Grayson Evans' Modest Proposal: NO MORE VALVES! NO MORE TUBES! THERMATRONS FOREVER! (and a great video)

First, a big THANK YOU to Grayson KJ7UM and to Zeynep, his wife and video editor.  The above video is a really excellent look at not only the technical characteristcs of thermatrons, but also at the history of their development.  There is a lot to be learned in this wonderful video. I am glad that no one was shocked in its production. And I am glad that SolderSmoke is no longer the only podcast/videocast using a "shamless commerce" segment! 

Grayson's video and his "modest proposal" are eerily timely for me.  Just yesterday I dragged out my old thermatron 80/40 receiver and got it inhaling.  It uses 6U8s and 6EA8s which were featured in this video.  This morning I used this old thermatron receiver to listen to Tim WA1HLR, who has been using thermatrons for many years. 

I have also been talking about Compactrons -- specifically the 6T9 -- on the podcast.  This prompted Jeff Tucker, W9TH to send me the PC board for the simple 6T9 circuit that I should have built as a teenager.  I also got words of encouragement from Mike WA6ARA.  The pressure is building!  

Finally, this gets us to Grayson's "Modest Proposal."  See:  https://kj7um.wordpress.com/2026/09/16/a-modest-proposal/    He proposes that we STOP calling these devices "tubes" or "valves" and instead refer to them as thermatrons.  I am with him on this.  But I warned him that his proposal (even with modesty) would provoke HOWLS of protest from the many, many change-averse radio amateurs in the US and, especially in the UK.  I know from personal, lived experience (four years in London) that the Brits love their valves.  But, hey, Grayson is right!  So I will pledge -- whenever possible -- to use his preferred term.  Gentleman, don your Kevlar now!  

Thanks Grayson for the video, and for the modest proposal!  

Get the Third Edition of Grayson's excellent book "Hollow State Design"  here: https://www.hollow-statedesigns.com/books

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.

Wow! I Worked Steve KW4H in 1974 -- He was 15 at KP4USN. I was also 15, but in New York, using my Drake 2-B. And I STILL have the QSL card!

 

When I recently started e-mailing Steve KW4H about the Drake 2-B and about the SolderSmoke Direct Conversion receiver (that Steve successfully built), I noticed near the bottom of his QRZ.com page a picture of an old QSL card from KP4USN.  It looked familiar. 

Steve and I had already determined that we were very close in age.  Steve was a Navy dependent, on Puerto Rico at age 15.  I was up in Congers, N.Y., also at age 15.  I was on 15 meter CW.  

When I saw the picture of the QSL card, I checked my log book. You can see a cleaned up version of the log here.   Look towards the end.  You will see KP4USN. 

But as Steve pointed out, there were several operators.  And he was at this point mostly on SSB.  It seemed that the odds were against us.  But I pledged to try to dig up my old KP4USN QSL card. Steve asked me to tell him the name of the operator and he would tell me he knew him.   

At first I thought the QSL card had been lost, perhaps during one of the many moves between then and now. But early this morning I found it.  Slowly I turned it over.  There it was:   "73  Steve."  

Wow, it looked like the signature of a 15 year old.  I quickly e-mailed Steve and sent him the pictures of the card. He immediately confirmed that the handwriting was his!  Wow, 52 years after the contact, we were in contact again. 

I checked my records.  I had acquired my Drake 2-B only 2 days prior to this contact.  (That explains why I was on 15 meters -- my Lafayette HA-600A did very poorly on this band.  But the band sounded great on the Drake 2-B! ).  Later that day (into the night) I worked ZL2ACP.  I woke my parents up to tell them about that one.  The Drake 2-B was clearly worth every penny!  

There is another signature on the card.  Steve KW4H explains: That was Mike Reininga, who was a young guy back then in the Navy and was one of my elmers.  In order for the card to be mailed officially and paid for by the Navy, it was approved for mailing.  I just tried to look him up, and sadly, Mike passed away some years ago at age 58.  He was 21 when I knew him.

https://www.legacy.com/us/obituaries/courierpress/name/michael-reininga-obituary?id=22279830

Here is Steve as a young ham: 

I was first licensed as WP4EAI, and was living in Puerto Rico, as a Navy brat.  In 1975 I upgraded to General Class (boy, that 13 wpm code test was a white-knuckler -- these were the days when you had to take the exam in front of a steely-eyed examiner).  In the photo at the left, you can see some of the old wonderful gear that got me started in this hobby.  A Heathkit DX-60, Hammarlund HQ-180A, and some other stuff I can barely remember.  Some original QSL cards are on the left.  I also operated KP4USN from time to time on the base, and was frequently a control operator for the Maritime Mobile Net, then on 14.313 Mhz.  Stateside, I was licensed as WB4EZM.

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

Here I am at age 15: 

And here is a description of my early radio life: 

https://soldersmoke.blogspot.com/2023/12/the-beginning-of-my-radio-life.html

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.  

Other Workshops: Zen and the Art of Model Making -- Please Comment

This one may seem a bit far off our normal path, but I think this fellow has a lot of philosphy that applies to ham radio homebrewing.   His story of the art teacher who advised his students to get up each morning and do something that you love to do is good advice.  

What other advice and philosophy did you hear in this beautiful video?