was done back in 1997.  But I think we should do it again, this time with the actual test model. 

Here are the earlier SolderSmoke blog posts about Sputnik and Sputnik-related projects: 

https://soldersmoke.blogspot.com/search?q=Sputnik

Steve Silverman sent the auction posting to me.  Thanks Steve. 

It just so happens that earlier in the week I was out at the Air and Space Museum facility near Dulles Airport, where I saw this flight backup of the Vanguard satellite: 

Using Noise to Sweep a Filter with the TinySA

 

I've been meaning to try this for a long time.  Years ago Tony Fishpool and Graham Firth wrote about using a noise generator and a spectrum analyzer to sweep the bandpass of a filter. The idea here is to send very broadband noise into a filter, and then use a spectrum analyzer to see which frequencies make it through.   

I thought about building a noise generator like the one in Tony and Graham's book, but then it occurred to me that probably had one sitting on my bench.  Sure enough, a look at the manual for my cheap FeelTech function generator revealed that PRESETS 3 and 8 are noise generators.   I quickly pulled out a 9 MHz filter that Dean KK4DAS had given me, put the noise into one end and the TinySA on the other end.  Bob was quickly my uncle.  See above.  

More recently Tony G4WIF built a comb generator as a noise source: 

http://www.fishpool.org.uk/combgenerator.htm

Thanks to Tony, Graham, and Dean.  And to the folks who developed the TinySA. 

Why Does Solder Smoke Always Go Right Into Your Face? Now We Know

Because our podcast and blog is called SolderSmoke, I felt compelled to post about this video in which a fellow does some pretty interesting research into how solder smoke actually moves.  We don't often see this much concern about the behavior of our beloved smoke. 

Thanks to Todd K7TFC for alerting us to this.  

I use a small fan to disturb the airflow pattern. 

How to Listen with your TinySA

We don't get many chances to do hardware work on a piece of gear like the TinySA, but here we have one.  I mentioned this a while back:  Not only will the TinySA display the signals it detects, but it will also allow us to listen to these signals.  Very cool.  I am going to do this.  

Here is the link showing how to do the mod: 

https://tinysa.org/wiki/pmwiki.php?n=Main.Listen

All the cool people listen to classic rock with a TinySA: 

SETI, Proxima Centauri, The Parkes Dish, and Intermodulation Distortion?

 

https://www.sciencealert.com/exciting-mystery-space-technosignals-were-indeed-produced-by-sentient-life-us

A cosmically interesting troubleshoot.  But I'm not sure about their explanation.  Why would the intermod disappear when they moved the Parkes Radio Telescope off of Proxima Centauri?  

Putting a Ceramic Filter in the "Mate for the Mighty Midget" Receiver

It is really simple.  I had one of the +/- 3kHz (6 kHz wide) 455HT filters on hand.  The spec sheets call for 2000 ohms at both ends, but looking at the schematic it appeared that I already had high impedance on both sides of the filter.  I put a .001 uF cap on the input side to keep the DC voltage off the filter (see above and below). This capacitor allows us to avoid the dreaded problem of electro-migration that is so nicely described by SV8YM here: 

http://sv8ym.blogspot.com/2010/07/mysterious-case-of-withering-filters.html. 

Tasos also provides a good description of the innards of those little black boxes that contain ceramic filters. 

Once you get the filter in your receiver, you have to carefully place the BFO signal in relation to the filter passband.  I have trouble properly sweeping 455 kHz filters -- my HP8640B will not go that low.  Nor will my Antuino (I need to modify the code -- someone help me please).  I know the NanoVNA will do the job, but I just couldn't seem to get it to work.  So I went "old-school" and manually swept the filter using my FeelTech sig gen and my Rigol scope.  This gave me a rough idea of where the passband was.  I put the BFO on the low end of the filter passband, at 451 kHz.

   

With this filter the MMM RX has become a real asset.   The 6 kHz bandwidth allows for nice reception of both SSB signals and AM sigs.   I may try to use one of the +/- 2 kHz filters  (4 KHz wide), but so far I have not been able to find a source for this part. 

WA9WFA's Mate for the Mighty Midget 1966 QST Receiver

Scott WA9WFA and I have been exchanging e-mails about his Mate for the Mighty Midget receiver project.  This morning I finally took a look at Scott's we page on this effort.  There was a lot there that resonated.  For example: 

"I remember the moment very clearly.  June 1966 I was sitting in a lawn chair reading a stack of QST's that I had brought along to the summer cabin.  The February 1966 issue the Beginner and Novice section introduced the "Mighty Midget Transmitter", a 10 watt crystal controlled transmitter.  The April 1966 issue Beginner and Novice section introduced the "Mate for the Mighty Midget" which was a three tube super-heterodyne Novice type receiver.  Over the course of that summer I read and re-read those articles a jillion times.  Being 13 years old, I didn't have the electrical or mechanical skills to pull off such a project so I could only dream about it.  In 1970 I bought a handful of the parts.  In 1976 I bought more parts.  In 2021 I decided to build it while I still had the ability to do it.  This project is only my second homebrew radio project so I am still learning things every second of the way...

 

While I am not expecting to much in performance, the 13 year old in me is ever hopeful that this 1966 Novice receiver will be the most wonderful radio ever made.   73, Scott WA9WFA"

Scott's MMM RX page: 

https://www.qsl.net/wa9wfa/MateForTheMightyMidget.htm

Scott and I are now both updating the MMM RX by substituting 455 kHz ceramic filters for Lew McCoy's FT-241 crystal filter.   I have my filter wired in now, and it is working well.  Scott plans on soldering his in today.  I will post on this mod soon. 

On his QRZ.com page, Scott notes the need to fight the temptation to further soup-up this simple receiver:  "I did have to resist the temptation to add another audio stage, a mechanical filter, AGC, 2nd IF amplifer stage, etc..."

Exactly right Scott.  Resist the temptation.   Simplicity is a virtue.  I do use an outboard, powered computer speaker, but I justify this by telling myself that I just don't want to use headphones.  But I could use headphones, so this is OK.  OK?  

Scott's QRZ.com page: 

https://www.qrz.com/db/wa9wfa

I must add that I think the yearning of Scott's inner 13 year-old can be fulfilled by the MMM RX.  I think it is pretty wonderful.  It is -- in my view  -- not as good as a Drake 2-B, but it is FAR better than an S-38E, and it is better than a Lafayette HA-600A (wjm).  

Tribal Knowledge: Pete N6QW on "How to Make Things Work"

 

BUILD IT LIKE THIS

Yesterday Pete Juliano published a blog post that contains an enormous amount of tribal knowledge and good advice for homebrewers.   As I read Pete's post, I thought back on my own failed teenage efforts at homebrewing -- the Herring Aid Five fiasco came to mind.  I also thought of Farhan's comments about his similar frustrations with early homebrewing efforts (though I find it hard to believe that Farhan EVER had trouble making something work). 

Above we see a large N6QW prototype breadboard.  Note how it is easy to see where the various stages start and stop.  This is key to understanding and troubleshooting a complex rig.   If you want to see the antithesis of this approach, here it is:

DO NOT BUILD IT LIKE THIS

This was supposed to be an 80 meter DSB transceiver.   The builder (who will remain anonymous) obviously didn't get it to work.  I think he should try again, using Pete's methodical approach. 

Check out Pete's great advice here: 

http://n6qw.blogspot.com/2021/10/how-to-make-things-work-tribal.html

Thanks Pete! 

Super-Regeneration is Super-Strange

Farhan VU2ESE is largely responsible for this.  He has recently been talking about VHF.  (More about this in due course.).  This started me thinking about my failed effort in London to get on 2 meter AM.   My plan was to use the transmit portion of this HW-30 (above) with a 2-to-10 downconverter and my trusty Drake 2-B for receive.  

Tony G4WIF also bears some responsibility:  When I expressed interest in Farhan's VHF work, Tony sent me two articles from SPRAT.  Both of them were about super-regenerative receivers.  

Farhan's comments caused me to pull the HW-30 out of storage.  I started poking around the transmitter.  But then I noticed something:  On receive, the AF amplifier was obviously working.  Then, when I tuned through the 2 meter band, the rest of the receiver seemed to be working too.  I fired up the HP-8640B sig gen on 2 meters and turned on the AM modulation.  Indeed, the old receiver was inhaling!  

This launched me into an effort to understand how super-regenerative receivers work.  There are a lot of really weak explanations out there. You get the distinct impression that the person explaining the circuit does not understand it himself.  This makes explaining it very difficult.  I am not the only one to notice this phenomenon:  Mike WU2D commented on this in one of his excellent super-regen videos.  This one:  

https://www.youtube.com/watch?v=QOhNPLT8R10

Mike very kindly said the operation of this circuit seems like "magic."  I was thinking more in terms of Voodoo.  

Howard Armstrong discovered super-regeneration years after he invented plain old regeneration.  The new discovery came around 1921.

It looks like VHF guru Frank Jones had very early misgivings about super-regeneration.  In his 1934 classic 5 Meter Radio Telephony, Jones seems unenthusiastic about the circuit and about our ability to understand it:  "To explain, simply, exactly how this form of detection takes place is not a simple matter, but some of its characteristics are easy to visualize."  In this book, Jones goes on to predict that super-regens will be superseded (!) by superhets.  Indeed, in his 1961 book VHF for the Radio Amateur there are no super-regen circuits; all the receive systems are down-converters to HF receivers. 

Still, with that HW-30 hissing away right next to me, I feel I need to understand how the super-regen works.  I'm not there yet, but I'm trying.  Here are some good resources: 

A good article from Wireless World 1946:  

http://www.r-type.org/articles/art-285.htm  

A student's write up of his effort to understand: 

https://folio.brighton.ac.uk/artefact/file/download.php?file=597679&view=111191

But the best so far (for me) is from Frederick Terman (one of the founders of Silicon Valley) in  his 1943 classic Radio Engineer's Handbook.  Click on the images for a clearer view. 

I will definitely try to get the HW-30's 5 watt AM transmitter going.  I am not so sure I'll do anything with the receiver.  I think this is a matter of picking your battles and "finding joy."   I didn't find joy in FT-8, so I stopped working with it.  Same with my HA-600A, DX-40 Novice rig.  Same with CW in general.  And the same with SDR.  I suspect that super-regen receivers may also fall into this category.  I mean, let's face it, if you are not fond of ordinary regens, is there any real chance that you will like SUPER-regens?  Even Frank Jones seems to have disliked them.  And there is a reason Howard Armstrong moved on to superhets -- they are better! But still, that receiver is hissing away at me...  Stay tuned. 

Homebrew Tiny Space Telescopes from the Netherlands

It is good every once in a while to step back from our electronic work benches and take a look at what other kinds of builders are making.   Hack-A-Day led me to this wonderful video from Holland.  There is great background information on telescopes, but the really great part is the interview with the Dutch fellow who is actually making -- in his home workshop -- these tiny telescopes.  Icing on the cake:  One of them will be used in a student Cube-Sat project in Oregon.  

Be sure to stay to the end for an intriguing presentation by Dr. Liam Fullersheit. 

No Longer On the "Shame Shelf" -- Pete Fixes His KWM-1

 

I think a good troubleshoot is almost as satisfying as a successful homebrew.  And we can sense that high level of satisfaction in Pete N6QW's description of his repair of a Collins KWM-1:   

http://n6qw.blogspot.com/2021/10/resurrection-of-kwm-1-sn-673.html

I liked Pete's troubleshoot/repair story, but -- as is often the case -- I struck by his turn of a phrase.  I think Pete has added something important to the SolderSmoke lexicon: 

THE SHAME SHELF 

Most of us have a shelf like this. I have an HW-101 on mine.  Pete shows us that there is hope -- there is path off of the shame shelf.  You just have to know stuff.... Or have IBEW friends like Pete who can advise you. 

2 Meter Homebrew: The Fredbox (Video)

I predict a rebirth of interest in 2 meter homebrew.  This will probably hit around Christmas time.  The impetus will come out of Hyderabad, India.  At this point, I can say no more. 

I was thinking about all of this today.  I remembered "The Fredbox."  G3XBM's report on this fantastic rig was carried on this blog before it was even a blog.  And the Fredbox goes back much further in time -- back to the mid-1970s.  It must have been great fun to have QSOs with this rig in Cambridge England back in the day.  G3XBM actually crossed the English channel with this 10 mW rig.  FB.  

When I was in London (2003-2007), G3XBM's post on the Fredbox got me interested in 2 Meter AM.  I had a down-converter that let me listen, and I went as far as modifying a Benton Harbor Lunchbox for the proper AM transmit frequency.  I don't think I made any contacts, but I still have the bits and bobs of this rig, so if anyone in the Northern Virginia area wants to get on,  please let me know -- I will blow the dust off this project and will build a 2 meter antenna.  

Here are more details from G3XBM on The Fredbox:  

https://sites.google.com/site/g3xbmqrp3/vuhf/fredbox 

Hans G0UPL got into the Fredbox in 2009 and 2016: 

http://www.hanssummers.com/fredbox.html

SolderSmoke Podcast #233: PIMP, Boatanchors, Novices, MMM, Heathkits, DC Receivers, Mailbag

SolderSmoke Podcast #233 is available. 

http://soldersmoke.com/soldersmoke233.mp3

Travelogue: Cape Cod. SST. Marconi Site.

The WFSRA:   The World Friendship Society of Radio Amateurs.

Pete's Bench:

The Pimp.
The NCX rig.
The Collins.
The many DC receivers built worldwide.
The parts shortages are real! Several key radios on hold. Si5351 sub.
Talk to G-QRP convention

Bill's Bench:

FT-8. Not for me. I tried it.
Novice Station Rebuild.
Globe V-10 VFO Deluxe.
Selenium rectifier removal CONTROVERSY?
Not crazy about my Novice station. Not crazy about CW. 
Mate for the Mighty Midget. Again. 
Mike W6MAB -- Detector problems LTSPICE Check
One more mod for MMM RX. Ceramic filter at 455.
Dropped screw inside tubular cap on Millen 61455 transformer. 
Talk to the Vienna Wireless Society
Thinking of a Moxon or a Hex beam.


BOOK REVIEW Chuck Penson WA7ZZE New Heathkit Book. http://wa7zze.com

Mailbag

-- New SPRAT is out! Hooray!
-- Todd K7TFC sent me copy of Shopcraft as Soulcraft. FB.
-- Dean KK4DAS building an EI9GQ 16 W amp. FB.
-- Jack NG2E Getting close on Pete's DC receiver.
-- JF1OZL's website is BACK!
-- Tony K3DY sent link to cool books. 
-- Sheldon VK2XZS thinking of building a phasing receiver.
-- Peter VK2EMU has joined the WFSRA. FB!
-- Ned KH7JJ from Honolulu spotted the Sideband Myth in the AWA video.
-- Chris M0LGX looking at the ET-2, asks about the variometer.
-- Pete Eaton Nov 64 anti HB rant in november 1964 QST. Wow.
-- Josh Lambert Hurley spreading FMLA stickers in the UK. FB
-- Stephen VE6STA getting ready to melt solder.
-- Got a great picture of Rogier PA1ZZ back on Bonaire.
-- Farhan reading the manual of Hans's new digital rig.
-- Paul G0OER wonders if FMLA getting ready to move on 5 meters.

Recent Homebrew Projects from Jan PA3GSV (of "Mate for the Mighty Midget" Fame)

 

Recent talk of the Mate for the Mighty Midget receiver and Pete's PIMP SSB transmitter brought me back in contact with the work of Jan, PA3GSV.  I took a look at his QRZ.com page and found that he has some projects that rival even his seemingly unbeatable MMM RX project. 

Check it out for some real homebrew eye candy: 

https://www.qrz.com/db/pa3GSV

Bill's 52 year-old Apollo 11 Time Capsule -- What Should I Do?

 

When I was a kid, I was an Apollo 11 fanatic.  I was ten years old when they landed on the moon.  I was convinced that the newspapers and magazines from that event would someday be worth A FORTUNE! So, as a ten year-old, I double or triple wrapped a bunch of them in plastic and put the package up in the attic of my parents' house.  Where they sat undisturbed for more than half a century.  

We were recently getting ready to sell the house, and I asked if my Apollo 11 newspapers were still up in the attic.  They were!  So the time capsule has come back to me after all these years (see above).  It remains unopened.    

Obviously this is not worth the fortune that my ten year-old self thought it would be worth. (Hey, I was 10!)  But it is worth something to me.  I know we have a lot of fellow space geeks reading the blog, so let me ask for advice:  What should I do with this?   

Another M^3: The Michigan Micro Mote

Move over Michigan Mighty Mite and Mate for the Mighty Midget.   There's a new M^3 in town.  And it is SMALL. 

Hack-A-Day had an article on this today, and while it seems only tenuously connected to ham radio, I found it intriguing.  

Check it out.  Who knows, someday people may be operating in "dust mode":  

https://hackaday.com/2021/10/04/snails-sensors-and-smart-dust-the-michigan-micro-mote/#more-498450

Dean KK4DAS Builds an EI9GQ 16 Watt RF Amplifier (and Noodles in the Process)

 

I really like Dean's description of the building process, especially where he describes the need to sit down with paper and pencil for some noodling.   We see that in the picture above.  Too often we hear from guys who seem to be looking for detailed, step-by-step instructions, and then get frustrated and stuck when this kind of detail isn't available. Dean shows what to do in this situation:  noodle! 

Check out Dean's blog post on this project: 

https://kk4das.blogspot.com/2021/10/ei9gq-16-watt-power-amp-start-to-finish.html

Dean's post made me think about the origin of the verb "to noodle."  We know it has its origins in music.  Google provided this interesting explanation: 

To noodle around on something, while it does make use of the noodle (head), may derive from the regional German nudeln, to improvise a song, or from the late-19th-century Scottish sense of noodling as humming a song to oneself. By 1937, to noodle was to fool around with notes to create music.

We noodle around with parts and schematics to create rigs. 

Scott WA9WFA's Mate for the Mighty Midget Receiver is WORKING! (Video)

Wow, Scott got his Mate for the Mighty Midget receiver to work and he is obviously overjoyed with the result.  All of us who have struggled with a homebrew project know just what this feels like.  And it is very cool that Scott got some useful guidance from Charlie Morris in far-off New Zealand.   Congratulations Scott.  I'm really glad you stuck with it.  

Scott's success comes at a good time:  Pete N6QW is building W4IMP's three tube "IMP" SSB transmitter (also from the 1960s).   I accept responsibility for naming Pete's project:  It will be known as "Pete's IMP" or, memorably,  "The PIMP."  For a look at Pete's rig go here: 

http://n6qw.blogspot.com/2021/09/lets-build-something-with-vacuum-tubes_23.html

Scott had problems getting Lew McCoy's 455 kc crystal filter to work.  So did I.  It turns out that this is a very old problem, going back to World War II.  In Don Stoner's 1959 "New Sideband Handbook" on page 54 he writes of homebrew filters in the 400 to 500 kc range:  

"Inexpensive crystal filters constructed from war surplus FT-241 type low frequency crystals are very popular with the 'do it yourself' hams. These CT cut crystals have been plentiful and relatively cheap for a number of years and are in the hands of many Amateurs. The general run of war surplus crystals may or may not be good. Experience has shown that one out of four of these crystals are usually defective in one way or another." 

Stoner was writing just 14 years after the war.  Add another six decades to the age of these crystals -- often decades spent in musty basements -- and you can imagine the percentage of bad 455 kc FT-241  crystals increasing.  So I think Scott is wise to seek an alternative to McCoy's crystal filter. 

Scott's original build of the MMMRX receiver is just so nice.   In the video he says he plans to go back to it after he gets the expanded version fully functional.  He should definitely do that -- his  original version looks so good.  I think it is probably very close to working properly. 

Thanks Scott, and again, congratulations OM. 

Selenium RECTIFIED

Selenium rectifiers. The name kind of sounds like Dilithium crystals, possibly related to flux capacitors. 

Anyway, there were two of them in the Globe Electronics V-10 VFO Deluxe that I recently bought.  Obviously they had to go, so I took them out yesterday, replacing them with a 1N5408 silicon rectifier.  

The new diode had a significantly lower voltage drop than the selenium rectifiers -- this pushed the output voltage from the power supply up to around 200V.  It is supposed to be around 185 V.  So I put a 470 ohm,  5 watt resistor (found in the junkbox) in series.   This brought the output voltage to 167 V.  Close enough.  VFO seems to be working fine.  

I'm glad I did the extraction before these aging components released their nasty toxic smoke. 

W3HWJ has a good article on replacing these nasty old parts, with some interesting info on their history:   http://www.w3hwj.com/index_files/RBSelenium2.pdf

Backgound on the element Selenium:  https://en.wikipedia.org/wiki/Selenium

Chuck Penson's Amazing New Book about Heathkit Amateur Products

 

I was very pleased to read that Chuck Penson WA7ZZE was publishing a book about Heathkit's amateur radio products.  His book is a really great guide, providing a lot of fascinating information, stuff that even those of us who have spent decades with pieces of Heath gear didn't know.  For example, I never knew that an after-market dial had been available for the HW-101.   And I didn't know that the Indian names used for many of the Heath rigs (Comanche, Apache, etc.) resulted from a suggestion from Roger Mace's wife, who was Native American. 

Chuck's book arrived just as I was putting my DX-40 novice transmitter back on the air after almost 50 years.  TRGHS.  Who knew that there were TWO versions of the DX-40?  I didn't, but Chuck did, and his book explained how to spot the difference (flashlight through the side vents -- I have the very slightly more modern version). 

When I opened the book for my first peek inside, the page opened to the QF-1 Q multiplier.  I immediately felt guilty about having brutally cannibalized several (well maybe more than several) of these things.  But right there in the text Chuck repeats my justification for the carnage:  He notes that the tuning cap has a nice 14:1 turns ratio.  Exactly.  How could I NOT pull those beautiful variable caps out of that old regen device, for re-use in superhet receivers and BITX transceivers?  

This is a wonderful book that belongs in the workshop libraries of all those who have used and loved Heathkits over the years.   

Order yours here:  

https://wa7zze.com/amateur-radio

Thanks a lot Chuck for making such a great contribution to the radio art and to ham radio literature. 

N2CQR (WN2QHL) Novice Station Re-Created

 

There it is.  The 2021 re-creation of the WN2QHL Novice Amateur Radio Station.  This is what I had when I first went on the air in April 1973 from Congers, NY. 

-- I got my first Lafayette receiver (WITH JEWELED MOVEMENTS!) for Christmas in 1972.  My mom drove all the way into New Jersey to get it for me. 

-- I bought my first DX-40 and the Globe VFO Deluxe from someone in the Crystal Radio Club.

For this re-creation station: 

-- I got this recently acquired Lafayette free-for-pickup from a very kind SWL in the Shenandoah valley.  (I've discussed this receiver extensively here.) 

-- The DX-40 is the result of a couple of junkers that I bought in a hamfest some 23 or 24 years ago.  It might have been the Timonium Hamfest.  I cannabalized one of them and made one good DX-40 out of the two.  Parts of the cannabalized unit carry on the good fight as pieces of my balanced  antenna tuner (the coils were useful there) and as the chassis for my first SSB transmitter. 

-- The Globe VFO Deluxe was harder to recover.  There are just not a lot of these things around.  I actually put up a plea for one of these on the SolderSmoke blog.  Not even the IBEW could come up with one of these things.  But then, last week on Facebook I came across a fellow who was selling one.  Deal!  Check our the nice Juliano Blue light indicating 40 meter operation. 

Putting these three devices together was more challenging than I thought.  To get them to work together decently three different things had to happen as the result of throwing one switch: 

1) Antenna had to switch from receiver to transmitter. 

2) Receiver had to be largely muted (leaving some key-down signal for sidetone).  

3) VFO had to be turned on (I left it running and just keyed the DX-40).  

Fortunately I have almost 50 years more experience than I did when I first set this station up.  So I was able to do this better in 2020 than I did in 1973.   I had a 3PDT relay that I had built for a DX-60 station.  I was able to use it to do all three things described above. 

Muting the Lafayette was a bit tricky.  On the back octal connector they have two post  (1 and 3) that are normally connected.  Disconnecting 1 from 3 completely mutes the receiver by cutting off a needed ground connection to the RF amplifier and to an IF amplifier.  The Lafayette manual tells you to connect these terminals to the "muting voltage" presented by your transmitter.  The DX-40 doesn't have such a voltage, and I was reluctant to connect any voltage to this terminal for fear of blowing up the RF and IF amplifiers.  I figured that just putting a big resistor across 1 and 3 would mostly mute the receiver.  The 3PDT relay shorts this resistor on receive, un-muting the receiver. I use a 500,000 ohm resistor.  It works well, but the sidetone is chirpy while the actual signal is not.  This is a bit annoying. 

I re-capped the DX-40 when I got it back in the late 90's.  Those caps are still good. 

The Globe VFO had also been recapped.  But it still has selenium rectifiers in there.  I will change them ASAP.  Also, the Globe VFO had a somewhat mysterious second transformer in there.  I wondered what that was.  I measured the output:  6.3 V.  That is a filament transformer.  My guess is that the filament winding in the main transformer went open, maybe as a tube failed. Instead of replacing the whole transformer, they just popped in a replacement filament transformer.  That's fine. 

I've been on the air with this rig, mostly on 40, as I was as a Novice.   I can work anyone I hear on 40 meter CW and my CQ's are heard in Europe (as shown by the RBN). 

I'm struck by how physically BIG these pieces of gear are.  Much bigger than our beloved BITXs. 

Regarding T/R switching:   There was a line in the 1973 ARRL Radio Amateurs Handbook that really got to me back in 1973:  Page 640, in the chapter entitled "Assembling A Station:" "

"In any amateur station worthy of the name, it should be necessary to throw no more than one switch to go from the 'receive' to the 'transmit' condition." 

By this standard, my station was probably unworthy of the name.  I don't remember how I handled T/R changeover, VFO keying, receiver muting and sidetone,  but it almost certainly involved throwing more than one switch.  But now, I am happy to report, my novice station is finally up to the ARRL's high standards.  As Pete says, "When you know stuff you can do stuff." 

The World Friendship Society of Radio Amateurs

Rod Newkirk, W9BRD wrote the "How's DX?" column of QST magazine from 1947 to 1978.  He had a wonderful writing style.  His column was an inspiration for many of us -- I write about the impact it had on me in my book SolderSmoke -- Global Adventures in Wireless Electronics and here on the SolderSmoke blog. 

Rod's son David Newkirk is radio wizard himself and has produced many great articles for QST and other publications.  His dad is a Silent Key and David has taken his call.  

This morning I was looking at an article on David's web site in which he looks at some of his dad's old QSL cards.  Most of the affiliations on the cards (ARRL etc.) are easily recognizable, but there was one that was unclear:  WFSRA.  

David figured out what it was: 

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

A W9BRD Affiliation Mystery Solved

My father's pre-World-War-Two QSL cards include the usual list of affiliations: ORS (Official Relay Station), RCC (Rag Chewer's Club), WAC (Worked All Continents), A-1 Op (A-1 Operator's Club). One affiliation, WFSRA, remained mysterious. A clue in the correspondence column in March 1938 QST pointed me to an "I. A. R. U. News" item on page 74 of July 1935 QST, and I had my answer:

W.F.S.R.A.:
    The World Friendship Society of Radio Amateurs has requested publication of the following pledge, which is the sole obligation for membership in the Society:
    "I hereby promise that I will, to the best of my ability, make such use of my amateur radio station as will be conducive to international friendships; that I will never voluntarily permit by station to be used as the tool of selfish nationalistic interests; and that I will do what I can, as a radio amateur and as an individual, to promote world peace and understanding. (To be followed by the signature, address and station call.)"
    Membership in the Society is open to all amateurs in all countries. All that is necessary to become a member is to copy and sign the pledge, and send it to the secretary, Duane Magill, W9DQD, 730 N. 6th St, Grand Junction, Colorado, U.S.A. Copies are preferably to be made in English or French, but may be made in the language of the member."

----------------------------------- 

The WFSRA was apparently one of the many, many peace organizations that were born in the interwar period in response to the carnage of WWI.  In addition to the QST correspondence mentioned by David, Google shows WFSRA in many articles in UK ham and SWL publications, and  there is one mention of it in the May 1954 edition of Boy's Life magazine.    

Much as the CBLA seems to have been presaged by the FMLA, the IBEW seems to have much in common with the WFSRA. 

Lighthouse Larry's GE Sideband Handbook

 

There is lot of information about early SSB and DSB operations in the GE Sideband Handbook (1961).  Lighthouse Larry is very informative.  Early in the book there is a guide to help homebrewers select intermediate frequencies that will work well in SSB and DSB rigs. 

Here is the book.   Remember, we are dealing with tubes and high voltage here: one hand behind your back.  Volts jolt but mills kill!  

http://www.rsp-italy.it/Electronics/Books/_contents/radio/Sideband%20handbook%20-%20GE%20-%201961.pdf

VE7SL's Beautiful Single Tube Transmitter and Single Tube Regen Receiver

Just stunning, in their simplicity and beauty.  Really amazing work.  Kind of reminiscent of my ET-2, but with tubes, and much nicer construction.  More details here: 

RECEIVER: https://qsl.net/ve7sl/neophyte.html

TRANSMITTER: https://qsl.net/ve7sl/neotx.html?fbclid=IwAR3cM6tSRjyTsNouHWVz_buuzz4C9O-IwQbdZM5dekkle69ZW7-JBQcHTVI

Three cheers for Steve VE7SL!  I've been linking to his blog for several years, but somehow I missed this magnificent red rig.   

Steve's online notebook: https://www.qsl.net/ve7sl/

Steve's blog: http://ve7sl.blogspot.com/

Video: N2CQR Talks About Homebrew SSB with The Vienna Wireless Society's Makers Group

It must have been great to have been a ham during the heyday of homebrew gear.  Imagine walking into your local club and finding a dozen or so people who share your passion for melting solder and homebrewing your own equipment.  Well, I got a taste of that thanks to the Vienna Wireless Society's Makers Group.  Led by Dean KK4DAS, this group of intrepid radio amateurs has built versions of Pete Juliano's Simple SSB transceiver.  They are finalizing the rigs; many are already finished.  And I could tell from the questions and the discussion that I was talking to a bunch of guys who knew which end of the soldering iron to grab.  It was really wonderful to talk to people who had gone through the experience of building an SSB transceiver, who knew from personal experience that it is not as easy as it seems. And I could tell from the questions that many of these guys are already thinking of their next projects, of how to put to use the experience they gained building Pete's SSB rig. 

Dean asked me to talk to the group about my recently completed "Mythbuster" rig.  This was a good topic for the group because my rig is similar enough to the Simple SSB that they could relate to it, but different enough that it could give them ideas about how they might do things differently next time. 

I really enjoyed this session.  I'm glad that VWS captured it on video.  I think SolderSmoke listeners and readers will like watching this video.  

Thanks to Dean KK4DAS and the VWS Makers group for hosting me.  And thanks to Jacek KW4EP for helping with the video. 

Here is the Vienna Wireless Society's YouTube Channel: 

https://www.youtube.com/c/ViennaWirelessSociety

Great News for Homebrewers: JF1OZL's Amazing Web Site is Back!

I was very happy to read this morning (on the G-QRP e-mail list) that the amazingly useful web site of Homebrew Hero Kazuhiro Sunamora has been resurrected after too many years in 404 status. 

Here it is:

https://www.qrp-ja.net/jf1ozl/index.html 

There is a LOT of tribal knowledge and lot of great ideas on his site.  Kazuhiro-san has apparently quit wireless, but is climbing mountains near his home.  We hope is doing well and that he will someday return to radio (perhaps for the peak of cycle 25).  

We last posted about him back in 2011.  In the comments to that post you can see the sad news about the demise of his web site (which is now back on the web): 

http://soldersmoke.blogspot.com/2011/12/homebrew-hero-kazuhiro-sunamura-jf1ozl.html

JF1OZL's bio: 

My name is Kazuhiro Sunamura. I am a 50 year old mechanical engineer, born in 1956. I am not an engineer in electronics. I have been interested in electricity and radio from the age of ten. For the last ten years, I have been active on my ham radio station JF10ZL. I have also written articles about my some of my radio projects in Japanese for the Japanese CQ Magazine. Now I have decided to get onto the internet and will take the opportunity of showing you my equipment and ideas. Please have a look at my schematics. I will be very happy if this material helps you with your own radio projects. I am a member of the J.A.R.L. affiliated Tsuchiura Club, the local ham club in my home town.