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Showing posts with label Tubes. Show all posts
Showing posts with label Tubes. Show all posts

Monday, February 19, 2024

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/

Jean Shepherd has Trouble with his Heising Modulator (and his date)


This is probably Jean Shepherd's best program about homebrew ham radio.  It is about how we can become obsessed with the problems that arise with equipment that we have built ourselves, and how normal people cannot understand our obsessions.   

I posted about this back in 2008, but I was listening to it again today, and quickly realized that it is worth re-posting.   Realize that Shepherd's Heising modulation problems happened almost 90 years ago.  But the same kind of obsession affect the homebrewers of today.  

Note too how Shepherd talks about "Heising" in Heising modulation.  Heising has an entire circuit named for him, just like Hartley, Colpitts, and Pierce of oscillator fame.  Sometimes, when I tell another ham that my rig is homebrew, I get a kind of snide, snarky, loaded question:  "Well, did you DESIGN it yourself?"  This seems to be a way for appliance operators to deal with the fact that while they never build anything, someone else out there does melt solder.  They seem to think that the fact that you did not design the rig yourself makes your accomplishment less impressive, less threatening.  This week I responded to this question with Shepherd's observation -- I told the enquiring ham that my rig is in fact homebrewed, but that I had not invented the Colpitts oscillator, nor the common emitter amplifier, not the diode ring mixer, nor the low-pass filter.  But yes, the rig is homebrew, as was Shepherd's Heising modulator.    

Guys, stop what you are doing. Put down that soldering iron, or that cold Miller High Life ("the champagne of bottled beer") and click on the link below. You will be transported back to 1965 (and 1934!), and will hear master story-teller Jean Shepherd (K2ORS) describing his teenage case of The Knack. He discusses his efforts to build a Heising modulated transmitter for 160 meters. He had trouble getting it working, and became obsessed with the problem, obsessed to the point that a girl he was dating concluded that there was "something wrong with him" and that his mother "should take him to a doctor."

This one is REALLY good. It takes him a few minutes to get to the radio stuff, but it is worth the wait. More to follow. EXCELSIOR! FLICK LIVES!

Saturday, February 17, 2024

Nate KA1MUQ's Amazing Thermatron Receiver



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!  

Saturday, February 3, 2024

Armand's Receiver -- A Beautiful Regen from WA1UQO


Armand writes:
The video above shows a quick pass up 40M. The radio sounds better than the video would have you believe (better than I expected). So now the Select-o-Ject circuit is next (Stay tuned Grayson).
A long list of folks helped with bringing this project as far as it has come. The original description was by Bruce Vaughan, NR5Q SK. Jim Stoneback, K4AXF tweaked it and added the Select-o-Ject circuit.
The power supply picture (below) shows a ganged potentiometer and two empty sockets. These will be for the Select-oJect.
Anyway, it was a fun build and I learned a lot. Now I'm at the point that Farhan advises to make a cup of coffee and just enjoy listening.
73, Armand

 

Receiver

Power Supply 

Monday, January 29, 2024

The System Source Museum (Computers, Maryland)


Thanks to my friend Bob KD4EBM for alerting me to this.  Bob provides some very useful background: 


(Just north of Timonium, colocated with the future home of the National Electronics Museum)

System Source has a computer museum displaying technology from the inception of computing. Founders Bob Roswell and Maury Weinstein opened ComputerLand, a predecessor to System Source, in 1981. Rapid advances in technology in the early 1980’s made some ComputerLand inventory obsolete before it could be sold. Bob and Maury’s old ComputerLand store on Redwood Street had a bank vault in the basement, so they filled it with vintage tech.

Wow, that bank vault in the basement is really intriguing.  We need to find more of those.  

The Usagi guy's 6AU6A T-shirt is pretty cool.  I also liked his reference to Tracy Kidder's book "The Soul of A New Machine."  I happen to be re-reading that book now.  I'm struck by the complexity of even the computers of the late 1970s.  At one point Kidder notes that there is only one guy on the hardware team who has a complete grasp of how the hardware in the new machine actually works.  The software was probably even more inscrutable.  And of course, things have gotten a LOT more complex.  This is the big reason that I have decided to stick with simple, analog, discrete component, HDR rigs that I can understand.  To each his own.  One look at the wiring on some of those old computers tells me that this is not for me.  

Thursday, November 30, 2023

AA9IL's Sputnik Tube, Altoids Tin Transmitter

November 24, 2023
Hello Bill
I have just built an tested a 20 meter “Sputnik” transmitter. It uses two Soviet era “rod” tubes and is fixed tuned to 14.060 MHz.  I was able to compress the design to fit in an Altoids tin. The plate tuning capacitor was replaced with a fixed capacitor value closest to the variable for peak power out. Plate voltage is 90 volts and I key both the oscillator and PA via the B+ line. Power output is around 200mW and my first test transmission from the Chicago area was picked up 864 miles away on the east coast via the Reverse Beacon Network. It was definitely Joy of Oscillation and Joy of Transmission!

73, Mike
AA9IL
EN52
----------------

Mike's rig has been heard by many Reverse Beacon Network stations: 


------------------
November 29, 2023
Bill: 
I started a QSO with AC2C in Ellicott, MD who responded to my CQ but the band dropped (20m)
But that’s a good start and I’ll keep at it!  So, yay!
73 Mike
-------------------

Here are some earlier blog post on rigs using Soviet rod tubes: 

Tuesday, November 21, 2023

Mr. Carlson's ART-13 Transmitter (with Dynamotor)


Here we have a really cool video from Mr. Carlson.  In it he reveals (admits!) to what we already know:  HE IS A HAM RADIO OPERATOR.  FB Mr. C!

You can see that he is a true ham, with a true case of THE KNACK, when you see his reaction to the inside view of the ART-13.  He seems to gasp as he notes that there is a lot of "RF goodness" in that box.   There is a vacuum relay, a bread-slicer capacitor, there is even a variometer. And lots of good, big THERMATRONS.  Only a true ham, a true Knack victim can recognize this RF goodness. 

The Dynamotor that goes with this transmitter is really interesting to me.  I have been hearing these things whining in the background (audible noise, not a signal defect) on many early morning (Saturday 3885 kHz) of the Old Military Radio Net.  I can often hear the dynamotor of Buzz W3EMD as he transmits from Rhinebeck, New York.   It was great to see the inside of this device.  

Back in 2017, Hack-A-Day took a look at Dynamotors: 

There are several good ART-13/BC-348 pictures on W3EMD's QRZ page:

I was especially taken by the handwritten frequency chart on the front panel of the ART-13.  This reminded me a lot of the handwritten readout that I have been using on various rigs, including (most recently) the 15-10 SSB transceiver. I hope Paul focuses on this paper-and-pencil frequency chart;  it is nice to step away a bit from the glowing numerals of San Jian. 

Mr. C points out that the ART-13 was the transmitter that was paired up with the BC-348 receiver.  He will be working on both in the weeks ahead. 

Thanks Mr. Carlson. 73 OM. 

Thursday, November 16, 2023

The Grid Leak Detector -- Follow-up from Yesterday's Post on the Whole Earth Catalog's "Hippy" One Tube Receiver

Click on image for a better view
When I first looked at it in the Whole Earth catalog circuit, I thought it was a regen.  But a commenter correctly questioned this conclusion.  I remembered the grid leak circuit (WN2A provided more info in the comments).  This morning I found a Wikipedia page that explains it all very well.  I especially like the description of how this detector works both with small signals in the "square law" range of the tube, and with larger signals in the linear range of the tube.  The history of the discovery of the need for the large resistor is also very interesting.  I remember building FET amplifiers and finding that they would -- after time -- shut down.  This would happen as charge built up on the gate.  I had neglected to include the normal 100k ohm resistor (that would "leak" this charge to ground).  Once I put this resistor in, the amp worked fine.  

Here is the Wikipedia article:  


Wednesday, November 15, 2023

Whole Earth Catalog Part II: More on SWL (and a Hippy One-Tube Receiver)

Click on image for a better view

Lee McKusick was correct about many things, but of course we were a bit disappointed by his focus on store bought gear.  But the 1971 Whole Earth catalog made up for this by publishing the schematic for a very simple single-triode receiver: 

Click on image for a better view

There is a follow-up article on grid leak detectors here: 

Wednesday, October 11, 2023

Sunburst and Luminary: Apollo "Rope" Memory, and other items of interest

 

Wow.  That is the method that they stored computer memory for the moon missions.  When they were satisfied with a program they would say it was time to "put it on the rope."  

Here's an article on the women who built the rope memory (and the integrated circuits used in Apollo). This reminded me of the women's collective in Hyderabad that "wove" the ferrite core transformers for Farhan's BITX rigs: 

https://www.sciencenews.org/article/core-memory-weavers-navajo-apollo-raytheon-computer-nasa#:~:text=Core%20memory%20used%20metal%20wires,to%20create%20a%20particular%20pattern.

Here is a Wikipedia article on core rope ROM memory with some great illustrations: 

https://en.wikipedia.org/wiki/Core_rope_memory

The Rope

Other stuff of interest that I have spotted so far in the book Sunburst and Luminary -- An Apollo Memoir by Don Eyles:  

-- Not long before the fatal Apollo 1 fire, an MIT colleague of Don Eyles had a drink with Astronaut Gus Grissom.  Grissom unloaded about the poor state of the spacecraft, saying that, "What we have here is a Heathkit."  Grissom died in the fire. 

-- Eyles mentions the use of 6L6 tubes in analog audio amplifiers. 

-- MIT's Doc Draper used a Minox camera.  

-- When the Apollo 11 astronauts came back and were living for two weeks in an isolation chamber, NASA had bulldozers on standby to bury the whole thing ("astronauts, staff and all") in case some dangerous moon bug was detected.  (Is that true?) 

-- At one point soon before an important missile test, engineers realized that they needed an isolation transformer.  They did not have enough time to order one.  So they took an isolation transformer out of one of their soldering stations and used it in the missile.  It worked. Sometimes you just use what you have on hand. 

Thursday, September 28, 2023

A Look at Old Radios in Australia (video)

I thought you guys would like Peter Parker's latest video.  And in it, Dean KK4DAS might see a clue or two for his Halli restoration/repair project.  

What really struck me was the dial markings on the Australian radios.  They seem to be mostly oriented toward the reception of Australian AM or LW broadcasters -- not many exotic DX locations are marked.  Australia is big! 


Looks like a lot of crystal detectors in glass tubes.  At first I thought they might have been coherers, but I think they are crystal detectors. 

Many variometers visible. 

I saw one Geloso-Milano Communications 8 receiver.  Va bene! 

I also saw one "Tasma 780" Superhet.  Cool name! 

What is up with the "Green Theme"? 

I have some of the headphones they showed. 

Please note in the Comments section anything special that you noted in watching Peter's FB video. 

More on the coil winding machine here: 

Friday, September 15, 2023

HB2HB -- A Contact with Denny VU2DGR (video)

At first I didn't realize it was Denny.  On September 11, 2023 at about 2330Z I had walked back into the shack after dinner.  I think DX spots showed an Indian station on 20 meter SSB.  Without realizing who it was, I tuned him in on my Mythbuster rig, heard the other station sign off, and quickly threw in my call.  Denny came back to me right away, and I think both of us then realized that we recognized the call of the other station. Wow, it was Denny, VU2DGR, the Wizard of Kerala!   At the time of the QSO, I didn't have my phone with me; after we spoke, I went to get it,  so the video above captures part of Denny's subsequent contact. (You can also at one point hear Guapo barking.) 

Denny has been running a wonderful station that combines SDR gear with and HDR tube type amplifier and a homebrew Moxon.  

Here is Denny's station. The transceiver is a RadioBerry.  the amplifier and power supply are on the other table.  


Here is the homebrew tube-type amplifier.  This is the part of the station that really puts the HB in HB2HB! That's the power supply on the left and the amplifier itself on the right: 


That amplifier has three 807s in it, with a 6L6GC: 



Here's a video on the RadioBerry transceiver. 


Finally, here is Denny's magnificent homebrew 20 meter Moxon: 


Thanks Denny! 

Thursday, September 14, 2023

Building Nixie Tubes for a Hiroshima Project


Thanks to Bob Scott KD4EBM for alerting me to this wonderful video.  It seems especially timely, given the recent release of the Oppenheimer movie.  

I posted back in 2000 about Dalibor Farny and the Nixie tubes he makes in a castle in the Czech Republic:

In this more recent video (above) Dalibor describes a very cool and very challenging Nixie tube project:  A museum in Hiroshima Japan was presenting an art project designed by a Chilean artist.  The display needed a lot of large, custom-made Nixie tubes, some of which would display Japanese language characters.  So: Museum in Japan, Chilean artist, Nixe maker in the Czech Republic.  There are big geographic challenges before you even get to the technical challenges.

Dalibor does a great job in describing all of the challenges that they faced.  The technical stuff will be especially interesting to SolderSmoke listeners.  His description of the evolution of his Czech workshop fits very well with our "other kinds of workshops" theme. 

The video is really worth watching.  Check it out (above).  The ending is quite moving. 

Thanks again to Bob Scott.   Congratulations to Dalibor, his crew, and to all those involved in this Hiroshima museum project. 

Saturday, August 19, 2023

Valveman -- The Story of Gerald Wells


Don't be deterred by the annoying test patterns at the start of this video.  Just skip past them.  The rest of the video is quite good.  Or you could just click on this link and avoid the first 83 seconds of test pattern:  https://youtu.be/Y8w6iwaAGJ4?t=83

Gerald Wells has been mentioned on this blog before, but I don't think we've ever presented the full documentary on this fellow.  Here it is.  Gerry is clearly one of us: a radio fiend, obsessed (as he admitted!) with wireless, a victim of THE KNACK.   

George WB5OYP of the Vienna Wireless Society got to meet Gerald Wells and visit his museum. George alerted me to this video.  Tony G4WIF also was able to visit Gerry and his museum. 

The documentary is full of interesting stuff, and is, in itself, a Knack Story.  Wells mentions the Crippens murder so well described by Eric Larson in "Thunderstruck."  It was this crime that brought radio to the center of public attention.  

Tuesday, August 15, 2023

The Wizard of Kerala (India) -- Denny VU2DGR -- SDR and HDR

 
His signal was just booming in on 20 meter SSB yesterday evening.  It was one of the strongest signals I've heard from India.  I wasn't able to get through the pileup, but I heard mention of a homebrew station at his end...  Sure enough a look at his QRZ.com site shows that a LOT of solder has been melted in his shack.  Both SDR and HDR stuff.  Tube projects including an 807 amplifier made from "components collected from the scrapyard." And a homebrew 20 meter Moxon.  Check it out: 


FB Denny!

Kerala is on the southwest tip of India.  It is something of a hotbed of technological innovation.  My only Indian contact using my current series of homebrew dual-banders was with VU3TPW -- Renju is also in Kerala. 

Tuesday, June 20, 2023

Part 2: CuriousMarc Fixes an All-Discrete Counter -- "Like an IC, but in discrete form."

Marc nicely sums up this project with this line:  "It's an IC but in discrete form!"  On the same theme, he later says, "Who needs a logic analyzer when you can do a visual debug with neon bulbs?" 

Very cool.  Lots of troubleshooting and repair lessons in this video: 

-- Again we see the benefits of paper manuals.  (Todd K7TFC commented astutely on this under yesterday's post.)

-- 2N2222s to the rescue.  

-- A surprisingly large number of bad transistors (6?) found.  Why did they go bad? 

-- Marc repeatedly says, "Let me poke around."  Poking around is often important.  Mark fixes the reset line after poking around.  He is not sure HOW he has fixed it, but he has... by poking around.  Sometimes this happens.  Thank God for small favors. 

-- Marc has some fancy HP board extenders.  I am jealous.  

-- He also has a cool de-soldering tool.  More jealousy.  Want one. 

-- Marc's understanding of how the HP engineers had to put one of the flip-flops "on the edge of stability," and how his 'scope probe was capable of disturbing this stability. 

-- Remember that those Nixies are TUBES with enough voltage on them to really zap you.  So be careful in there.  This is an especially dangerous mix of transistor tech and tube tech.  With transistors you can work on them with the rig fired up.  With tubes, well, you have to be careful.

Part III tomorrow. 


Sunday, April 23, 2023

Helge LA6NCA's Altoids Tin Receiver


Here's another great video from Helge LA6NCA.  This is a follow-up to his Altoids Spy Transmitter project.   Really well done.   Hack-A-Day called this receiver "regenerative" so naturally I was disappointed, but when I watched I realized that it is NOT a regen but is instead a direct conversion receiver.  TRGHS.  All is right with the world.  Thanks Helge!  73 

Tuesday, April 18, 2023

CuriousMarc Powers up (and Explains) Old Cathode Ray Tubes


Wow, really cool video from CuriousMarc and the guy who wrote the "Open Circuits" book.  But fellows, you really need to be more careful with the high voltage. Remember poor Ross Hull.  One hand behind the back would help.  Volts jolt, but mills kill.    

Sunday, April 9, 2023

Arnie Coro CO2KK (SK) Provides More Info on the Islander DSB rig

Peter Parker VK3YE found this message from Arnie CO2KK in the Wayback Machine.  We continue to look for more information on the Jaguey solid state DSB rig. 

Arnie wrote: 

Several years ago an amateur in central Cuba was approached by some of his young friends to help them build their first rig. CO7PR, Pedro, a telecommunications technician for the phone company, had a vast experience both with vacuum tubes and solid state circuits, plus that special gift of designing and building with whatever is available. After a few days, Pedro came out with the "Islander" prototype, a low parts count, easy to build single band transceiver!

Here is the circuit description of that little radio that has provided many cuban young and old, newcomers to our hobby, with their first rig... and the challenge to improve it.


RECEIVER:

It is a direct conversion, YES, a DC receiver made with vacuum tubes. The very thought of having those tube filaments fed from the AC power supply and at the same time having 80 or 90 dB of amplification made me shudder when I first talked to Pedro on the very popular here 40 meter band! You are LOCO Pedro, I told my good friend... CRAZY, those poor kids are going to hear 50 percent 120 hZ hum when they tune across the 7 megahertz band.

Yes Arnie, you are right, it has a little background hum, but by using a small loudspeaker and small coupling capacitors... it's tolerable! The receiver shares, in its original version, the same antenna input as the transmitter output stage, a PI network, but we soon learned to add a separate LC tuned circuit first and latter a bandpass double tuned input filter...PLUS a signal attenuator... a very primitive but effective attenuator... just a 10 k potentiometer!

For an RF amplifier stage the Islander uses a russian pentode, which is the equivalent of the popular TV IF amplifiers of the 50's... looks like a 6CB6, for those of you that fixed TV sets 40 years ago or so.

The 6 "little spider" five, as everyone knows that tube here,has a lot of gain, and it can be kept rather stable by a judicious choice of screen and cathode resistor values.. Noisy pentagrid converter follows!

The 6A2P... a russian 6BE6, was the first tube type used in the Islanders, later some people tried the ECH81 triode-hexode and found it works better.

The circuit of the 6A2P-6BE6 is quite straighforward... a... you guessed right... PRODUCT DETECTOR... fed from the vacuum tube VFO... and providing its audio output to the two stage audio amplifier.

Audio amplifier is made with a triode-pentode tube of which plenty are locally available from defunct TV's... the ECL82 and the 6F4P and 6F5P of east european and russian manufacture respectively provide a lot of gain.

So... that's your receiver.. quite straightforward, works on 160, 80 and 40 meters by just changing the input filter and the VFO injection, it does NOT provide very good selectivity at all, but during the daytime, when the 40 meter band is used for local and regional contacts, it puts those new hams ON THE AIR!


VFO... the big problem amigos!

CO7PR worked very hard to try to make a stable vacuum tube VFO... and he almost made it..

YES, ISLANDERS drift, some not too much, others are not so good, depending on who built the rig, and how close they followed Pedro's advice at first, and Arnie's CO2KK later (as yours truly became quite involved in the project, as soon as I found that it was THE way of getting all those guys ON THE AIR!)

VFO is made with ONE of the 6 "little spider" 5 pentodes... By the way, I am sure you will like to know why the tube is locally known like that... the ZHE letter of the Cyrillic alphabet is something difficult to pronounce to a cuban - or any other non slavic for the matter - and it resembles like a little spider on the tube's carton and... that's why it is not a 6 "ZHE" 5 but a 6 "little spider" five!!!

The VFO cleverly works at one half the operating frequency... and then it DOUBLES frequency at the plate circuit... output is via a link to the pentagrid or hexode mixer depending on which type you use.

BUT... the VFO also has a second output to the transmitting chain.. Well that's the receiver... OH YES... the VFO is fed from a VR tube, a gaseous discharge voltage regulator similar to a VR-150 or VR-105... CO7PR advises to use the VR105, but when building the Islander, special in the countryside, that's a very hard part to find, as old TV sets don't use VR tubes! So people use whichever VR they can find. ZENERS? They are only available locally for 6 to 24 volts, so they can't be used with this rig.


ISLANDER DSB AND CW transmitter circuit:

From the VFO plate circuit, you pick up 7 mHz energy (usually you must wait at least half an hour for that said 7 mHz energy to be stable enough in frequency) and feed two diodes (ex-video detectors from russian TV type D20) acting as what I like to call BALANCED AND UNBALANCED modulator!

When used for DSB, it is certainly a DSB generator... but when you want to work CW, it must be UNBALANCED.something easy to achieve with just a resistor from the +12 volts line and a switch!

The balanced modulator receives its audio from a carbon microphone capsule salvaged from an old telephone, and conveniently connected to same +12 volts with some additional filtering via biggest possible electrolytic + small ceramic dogbone from TV set IF amplifier as RF bypass... no dogbone capacitor there... strange howls on Islander audio as RF leaks into balanced modulator you know.

So dogbone ceramic capacitor is a must! No, disk ceramics are not locally available, so people must use the next best choice... dogbone ceramics in the 100 pf to 5000 pf range, usually rated at 300 volts or so... (that 300 volt rating we learned the hard way, but more about that later.)

The original version of CO7PR's Islander ran with the carbon microphone, no MIC LEVEL control option, as he really wanted to keep things simple... later versions have audio preamps of various designs, and some even have a sort of primitive compressor.. From the balanced modulator the DSB (plus a little carrier leak that is always there) drives the rig's one or two transistor low level RF amplifier, which is made using whatever NPN silicon transistor is available, usually KT315's salvaged from TV's too. the KT315 is sort of a russian version of the 2N2222, so you understand why we use it here!

RF voltage reaches then the grid of an ex-video output amplifier vacuum tube, and there you are... about 2 to 5 watts of either DSB or CW on 40 meters and a new cuban amateur ON THE AIR!

Before I forget... keying... a little chirpy always because of so many interactions between simple circuits, sometimes not too well shielded, first time builder etc.

BUT... ISLANDER is ON THE AIR providing that young kid from the local junior high school or that doctor that always wanted to be a ham, or maybe the fresh out of school electronic technician, with the fascination of their first ever rig. YES, they drift, and some drift badly, when the frequency determining capacitors in the VFO are not too good... (most of the time), as I said they are a little chirpy. and the receiver's selectivity makes working 40 meters at night almost impossible (although some wizards do make nightime contacts at the low end of 7 mHz) BUT. YES, they are ON THE AIR.

Today there are a few Islanders still on the air, and some are even still built brand new (with many of CO7PR's and CO2KK's mods), but the trend is for all solid state rigs centered around CO5GV's and CO2JA's prototype the "JAGUEY," a design that draws a lot from Wes Hayward's Solid State Design for the Radio Amateur, and as of late, with lots of ideas coming from SPRAT, the G-QRP club magazine and QRPp from NORCAL, the Norther California QRP club!!!

In a future posting I will describe the "Jaguey," too.

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

More info on the Cuban DSB and AM rigs can be found here:

https://soldersmoke.blogspot.com/2023/04/more-info-on-cuban-jaguey-solid-state.html 

https://soldersmoke.blogspot.com/2023/03/homebrew-am-from-cuba.html

https://soldersmoke.blogspot.com/2023/03/more-cuban-homebrew-from-80s-and-90s.html

https://soldersmoke.blogspot.com/2023/03/schematics-for-cuban-islander-double.html

https://soldersmoke.blogspot.com/2023/03/the-islander-homebrew-dsb-rig-from-cuba.html

https://soldersmoke.blogspot.com/2023/03/needed-more-info-on-cuban-islander-or.html


Thursday, April 6, 2023

Helge LA6NCA Builds a Double Sideband Thermatron Transmitter


Helge is an amazing homebrewer. Check out the shack.  Note the R-390 and the Tek 'scope.  Watch how Helge designs his rig.  Watch him check the 3-D printed coil and the variable caps for resonance.  Most of all, watch his happiness when the new transmitter works.  I just wish he would have showed us some OM complaining that he was on the "wrong" sideband. FB Helge!  Thanks. 
Designer: Douglas Bowman | Dimodifikasi oleh Abdul Munir Original Posting Rounders 3 Column