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Sunday, February 25, 2024

Innovation and a Dual Band Sweep with Version 2 of the 15-10 Transceiver

Here are a couple of videos on Version 2 of my 15-10 SSB transceiver.  In the video above I try to show the advances and innovations that have been made since the start of my BITX construction adventure back in 2013.  

 The video below shows the receiver in action this morning on 15 and 10 meter SSB.  I think it sounds pretty good. 

Click on the image for a better look

Farhan asked what the passband of the 25 MHz crystal filter looked like.  I sent him this.  I think it looks very good, and shows that it is possible to use an IF this high.  This permits us to not only set up the transceiver for dual band coverage (in this case 15 and 10 meters), but it also allows for a lower frequency VFO (in this case around 3.5 MHz) with a resulting increase in VFO stability.  

Saturday, February 24, 2024

More on "Kludge" -- Merriam-Webster's Pronunciation Guide


What say our British cousins?  How do you pronounce the word? 

Kluge as in huge? 

Kludge as in fudge? 

Innovations and Inventions in Garages and Basements

The Hewlett-Packard garage

There is a lot of inspirational stuff in this blog post, especially for those of us who work in home workshops, often in garages or basements. 

Thanks to HackaDay for alerting us to this. 

Thursday, February 22, 2024

Some of my Double Sideband Rigs: Azores, Virginia, Dominican Republic

The above video describe a round of mods to the much modded DSB rig. And my alleged winning of the ARRL Sweepstakes (in a very elite category). 

The video above shows where I took the rig in 2014.  Bahia Rincon, Samana peninsula, Dominican Republic.  You can also see my power supply. 

Here is an article on the first DSB rig that I built, out in the Azores:  


I think the article captures well the trials and tribulations faced by new homebrewers, perhaps with the twist that comes from being out in the middle of the Atlantic ocean.  

Mike WU2D is having similar fun with his homebrew 10 meter DSB transceiver: 

I was struck by how similar Mike's early QSO experiences were with mine.  We both put our DSB transmitters on the air before they made their way into real cabinets or boxes. 

Here's mine from 2001 in the Azores: 

The Mars Helicopter and its CO2 Insulation

This video isn't about homebrew ham gear, but nonetheless I found it very interesting.  Of particular interest is the bit about their need to find a very low-weight insulator to protect the instruments from the cold of the Martian night.  Aerogel would have been too heavy.  So they just filled the instrument chamber with Carbon Dioxide.  That was their insulator. Think about that, especially those of you who still deny CO2's ability to heat up the atmosphere.  

There is a lot of great stuff on Veritasium's YouTube  channel:  

Monday, February 19, 2024

Grayson Evans KJ7UM Video on Homebrewing with Thermatrons

Grayson Evans KJ7UM is the author of Hollow-State Design for the Radio Amateur, a wonderful book about using Thermatrons (aka tubes, or valves) in radio projects. Buy it here:


More info on the book is here: https://kj7um.wordpress.com/2020/12/02/hollow-state-design/ In this video, Grayson talks about construction techniques (including the use of Thermatron Me-Pads), and Manhattan construction for Thermatron projects. FB! Visit Grayson's blog: https://kj7um.wordpress.com/

Jean Shepherd has Trouble with his Heising Modulator (and his date)

This is probably Jean Shepherd's best program about homebrew ham radio.  It is about how we can become obsessed with the problems that arise with equipment that we have built ourselves, and how normal people cannot understand our obsessions.   

I posted about this back in 2008, but I was listening to it again today, and quickly realized that it is worth re-posting.   Realize that Shepherd's Heising modulation problems happened almost 90 years ago.  But the same kind of obsession affect the homebrewers of today.  

Note too how Shepherd talks about "Heising" in Heising modulation.  Heising has an entire circuit named for him, just like Hartley, Colpitts, and Pierce of oscillator fame.  Sometimes, when I tell another ham that my rig is homebrew, I get a kind of snide, snarky, loaded question:  "Well, did you DESIGN it yourself?"  This seems to be a way for appliance operators to deal with the fact that while they never build anything, someone else out there does melt solder.  They seem to think that the fact that you did not design the rig yourself makes your accomplishment less impressive, less threatening.  This week I responded to this question with Shepherd's observation -- I told the enquiring ham that my rig is in fact homebrewed, but that I had not invented the Colpitts oscillator, nor the common emitter amplifier, not the diode ring mixer, nor the low-pass filter.  But yes, the rig is homebrew, as was Shepherd's Heising modulator.    

Guys, stop what you are doing. Put down that soldering iron, or that cold Miller High Life ("the champagne of bottled beer") and click on the link below. You will be transported back to 1965 (and 1934!), and will hear master story-teller Jean Shepherd (K2ORS) describing his teenage case of The Knack. He discusses his efforts to build a Heising modulated transmitter for 160 meters. He had trouble getting it working, and became obsessed with the problem, obsessed to the point that a girl he was dating concluded that there was "something wrong with him" and that his mother "should take him to a doctor."

This one is REALLY good. It takes him a few minutes to get to the radio stuff, but it is worth the wait. More to follow. EXCELSIOR! FLICK LIVES!

Saturday, February 17, 2024

Nate KA1MUQ's Amazing Thermatron Receiver

Wow, some really wonderful work is taking place in Nate KA1MUQ's basement in California. 

-- I really like the pill bottle coil forms.  I wonder if Nate faced suspicion (and possible arrest) in the pharmacy when he asked for the pill bottles.  (I got some suspicious looks when I went I asked for empty pill bottles while building my thermatron Mate for the Mighty Midget receiver back in 1998.) 

-- The variable capacitors are also quite cool, as is the big rotary switch.   Is that for band switching? 

-- Oh  man, all on a plywood board.  Frank Jones would approve!  

-- Indeed Nate, that beautiful receiver NEEDS an analog VFO.  And we need to hear it inhaling phone sigs, not that FT8 stuff. 

-- Please keep us posted on your progress.  And of course, one hand behind your back OM.  Lots of high voltage on those thermatrons.  

Thanks Nate!  

Friday, February 16, 2024

Shuji Nakamora and his (Juliano) Blue Gallium Nitride LED

Lots of great stuff in this video:  

-- They get the charge carrier thing right:  contrary to many presentations, holes don't really move in a semiconductor.  Electrons move to fill holes, making it appear that the holes are moving. 

-- Interesting that Nakamura was so willing to defy company orders for so long. 

-- The description of the discipline that powered his inventiveness is inspiring. 

-- The way he was treated (badly) in Florida because he lacked a PhD is sadly illuminating. 

-- The discussion of corporate infighting is interesting.  

We wrote about Nakamura before:  https://soldersmoke.blogspot.com/2021/02/shuji-nakamura-inventor-of-juliano-blue.html

Thursday, February 15, 2024

More Inspiring Mail! Another "First Ever Receiver was Homebrew"

Frank's Lowfer Beacon Receiver

It was great to hear from someone else who, like Scott KQ4AOP, heard his very first signals on a homebrew receiver.  That is a really wonderful way to start.  Frank's first receiver was built around the NE602 chip.  I had trouble understanding this IC but I finally cracked the code: 


The picture that Frank sent is of a more recent project, this one a Lowfer receiver that picks up signals from beacons. 


Hello Bill, 

I just wanted to message you and tell you I really enjoyed your book Soldersmoke. I've been listening to the podcast as well.  On the latest one you mentioned a fellow who heard his first ham radio signals on a homebrew receiver, and that's how it was for me as well! There were lots of articles about using  the NE602 in the electronics magazines back in the day. I put one of the circuits together and it worked pretty smoothly... I eventually got my ham radio licence (KC8JJL) sometime in the 90's. The first time I met a ham was when I showed up to take the test!  

I don't do much transmitting these days but I still love to listen and tinker.  Here's a picture of a direct conversion LF receiver I put together... It uses an NE602 and is varactor tuned. It only covers from around 300Khz to just over 400khz  but there are still a few beacons I can hear in MI and WI. 

Frank James

Wednesday, February 14, 2024

We Get Mail! Red Poster? Really a Tapestry from Ecuador

Listener Tobias was laid up yesterday, following the extraction of wisdom teeth. (This seems like an appropriate follow-up to our talk in SolderSmoke Podcast #250 of sBITX "wisdom files" to correct FFT "hallucinations.") Tobias does not appear to have been hallucinating, but he was having trouble seeing what he thought to be a "red poster" in my shack.  

In fact, what he was seeing was a red tapestry from Ecuador that was sent to me by Galo Constante HC1GC way back in 1993.  I was in the Dominican Republic, running my first ever real homebrew transmitter.  Here is an article about this project: https://www.gadgeteer.us/TXHB.HTM  I think Galo was also QRP homebrew.  My log shows that I worked  him eight times from the DR. 

Mitad del Mundo =  Middle of the World (a reference to the equator). 

Here is the QSL I got from Galo: 

Here's a 2022 blog post about a resurrection of this old rig: 

Thanks Tobias for spotting the HC1GC tapestry and reminding me of some great QRP contacts. I hope you feel better OM.  73  Bill 

Tuesday, February 13, 2024

Ferdy HB9DSP's 5 band Moxon -- The Moxhorn!

Click on the image for a clearer view

Wow, I couldn't even build a 2 band Moxon, but Ferdy has built a 5 band version.  He told me that he had to tweak the elements a lot to get acceptable SWR's on all the bands.  20 and 17 are especially tough, because they are so close in frequency.  

More info on his great QRZ page: https://www.qrz.com/db/HB9DSP

Thanks Ferdy! 

Designer: Douglas Bowman | Dimodifikasi oleh Abdul Munir Original Posting Rounders 3 Column