Listening to 40 meters on the DC Receiver -- And I Heard a Distinguished Homebrewer!

I made the video above to show postential builders how useful our Direct Conversion receiver really is.  Late in the video (starting at 11:17), I heard a station calling CQ.  It was N4QR.  A check of QRZ.com shows it was Bob Null.  Here is picture from Bob's QRZ page: 

Check out the old general coverage receiver and -- wait for it -- the homebrew thermatron transmitter.  TRGHS. 

Google led me to this amazing video by Stever N4LQ that describes a book that N4QR put together on how to build thermatron transmitters from Junkbox/Hamfest parts: 

Steve N4LQ is in contact with Bob N4QR and asked him which transmitter he was using when I heard him.  Bob said he thinks it was his 30 watt 807 final transmitter. 

Thanks Bob. and thanks Steve!

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

Excellent New Video from Grayson KJ7UM on his Thermatron version of the Michigan Mighty Mite

Here is a really wonderful video from Grayson Evans, KJ7UM, author of Hollow-State Design for the Radio Amateur.  

I really loved this video.  Throughout we see Grayson's sense of humor.  Early on he explains the differences between a tube (what remains from a roll of paper towell), a valve (like the plumbers use) and a THERMATRON (like a 6146).  Grayson is the inventor of the word Thermatron.  We should all pledge to use it whenever possible. 

Grayson's humor also shows up when describing the parts acquistion process for the Thermatron Michigan Mighty Mite.  He puls out a coil (a huge coil) and laments that it is not -- despite its large size -- sufficiently inductive. 

There are wonderful shout outs to SolderSmoke, to Electric Radio, to the Color Burst Liberation Army, to Pete Juliano,  and to Rex Harper.  

Grayson describes the utility of Rex Harper's Thermatron ME pads.  

During the video, Grayson actually builds the Thermatron MMM.  In under 2 minutes!  He then experiences the Joy Of Oscillation, or JOO as it has come to be known.  OM needs a contact -- listen for him on 3579.  He is calling CQ.  

Grayson talks about his book, Hollow-State Design.  I have a copy with me here at SolderSmoke Shack South in the Dominican Republic.  Great stuff.   The above link takes you to Lulu, where you can order the book.  You can also get it from Electric Radio Magazine here: https://www.ermag.com/product-category/books/

Thank you Grayson for bringing us this video, and so much more over the years.  And for giving us the very useful and fun word:  THERMATRON!  

Grayson Evans KJ7UM Video on Homebrewing with Thermatrons

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

https://www.lulu.com/shop/grayson-evans/hollow-state-design-3nd-edition/paperback/product-5mpzqr.html?page=1&pageSize=4

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

Nate KA1MUQ's Amazing Thermatron Receiver

https://natesbasement123.blogspot.com/2024/02/thank-you-bill-dean-grayson-pete-and.html

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

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

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

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

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

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

Thanks Nate!  

SolderSmoke Podcast #249 -- Travel, Pete's 6BA6 rig, Books!, VFOs, SDR, Computers, Spectrum Analysers, Transistor Man! MAILBAG

New VFO for 15-10 Transceiver

Schematic below

SolderSmoke Podcast #249 is available:  http://soldersmoke.com/soldersmoke249.mp3

There is also a video version of this podcast: https://youtu.be/5xyaYivtOhw

Travelogue:  

HAPPY VETERANS' DAY TO PETE AND GRAYSON AND TO ALL THE OTHER VETERANS WHO ARE LISTENING. 

Trip out to San Francisco. Sticker placed on the corner of Haight and Ashbury:  See picture below.  Note other sticker.  Really Groovy! 

Cuban Cacharreo! Andy CO2AFV's Knack Story  https://soldersmoke.blogspot.com/2023/10/a-cuban-knack-story-and-pandemic-sits.html

Bill's DXCC-100.  DONE.   

Tribal Wisdom:  W1REX on HRWB https://soldersmoke.blogspot.com/2023/11/listen-to-rex-w1rex-lots-of-tribal.html

Pete's Bench:

Pete's 6BA6 rig

Pete's 6BA6 Rig

Pete Re-invents the Shirt-pocket SSB Rig

Pete's remake of the ShirtSleeve Transceiver

Pete Builds Two Computers 

Pete Adds a Second Band to his Homebrew SDR 

 

SHAMELESS COMMERCE DIVISION:  

BEZOS BUCKS ARE BACK!  PLEASE  BUY THERE! >>>>>>>>>>>>>>>>>>>>>>>

Mostly DIY RF:  Work proceeds in the Oregon Silicon Forest on P3ST kit development. Todd is confident the P3ST will be released on December 18th.Many other kits available now:  https://mostlydiyrf.com/ 

Sign up for the newsletter:  https://mostlydiyrf.com/subscribe/ 

Bill's Bench: 

Rebuild of the 15-10 VFO (for improved Dial Spread) (with yet another QF-1 capacitor) https://soldersmoke.blogspot.com/2023/10/dial-scale-linearity-spreading-out.html

Why Building for 10 meters is harder: https://soldersmoke.blogspot.com/2023/09/why-building-for-10-meters-is-harder.html

Copper Tape shielding of 15-10 rig. 

Crushing Spurs with Better Bandpass Filters (see blog post) https://soldersmoke.blogspot.com/2023/09/crushing-17-and-12-meter-spurs-with.html

Another 15-10 rig in the works... for SSSS.   Boards are accumulating... 

More problems discovered with the Herring Aid 5 Receiver . Lots of SS blog posts  Comment from Rick WD5L.  ) https://soldersmoke.blogspot.com/2023/10/a-big-error-discovered-in-1976-qst.html   Did you try to build one?  Did you succeed or did you fail?  Please let us know. 

The Basil Mahon books (blog posts) https://soldersmoke.blogspot.com/2023/11/basil-mahon-is-author-for-us-he.html

The Sunburst and Luminary book of Don Eyles (blog posts) 

The Art of Electronics by Horowitz and Hill (blog posts) 

Spectrum Analysers:  Tiny SA Ultra https://soldersmoke.blogspot.com/2023/09/the-tinysa-ultra-spectrum-analyser-video.html  and Polarad 632C-1; George WB5OYP gave me one of these spectrum analysers  (I NEED a manual! Does anyone have a manual or a schematic? )  : 

Polarad 632C-1

Stabilizing the EB63A (with Pete recommended LP filters from e-Bay. 

MAILBAG:

TRANSISTOR MAN T-SHIRTS!  Thanks to Roy WN3F! 

Todd VE7BPO on AF amplifiers.  Thanks Todd.  

Wes W7ZOI -- Always a privilege to exchange e-mail with Wes. 

E-mail from Jay Rusgrove W1VD. About the Herring Aid 5. 

E-mail from Eamon Skelton EI9GQ!  Amazing! 

HB2HB with Denny VU2DGR https://soldersmoke.blogspot.com/2023/09/hb2hb-contact-with-denny-vu2dgr.html

Nick M0NTV on diode matching for ring mixers: https://soldersmoke.blogspot.com/2023/10/does-matching-matter-diode-matching-for.html

Paul Taylor VK3HN on the new Elecraft CW rig. 

Dean KK4DAS fixed the noise in his Hallicrafters SW receiver.  A long battle, finally won. 

Dean also in contact with G3UUR. 

Ramakrishnan VU2JXN helping me set up a backup of blog on WordPress.  

Mark KA9OOI noticed that SS podcast archive appears gone.  In fact just temporarily relocated to http://soldersmoke.com/podcastarchive.html

(SS PODCAST Archive temporarily relocated to http://soldersmoke.com/podcastarchive.html) 

Andreas DL1AJG - Crystal radio video. https://soldersmoke.blogspot.com/2023/10/building-crystal-set-videos.html

George N2APB on the Herring Aid 5

Grayson KJ7UM experimenting with Varactors and Thermatrons! 

Thomas K4SWL on Mattia's DC receiver. https://soldersmoke.blogspot.com/2023/10/mattia-zamanas-amazing-direct.html

Bob Weaver of Dial Bandspread Linearity  fame.  Electron Bunker

Mike Bryce WB8VGE QRP Hall of famer -- he too couldn't get the Herring Aid 5 working. 

Kirk NT0Z wrote about the Wayback machine.  But this former ARRL staffer he also tried and failed to get the Herring Aid 5 going.  Way back when... https://soldersmoke.blogspot.com/2015/03/kirks-herring-aid-tuna-tin-and-regen.html

New 15-10 VFO with schematic

Dial Bandspread (Before)

At corner of Haight and Ashbury

Can you ID this Receiver? Grayson Finds a Homebrew Receiver in Germany. From the GDR. Circuit? Schematic? Thermatrons?

 

Grayson Evans KJ7UM (the author of  Hollow State Design) was recently in Germany where he spotted this museum display of a homebrew receiver built in the GDR (the old East Germany) around 1983 by a 13 year-old.   Very cool. 

Here is today's task for SolderSmoke:  Can you provide any more info on this receiver? The card indicates 0-V-1 which would be a regen with no RF amplifier, right?  Maybe something like this: 

https://www.qsl.net/pa2ohh/15tuberx.htm

 Look carefully at the pictures and try to gather any additional information on the receiver or its builder.  

Thanks Grayson! 

Building a Solid-State "Magic Eye" and Fitting it in the Old Tube's Glass Envelope

I was feeling kind of bad about my solid-state conversion thoughts.  I had gone so far as thinking about putting an FET and some resistors in an old tube's glass envelope.  There was something about this that felt well, kind of immoral. 

But then this morning Facebook sent me the video above.  This fellow built the solid state equivalent of an old Magic Eye thermatron!  And he put it inside the glass envelope of the old tube.  FANTASTIC!  

I feel better already. There are others with similar thoughts, and some who have put these thoughts into action!  Maybe now the Thermatron Protection Society will call off the protests outside my house, and I can stop wearing the Kevlar vest. I know, haters gonna hate, but after seeing this video I realize that I am FAR from being the most egregious of thermatron defilers. 

TRIGGER WARNING: Solid-Stating Old Tube (Thermatron) Gear (Including -- GASP -- R-390As)

Look at that.  Well, maybe some of you shouldn't. (I'm thinking of you Grayson.)  I found the Charles Smith YouTube channel while innocently looking for ideas on how to solid-state the HT-37 VFO assembly I recently bought on e-bay.  Charles Smith has some really great ideas in this area.  He solid-stated a Heath VF-1.  But he took it all to an extreme when he solid stated an R-390A.   Take a look at how he built the replacements for the thermatrons:  He used those plastic wall sockets that you screw into sheet-rock when you need to hang a picture.  This is real genius. He used the tube filament lines to carry DC to these new sockets. 

R390A Solid State Conversion Video #1:  https://www.youtube.com/watch?v=xhWzX874wYo

Charles Smith's YouTube Channel 

https://www.youtube.com/channel/UCpfh8gxL64qd22RaNPR-QFw/videos

He has videos on the HQ-170 (DEAN:  Just say NO!) and the SP-600.  He also covers the HQ-110, which is uncomfortably close to my HQ-100.  

Who is Charles Smith?   What is his callsign?    Charles Smith is KV4JT.  Here is his QRZ page: 

https://www.qrz.com/db/KV4JT

He has some great humor and wisdom in his videos: Procedures that are difficult or more trouble than they are worth are called "bugger-bears."  He advises that if your IF cans are stuck, you should "find a way to unstick them!"  Indeed you should!  He builds a cool jig to hold the IF section of the R-390A while you are working on it.  He provides similar protection (with two long screws) to the VF-1.  

Even though some of you will have to go to therapy after seeing all this, I say THREE CHEERS FOR CHARLES SMITH! 

Pete N6QW's Hybrid Wireless Set -- A Thing of Beauty, with Thermatrons

Pete Juliano is amazing.  He is admirably carrying a very heavy load of family responsibilities.  But  he still can build some really unique and innovative rigs.  He tells us that getting up at 3 am and only sleeping 5 hours per night allows him to do this.

Pete also blames Grayson Evans KJ7UM for this rig, what with the thrematrons and all.  Pete has a 7360 mixer in this rig, something that Grayson had in the 3rd edition of his Hollow-State Design book (get yours here:  https://www.ermag.com/product/hollow-state-design-2nd-edition/).  Pete reports that he first built the chassis for the tube (I mean thermatron) portion of the rig in the 1970s -- it has been in his junkbox ever since.  Grayson admires Pete's compact construction and point-to-point wiring.  

I too noticed very poor conditions on Field Day this year.  

Three cheers for Pete Juliano!  

SolderSmoke FDIM Interviews: A BRAVE HAM! Grayson Evans KJ7UM Presents a 50 Watt Amplifier to THE QRP GROUP!

Wow, talk about walking into the lions' den!  Grayson Evans, author of "Hollow State Design" and guru of all things thermatronic, went to FDIM and made a presentation TO THE QRP GROUP on how to build a 50 watt amplifier with a 6146 thermatron.  In New York that would have been called chutzpah.  The QRP ARCI guys seem to have tolerated this QRO-heresy; I'm not so sure the zealots over in G-QRP would have been quite so tolerant.

Grayson gave a nice shout out to SolderSmoke's Pete Juliano.  

And he offered some sage advice to those who live in fear of high voltage:  "Don't touch anything with high voltage on it."  Words to live by my friends.  He even managed to call those who shy away from high voltage "wimps."    This was all very reminiscent of the unforgettable safety advice he offered in his August 2021 interview on Ham Radio Workbench: "Try not to swallow anything, and don't sit on the thermatrons." I mean, who can argue with that? 

You can listen to Bob Crane's interview with Grayson here (about 6 minutes total): 

http://soldersmoke.com/2022 KJ7UM.mp3

Check out Grayson's  Hollow-State Design Book 3rd Edition: tinyurl.com/hollowstatedesign3

Check out Grayson's technical blog:kj7um.wordpress.com

Thanks Bob and thanks Grayson. 

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  

KG7TR's Magnificent 75S-2B Receiver -- Tubes, an Si5351, an Arduino, a Bit of Collins, and a Bit of a Drake 2-B

 

Oh man, I share this with much trepidation because the last time I posted something about the work of Mike KG7TR,  Pete N6QW said he felt like putting all of his own work in the dumpster, so much better was the artistry of KG7TR.  This receiver is so cool and so well-done that we now  might have to post a guard outside the N6QW shack -- heck Mike even has an Arduino Uno and an Si5351 in there!  Don't do it Pete!

I was led to this magnificent receiver by the very humble 6U8 tube.  Scott  WA9WFA and I have been learning (mostly from Grayson KJ7UM) that the much used and sometimes loved 6U8s (three of them in our "Mates for the Mighty Midget")  might be a bit long in the tooth, old even by Thermatron standards.  I was worried when I remembered that my Drake 2-B has a 6U8 in it -- V2, the first mixer.   So I Googled for more info and was led to this amazing receiver, a 2018 creation by KG7TR.  How did we NOT see this for almost four years?

Here is more info and pictures: 

http://www.kg7tr.com/75s-2b-receiver.html

Here is Mike's write-up of the project: 

http://nebula.wsimg.com/c2281e9bdf3b54da42ca4b0b541b4ec9?AccessKeyId=D18ED10DA019A4588B7B&disposition=0&alloworigin=1

Mike KG7TR's web site:

http://www.kg7tr.com/ 

As for the 6U8s, well Grayson says the tube has been getting something of a bum rap.  And  KG7TR has two of them in this receiver, so I will obviously have to give the 6U8 another chance.  

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

I didn't know that Lew McCoy had his own crystal and crystal filter company: 

http://www.kg7tr.com/the-real-mccoy.html

SolderSmoke Podcast #232 -- Mythbuster, Pete's Tube CW Rig, Pete's DC RX and Simple SSB Rig, NanoVNA and TinySA, Very FB Mailbag

SolderSmoke Podcast #232 is available -- Crank it in Robert!

http://soldersmoke.com/soldersmoke232.mp3

Featuring a guitar intro by Pete "Bluesman" Juliano,  playing his own composition: "Juliano Blues." 

Upcoming GQRP convention and the N6QW rig
Frank Jones and the FMLA -- Possible Victory?
IBEW Stickers:  NASA, Johns Hopkins APL....
Cycle 25 Lookin Better Today:  SFI 93   SN 47
 
Pete's Bench:
Toobular!  A Tube Transmitter
SR-160
Simple SSB rigs around the world! 
KI7NSS's Pacific 40
 
Bill's Bench
The Mythbuster and the Struggle Against the Urban Legend
W2EWL's Cheap and Easy SSB
W4IMP's IMP. Articles in ER by Jim Musgrove K5BZH and Jim Hanlon W8KGI
The Spirit of Homebrew SSB. From Electric Radio K5BZH December 1991
Reduced Front End Gain on the DIGITIA
Back on 17!  HP3SS sells HBR receiver to Joe Walsh
Maybe another Moxon?
 
SHAMELESS COMMERCE DIVISION
 
Test Gear
NanoVNA -- Alan W2AEW helped solve mystery of why NanoVNA not providing accurate readout of circuit impedance.  Over driving.  Need attenuator. 
TinySA -- Limited Resolution Bandwidth.  But you can listen with it!  See video on blog.
 
MAILBAG
-- Google Feedburner to end e-mails from the blog :-(
-- Paul VK3HN -- TIA AGC? Farhan and Paul looking into options 
-- Ciprian's Romanian Mighty Mite
-- Dino KL0S SolderSmoke GIF and graphical presentation on sideband inversion
-- Allison KB1GMX helped me on 24 volts to IRF 510 issue.
-- Dave K8WPE Wabi Sabi and Martha Stewart. And thanks for parts!  40673s!
-- Steve N8NM building a 17 meter rig with 22.1184 crystals in a SuperVXO and a 4 MHz filter.  
-- Dean KK4DAS restoring an old Zenith.  One hand behind your back OM. 
-- Pete Eaton debating SSB or DSB for 17.  Go DSB Pete!
-- Richard KN7FSZ a FB HBer.  Asked about my solid-stating of Galaxy V VFO.  
-- Walter KA4KXX on benefits of no-tune BP filters like Farhan's   FB. 
-- Jack 5B4APL on Time Crystals and Homebrewing in the 4th dimension.  FB OM!  
-- Moses K8TIY listens to the podcast with his young son Robert.  Crank it in Robert! 
-- Farhan and the SBitx on Hack-A-Day
-- Also Tom's receiver from junked satellite rig on Hack-A-Day
-- Todd K7TFC sent in beautiful message about the spirit of homebrewing. On the blog.
-- Grayson KJ7UM was on Ham Radio Workbench with George Zaf
-- AAron K5ATG running a uBitx with a  homebrew tuner and antenna.  Hope I can work him 
-- Heard Mike WA3O last night on 40 DIGITIA.  Water cooled amplifier

Grayson Evans KJ7UM on the Ham Radio Workbench Podcast

 

OM Grayson was on the HRWB podcast with George Zaf and company. This was a really informative and entertaining session.  For example, when asked if special precautions are needed when working with thermatrons, Grayson replies, "Well, try not to swallow anything... and don't sit on the thermatrons."  Words to live by my friends.  Grayson's story about cooking Tektronix scopes in a refrigerator re-purposed as an oven (after cleaning the 'scope with a Home Depot power washer) is the kind of practical advice that readers of this blog REALLY NEED!  

But seriously, I learned a lot just listening to Grayson talk about thermatrons with George and the HRWB crew.  

The interview includes nice shout-outs to SolderSmoke, SPRAT/G-QRP, and Electric Radio magazine. 

Check it out:  https://www.hamradioworkbench.com/podcast/hollow-state-design

Stay to the end for some thermatron-related password management advice from George. 

Thanks to Grayson and to all the folks at HRWB. 

Aladdin's Lamp == The Vacuum Tube (aka The Thermatron) (Video)

After our posting of the video about 1957 transistor production, our friend Peter O'Connell VK2EMU asked for some equal time for vacuum tubes.  He sent me this 1940 Western Electric video.  It is quite interesting. 

-- I like the Aladdin's lamp metaphor.  When I was out in the Azores I thought of my homebrew 17 meter DSB rig as my "magic carpet." 

-- Lowell Thomas was brought in to narrate.  His voice sounds a lot more natural than that used to narrate the transistor film. 

-- To explain the effectiveness of transcontinental telephony with vacuum tube repeaters, they compared the system that of a relay of "hog callers" claiming that it would take 100,000 hog callers to carry a signal from New York to San Francisco.  So perhaps this could be a rival to db?   100,000 hc? 

-- Arlington to Paris 1915 caught my eye -- Arlington Va. is right down the road. 

-- The film of Edison in his lab was good to see.  And note the importance of his lab notebooks. 

-- The explanation of thermionic emission was quite good.  But of course too much credit was given to Lee DeForest. 

-- The breathless description of the amazing uses of tube technology was for me a reminder of how recent this technology is.  My father started as New York City cop in the 1950s.  He always referred to his police car as a "radio car." 

Hey, are any radio amateurs out there using one of those big water-cooled tubes?  If not, why not? 

Grayson Evans KJ7UM's New Blog -- Lots of Great Technical Info

 

Our friend Grayson Evans KJ7UM, author of "Hollow State Design" has launched a new blog.  It is filled with great technical info.  The blog has links to the articles Grayson wrote for Electric Radio magazine.  

Check it out:  https://kj7um.wordpress.com/ 

Builds Oscilloscope at age 12! Nick has THE KNACK

Thanks to Grayson Evans for sending us this very encouraging video.  
It is from Tektronix;  I wonder if Alan W2AEW provided some ideas and inspiration? 

More stories like this:  https://www.tek.com/stories  

Radio Art -- Zenith Tube Ad

This ad was recently shown on the K9YA Telegraph.  I was wondering about its origins.  I asked noted thermatron guru Grayson Evans -- he referred the question to fellow tube guru and author Ludwell Sibley.  OM Ludwell gives us the origins: 

She’s in a promo for Zenith, an Italian prewar brand that sold European triodes of types originated by Philips, and a few equivalents of American types.  She’s based on classical Italian art.  Doing a high-wire act while holding a small early-‘20s European           radio! I have an 11 x 17 glossy color print framed on the wail in the display room.  I ran       her as the cover art in a long-ago issue of “Tube Collector.”  “Three cheers for the red,       white, and green!"

Ludwell Sibley is the editor of "The Tube Collector."   Great stuff.  Their web site is here: 

http://www.tubecollectors.org/tubecoll.htm

Sibley's book "Tube Lore" can be purchased here: 

https://www.amazon.com/Tube-lore-reference-users-collectors/dp/0965468305/ref=sr_1_1?keywords=Tube+Lore&qid=1569660647&sr=8-1

Thanks Grayson, Ludwell, and to the K9YA Telegraph. 

Manhattan-style Vacuum Tubes: "An Evolution of Thermatron Homebrew Techniques" by Grayson Evans

Grayson Evans was at Dayton.  Scheduling problems prevented him from being interviewed by ace correspondent Bob Crane, but Grayson was kind enough to e-mail us the essence of his presentation.  And it is really wonderful.  He brings the advantages of the Manhattan construction technique (fast prototyping, all components on the same side of the board, easy modification) to the world of tubes (aka valves or, as Grayson prefers, thermatrons).  We also see in Grayson's work an admirable willingness to bridge the digital-analog design, to bring into his rigs the best of the old and the new.  Thanks Grayson!

Grayson writes:

An Evolution of Thermatron Homebrew Techniques

For a long time I have been trying to develop some techniques to prototype Thermatron projects as easily as the typical “Manhattan style” solid-state construction.  Thermatron projects you see now-a-days still use the traditional technique of mangling aluminum-drilling and mounting everything to a “bud” style chassis. This just takes too much time and my projects always look disappointing.

Fortunately, around two years ago, Rex Harper, W1REX, came to the rescue after hearing an earlier talk of mine and developed a set of thermatron socket pads. The MeTubes panel from QRPme consists of 10 prototype pads for thermatron sockets. The panel has v-scores for breaking the panel into single tube pads. The panel has pads for mini 7 & 9s, octal, compactrons and acorns. Awesome.

The best sockets to use with the pads are PCB style.  These provide a large pin area to bend out and solder to the pad (see photos). 

I pre-mount a dozen or so of the 7-pin and 9-pin sockets on MeTube pads so I have them ready to go when prototyping. The “crude” example below shows and 7 and 9-pin socket on one of my prototypes.  I think this was a microphone amp for my AM transmitter.  Pardon the mess.

The nice thing about the pads is that they provide plenty of room to tac solder lots of parts to a single pin–easy to add or remove parts.  This is a lot easier than using the traditional tube socket pin. 

Prototyping thermatrons in this way is FAST.  No more punching out holes to hold thermatron sockets in aluminum chassis!

But it is still nice to be able to have the thermatron on the “top” of the board and the components on the “bottom” of the board.  To do this and still use the MeTube pads, the thermatron has to be mounted on the other side.  I did this by mounting the socket through the MeTube pad.  This requires making a hole in the center of the pad to pass the socket through and then soldering the pins in the usual way.  This is way easier with PC mount thermatron sockets and make a very nice installation. 

This technique has some great advantages over using the traditional socket with pins.  The pad has a lot more room to mount components to each pin.  Normal thermatron socket pins are difficult to attach more than two wires and it’s a bit more difficult to get a good solder connection.  The pads are easy to solder to and allow components to be easily attached in any direction since the “socket” is now flat.

It is also easy to attach the socket/pad to a copper clad board.  The same hole must be made in the copper clad board to pass the top of the socket through, then the pad is superglued to the board in the regular way.  



This is another example of “right side up” thermatron mounting on a prototype test board for crystal filters.  I mounted a small “plug board” (not sure what you call these things) in the center to allow me to easily swap filter components.  Notice the acorn thermatron soldered direct to the pad.  The board works great, the filter design sucked.  I gave up.  Maybe too much distributed C.

I used this technique, combined with Roger Fell’s idea of using inverted aluminum chassis, to build my latest project, a QRP AM/CW transmitter.  I’ve been wanting to try out a few new ideas and this seemed like a good project to try them on.  I also wanted to build the transmitter in modular “blocks”, interconnected in a similar way to Rogers. It worked pretty good although I am still trying to get the thing to work right.  Even new construction techniques can’t cure my screwups.  BTW, the ANALOG VFO is ROCK SOLID.  +/- 10 Hz over 30 min.   Even I was impressed.  The Hartley oscillator is the best circuit for thermatron circuits by far.

I’ll send an update when I get it fully working on AM and CW.

73,

Grayson

TA2ZGE