A Tale of Two Old Analog VFOs -- Artificial Intelligence's Role. PLEASE COMMENT!

The Kenwood VFO under test, with 2 Yaesu VFOs Standing By 

I have sung the praises of the VFOs taken out of the old Yaesu FT-101s.  I am using them in two homebrew 20 meter SSB transcievers,  one in the Dominican Republic, the other here in Virginia.  We started buying these things just for the anti-backlash reduction drives. But the vendors would send along the reduction drives AND the entire VFO module.  These circuits were all analog, and all discrete component.  I understood them, and had completely homebrewed circuits very much like them.  So I felt comfortable using them. 

Somewhere along the line, I got the VFO from a Kenwood TS-820s.  My motivation was the same:  I wanted the anti-backlash reduction drive. But as with the Yaesus, the entire VFO box came with the purchase.    The frequency on this one was much lower than the Yaesu.  the Kenwood ran from 5-5.5 MHz, the Yeasu was up around 9 MHz.  On this alone, the Kenwood seemed better.  

I recently put the Kenwood on the bench and began testing it.  I used Artificial Intelligence (AI) in the tests.  The results were good and bad.  Sometimes AI helped, sometimes it made matters worse.  Mike WU2D recently used AI to look at the tubes of an old receiver he was working on.  He too was impressed by the usefullness of AI, but I think he too had some misgivings. Here are some of Mike's conclusions: 

Let's start with a fundamental question:  I asked Gemini which of the two "ages better."  Gemini said that the Kenwood was superior in this regard.  I disagree.  Here is why: 

-- Tuning on the Kenwood was very jumpy and very scratchy.  AI correctly said that this was probably due to corrosion over the years on the connections between the main tuning capacitor and ground.  Strike 1! AI recomended cleaning with DeOxit. As a last resort they recommended putting some solder wick between the rotator shaft and ground.  I did that and it fixed the problem (you can see the solder wick in the picture above), but I never had to do that with the Yaesu VFOs.   

-- The schematic of the VFO shows a .9 V RMS output from the VFO.  But it does not specify a 50 ohm load.  Here is the Yaesu schematic: 

AI kept insisting that I use a 50 ohm load.  When I did, the output was reduced down to 54 m V rms. I questioned AI about the load, but it kept insisting on 50 ohms.  Only later, did AI point out that in the Yaesu, the VFO would feed into a HIGH IMPEDANCE load.  Strike 2. 

-- Gemini kept warning about the Q3 and Q4 transistors. They were 2SC460 transistors with weird (ECB) pinouts.  And they were prone, it said, to a horrible sounding disease: "Original Hitachi 2SC460 transistors are infamous in vintage ham gear for silver migration ("black foot disease"), where the lead plating oxidizes, turns black, and causes severe noise, leakage, or intermittent oscillation failure." AI happily recommended replacing them with 2N3904s.  I did this, but the voltage on the emitter was way off.  AI blamed this on the new transistors (that it had recommended!) saying that their hfe was too high (so, uh, why did you recommend them?).  It then said that the direct coupling from Q3 to Q4  was at fault;  it recommented putting a .001 uF cap between these two transistors, along with two resistors for the biasing of Q4.  I did this.  I am not sure if it was necessary.  Strike 3. 

-- Gemini said I should check D3. It was germanium, you see, and "notorious"  for going open.  It was open.  I replaced it with a wire, but AI had a fit.  It worried that voltage from the follow-on circuits in the Kenwood would mess up the voltages on Q4.  I told AI not to worry about this -- all I had was the VFO!  Strike 4. 

-- I still wasn't getting good output.  Here AI was very useful.  First it told me to check the voltage on the emitter of Q4.  It was too high.  Then it told me to look at the resistance to ground from the emitter of Q4.  Uh oh.  It was open.  I quicky went through the connections to ground.  L6 was open.  I relaced it with 100 uH inductor. This corrected the situation.  I now had 1 volts AC rms at the output with no load and .8 V AC rms with a 1000 ohm resistor in the load.  SCORE ONE FOR AI. 

So, looking back, I came to several conclusions:  

-- Gemini was just wrong in saying that the Kenwood VFO ages better than the Yeasu VFO.  The Kenwood had Germanium diodes, weird transistors that get "Black Foot" disease, main tuning caps that get scratchy due to corrosion, inductors that go open.  Yuck.

-- You have to take the recommendations from AI with a grain of salt (see WU2D's conclusions above).  Sometimes they are right, sometimes they are wrong, and sometimes they recommend things that might not be necessary.  Dean KK4DAS points out that AI's seem to do better when you upload the schematic.  Maybe this lets AI analyse it using a simulator.  I had not done this.

-- I will probably use the Kenwood VFO in a 17 meter SSB transceiver.  I recently bought some 13 MHz crystals for the filter and the BFO/Carrier Oscillator from Mouser.  And AI confirms that this combination should not produce any problematic spurs.  We'll see.  The ultimate test is still real-world construction. 

What do you guys think about using AI in projects like this?  Will AI improve? 

CuriousMarc and Company Fix an Old Analog Device (an Apollo Hand Controller)

I really liked this repair video (above), not because I will ever fix an Apollo-era hand controller (I won't) but because it illustrates well what can go wrong with older, analog gear.  And how you fix it.  

You watch as Mark and Mike try to figure out what was wrong.  This brings us back to the diagnostic questions that Richard Feynman posed to his neighbors when, as a boy, as he fixed their AM radios back in Brooklyn.  "My God! He fixes radios just by thinking!" exclaimed one amazed customer. 

Once (well, several times) after they thought they had it figured out, they used simple test gear (a DMM) to find the short.  Then they fixed it, and brought the controller back to life. This wasn't easy.  It involved lots of digging (almost literal digging) and put at risk some irreplaceable parts.  But they did it.  Three cheers for the CuriousMarc team. 

BTW:  What was that liquid that Marc used to replace the insulation that had been scraped away to allow for testing? 

About the Guy Who Brought Us the AADE L/C Meter -- Neil W. Heckt

 

There it is.  The AADE L/C meter.  Many of us have been using these things for years.  I have two of them -- the one that I bought is here in my shack in Virginia.  The other was given to be by Todd VE7BPO and it is in my shack in the Dominican Republic. I sometimes wondered who was behind Almost All Digital Electonics.   Today I got the answer. 

Rishav is from Nepal,  He has been studying in Germany.   He is working on homebrewing the test meter (the company shut down when Neil passed away).  In the course of his research, Rishav gathered some very nice info about Neil W. Heckt, the fellow who created AADE and the meters that so many of us used.  Thanks Rishav! 

Memories of Neil W. Heckt

My work with Tobias (KK7BCO/2M0TFF) on a LC meter as the fifth build in Red Summit RF's Homebrew Workbench series for beginners introduced me to the clever LC meter design of Neil Heckt. As we celebrate his work by building one ourselves, in this post I hope to celebrate his life through the memories of those who knew him.

Neils's AADE L/C Meter IIB was a great hit, with thousands of units sold both as kits and as fully assembled instruments. It is not difficult to find praise for the meter. Many owners have written about its accuracy, usefullness, limitations, and clever design. Scattered among those reviews, however, are also small glimpses of Neil himself—stories from people who corresponded with him, asked him for help, or sent their meters back to him for repair. The reviews of the AADE L/C Meter IIB on eHam.net are particularly valuable in this respect. Many are written by people who dealt with Neil directly, and aongside their praise for the meter they remembered his kindness, honesty, and unusually generous customer service.

Memories

There is surprisingly little written about the man behind the instrument. While trying to learn more about him, I found most of the biographical information in his obituary. While searching further, I came across a moving remembrance titled Celebrate the Sun, written by Jill L. Ferguson, Neil's daughter-in-law. It offered something quite different from the technical accounts and product reviews: a glimpse of Neil as a husband, father, and person. One story in particular reveals a wonderfully personal side of him:

She (Kay) said her favorite book and life philosophy came from Celebrate the Sun. Back before she and Neil dated she had told him about this book. Not only did he borrow her copy and read it, but he photocopied the whole thing and pasted page by page into a photo album and intermixed the pages with his own photographs of the sun, of himself on hikes, and of the two of them walking in the woods. He decorated the front of the book with black electrical tape and two die-cut pelicans as they are key characters in the book. After Neil and Kay moved in together and married, she found this book he had created but had never told her about. She intimated that part of the way she knew he was the man for her was because he had taken her interest in this book so seriously. On his last night, she had the book Neil had created with them in hospice center and was reading the end of it to him shortly before his passed.

I was deeply moved by the story and wrote to Jill to ask whether she might be willing to share a few more memories of Neil, and perhaps a photograph. She kindly replied that she would speak with Kay, Neil's wife, and with Neil's son, her husband.

Two days later, I received a message containing a wonderful remembrance written by Kay herself, together with a photograph of Neil as a younger man. I have reproduced both here.

Photograph of Young Neil, thanks to Jill, sent to me by Kay.

Neil Heckt worked for the Boeing Company for more than 30 years. He was a member of their early air and space team. In his earliest years he worked on getting satellites into orbit and later getting men onto the moon. He developed his first inventions during those years which, of course, were owned by Boeing.

When we met he was a few short years from retirement. He was anxious to start his own business and create new products unrelated to his work at Boeing. He named his company Almost All Digital Electronics.

The inventions that followed seemed focused on developing ways to measure very, small units of...? He invented an atomic clock. It is my understanding that the Bureau of Weights and Standards in Colorado used it and that it was displayed there. Here I must state that I am woefully unknowledgable about any aspects of his work. I am neither a business woman or an inventor so, though I found him brilliant I rarely understood what his inventions really did. We were very different in many ways but genuinely admired each other's talents.

The last invention was an L/C Meter kit for hobbyists. He did very well with that product. The arrival of the internet and eBay made it a commercial success.

I thought his philosophy about not patenting his products was unusual. He told me that he developed a product, sold as many as he could and when someone copied his work he would stop production and leaveit to someone else to deal with it while he invented something else.

He had talents and ideas brewing in his brain that craved to be made real. He told me that whenever he needed money he would invent something that people would buy and then he paid his bills.

He wasn't like me and the people in my world who took on a second or third job when we needed money. I found his confidence and creativity to be amazing!

Neil was scrupulously honest in his business . Once he purchased two antique vacuum tubes for less than $100 from an eBay customer. When they arrived he discovered that they were quite valuable. He wrapped one tube up and sent it back to the customer with a note telling him what it was worth. Instead of selling it and making a good deal of money he sent it back. I asked him why. He said it wouldn't be fair to the seller for him to keep all of it for himself because the guy just didn't know what he had.

If anyone had a problem assembling one of his kits they sent them to him and he would fix their problems without charge.

Neil was sick for many years before his death. His brilliant mind was with him to the end.

I hope these memories help preserve not only Neil Heckt’s work, but also something of the thoughtful, generous, and inventive man remembered by those who knew him.

***

Steve KW4H's Restoration of a Drake 2-B -- Part 3 -- Alignment With a New Calibrator

Steve KW4H writes: 

The passband tuner realigning went just fine. To do this, I remove the audio output transformer and push it aside, insulating it from from the components on the chassis underside using a snack-size baggie.  Then, it's necessary to clip the frame of the audio transformer to ground so audio works.  I won't go into the nitty-gritty technical steps, but am just pointing out that in order to align that passband tuner you've got to get that transformer out of the way.  In the 4-line, Drake solved this inconvenience by putting the passband tuner above the chassis, with all of the alignments easily accessible.

 The 2-B is receiving, but not totally realigned yet.  But before we do that, I'm installing a custom-built calibrator/marker generator that will plug right in to the calibrator socket on top of the chassis.  This calibrator provides selectable 25/50/100 kHz spacing (I'll preset it for 50 kHz).  A note for you:  it's operated by the "CAL" switch on the front panel, and is rewired to run on that 9V battery I've installed on the bottom of the chassis (see photo).  The calibrator consumes almost no power when switched on and the battery should last a very long time.  But now you know where the power source is for the calibrator.  I've also attached a photo of the calibrator so you know what it looks like -- for the 2-B, the screw terminal isn't installed on the circuit board -- instead, I wire it directly to a Drake-style 4-prong plug that fit right into that calibrator socket above the chassis.

 The signal from the calibrator will be used for some of the alignment steps, so I like to install it at this phase.

More on the Drake 2-B from Steve KW4H -- Part 2 -- Recapping. Cleaning Tubes and Sockets. Tube Tester

The recap is finished.  You can see the new Hayseed Hamfest cap on the chassis, as well as the other new caps.  In these receivers, I also replace every old paper cap -- even the ones in the so-called "hard to get to" places.  On the Drakes, you have to work sideways as many of these boards are vertically mounted.  Drake did that to save space and give their gear a smaller footprint.  The tradeoff is the workbench gymnastics.

The 2-B now has a brand new, 3-wire power cord.  The old bypass caps on the AC line were removed, and a new ceramic safety cap installed on the hot line, between the bottom of the fuse holder and ground.  The original purpose of these capacitors was to filter out household AC line noise.  Such things are rarer these days as household appliances are better designed, but for completeness purposes I think a safety cap on the hot line is reasonable.  

All the tubes were tested and substitutions made where needed.  A word about tube testers:  they're good for discovering major faults, but IMO the best tube tester is the circuit it was designed to run in.  So for these tests I'm just looking for shorts, gas leaks, and obviously weak tubes.  

In addition to testing the tubes, each tube socket is cleaned with a disposable interdental cleaner dipped in 99 percent isopropyl.  Following this, the tube pins are lightly brushed with DeOxit D-100L on the end of a q-tip.  All it takes is just a light film.

The 2-B powered up!  We have contact -- and, of course, some other issues to deal with.  The preselector capacitor was noisy -- the cover was pulled off and it was sprayed and brushed to remove any "whiskers" or other contamination that might cause unwanted conduction between the plates.  It's better now, but I'll keep an eye on it throughout the rest of the process.

Since the passband tuner had to be removed and repaired, it's clear from the sound of things that the passband tuner badly needs to be realigned.  That's going to be done next -- as long as we can jam a signal through the receiver, it's best to realign the passband tuner before swinging around and running through the overall alignment process because it has such a profound effect on the audio and signals.  Also, aligning the passband tuner is logistically more complicated than in Drake's 4-line, as two of the slugs aren't easily accessible.  I'll send some photos later showing how we get around that problem.

SolderSmoke Podcast 266: TROUBLESHOOTING! Test Gear, LA6NCA, ZIA Rig, Australia, Nuvistors, 75 AM, MAILBAG

SolderSmoke Podcast # 266 is available. 

Video version: https://www.youtube.com/watch?v=_hbLmsFxzx4

Audio version:  http://soldersmoke.com/soldersmoke266.mp3

Travelogue:   Dean to Boston, Bill to Glenmore in Maryland.  

Discussion of AI, data centers, and ham radio. 

Dean's Bench:  

--  Troubleshooting 

--  Why we emphasize building in stages

--  Understanding what your test equipment is telling you

--  Measuring everything and expecting precision from analog circuits.

  

--  Recent examples from our Discord channel, examples were my rigol scope was lying to me.

Pete's Bench:  

-- Helge LA6NCA's Rig

-- Troubleshooting when the data fools you:  The ZIA rig. 

SHAMELESS COMMERCE DIVISION: 

-- Mostly DIY RF. 

-- Please continue to comment on blog posts. 

-- Please think about becoming a Patreon sponsor/ 

Bill's Bench:  

-- Working Australia on 20 and 17 SSB. 

-- Putting 80 meter antenna back up.  But high (August) noise level on 75. SOLVED! 

-- Nuvistor adventures with 1964 Parks Electronics Converter. 6CW4s. 

-- Thinking of audio derived S-meters. 

Mailbag: 

Grayson KJ7UM -- admiration for Helge LA6NCA. 6L6 Rig. 

Hidehiko JA9MAT's super regen, And FT-101 VFO Box. 

Chuck WB9KZY on older UK covert listening devices. 

Paul VK3HN:  Australian CBLA rig. 

Andri in Bandung, Indonesia -- Built a SolderSmoke DC receiver. 137 built so far! 

Mike WN2A liked 3885 kHz post (not everyone did -- AI Slop?) 

Walter KA4KXX liked piece on G0UPL breaking the I and Q code of Si5351.

Bob KD4EBM and Peter VK3TPM on AI. 

Ryan KJ7KVD will build MMM when family duties permit. 

Chris KD4PBJ noted SolderSmoke on a ham radio sign sheet.  FB.

Eric 4Z1UG -- Interviewed Will N5OLA (Heathkit Guy) https://www.qsotoday.com/podcasts/n5ola

K6AUS seeking understanding on mixers.  FB! 

K6AUS:   Did Drake make any 2Bs with serial numbers 3000-4000? https://nomadiq.net/blog/post/how-many-drake-2bs-were-ever-made

I am still looking for a Drake 2B for K6AUS.

NT0Z -- Kirk.   A big fan. Thanks. 

The Smith Chart -- Veritasium Explains its Origins and How it Works

This is really interesting and represents one of the best explanations of the Smith Chart that I have seen.  

One quibble:  In the beginning, they make it sound like all refelcted power in a transmission line is lost.  That is not really true.  Much depends on the frequency, the type of line used and the length of the line. The video presents this "SWR loss" as being very significant, and many hams seem to think that any SWR worse than 1:1 will kill their signal.   

Look at the question that I put to Gemini: 

I am a radio amateur. My SWR meter shows an SWR of 2:1. I am using 50 feet of RG-58 coax to a dipole antenna. The dipole is cut for 40 meters and I am operating on 40 meters. My rig is putting out 100 watts. How many watts are being reflected? How many watts are being radiated? 

Gemini calculated:  

Assuming your SWR meter is located at the transmitter and shows exactly 100 watts of forward power, 11.1 watts are being reflected at the meter, and approximately 76.1 watts are actually being radiated by your 40-meter dipole.

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

That means that in this scenario, I am putting into the transmission line 100 watts and 76.1 watts are being radiated.  That means that the loss resulting from this SWR of 2:1 will be about 1.186 db.  With one S unit equaling about 6 db, this is clearly not enough to worry about.  

Also, lets remember that we could put a 50 ohm dummy load at the far end of our transmission line and achieve an SWR of 1:1.  But that dummy load would not radiate.   

Three cheers for Veritasium for doing this Smith chart video. 

Thanks to Rogier PA1ZZ and to Mike WN2A for sending this video to me. 

Please put below your comments on the video and my observations. 

How to Build a MODERN Electronics Workshop (and How Much it Might Cost) (PLEASE COMMENT)

First, kudos to this fellow for pronouncing "solder" correctly.  The L is silent (sorry to our British readers).  He does have an accent, but he is in Texas, and has picked up the CORRECT pronunciation.  So kudos. 

I really liked the video.  It represents a movement into the modern age of electronics.  I know that we usually talk about HDR, and homebrew rigs that -- while solid state -- are from the early 1970s.  There  has been a lot of progress since that time.  This video is a reminder of that, and talks about what we can do to participate in this modernity. 

Some observations: 

-- The microscope.  Looks cool, but it is kind of scary... 

-- The tiny digital rechargeable soldering iron looks like a great idea. 

-- I agree on the mechanical (non chemical) soldering tip cleaner idea. 

-- The 3D printer info is very useful.

-- Enclosures?  I am still in the 1/8 inch plywood era.  I have a ways to go. 

-- We could use more info on CNCs. 

-- I didn't know that you could get a pick-and-place machine for the home.  Probably just as well! 

-- I like the thermal camera.  I also like his suggestion that you could just burn your fingers! 

-- I think an oscilloscpe is a must, even early on.  I agree on the need for a multimeter.  

-- Indeed, a good PC is a must.  

What were your reactions to this video? 

Q Dope, AI, and Homebrew Q Dope: Putting Packing Pellets to Good Use

 

Our friend Grayson KJ7UM recently asked about something that brought back old ham radio memories: Q Dope.  No, this not some new scary narcotic.  It is an old liquid that many of us had on our shelves until it dried out.  It turns out that AI knows all about it: 

"Q dope" was a specialty product—essentially a high-quality polystyrene lacquer—widely used by radio builders and amateur radio operators, particularly in the mid-20th century. It served as a protective coating for hand-wound coils and transformers in RF (radio frequency) circuits.

Why it was "Special"

Its primary value lay in the combination of two properties essential for high-performance radio gear:

• Low Dielectric Loss: When you wind an air-core coil for a tuned circuit, you want the "Q factor" (Quality factor) to be as high as possible. The Q factor measures the efficiency of the inductor, representing how well it stores energy versus how much it loses to resistance and dielectric absorption. Standard varnishes or glues could introduce "lossy" materials into the magnetic field of the coil, effectively lowering the Q and broadening the bandwidth of the tuned circuit (which reduces selectivity). Q dope was formulated specifically to have an extremely low dielectric constant and low loss tangent, meaning it wouldn't "dampen" the energy in the circuit.

• Mechanical Stability: Without a binder, hand-wound coils can be microphonic or physically unstable; if the wire moves due to vibration or thermal expansion, the inductance changes, causing the frequency to drift. Q dope acted as a cement that locked the turns of wire in place without adding the electrical losses of common adhesives.

Modern Context

While the term "Q dope" is less common in modern surface-mount or PCB-based electronics, it remains a topic of interest for those working with vintage radio restoration or homebrewing equipment where the specific electrical characteristics of air-wound inductors are required.

Because it is essentially just polystyrene dissolved in a volatile solvent (like toluene or acetone), it was also notorious for being simple to "home-brew." Many hobbyists simply dissolved scrap pieces of clear polystyrene (often from discarded plastic items) into a solvent to create their own batch, which served the exact same purpose as the commercial product.

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

And wow, here is a video on how to homebrew your own Q dope.  Finally those annoying packing pellets are useful for something: 

CuriousMarc Repairs the French Oscilloscope of His Youth -- ACHTUNG!

It was very cool to watch CuriousMarc go back and repair the French Oscilloscope that he used as a kid. 

I was reminded of my work on a Tek 465 scope.  There is a LOT of high voltage around those CRTs.  I needed to measure the HV on my Tek 465 -- Alan Wolke W2AEW lent me a high voltage probe. Thanks again Alan.  I eventually gave up on the Tek 465 but that was because mine had plug-in transistors.  Yuck -- one bump of the elbow during troubleshooting and you could easily inject new problems into the broken machine. 

Marc's work also caused me to think about working on the HAMEG 10 MHz scope that I have in the shack.  Also there is the older Eico scope that was so bad and so limited in bandwidth that it has been banished to the basement.  But I must say, watching Mark move around high voltage made me realize why so many of us have migrated to solid-state scopes.  I have modern Rigol scopes in both my shacks. 

As with Mr. Carlson, I must say that Marc should be more careful with energized gear and capacitors that hold their charge.   Marc seems to think that those insulating gloves protect him from HV, but he still grabs that beast with both hands and makes skin to metal contact with at least one arm.  Yikes!  Don't do that!  Volts jolt but mils kill OM!  One hand behind your back!  Marc does recognize the danger, and displays this sign at least three times during the video.  (Marc is obviously NOT a dummkopf!)     

Google Gemini said this about the sign: 

The language is German (though it is a bit grammatically jumbled and misspelled).

Translated to English, it roughly means: "Is it not for work by blockheads!" or "Is this not for use by fools!"

A Quick Breakdown

The phrase looks like a slightly mangled variation of a classic piece of old internet joke-lore known as "Blinkenlights."

Back in the early days of computing, tech rooms often had mock-warning signs posted in broken, comical German (often called "Mock-German" or "Germlish") to warn non-technical people not to mess with the machines.

If you are looking at a quirky warning sign or an old tech joke, the proper full phrase usually goes something like this:

"Achtung! Alles Lookenspeepers! Das computation-machine ist nicht für gefingerpoken und mittengrabben! Ist easy schnappen der springenwerk, blowenfusen und popencorken mit spitzensparken. Ist nicht für gewerken bei dummköpfen!"

In short: "This is serious equipment—no touching, and it's definitely not meant to be operated by fools!"

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

And be sure to check out the oscilloscope music as seen by Marc's old scope: 

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

"Troubleshooting Analog Circuits" by Bob Pease

 

I used to say that at a hamfest, you should get three things:  1) some parts 2) a tool, and 3)  a book.  I thought I had maxed out on books.  Until Bob KD4EBM sent me this one.  I made room for it. 

Just consider some of the chapter headings and sub-headings:

 

-- The Philosphy of Troubleshooting. 

-- Quashing Spurious Oscillations

-- Oscillations Crop up

-- Roundup of "Floobydust:" Loose ends that don't fit elsewhere

-- Real circuits and real problems

-- Experts have no monopoly on good advice

-- Learn to recognize clues 

-- When computers replace troubleshooters, Look Out

-- Understanding diodes and their problems

-- Identifying and avoiding transistor problems

Sadly Bob died in 2011. But his good advice and wisdom lives on: 

https://www.qsl.net/n9zia/pease/index.html

Get this book:  https://www.amazon.com/Troubleshooting-Analog-Circuits-Design-Engineers/dp/0750694998

CuriousMarc Fixes the HP-182C Power Supply -- But More Fun to Come!

I really like how Marc stops and gives an account of all the parts he has changed,  and that he HONESTLY talks about parts that he mistakenly replaced, or replaced when the original turned out to be good.  Too often wizards write about their troubleshooting experiences and conveniently leave out these inconvenient changes.   But this is a big part of the troubleshooting game, and I am really grateful that Marc describes what really happens, WARTS AND ALL! 

I must say, Marc's replacement parts drawers are looking kind of empty.  He needs spare parts for videos like this.   

Wow, plastic polish!  Who knew?  I want some.   

Marc is a ham.  His callsign is AJ6JV. 

This kind of video is ALMOST enough to get me to work on my old HAMEG 'scope. 

In the next video Marc pledges to take on the 1966 trigger circuits.  

ElectroBOOM! CuriousMarc Tries (and fails) to fix an old HP182C Oscilloscope -- Words of Wisdom for all Homebrewers

"You try your best to improve something that already almost works... and then you ZAP it entirely in the process.  This is the worst feeling ever.  But don't kick yourself.   This is our lot.  We are made to suffer." CuriousMarc

Indeed.  Take heart homebrewers.  Even CuriousMarc (who is a ham!) has been there and done that. 

This particular CuriousMarc episode was, I think, especially good: 

-- It reminded me of WHY I gave up on my beloved Tek 465 and went with Rigol DSO scopes.  I found I was fixing the Tek scope too often.  Plus, my Tek 465 had PLUG-IN TRANSISTORS.  Yikes!  One false move and you would insert 2 or 3 new problems into the already broken 'scope.  The high voltage in there was really scary.  I had to borrow a high voltage probe from Alan W2AEW.  I survived, but we shouldn't have to risk our lives for hobby test gear!

-- I would advise all homebrewers to be more careful around the really high voltages you will find in old 'scopes and TVs.  Remember the lesson of Ross Hull:

https://www.wia.org.au/members/contests/rosshull/documents/Ross%20Hull%20-%20VHF%20Pioneer.pdf

Read the article that starts on page 7:

 https://www.rsp-italy.it/Electronics/Magazines/QST/_contents/QST%201938_11.pdf

-- Marc struggled with a junction FET.  This reminded me of the raging J310 debate on the Discord channel for the SolderSmoke Direct Conversion Receiver. 

-- We see the oscillator signal flat-topping when it turns on the diodes -- again DC RX memories. 

-- Marc had trouble seeing how the oscillator would start.  I too had trouble understanding how an oscillator would get going. 

-- At one point Marc replaced a transistor with a device that grounded the drain.  This will happen if you switch too quickly from say an RD06 to an IRF-510.   With the IRF-510 you need to insulate the tab from the grounded heat sink.    

It will be great to see, in subsequent episodes, how Marc makes it work.  It is really great to see someone present an unvarnished view of how troubleshooting really works.  

Thanks Marc.   73 

Here is Marc's YouTube channel:

https://www.youtube.com/@CuriousMarc

Rob VK5RC's FB SolderSmoke Direct Conversion Receiver. MDS?

Rob VK5RC has completed his SolderSmoke direct conversion receiver.  Congratulations Rob.  And it is good to know what we have a Medical Doctor among our builders -- this adds prestige and expertise to the project. 

Rob measures a Minimum Discernible Signal at -95 dbm.  I think that is kind of weak performance.  Much depends, of course, on how you define "descernible."  Some books say you need a 10 db increase in audio.  Others say you just need to be able to tell there is a signal there.  I have gone with the latter definition and have measured MDS of around -120 dbm.   I wonder why there is such a difference in measured MDS.  

In any case, it is great to see Rob's receiver inhaling all of that great Australian SSB (see video above).  Thanks Rob, and congratulations.  

SolderSmoke Direct Conversion Receiver Challenge -- Bonus Video -- Using an Oscilloscope to Test Your Receiver

 SolderSmoke Challenge – Bonus Episode – Using your oscilloscope to test your DCR

 

New homebrew radio builders often struggle with test and measurement.  You can build a board perfectly but if you don’t have your tools setup correctly you won’t be able to tell if your board is working, or worse you’ll thing it is not working when it is working perfectly.  In this bonus episode Dean, KK4DAS takes us through the basics of configuring and oscilloscope to test the boards, particularly the  PTO oscillator, buffer, and the mixer. 

 

We say this often, but if you really want to learn about oscilloscopes and test and measurement there is no better resource than our friend Alan, W2AEW’s YouTube Channel.  Check it out!

 

 

Alan Wolke, W2AEW’s YouTube Channel:

https://youtube.com/@w2aew?si=TEZcVYWOG8Frce1c

 

Join the discussion - SolderSmoke Discord Server:

https://discord.gg/Fu6B7yGxx2

 

Documentation on Hackaday:

https://hackaday.io/project/190327-high-schoolers-build-a-radio-receiver

 

SolderSmoke YouTube channel:

https://www.youtube.com/@soldersmoke

 

SolderSmoke blog DCR posts:

https://soldersmoke.blogspot.com/search/label/TJ%20DC%20RX

SA2CLC Fixes the Cavity Resonator on his HP8640 -- Not for the Faint of Heart!

 

https://sa2clc.blogspot.com/2025/01/hp8640-died-this-is-me-catching-up-on.html?m=1

Clip Leads Made with FAKE WIRE! Buy Good Ones from PARTS CANDY!

We don't see many videos about clip leads,  but this one fits in well with our esoteric subject matter. 

Carlos of Parts Candy (our sponsor) responds: 

Interesting video. Yes the clips we make are nickel plated steel but the wire is tinned copper. When I was making custom orders I made some custom clip lead sets using 100% copper clips for a few people who really needed the low resistance. In most applications the steel clips should be fine. The resistance for 12” clips is about 12mOhms and the 32” clips are around 24mOhms, iirc.

The bottom lines:  1)  Don't scrimp with a crimp -- get a good solid soldered clip-wire connection from Parts Candy. 2) Parts Candy wires are not fake.  They are tinned copper 3) The metallic composition of Parts Candy clips does not degrade performance. 4) But if a customer really needs copper clips, Carlos can make them too. 

Parts Candy web site:  https://www.partscandy.com/

Using a Photomultiplier THERMATRON to Detect Single Photons

I've been a fan of Jeroen's YouTube channel for a while now.  He has a very nice approach, combining theoretical knowlege with practical experiments and equipment builds.  Here we see him using a photomultiplier tube and a board acquired in flea market to build his photon detector.  

This video has a lot to offer us.  First, there is a single thermatron.  There is a tube socket.  There is a (really small!) high-voltage power supply.  He uses an oscilloscope. There is a laser.  There are photons.  And at one point, a single photon.  

Having recently built a simple Wilson Cloud Chamber, my attraction to this device is easy to explain.  I suspect our friend Grayson will be interested in it for Thermatronic reasons.   There is a Part II.   Check out the YouTube channel: 

https://www.youtube.com/@HuygensOptics  

Here is more info on the channel and it's creator: 

Hi, my name is Jeroen and on the Huygens Optics channel I publish videos on personal projects. My main fields of interest are optics, mechanics and photolithography. The videos aren't targeted towards a general audience but for people with a passion for science and technology (e.g. my fellow nerds). The channel is named after the famous Dutch mathematician, astronomer and inventor Christiaan Huygens (1629-1695). He was the first to publish a mathematical description of the wave properties of light, and also discovered Saturn's rings.

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

Thanks Jeroen

Bill N2CQR Builds Yet Another Mythbuster Transceiver

 This one is for 20 meters (no need for 75) and will go to the Dominican Republic.

6 crystal filter at 5.2 MHz. VFO from old Yaesu FT-101 Termination Insensitive IF amplifiers using boards from Mostly DIY RF No RF amp ahead of the mixer. First mixer is homebrew diode ring. Bandpass filter has 4 LC circuits. Steep skirts. Low insertion loss. Bal Mod/Product detector has two diodes (singly balanced) Carrier osc is crystal controlled and homebrew. Audio amp starts with a 2N3904 amplifier followed by an LM386 board. Transmitter portion will be done next.

The crystal filter as seen on the Antuino

Filter on the blank board. 

Bandpass filter (-20 db = 0)

VFO box, carrier osc, Bal Mod/Product Detector, AF amps

The Antuino looks at the Crystal Filter

Sherwood: "It's Time to Clean Up our Transmitters"

 

http://nc0b.com/qst-article/NC0B-QST-Nov-2019.pdf

As an analog, HDR, discrete component, radical homebrew fundamentalist, obviously I have been concerned about all the hype about SDR.  SDR advocates often make it sound as if those of us who build with discrete analog components (crystal filters!) are hopless troglodytes, about to be thrown on the ash heap of radio history.  Or something like that.  They sort of imply that without the cleansing benefits of SDR, our signals will remain hoplessly dirty. 

I find it interesting that Sherwood concluded that the cleanest transmitter he ever owned was a Collins 32S-3!  He compared the two tone output of this old rig to that of a modern transceiver.  This was in 2019.  See above.  HDR wins. 

Don't get me wrong.  I want to clean up the signals from my HDR rigs.  But I am encouraged by Sherwood's remarks.  I do not think I will have to go SDR in order to have a clean signal.   I may just  do some two-tone tests on the rigs,  make some adjustments, and maybe build a class A Thermatron .1 kW linear.