How The Physics of Resonance Shapes Quantum Reality

Here is an interesting article that appeared in Wired.  It will resonate with many SolderSmoke listeners!

https://www.wired.com/story/how-the-physics-of-resonance-shapes-reality/#intcid=_wired-bottom-recirc_972910f0-7b0e-4a47-84bf-3a375ead6667_text2vec1-reranked-by-vidi

Differential Temperature Compensation Capacitors in the Hallicrafters HT-37 Main VFO Tuning Circuit

 

I've been watching with great interest Mike WU2D's excellent series on VFO construction.  His second video is especially interesting because he talks about how we can use a split stator differential capacitor to build a temperature compensation circuit that will allow us to "dial in" the proper amount of temperature compensation.  

The heart of this circuit is the split stator differential capacitor.  The stator is split; but there is a common rotator. As the rotator moves, the capacity across one part of the capacitor increases while the other part decreases -- thus the total capacity remains unchanged.  If we connect two capacitors of the same capacitance BUT OF OPPOSITE TEMPERATURE CHARACTERISTICS -- we can use this split stator cap to select just the right amount of temperature compensation.   Very cool.  Even cooler:  Mike actually built a split stator differential capacitor.  That, my friends, is dedication. 

I was sitting here this morning thinking about all this when it occurred to me that right in front of me was a capacitor that might be relevant to all this (see above).  I bought it on e-bay one year ago after Pete N6QW had alerted me to it.  It is the main tuning capacitor from an HT-37 transmitter.  What attracted us was the big anti-backlash mechanism.  But now I realized that it had another charming feature.  

Looking at it a bit more closely I saw a split stator differential cap just like the one that Mike had made.  Attached to the two rotors were two tubular capacitors.  The three caps are in parallel with the main tuning cap.  Bingo -- this is a temp compensation circuit.  

I checked the HT-37 manual.  The manual says that temp compensation is set at the factory.  OK.  But the schematic does not show the split stator caps and the two tubular caps (see below).  Could it have been that this circuit was added later perhaps to address drift? (We do see it in the HT-32B schematic -- see below.)

HT-37 VFO SCHEMATIC

Anyway, it was very cool to find this example of the circuit Mike was discussing.  In the photo at the beginning of this post you can see the three caps.  Below you can see the split stator cap in the background. 

In the comments a reader points out correctly that this circuit was discussed in the ARRL book "Single Sideband for the Radio Amateur."  Indeed, it is on page 51 of the 1970 edition, ARRL  gave credit for the circuit to Hallicrafters: 

HT-32B VFO Circuit

Joe Carr K4IPV (SK) also discussed this circuit.  In his article in Popular Electronics in August 1993, he too gave credit to Hallicrafters.  Carr also gave some detailed instructions on how to use the circuit to stabilize a VFO.  See pages 78 and  79 of the August 1993 Poptronics: 

https://worldradiohistory.com/Archive-Poptronics/90s/93/PE-1993-08.pdf

Podcast (Audio) Version of Bill's Talk to the L'Anse Creuse Amateur Radio Club

Tony G4WIF suggested that I make this talk available as an audio recording.  Good idea. Here it is: 

http://soldersmoke.com/N2CQRHomebrewing.mp3

6EA8s in the Mate for the Mighty Midget, and WA9WFA Re-Builds a Heath HW-12

I reported to Scott and Grayson that I had finally gotten around to changing the three aging 6U8 tubes in my Mate for the Mighty Midget receiver.  I replaced them with three more youthful 6EA8s.  This switch really seemed to perk up the old receiver.   I'm listening to 75 meters on it right now. 

Speaking of 75 meters, Scott sent me this picture of his latest effort:  re-building a Heathkit HW-12.  FB.  This is a way of experiencing (or re-experiencing) the construction of a Heathkit.  I did something similar, but much less complicated)  with a Heathkit VF-1.  Scott did a wonderful job taking this old rig apart.  That PC board looks great (see photo below). 

Scott's e-mail:  

Hi Bill and Grayson, I’m glad to hear of your good results with the 6EA8’s in your MMMrx! I had similar results when I finally got rid of the 6U8’s with their iffy performance and went with the 6EA8’s.  I did put a set of 6GH8A’s and tried it out, it worked, but I don’t have any data on performance improvements.  After completing the outboard power supply and audio amplifier, I’ve taken a break from my MMMRx and it’s sitting there on the bench. I’ll get back to it in a while.  

 

In the meantime I’ve started a new project where I’m re-kitting a Heathkit HW-12 eighty meter transceiver.  I have completed the disassembly process including the pcb.  I bought a Hakko vacuum desoldering iron for taking all (ALL) parts off of the pcb, and it’s bare now.   I’m planning to start rebuilding this coming week.  73 Scott WA9WFA  

Bill Talking about Homebrew Radio with L’Anse Creuse Amateur Radio Club (Michigan) -- February 2, 2022 (Video)

This was a very nice meeting.  We just talked homebrewing and why it is such an important part of ham radio.  Video above

Topics included:

-- Jean Shepherd

-- Being "Electrically Inclined" 

-- The Herring Aid 5

-- Radio Clubs around the world

-- The Shame Shelf

-- Making mistakes, releasing smoke

-- Errors in ham radio magazines and schematics

-- The importance of understanding the circuit

-- The Michigan Mighty Mite

-- Building a power supply for the HW-32A

-- The origins of the SolderSmoke podcast

-- Knack stories, the IBEW and what we all have in common

-- The importance of books

Thanks to The L'Anse Creuse ARC for the invitation. 

Video of SolderSmoke Podcast #235

Pete and Bill in LIVING COLOR! 

SolderSmoke Podcast #235 is available for download: 

http://soldersmoke.com/soldersmoke235.mp3

Travelogue:

6 weeks in the DR for Bill
One contact on uBITX. More SW listening.
Repaired my Chrome Book in Santo Domingo!
Christmas Present for All: James Web Space Telescope launch

Bill's Bench

-- Understanding the NE-602 (see blog post)

-- Thinking about a 17/12 dual bander.  Looked at old G3YCC Tx for circuits... 

-- Using Spurtune08. WB9KZY found it.  In the LADPAC zip file here:

https://web.archive.org/web/20091222012628/http://w7zoi.net/emlad08_123.html

-- Then Put G3YCC Acores SSB TX back in operation

-- Put W4OP Barebones Superhet on 17 with NE602 down converter.

-- Netting and audible spur problems 

-- Now working many stations with this old "split" TX/RX

Pete's Bench

-- The Peashooter

-- Dean's VWS build of your DC RX

-- Building a SSB Transceiver Doc

-- Homebrew Crystal Filters

-- The shrinking of the PSSST

-- PSSST on Hack-A-Day

Bad Dead Soldering Stations

-- My X-Tonics 4000 dies.   But it left behind a great box with ample socketry. 

Mailbag: 

AA1TJ Mike Rainey --- Again in the Hobbit Hole! 486 kc RX

Thomas K4SWL -- Radio Astronomy and the Raspberry PI 

WC8C Dennis Invite to the L'Anse Creuse ARC   FB  Fun

Todd K7TFC got boosted at Tektronix Beaverton Ore.  

What happened to Chuck Adams K7QO?  His work taken off the net.

W1MJA ex WN2RTH 

N7DA worked W7ZOI in Sweepstakes.  FB

Kirk NT0Z formerly of ARRL HQ

Farhan VU2ESE was up in the Pench Forest, trying to spot a Tiger! 

We spoke to Farhan's Lamakaan ARC in Hyderabad.  QO-100 beam down! 

Dean KK4DAS's 16 watter.   On SS blog

Scott WA9WFA  Bad 6U8s?   Ordering 6EA8s

Bruce KC1FSZ Peppermint Bark gift box

Mike WU2D:  Book by Frank Harris on Homebrew radio

Bob Scott KD4EBM So many good ideas and links 

Rogier PA1ZZ sending parts packages -- Thanks Rogier

SolderSmoke Podcast #235 NE-602, Azores Rig, Spur Problems, SSB Rigs, Peashooter, HB Filters, MAILBAG

SolderSmoke Podcast #235 is available for download: 

http://soldersmoke.com/soldersmoke235.mp3

Travelogue:

6 weeks in the DR for Bill
One contact on uBITX. More SW listening.
Repaired my Chrome Book in Santo Domingo!
Christmas Present for All: James Web Space Telescope launch

Bill's Bench

-- Understanding the NE-602 (see blog post)

-- Thinking about a 17/12 dual bander.  Looked at old G3YCC Tx for circuits... 

-- Using Spurtune08. WB9KZY found it.  In the LADPAC zip file here:

https://web.archive.org/web/20091222012628/http://w7zoi.net/emlad08_123.html

-- Then Put G3YCC Acores SSB TX back in operation

-- Put W4OP Barebones Superhet on 17 with NE602 down converter.

-- Netting and audible spur problems 

-- Now working many stations with this old "split" TX/RX

Pete's Bench

-- The Peashooter

-- Dean's VWS build of your DC RX

-- Building a SSB Transceiver Doc

-- Homebrew Crystal Filters

-- The shrinking of the PSSST

-- PSSST on Hack-A-Day

Bad Dead Soldering Stations

-- My X-Tonics 4000 dies.   But it left behind a great box with ample socketry. 

Mailbag: 

AA1TJ Mike Rainey --- Again in the Hobbit Hole! 486 kc RX

Thomas K4SWL -- Radio Astronomy and the Raspberry PI 

WC8C Dennis Invite to the L'Anse Creuse ARC   FB  Fun

Todd K7TFC got boosted at Tektronix Beaverton Ore.  

What happened to Chuck Adams K7QO?  His work taken off the net.

W1MJA ex WN2RTH 

N7DA worked W7ZOI in Sweepstakes.  FB

Kirk NT0Z formerly of ARRL HQ

Farhan VU2ESE was up in the Pench Forest, trying to spot a Tiger! 

We spoke to Farhan's Lamakaan ARC in Hyderabad.  QO-100 beam down! 

Dean KK4DAS's 16 watter.   On SS blog

Scott WA9WFA  Bad 6U8s?   Ordering 6EA8s

Bruce KC1FSZ Peppermint Bark gift box

Mike WU2D:  Book by Frank Harris on Homebrew radio

Bob Scott KD4EBM So many good ideas and links 

Rogier PA1ZZ sending parts packages -- Thanks Rogier

NASA Video of Moon Orbiting Earth (Looks Fake, but Is Real)

https://scitechdaily.com/this-is-real-nasa-camera-a-million-miles-away-shows-moon-crossing-face-of-earth/

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: 

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

Thomas K4SWL -- SOTA Activation on Bearwallow Mountain, North Carolina (video)

Thomas put out a very nice video of his recent activation of Bearwallow Mountain in western North Carolina.  Really nice.   It was fun to see the QSOs and the logging as he did it.  Very cool that he worked Christian F4WDN --- Jack NG2E also worked F4WDN on a recent activation in the Shenandoah area of Virginia. 

More details on the activation here:  

https://qrper.com/2022/02/summits-on-the-air-pairing-the-elecraft-kx2-and-chameleon-cha-mpas-lite-on-bearwallow-mountain/

Thanks Thomas! 

Barefoot Ham Radio -- PA2OHH's Wonderful Web Site

I first saw the link to Onno's site on Peter VK2TPM's blog.  And at first I confused it with the site of another great homebrewer Miguel PY2OHH.   This is all very IBEW:   On the website of an Australian ham,  I spot the web site of a Dutch ham living in Spain and briefly confuse him with a Brazilian homebrewer with a very similar callsign.  TRGHS. 

Onno PA2OHH has an inspirational approach to the hobby that he presents in a  really wonderful website.   Here is his intro to Barefoot Radio: 

Barefoot technology and Barefoot power!

Barefoot technology or simple, non-professional radio technology and real Barefoot power or harmless QRP power, that is what you will find here. There are some complex designs but many designs are simple radio amateur circuits. They will never be used professionally!
These simple circuits and rigs can give you much fun: home brewing, portable activities during holidays, etc.
Batteries and inverted V dipole antenna's with a fishing rod as the center support are all you need to make many QSO's.

Much fun!
Barefoot technology and Barefoot power can give you much fun, but is not perfect... There are disadvantages like VXO control instead of a VFO, direct conversion receivers that receive both sidebands and simple frequency displays that are not so easy to read. But working with such simple equipment is often more exciting than working with a much better commercial transceiver.
Perhaps that you cannot believe that you can make many QSO's with QRP power of only 1 watt. Indeed, some practice is needed in the beginning so do not give up too soon. Every boring standard QSO becomes an exciting experience with QRP power!

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

Check out Onno's site:  https://www.qsl.net/pa2ohh/

Mike WU2D -- VFO Video #3

Mike WU2D continues to show us how it is done.  I hope to make all my future VFOs using the techniques he describes.  Thanks Mike. 

Exorcism Lite -- Spur Suppressed on 17 meter Transmitter -- Split TX/RX Station On The Air

I spent most of January in the tropics, away from my workbench.  This seems to have had a good effect on my 17 meter split TX/RX project.  As I was leaving, heading south,  I was thinking about several difficult options to deal with my spur problem (see previous blog posts). I thought about turning the transmitter into a transceiver by building a receiver board.   I thought about putting San Jian frequency counters on both the transmitter and the receiver, then doing a visual numerical "netting" by just putting the two devices on the same frequency (I actually ordered 3 San Jian counters).   The counter option was even more complicated than it at first seemed -- I would have to build a converter to shift the RX VFO frequency up.  VK2EMU suggested a tube type "Magic Eye" (interesting idea, but also complicated).   This was getting out of hand. 

When I got back home, I took a new look at the problem.   I decided to take one more shot at suppressing the 8th harmonic of the carrier oscillator.  I had already built a new oscillator and buffer using the circuit from Farhan's BITX20.  And I had put it in a metal box.  Now I decided to do three things: 

1) Tighten up the low pass filter at the output of the buffer by moving the cutoff frequency lower (to around 7 MHz) thereby getting a bit more suppression at 41 MHz

2) Try putting a series LC shunt circuit tuned to 41 MHz  at the output of the carrier oscillator (between the oscillator and the buffer). 

3)  Reduce the voltage to the oscillator/buffer.  I have this on a pot, so I can adjust it down to the point where the remnant of the harmonic is no longer audible, while keeping the main carrier osc signal sufficiently strong. 

It seemed to work.  I could now hear the desired frequency for spotting, without the confusing tone from the spur.  

Why had I been able to do this back in 2002 in the Azores using a simple trimmer cap to ground?  My guess is that I was using my Drake 2-B as the receiver.  The trimmer cap to ground may have reduced harmonic output.  And I was probably cranking back the RF gain on the 2-B to the point where I could hear the desired signal but not the remnants of the spur.  I have no RF gain control on the Barebones Barbados receiver that I am using in this project. 

So, what's the lesson from all this?  Well, if you are faced with a serious technical problem, and you find yourself considering complicated and difficult solutions,  go to the Dominican Republic for about a month (especially if it is January or February), and then take another look at the problem when you return.  If you are unable to travel this far or for this long,  taking a walk or taking a weekend break from a troublesome problem will likely have a similar mind-clearing effect. 

The video above shows part of a February 1, 2022 QSO with Gar WA5FWC using the split TX/RX 17 meter rig.  Gar is an amazing long-time SSB homebrewer who got his start with phasing rigs back in the day. 

The NCDXF/IARU Beacons (very useful website)

 

So there I was, innocently checking the lower end of the tuning range on my now 17 meter SSB Barebones Barbados W4OP receiver.  I had it tuned to the bottom of the 17 meter phone band.  All of a sudden I hear YV5B in CW.  It was obviously a beacon transmission. 

I had forgotten about these beacons.  Some quick Googling brought me to a very up-dated web site: 

https://www.ncdxf.org/beacon/

The site shows exactly which station is transmitting at any given moment.  There is also a very handy map display giving beam headings and distance from your location.  

So far, I'm only hearing YV5B and VE8AT.  I hope to hear more once the Coronal Mass Ejection is behind us. 

Check it out.  Leave your receiver on 18.110 MHz.  Let us know what you are hearing.  

Three cheers for the NCDXF and the IARU! 

Mike WU2D Shows Us How to Do Temperature Compensation in Homebrew LC Analog VFOs

In several of the articles that I have seen about the homebrewing of VFOs the authors seem to throw up their hands when the subject of temperature compensation comes up.   They seem to just say, "This is hard.  Not for the faint of heart.  Good luck with that!"   But in this great video Mike WU2D shows us in very practical terms how to do temperature compensation of VFOs.   This is really great news for those of us who prefer old style coils and caps to Si5351 chips.  Thanks Mike!  

Image of James Webb Space Telescope In Position at L2

https://www.inverse.com/science/james-webb-photo-final

A very nice shot of the James Webb Space Telescope, nearly 1 million miles away, taken from Rome. 

"From Crystal Sets to Sideband" -- A Great Book about Homebrew Radio by Frank Harris K0IYE (FREE!)

I first came across the above picture of K0IYE's inspirational, completely homebrew station many years ago in the pages of "World Radio" magazine. I have already linked to Frank's book many times over the years, but it is so good that I regularly feel compelled to write about it again. Frank updates the book. Just check out the introduction to his website. Frank even has a Spanish language version of his book. All for free. Thank you Frank.

The introduction to Frank's web site:

Over the last century amateur radio has evolved into numerous different

hobbies. Some hams enjoy weekend contests in which they try to

contact as many stations as possible. Others talk to as many of the

world's 341 call areas as possible and collect QSL cards to prove it. Other

hams just like to ragchew with friends. Still others communicate over

long distances at UHF frequencies using satellites, meteorites, aurora and

other substitutes for a sunspot-charged ionosphere. Some hams provide

communications for their communities during emergencies.

Many of us have returned to the early days of radio by building our own

equipment from scratch. Most home builders start by building QRP (low

power) transmitters. If this doesn't satisfy your urge to build something,

you can move on to build the entire station. That is what this website is about.

https://www.qsl.net/k0iye/

Mike WU2D on VFOs (with additional Tribal Knowledge from Frank Harris K0IYE)

Great stuff from Mike and from Frank Harris K0IYE.   But when I put the VFO in a box, I usually try to put the frequency determining components (the coil and most of the caps) in the box, with the powered components (transistor, Zener,  voltage dropping resistors) outside the box.  If I put these powered components in the box, I find there is some drift as these components slowly heat up the interior of the box. 

Dean KK4DAS and he VWS Builders have just stated building analog VFOs, so Mike's video is very timely for them. 

Looking at the Galaxy's Spiral Arms with a Dongle, a Raspberry Pi,and a Homebrew Antenna

I told Farhan that the world NEEDS a homebrew Raspberry Pi observatory at Lamakaan in Hyderabad. They are on it.  

This looks very do-able.  And fun.  And UHF.  And SDR. And Raspberry Pi. 

I'd like to build one too.  I was encouraged by the video demo -- it was done in Alexandria, Virginia, very close to where I live. 

A while back I was lamenting to Dean that I reluctantly threw away a DISH or DIRECT TV  satellite TV antenna.  I worried that I had discarded something that would have been useful for radio astronomy.  Turns out I didn't need it.   This video and the associated .pdf shows how to look at the galaxy with a simple homebrew (Home Depot!) horn.  

https://www.gb.nrao.edu/~glangsto/aas2020/Langston2020AasTelescopeWebinar.mp4

https://drive.google.com/file/d/1ssS_zBQWDEXMENc2_aqqPGxGkEEU5Ea3/view

Thanks to Thomas K4SWL of the SWLing Post for alerting us to this. 

Exorcism Not Quite Complete -- Thinking of Other Options

As often happens, I may have jumped the gun in declaring the exorcism of my 17 meter transmitter to be a success. As readers of this blog will recall, my problem was that when trying to "net" my separate 17 MHz receiver and transmitter, at around 18.116 MHz I could hear more than one tone as I tried to get to zero beat.  The 8th harmonic of my 5.176 MHz carrier oscillator was mixing with the 23 MHz VXO signal and producing a spur.  I could probably knock the level of this spur down below FCC limits, but -- and here is the problem -- I probably could never knock it down to the point that it would not be audible in the sensitive receiver that sits right next to the transmitter.  So this is really a netting problem, not really a spur problem. 

I don't want to try another filter frequency -- I have VXO crystals that really work only with a filter at 5.176 MHz.

So here is my current idea:  Build a receiver board and turn this thing into a transceiver.  Switch with relays the input and output of the 5.176 MHz filter, and use relays to switch to the receiver board the VXO and carrier oscillator signals. 

Making this thing a transceiver would eliminate the need for netting.  This should solve my problem. 

What do you folks think? 

73  Bill