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.

Steve KW4H's Notes on the Drake 2-B -- Part 1 - Excision of an Unnecessary Mechanical Filter

Obviously I am interested in the Drake 2-B.   Steve KW4H restores rigs of this vintage (similar to our own vintage!).  He has sent me some notes on his work on the Drake 2-Bs.  

Steve writes: 

Attached is a photo of a completely needless 455 kHz mechanical filter I found in this 2B.  Never seen this before, but I found the info -- this was the Henry DMF-2, which was a modification kit sold for the Drake 2A and 2B.  Yet more snake oil sold to the "I need a mechanical filter like a Collins" crowd.  There was a REASON why Drake didn't filter on 455 kHz -- it wasn't nearly as effective as filtering on 50 kHz, which is exactly what the passband filter does.  That, along with the 2-BQ Q-multiplier/speaker makes for a terrific receiver that rivals even many of the modern rigs of today.

That filter is clearly unnecessary, and Steve was completly right in getting rid of it.  Still, it is a Kokusai.  Pete N6QW gave me one of those.  I think I have it in my Mate for the Mighty Midget receiver.   One other note:  As a kid, Steve was in Puerto Rico and operated from the navy base club station KP4USN.  I have that station, during that period, in my log book (I worked KP4USN on April 12, 1974 on 15 CW).  I have to dig up the QSL card to find out if it was Steve, or one of his friends.  

Inside the NUVISTOR! Making a 555 Timer with Nuvistors!

This video is very cool.  When I saw them crack open a NUVISTOR, I should have known that this was Eric from CuriousMarc.  And it is!  

Here is the YouTube channel: https://www.youtube.com/@TubeTimeUS

And here is my video about the NUVISTORS in my 2 meter receive convertor: 

https://soldersmoke.blogspot.com/2026/07/my-parks-2-meter-nuvistor-converter-qst.html

Thanks Eric! 

Helge LA6NCA Builds a One Tube CW Transceiver -- And Makes a Contact!

Helge has done it again!  He has shown us the benefits of homebrew CW.  And he has done it with one tube.  FB Helge. 

Of course, I really liked the wooden box.  His is a lot nicer looking than mine.  I also liked how he carefully laid out the parts -- I seem to be stuck in my 13 year-old "build then design" mode.  Helge's way of doing it is better: design, build.   In that order! 

Some will quibble about a lack of 700 Hz offset between transmit and recieve.  With a VFO rig, this could lead to the stations chasing each other across the band.  But Helge is crystal controlled here, so I don't see a problem.  Is that right?  Please comment below. 

Thank you Helge for another great rig, a great schematic, and for showing us your obvious joy at reaching 400 km across the sea to your friend in Norway.  FB! 

KW4H -- Steve -- "Knobs > Menus"

 

I really like the "KNOBS are greater than MENUS" sign.  For years we have been saying that menus are for restaurants.  FB Steve.  

Steve's resotation man-cave is very interesting, as are the rigs he has on the shelf or on the bench.  Lots of good work is obviously being done there.  

I also have one of those KP4USA QSL cards. Steve and I got into ham radio at around the same time, so it is possible that he was on the other end of that QSO.  I will check. 

Check out Steve's QRZ page: https://www.qrz.com/db/KW4H

W9TH - Jeff -- Shames Me Into Building a 6T9er -- "You Have No Excuse"

 

First off, that my friends is a ham radio shack.  Note the many books.  And the many Heathkit HW-8s and at least one HW-7. There is a 'scope.  And sig gens.  And a vise!  This is a thing of beauty.  

Jeff sent me a KiCad circuit board for an 6T9 transmitter.  He heard me moaning about it on the SolderSmoke podcast.   As he notes, I no longer have an excuse not to build this things.  The Radio Gods are demanding it.  Who am I to say no? 

Check out Jeff's QRZ page: https://www.qrz.com/db/W9TH

And his website: http://w9th.com/     (QRP before QRP was cool!) 

Thanks Jeff! 

Will N5OLA (the HW-101 Guy) Interviewed by Eric 4Z1UG (Please comment!)

 https://www.qsotoday.com/podcasts/n5ola

This interview was a lot of fun.  I too was smitten at an early age by the HW-101.  I still have one on my operating table.  We are all lucky that Will is working in an innovative way on these old rigs.  Who can forget his shocking water and soap (followed by South Texas sunshine) approach to cleaning these often cruddy old rigs?  Thanks Will and thanks Eric for doing this interview.  

Please post your comments below.   

Helge LA6NCA Builds and Uses a Two Tube 80 meter Transceiver -- From Norway

This entire video is really excellent.  Thank you Helge! 

Once again, he shows us how to do it -- how to homebrew a useful rig, and how to put it on the air from the field.  POTA and SOTA operators take note! 

His receiver is direct conversion!  FB. 

I was delighted to finally see IRF510 FETs used the way they are ALLEGEDLY SUPPOSEDLY designed to be used (in the power supply). 

Helge's creation of 250 volts DC from a 12 volt battery is both ingenious and inspiring. 

His use of Altoids tins was just great and will be appreciated by GQRP. 

I really liked how Helge handled the need for CW T/R frequency shift.  FB. 

His generation of sidetone was also great and very creative.  

I did something similar with my ET-2 transceiver, but Helge had clearly gone beyond this.  

Thank you Helge!  

Someone Else Used the FT-101 VFO Box -- JA9MAT in Japan

Look at that!   The VFO from the venerable (1970s!) Yaesu FT-101 lives on, not only in Northern Virginia, but also in its country of origin, Japan! 

Hidehiko JA9MAT sent me the attached video of one of his homebrew receivers.  He described it this way:   12BE6(DET) + 6AW8A (Franklin VFO) based with L/C VFO Box from old rig.

In the video we see more a more detailed description: 

Hidehikosan explained about the FT-101 VFO box: 

My question:  The VFO looks like it originally came from an
FT-101.  What did you do with that? Did you add a Franklin oscillator
circuit and simply use the capacitor in the FT-101 box?

Hidehiko's answer:  Yes, I made a Franklin circuit in the small candy box and use the
FT-101's VFO as an L/C box.

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

There is a lot of homebrew goodness in this video:  the wood base (Frank Jones would approve).   The Altoid tins (GQRP would love this).  Thermatrons (that one's for Grayson).  And the aforementioned FT-101 VFO box (we are not alone!). 

Thanks again Hidehiko.  More homebrew goodeness from him in the days ahead. 

A Homebrew X-Ray Machine from North Macedonia

It has been a long time since we saw anything like the X-ray machine described in CL Stong's classic book "The Amateur Scientist."  Here are some other SolderSmoke blog posts about this (and related) stuff:  https://soldersmoke.blogspot.com/search?q=X-Ray

This one comes to us from the fertile workshop of Mikel Pavleski in North Macedonia.  We have covered his work before.  

This device is built around an old DY-86 tube from an old black and white TV.  Mikel describes a very simple test to determine if these tubes have leaked, or if they still have good vacuum. 

Mikel uses a really scary high voltage power supply.  

I like the FN-RISI radiation detector.  Want one!  

Note that Mikel used a remote turn-on when using this machine.  I hope there are no people in the apartment next door!  He does use a lead shield, but only on three of the four sides.  

The use of dental X-Ray film was really cool.   The development of this film in Mikel's lab reminded me of my developing of 35 mm film in a dark room I had set up in our downstairs bathroom.  I couldn't afford an enlarger.

Mikel warns that you should not try this at home!  Good advice!  

Thanks to Mikel, and to Hack-A-Day for alerting us to this project.

The Nuvistor, Thermatrons, RCA, Patents, the Rise of Asian Competitors (and my Parks Electronics 2 Meter Converter)

Asianometry always does a great job with this stuff, although I find myself grimacing when he speaks positively about Sarnoff.  Nevertheless the tube history is good (although he fails to mention that De Forest never figured out how his tubes worked).  

I have four Nuvistors!  They are in a 2 meter converter from Parks Electronics of BEAVERTON, OREGON. I may have this wrong, but I think the video said the Nuvistors were very expensive.  This can't be right.  Gemini AI says the 6CW4s in my Parks device sold for $1.50 to $2.50 in 1961. 

Three cheers for the Nuvistor!   I may try to see if they still work.  

The RT-6 and RR-6 Motorola "Spy Set"

I don't know if this rig really qualifies as a "spy set" but it nevertheless is very interesting.   It is a tube rig, designed for use by B-47 bomber crews who could not make it back from the Soviet Union after dropping their nuclear bombs.  Supposedly they would bail out, then use these radios to call for help. Good luck with that!  Note the fold-out CW key. 

This rig was also reportedly hidden in European countries as "stay behind" assets to be used in the event of a Soviet invasion. 

 Here is a web site with more info: https://www.universal-radio.com/catalog/hamhf/rs6.html

Pete N6QW's "Last Ditcher" CW Thermatron Rig -- Frank Jones would approve. A new installment of the FMLA series?

I like this rig.  Perhaps I like it too much.  I find myself plotting to build it myself.  I mean, I have tubes.  I have a bunch of old parts (many sent to me by Pete himself).  

Alas, I have to fight the temptation.  I have to tell myself that this is for CW (a mode that I have come to be impatient with).  And it is a thermatron rig that requires potentially lethal voltages. 

Still, Pete's construction technique is really neat.   It combines old style slat-board construction with modern copper clad boards.  Frank Jones would approve.  

I think we need someone to write another episode of the FMLA series, this one using Pete's build.  And maybe featuring Pete himself. 

Here is some needed background info on Frank Jones and the FMLA articles: 

https://soldersmoke.blogspot.com/2021/07/summer-reading-for-homebrewers-frank.html

I look forward to hearing from protential authors.  If the new articles are good,  I will put them on the SolderSmoke blog.

Helge LA6NCA's Norwegian Paraset

This is a very cool video.  I even liked Helge's creative use of AI for the narration.  It was amazing that this old rig still works.  

Thanks you Helge.  And thank you to all the brave members of XU, who so valiantly risked it all in the fight against Fascism. See: https://en.wikipedia.org/wiki/XU 

A Quick Review of "Open Circuits" by Eric Schlaepfer and Windell H. Oskay

Wednesday's post about this book caused me to pull it off my shelf and to take another look.

Highlights from the SolderSmoke perspective: 

Page 34  Glass Capacitors.  Phil W1PJE left me some. 

Page 48  Ferrite Beads.  Underrated.  People often don't think they will work. 

Page 66 Glass-Encapsulated Diodes.  Yes, 1N4148's in our Direct Conversion Receiver. 

Page 70 2N2222.  In a metal can. 

Page 72 2N3904.  We use them so often. 

Page 90 Color LEDs.   The Green Hornet beacon in Cap Cana, Dominican Republic. 

Page 116  Electromagnetic Relay.   We use them a lot. 

Page 142 DIP sockets  I recently struggled with them with my NE602 chips. 

Page 182  12AX7.    Thermatron! 

Page 186 Cathode Ray Tube.   I have some. CuriousMarc recently fixed one. 

Page 190 Mercury Tilt Switch. I had one as a kid.  You can change a reflector to a director.  

Page 196  Dipped Silver Mica Capacitor.    We use them.  A lot.  Sometimes as NP0 caps. 

Page 198  IF transformer.  S-38E.  HQ-100.

Page 206 - 207 Point Contact Diode and Germanium Diodes.  Crystal radios. Great fun. 

Page 210 Windowed EPROM. Was this the Rom chip in the TW-100s? 

Page 212 Core Memory.  Rope!   As used in the Apollo spacecraft. 

Page 228 Single-Side Printed Circuit Boards.  Almost (but not quite) Manhattan. 

Page 238 MicroSD Card.  I have one in my Drone. 

Page 262 Crystal Oscillator.     TCXO?  In a can?  As in Dean's WSPR transmitter? 

What do you guys think? 

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

Radio Receivers -- 1942 Training Film -- Crystal Sets to Superhets

This 17 minute film provides a good but simplified description of the state of the art at the start of World War II. 

--  The description of how a signal gets to the input coil of a receiver is quite good.  Imagine if that coil had no good ground, and no counterpoise.  We see the importance of the counterpoise in this video: https://soldersmoke.blogspot.com/2023/03/an-antenna-for-high-school-direct.html

-- I like the repeated demonstration of the reality of envelope detection.  Too often people have bought into the idea that envelope detection is not real, and that some form of mixing using the carrier in lieu of the local oscillator is what is really happening.  That is just not true.  Envelope detection as described in this film is real. 

-- The description of mixing is very simplistic.  They describe the generation of the difference product, but not the sum.  But hey, the film is only 17 minutes long!  It takes a lot longer than that to fully describe mixing (ask me how I know!).  

-- At the very end, there is a shout-out to the BC-348.  FB. 

Homebrew Cylindrical Variable Capacitors: What the Steering Wheels are Controlling in Danny's Regen Receiver

Grayson KJ7UM asked a very good question about Danny ON1MWS's regen receiver:  What were those two very cool "steering wheels" actually controlling?.  

Perhaps because of our recent experience with Permeability Tuned Oscillators, I kind of assumed that we were talking about some form of variable inductor.  But no, I was wrong.  They are for homebrew variable capacitors.  That just makes it a lot cooler.  

Danny explains: 

Dear Grayson,

Tnx for the compliments. I used to build normal square boxes while I was a mechanic in a light advertisement factory. We had a one hour lunch break and were allowed to work for ourselves during the break. But I left that firm in 2019, as a consequence I had to find a way to build rigs without custom square boxes… the result is wood, tin cans of all sorts and a simple ground plate. After posting my CW rig on the FB group ‘the art HAM radio homebrew’ in 2023, Steve Fabricant noted ‘It could be a radiosonde that they sent down from a saucer to detect intelligent life, and failed.’ LOL, I found that very funny actually. 

 

As for your question, all of my homebrew tuning capacitors have a shaft made off a M8 (about 8mm) threatened rod. The rod turns through a steel girder bracket. I am not sure how these things are called in English, but they are easy to find on the net and very cheap. The rod is the ‘ground’ of the capacitor. The ground plate is clearly visible in the pictures of the solid state regen and the ground plate is hidden under the wood in the tube regen. In the case of the tube regen, the left tube has an inner diameter of 10mm and the right one about 13mm. The right one is coarse and the left one fine tuning. Not sure about the capacitance. 30pF at most I think. The tube regen tunes from 7 to 7.25 Mhz so that's ok.

As you turn the rod the rod will shift in or out the metal tube. The tube is obviously the ‘hot’ side of the capacitor. The M8 rod moves 1.25mm for one turn of the rod. If memory serves me right the tube is 80mm for the tube regen, so we have a tuning gear reduction of 80/1.25= 64. The hot side is connected to the main tuning coil to create a tank circuit.

I did try different designs before but this is the best one. The tube/treaded rod capacitor is just as good as a commercial one. One thing I learned is that any friction must be avoided in a homebrew capacitor or it is useless in practice.

I am going to try to build a similar 400pF version for a homebrew crystal set as I wrote to Bill. It will be huge I guess.. I think I will need a 2”tube… But my current homebrew projects are insulating our house better as our natural gas prices are rising.

Like the way you call tubes Thermatrons. Yes, sound much cooler and more fitting for these beautiful devices. My ultimate aim is building a one band thermatron SSB exiter. No time for the moment.

Kind regards Danny.

This technique could prove very useful in homebrew projects.  We found it very difficult to source suitable variable capacitors for our direct conversion receiver.  That is why we went with the PTO circuit.  But this technique makes it possible to actually homebrew the capacitors.  FB Danny.  

Thanks Danny.  Thanks Grayson.

ANOTHER AMAZING Homebrew Station -- This one from Belgium -- ON1MWS

 

Those large "steering wheels" on the regen rig caught my attention, and I'm glad they did, because they led me to the sites of Danny ON1MWS. 

https://www.qsl.net/on1mws/

https://www.qrz.com/db/ON1MWS

Danny writes on his QRZ page: 

I'm especially interested in homebrewing my own station. everything from the power supply to the antenna is scratch-build. I have no commercial ham gear, nor do I use pre-fabricated kits or DDS chips.

My gear is a toy compared to a modern station. And it will never even come remotely close to commercial gear. However, the journey to learn how radio circuits work, improve the station and add capabilities over the years has been satisfying. R&D as amusement.

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

FB Danny!  Thanks for the rigs and web sites.  73  Bill N2CQR

The Coastwatchers -- Their Rigs and Their Islands

 

AWA Teleradio 3BZ used by coastwatchers during the war Source: Australian War Memorial (P01035 .006)

Here is a great site about the AWA 3BZ Wireless set: 

https://www.qsl.net/vk2dym/radio/3BZa.htm . 

AWA 3B SET

Here's a good article about the Coastwatchers: 

https://www.military.com/daily-news/investigations-and-features/2025/12/22/former-school-teacher-led-guerrilla-army-behind-japanese-lines-solomon-islands-and-helped-us-win.html

Guadalcanal 1943

I've been interested in the Solomon islands lately because my wife and I have been watching a YouTube video channel about a family living on Uepi island: 

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

Uepi is right on "the slot," near New Georgia. 

There are WWII remnants still visible (underwater) at Uepi: 

AI Overview

Uepi Island in the Solomon Islands is famous today for its World War II history, particularly its abundant, accessible WWII wreck dives (aircraft & ships) in Marovo Lagoon, a key battleground during the Solomon Islands Campaign, offering divers a tangible connection to the fierce fighting between US and Japanese forces. The area, near major WWII sites like Guadalcanal, features underwater artifacts like Japanese Zeroes and US Corsairs, with the modern Uepi Island Resort preserving these historical relics within its dive operations. 

Uepi's WWII Significance

• Location: Uepi is situated in the Marovo Lagoon, part of the Solomon Islands, which were central to the brutal Pacific Campaign of WWII.
• Wreck Dives: The waters surrounding Uepi are a "treasure trove" of sunken WWII aircraft (like P39 Air Cobra, Japanese Zeroes) and shipwrecks, making it a prime destination for historical diving.
• Preservation: The Uepi Island Resort actively manages and promotes responsible diving at these sites, emphasizing that removing artifacts is illegal. 

Key WWII Sites & Wrecks Near Uepi

• Wickham Harbour: Located near Uepi, this area contains significant WWII wrecks, accessible via boat trips from the island.
• Aircraft: Divers can find Japanese Zeroes, American Corsair fighters, and potentially B24 bombers, often in challenging conditions, with efforts to move some to cleaner areas.
• Marovo Lagoon: As one of the world's largest saltwater lagoons, it holds numerous historical remnants from the intense fighting.