Re-building the Islander DSB/CW Tube Rig in Cuba

The VFO Board

The "motherboard" for an Islander

Islander boards recently obtained in Cuba by CO7WT

Pavel CO7WT is making great progress in re-building an Islander DSB rig, the same kind of rig that got him started in ham radio, and that was so popular in Cuba years ago.  Here are some background blog posts on this rig:  https://soldersmoke.blogspot.com/search?q=Islander  In essence, the Islander was the earlier tube DSB/CW rig; the Jaguey was a later, solid-state DSB/CW rig. 

When they get this Islander going, hams outside Cuba should definitely try to work this re-creation of an important rig. 

Thanks Pavel for all the information.  I will share with the group info that Pavel sent about temperature stabilization techniques used on this rig.  

Pavel CO7WT writes: 

Great news, today I received the package from my colleague in zone 6.

Two original islander motherboards and one from the vfo!

I'm doing a search among old technical friends in the city and in the country to see if I can put together at least a transceiver motherboard.

Audio triode-pentode is easy, as is tx pentode and audio double triode.

The difficult ones would be the 6cb6 and 6bz6 of the receiver... At least according to what I have polled among my local friends...

Tomorrow some friends are going to start looking for bases and valves that can be used to build a trx islander.

All out of pure nostalgia. I intend to make it qrp, that is, up to the output pentode, which there is between 3-5W of power, that is enough for me.

I am looking for alternatives for small sources, perhaps I will use switching for the filaments and we will see what I can get for the 180-250v of the plates.

Earlier: 

CO7WT here, built a pair of the Islander back in the time, the most scary part was the power supply.

The 600V is 300ish V from the transformed DOUBLED stright from the transformer and if you look closely on the diagram the doubling capacitor need to be of good quality otherwise it will explode in the spot.

As you can imagine, using scrapped parts means that very often this capacitor explodes, even after a few months of duty, that was a common problem.

We used to use 47uF/800v from Germany that was almost easy to obtain, but exploded like fireworks a given day.

Later I learned that if you put a resistor of about 1k 5W in series and work it for a while like this [no real voltage at the end] it will behave in the future and this trick saved many, a trick that was shared with Coro CO2KK and he found the explanation on the taming/training of the dielectric after storage/inactivity will prevent it from exploding.

I think he made mention this on a DXers Unlimited program...

Big Success with Cloud Chamber

 

My Cloud Chamber

It was time to take a break from building SSB transceivers.  I wanted to build something completely different.  I went with something that I've wanted to build since I was a kid. Sometime in the late 1960s, I read about a Wilson Cloud Chamber in the book "The Amateur Scientist" by C.L. Stong  (my mom got the book for me, at great sacrifice).  

You have to make a little cloud in a chamber.  When an atomic particle flies through (as they do!) it will leave a little trace in the cloud.  Cool.  Literally cool: This is a dry ice diffusion cloud chamber.  You make the cloud by putting isopropyl alcohol in blotter paper at the top of the chamber. You then cool the bottom part (a lot) using dry ice. The alcohol evaporates, then is cooled into a cloud by the low temperature of the dry ice. Fortunately, my local supermarket has started selling dry ice (it was harder to come by when I was a kid).  For the chamber, I used a plastic container from the same superpmarket. For the light source I used a little LED workshop flasllight.  

I saw traces immediately, while I was setting the thing up.   

Here are two videos of what I saw during that first hour:  

This one minute video shows the traces I saw.  Look for the little whisps of "smoke": 

(2125) Traces seen on day 1 - YouTube

This one shows a few more traces, but then BOOM at about 27 seconds.  Check it out.  What is that?  (Thinking about it some more, I think this may have just been some higher humidity air leaking into the chamber and condensing suddenly.) 

(2125) Day 1 with Cloud chamber - YouTube

Here's the C.L Stong book.  My project begins on page 307

http://www.ke5fx.com/stong.pdf

So what band would this be?  Something in the nanometer range, right? 

Here is a video showing what you see in a large cloud chamber: 

https://www.exploratorium.edu/video/cloud-chamber

EXCELLENT Video Series on RF Amplifier Design

Run, don't walk, to this video series by RF MAN.   He is truly, THE MAN!  Pete N6QW found this series, passed it to Dean KK4DAS, who alerted me.  Thanks guys. 

This is a six part video series on how to design an HF 50 watt RF linear amplifier using our beloved IRF-510 MOSFET.  Each video is about 30 minutes long. 

The author (who is this genius?) makes great use of LTSpice.  I have been using this software for years, but still I learned a lot by watching these videos:  AC Analysis.  How to change the values of the things you are measuring.  Even something as simple as drawing a wire right through a component to get leads on both sides.  This is really useful stuff. 

RF Man goes through the whole design of the RF amplifier.  He describes how to use LTSpice to determine input and output impedances (he does this with a NanoVNA in another video).  He talks about the use of negative feedback, and temperature compensation.  There are swamping resistors as Q killers.  This is all great, real-world stuff.  

Especially useful for me was his presentation on how to do "two tone" IMD tests.

  

There is a lot to learn here.  RF Man has a really wonderful way of explaining complex theory, and demonstrating complex tests.   This series makes me want to build a MOSFET amplifier.  

Look for the six parts of this series.  Here is RF Man's YouTube channel: 

https://www.youtube.com/@rfmanchannel6915/videos  

Thank you, RF Man! 

The War of the Worlds -- In CW -- By Chuck Adams AA7FO

This is for CW fans, or for those wishing to improve their CW skills.  You can now listen to the entire H.G. Wells book in CW, thanks to Chuck Adams, AA7FO. 

This seems very timely becasue my son and I are watching the NETFLIX version of "The Three Body Problem" by Cixin Liu.   This deals with an entirely different war of the worlds.  

Check out Chuck's CW version of the book.  Thanks Chuck! 

https://www.aa7fo.com/war-of-the-worlds.html

Deep Space Station 43 -- Canberra, Australia

 

https://spectrum.ieee.org/apollo-era-antenna-voyager-2

From the IEEE article: 

The dish’s manufacturer took great pains to ensure that its surface had no bumps or rough spots. The smoother the dish surface, the better it is at focusing incident waves onto the signal detector so there’s a higher signal-to-noise ratio.

DSS-43 boasts a pointing accuracy of 0.005 degrees (18 arc seconds)—which is important for ensuring that it is pointed directly at the receiver on a distant spacecraft. Voyager 2 broadcasts using a 23-watt radio. But by the time the signals traverse the multibillion-kilometer distance from the heliopause to Earth, their power has faded to a level 20 billion times weaker than what is needed to run a digital watch. Capturing every bit of the incident signals is crucial to gathering useful information from the transmissions.

The antenna has a transmitter capable of 400 kilowatts, with a beam width of 0.0038 degrees. Without the 1987 upgrade, signals sent from DSS-43 to a spacecraft venturing outside the solar system likely never would reach their target.

https://spectrum.ieee.org/apollo-era-antenna-voyager-2

The Rad Receiver from N6GWB

Geoff N6GWB and his eldest have produced a really wonderful receiver, and have joined the elite ranks of those who have built their own receivers.   Congratulations to both!  ( Be sure to watch the video below.)

Geoff writes:

Though I built it, my eldest has retained naming rights.  Behold the Rad Radio Receiver, an Soldersmoke inspired build.  It’s a 40m DC reciever.  I had planned on making this a truly 50-50 N6QW N2CQR build, but I needed to get it done for a show and tell this Wednesday.  I have N6QW dual JFET RF amp and mixer modules.  I have the N2CQR ceramic ocillator circuit from the 2017 DC receiver project.  I had planned on including the all analog audio amp from the more recent N2CQR DC project, but alas, time got the best of me.  I was hoping to make the whole thing all-analog.  (I thought the all analog would get me more “hard work” kudos at the show and tell.) I ended up including a LM386 audio amp making this a bit of a cyborg.

I have included pictures of the receiver open and closed.  The closed pic includes bespoke decals.  I have also include a brief movie demonstrating the audio.

Many, many thanks for the inspiration and knowledge!

Geoff

N6GWB

A QRP Quiz Question

 

I have the answer from an excellent and authoritative source.  

Here is the question:  The rig I bought for one dollar at Winterfest was produced by MXM Industries of Smithville Texas.  What does "MXM Industries" mean?  Why was this the name of the company? 

Homebrew-to-Homebrew Contact on 17 meters with DL2RMM (Video)

 Here is short clip of a very cool HB2HB contact on 17 meters.  Thanks Jens! 

Check out his QRZ page here: https://www.qrz.com/db/DL2RMM

Woebot -- An AI-Based Therapy Bot for Us?

 

This was on 60 Minutes last night.  Of course it made me think of our many "Tales of Woe."  Perhaps this could be of use to us.   But I wonder how the bot would react to our typical problems: 

"I am feeling bad about myself becasue my RF amplifier keeps going into oscillation.  What should I do?"

"My opposite sideband suppression is inadequate because my filter skirts are too wide. What is your advice?" 

"My LC VFO drifts slightly and my SDR-using friends taunt me about this.  I feel dejected.  What should I do?"  

"The Raspberry Pi in my SDR rig is hallucinating and I can't find the needed wisdom files. Is there a support group for this?" 

"I have discovered spurs in the output of my transmitter.  They are 60 db down, but I still can't stop thinking about them.  What should I do?"

I can't help thinking that if Jean Shepherd had access to something like this, his Heising modulator trouble might not have spoiled his date with the girl from his school.  

What do you guys think about the Woebot?  

The Doug DeMaw Article that got me into Homebrew Double-Sideband

Just click on the images for a better view

Pete WB9FLW asked for this.  This was an important article for me -- it paved the way for my entry into homebrew phone gear -- this article was the basis for my first DSB transmitter, built in the Azores. 

I think Doug was a bit optimistic in saying that SSB operation was possible with this rig.  Maybe it was possible for Doug, but for most of us DSB is just a LOT easier to get going than SSB.  (I know that some people don't believe this, but I note that most of these folks have built neither DSB nor SSB rigs.  It always seems easier before you start to melt solder.)  

Be sure to check out the 10 meter DSB rig recently built by Mike WU2D.  He has 6 or 7 good videos on this project, including this one: https://www.youtube.com/watch?v=xThoAMv4zrw

Another CW Contact with the SupeRX/TX 40 (Video)

I changed the crystal in the transmitter.  I got a different rock from Mouser and am now on 7030.  

Wednesday April 3, 2024. On 40 meters in the afternoon with Mike KM4KY in North Carolina.

The Road to Perdition -- High Voltage Thermatron Perdition

Yuck -- Not mine

In the AWA Bulletins that Armand gave me at Winterfest, I saw mention of an AWA PC Board intended to allow for the upgrade of the venerable Heathkit HP-23 power supply.  

I have an HP-23B.  It came with my HW-101.   I replaced the capacitors in the supply many years ago, but they were of marginal voltage specs back then (I think I was in the Dominican Republic) and they have likely dried out considerably since then.  I am nervous about firing this thing up.  I fear for the big transformer... 

So I'm going to order the AWA's upgrade PCB.  

Of course, the danger (!) is that this could lead me back into the world of high voltage thermatrons.  That HW-101 has been taunting me for years.  It NEEDS restoration.  The first step would be to fix up the Power Supply. 

https://www.antiquewireless.org/homepage/pcb-item-10/

73.  And one hand behind your back OM.  

MXM SupeRX/TX 40 Rig Info

 

My SupeRX/TX 40 -- now on 7030 kHz

Click on schematics for a better view

Details on the receiver: https://archive.org/details/73-magazine-1991-04

Details on the transmiiter: https://archive.org/details/73-magazine-1991-12/page/10/mode/2up

Article on MXM Industries of Smithville,Texas:  

https://www.worldradiohistory.com/Hambrew_Magazine.htm

Click on images for a better view

Click on images for a better view

Ian Keyser G3ROO and Spy Radios

Above is a recent ICQ podcast interview with Ian. 

Here is a slightly older interview with Ian: https://www.itv.com/news/meridian/2018-10-19/daring-spies-who-broadcast-from-behind-enemy-lines

This sojoun into spy land started with this WTF video: https://www.youtube.com/watch?v=4f3ZJYdmpZw

Crypto Museum explains what the Mk 301 was all about:  https://www.cryptomuseum.com/spy/mk301/index.htm

 I have had Ian on the SolderSmoke blog several times: https://soldersmoke.blogspot.com/search?q=%22Ian+Keyser%22

N2CQR at the key with a G3ROO paraset

SolderSmoke Podcast #251 Aurora! CBLA, Winterfest, Legal Action Against SolderSmoke, HB sBITX, SDR, Raspberry Pi, Rounded Passbands, MAILBAG

Aurora Picture by Dean KK4DAS

SolderSmoke Podcast #251  4-1-2024

Audio: http://soldersmoke.com/soldersmoke251.mp3

Videos: Podcast 251 Aurora! CBLA, Winterfest, Legal Threat, sBITX, SDR, RaspPi, Rounded Passbands, MAILBAG (youtube.com)

Travelouge:  Dean goes to the North Pole to see Aurora. 

A CBLA Call to Arms! 

Winterfest.  Lots of goodies.  MXM Industries 40 meter transceiver. 1 dollar. 

Jean Shepherd. Recording of Bill talking to Shep in 1976. 

 https://soldersmoke.blogspot.com/2024/03/listen-to-me-talking-to-jean-shepherd.html

Legal Trouble: Could put us out of operation for a while.  We need listener input. 

November 2023

December 2023

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

Pete's Bench

Homebrew SDR (based on Zl2CTM’s original design) and how good it sounds.

Raspberry Pi Zero W is now working on FT-8 with digital adapter.

Ferrite Cores at Digi-Key (a replacement for the FT-37-43 where  you buy 100 and the price is 21 cents/each)

ADE-6 –great specs in HF but more expensive than the ADE-1

For Pete's recent blog posts, go to this site and click on "Archive" in the right column: 

https://n6qw.blogspot.com/2024/03/march-31-2924-happy-easter-to-those-who.html

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

Dean's Bench 

sBITX progress, McGyver-ing a lifted pad, replacing crystal on the CODEC board, sBITX success! See: 

https://kk4das.blogspot.com/2024/03/homebrew-sbitx-tx-modules-pa-lpf-and-mic.html

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

Shameless Commerce Division:  Please use the Amazon link on the blog to start your Amazon purchases. And please consider using Patreon to support the podcast and blog.  We try to send extra content to our Patreon supporters. Mostly DIY RF --  Boards, Kits and Pete's PSSST

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

Bill's Bench

More trouble with the 15-10 rig.  Rounded passbands in 25 MHz filter. See figure 4 in both links: 

https://www.arrl.org/files/file/QEX_Next_Issue/Nov-Dec_2009/QEX_Nov-Dec_09_Feature.pdf

https://www.networksciences.com/pdfs/tutorial.pdf

Experimenting with Balanced Mixers and Product Detectors. Paul VK3HN  Suggests the MC1496 chip; Walter KA4KXX points to SSDRA circuits

But it is on the air!  Using the PA from a BITX40 module and an RD06.  

Put an OLD dial from Pericles HI8P on 15-10 version 1.  Soul in the new machine.

Pericles' Dial on the 15-10 Rig 

Mailbag: 

Grayson KJ7UM's Hollowstate video. 

Mike WU2D's amazing 10 meter DSB transceiver. 

Jack AI4SV (Dhaka Jack) liked video of recent QSO with AzoresDSB rig

Mike AA1TJ and Dave AA7EE on backwaves and 100 uW QRPpppp

Dave G3UUR  on my curved passband problem

Alan W2AEW heard my only QSO with the MXM indsutries SupeRX/TX40

Wes W7ZOI, Mike WN2A, Walter KA4KXX. Farhan VU2ESE on passband, 

Ramakrishnan sent article about Charles Proteus Steinmetz.  Beautiful. 

Justin AC8LV built a receiver!  FB. 

San Francisco QRP:   KDOFNR TouCans Rig, and N6ASD Zinc-Oxide TX

Frank KC8JJL -- Another guy who heard first ham sigs from a homebrew rig. 

Nate KA1MUQ's homebrew thermatron superhet

Dino KL0S sent info on the PAL CB VFO I picked up at Winterfest. Airborne! 

Bob W8SX will be once again doing SolderSmoke interviews at Dayton.  Thanks Bob

Peter VK2EMU  Always good to hear from him.

Tobias Feltus -- Wisdom teeth removed, wondering if he will get sBITX hallucinations...

Rick WD5L continues to work on his Herring Aid 5

Ciprian YO6DXE wants to learn CW. No alerts from his FB Blog!

Todd K7TFC -- Likes CW, says it eliminates the Blah-Blah-Blah 

F1BFU's Amazing PSSST VFO

A QRP CW Contact (Video) with the Winterfest MXM SupeRX/TX 40 (1 Watt, Crystal Controlled Transmitter)

I picked this transceiver up at Winterfest for one dollar. 40 meters. Superhet receiver with 455 kc ceramic filter and 2 NE602s. Crystal controlled one watt transmitter on 7039.5 kc. I emailed Jeff KA2BKG and asked him to slide up a bit to my freq. I am glad he did. Thanks Jeff.

KD0FNR's Amazing San Francisco TouCans Rig -- A Rockmite and a Tuna Topper in a Pineapple Can Mounted on the Dipole in a Shopping Bag

Click on the image for a better look

This post has a definite San Francisco vibe. 

Hamilton KD0FNR appeared on the SolderSmoke blog way back in 2011.  Perhaps he should join forces with N6ASD who lives quite close to him in SF, and seems to share radio interests.  Also in their area is the esteemed Bay Areas blogger and homebrewer Dave AA7EE ; Dave recently sounded the CBLA alarm, alerting us to the presence of an intruder on 3579 kHz.  In the process, Dave mentioned the Pt. Reyes Web SDR, the presence of which came as welcome news to Hamilton. Finally, Dave and Hamilton mention the KPH Web SDR, which brings to mind Dick Dillman W6AWO who has been on the SolderSmoke blog several times.  

Hamilton and his kids have their rig (a Rockmite and a Tuna Topper in a Dole Pineapple can) mounted at the feedpoint of their dipole (in the red shopping bag above).   They link to it via WiFi and Bluetooth. FB.  Thomas Witherspoon has a nice presentation (by KD0FNR) of the TouCans project on his blog: https://qrper.com/2023/12/field-radio-kit-gallery-kd0fnrs-rockmite-20-and-tuna-topper/ 

Hamilton KD0FNR writes: 

At the moment, the kids whose dad I am, better known as the gang—12, 10, and 8 year-old Diaze, Mota, and Tawnse.. all internet aliases—are big into 20 meters QRP CW with Project TouCans, a Rockmite coupled to a Tuna Topper. The radio and the amp that popped us out of QRPp to plain-old QRP are both housed in a Dole Pineapple can with a tuna can as a cover and antenna mount. The whole rig is still very much mounted in our half-wave dipole! 

Project TouCans consists of a Rockmite feeding a 5 Watt Tuna Topper, all of which is housed in our dipole antenna. The Rockmite has a single crystal bandpass filter on it's rx input. That makes it a pretty wide reciever which is fine, but it's particularly sensitive to its tx frequencies, 14075.5 and 14058 kHz AND—for some reason I have yet to understand—10459 kHz. By watching the SDRs that now—thanks Dave—envelope us here at our home QTH in San Francisco, we can see the frequencies of incoming signals. That information keeps me from responding to 14059 kHz signals in vain.

And now, the headphone repeater: TouCans is completely wireless with respect to the ground. That means there's no power line, no feedline, no keyer lines and no headphone line. Keyer controls are handled via wifi to a Raspberry Pi Pico-W on the rig while audio is brought back to my headphones via Bluetooth. Power is provided by a USB-C battery pack that lives in the rig which is mounted above us in the antenna. (Yes, all of this is becuase I thought feedlines matches and baluns were too mystical and hard to understand years ago. Yes, this has probably all been more work than a balun. Yes, I am still totally enamored of my original design decision. :) ) Anyway, the bluetooth range is about 50 feet and the wifi range is shorter than that. The short of it is—pun not intended—that I can't quite use the rig while I'm in my office. But, I can send CQ to the rig every half minute or so via a memory keyer, then turn on the SDR in my office, and then sprint a bit closer to the rig when someone calls back. (It helps that houses in SF are a bit tiny.) So, SDRs are kinda an integral part of our QTH setup and it's awesome to learn about a new—to us—one! Thanks again!

How to Feel Bad about Carrier Suppression (and How to Get Over It)

Version 2 of the 15-10 rig continues to give me trouble.  But I guess it is "good trouble" because I am learning from it. 

You see, after you build an SSB rig, one of the critical alignment steps is the placement of the carrier oscillator/BFO frequency in relation to the filter passband.  (The IMSAI Guy has a good video on this -- see above.)  You want to place this oscillator somewhere on the downward skirt of the passband curve.  This will add to the carrier suppression already done by your balanced modulator.  There will always be some carrier remaining from the balanced modulator -- putting the oscillator frequency on the downward skirt of the filter passband adds to the suppression the carrier remnant.  

But you can't overdo it.   If you place that carrier oscillator frequency too far down on the skirt, you will start to cutoff the low audio frequencies in your transmit and received signals.  You will notice that your once beautiful sounding receiver suddenly sounds tinny and high pitched.  Yuck. 

So you go back to the books and the websites.  You look at the passband promissed by the Dishal software you used to design the filter.  See below:  

Click on the image for a better view

Surely with a passband as nice as that one, you will be able to find the sweet spot where the carrier is suppressed and your audio remains pristine.  

But I couldn't do this with the 15-10 rig.  I was forced to compromise: I had to accept less than optimal carrier suppression for less than optimal low frequency passband coverage.  And here is why:

Click on the image for a better view

The curve above is a much more realistic picture of what my filter passband actually looks like (see NanoVNA picture below).  The curve above is from the AADE software.  I found out that the Dishal software DOES NOT factor in important things like Q or ESR.  Dishal treats all crystals as "loss-less radiators."  So when you get up to 25 MHz where Q is important, AADE and other programs will show you that your passband has become curved.  And you can see how this curvature makes it difficult to get the kind of carrier suppression and audio response we want.  

What my filter looked like in a Nano VNA

Click for a better view

Look, the rigs work OK.  The receivers sound good to me.  The carrier is so far down that no one can hear it.  I have to remind myself that we are using 'SSB-SC" -- suppressed carrier, not eliminated carrier.  I've worked a lot of DX with these rigs.  But still,  I would like to improve the situation.  It kind of bothers me.  Homebrewers will understand. 

I have been experimenting with different balanced modulators.  I started with the simple two diode, single transformer, singly balanced design from Farhan's BITX20.  It works fine.  But I think I get a bit better suppresson from a doubly balanced diode ring.  I may try an NE602 Gilbert Cell.   I may also try to build a higher Q 25 MHz filter using low-ESR surface mount crystals from Mouser.  Stay tuned.  

Thanks to W7ZOI, VU2ESE, WN2A, KA4KXX, KK4DAS, N6QW, W2AEW, and G3UUR for all the good advice and encouragement.  Please put any additional ideas in the comments below.  

CBLA: A CALL TO ARMS!

Dave AA7EE alerted us to this attack.  Please follow-up by posting reception reports (and triangulations!) in the comments below.  Dave writes:  

Recently, an unlicensed beacon (for which read pirate) has turned up on 3579 KHz. It seems to be located somewhere in the Western US, in the tradition of unlicensed HF beacons dating back to the late 80's that were solar-powered, and located in remote areas of the Southwestern deserts. The very first ones were a cluster of beacons around 4096 KHz (a frequency for which crystals were cheaply and easily available).

Anyway, I am equal parts intrigued and miffed by this latest clandestine operation. Intrigued because of the mystery surrounding all such clandestine operations. Where is it? What does it look like? Who built it, and why? I'm also miffed because, well, dagnabbit - it's on our turf!

It can be heard nightly after dark in the West, on both the KFS and KPH SDR's, in Half Moon Bay and Point Reyes respectively. It sends a series of 22 dits, then the call letters KOK, then more dits.

This is an outrage, a travesty, and a direct assault on the sovereignty of all self-respecting CBLA recruits! I call on all denizens of colorburst land to dust off their Michigan Mighty Mites and other plucky little transmitters, and launch the loud, raucous battle cries of  CQ, CQ, CQ into the ether. We shall fight them on the airwaves, we shall fight them in our radio shacks while drinking hot chocolate, winding toroids, and reading QST. We shall go on to the end. We shall never surrender!

I'm telling you Bill, when the very foundations of our existence are threatened, there is nothing that a colorburst crystal and half a watt from a 2N3053 transistor can't achieve. By golly, we can do this.

Your obedient colorburst servant,

Dave

AA7EE

W1QG's Cave Dust Twins (and other Homebrew Rigs -- SDR and HDR)

I kind of arrived at Dick Benson's QRZ.com page by accident, but what a happy accident it was.  There is a lot of homebrew goodness on Dicks page, both SDR and HDR.  

Check it out:  https://www.qrz.com/db/W1QG/

Listen to me talking to Jean Shepherd in 1976. I was 18 years-old.

Wow, here is a blast from the past.  I recently read a good article about Shepherd by A. David Wunsch in the Spring 2022 issue of the AWA Journal. David correctly focused on Shep's obsession with the Heising modulator, and the very negative impact ("Your mother should take you to a doctor!") that this had on his dating life. 

I was telling my wife about this article, and I commented that I had once spoken to Shep during an early morning call-in show on WMCA New York.  I told her that someone had sent me a recording of this brief conversation. 

The call took place in 1976.  Shep was appaearing as a guest on the late-night radio show of Long John Nebel and Candy Jones.   I was 18 years old. My callsign was WB2QHL.  The recording was sent to me by Matt KC8COM in 2006. Thanks Matt!  In 2008 I played the recording during SolderSmoke Podcast #90.  But I think this call merits a post on the SoldedSmoke blog, so here it is.  You can jump forward to about 3 minutes, 49 seconds.   

http://soldersmoke.com/JeanShepherd1976WMCA.mp3

One side note.  I told my wife that some time after the broadcast, I was once again up early in the morning, kind of absent-mindedly getting ready for work when I heard Shepherd talking on WMCA to some guy about ham radio.  It took me a moment to realize that this was a re-run, and that that guy was me!  

When I first listened to this I didn't realize that later in the recording (around 9:30) another fellow calls in an asks Shep about why he uses CW.  Shep is kind of short with him and ends up advising him to "go back to CB." I should note that in my conversation with Shep earlier in the program,  I told him that I was usually on "40 sideband."  He was nice to me, but said that he was mostly on 20 CW. 

Here is a good Wikipedia article on Long John Nebel: https://en.wikipedia.org/wiki/Long_John_Nebel

And here's one on his wife and WMCA co-host Candy Jones: 

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

Finishing up (?) Version 2 of my 15-10 Transceiver (Video) -- An Annoying Residual Carrier Problem

Front panel is on. RF PA is installed. Balanced Modulator problem fixed (?) Rig is on the air with about 3 watts, working lots of DX.

But there is an annoying amount of carrier that is still getting through. It is only about .5 watts with sidebands of 100 watts PEP, but it annoys me, and it makes the setting of the carrier frequency in relation to the filter passband very critical: If I set the carrier a bit too far from the passband I get improved carrier rejection (from the filter), but I also lose the lows in both received and transmitted signals -- the RX just doesn't sound as good. I see it in both of the 15-10 rigs (IF of 25 MHz). There is less of it in the 17-12 meter rig (IF of 21.4 MHZ), and none of it in the Mythbuster (75-20 meters) (IF of 5.2 MHz). I am now wondering if this might be a consequence of my using a very high (25 MHz) single conversion IF in the 15-10 rigs. What do you folks think?

From my log: March 7, 2024 PUT VERSION 2 of the 15-10 RIG ON THE AIR! 10S 1528 OK2RZ Jiri – said I was 57! 15S 1539 S52WW 58 Damian. 15S 1602 SP1NQH Stev said I am big signal! 10S S58N 1726Z 10S S58N 1726Z 10S S57S 1728Z 10S IK4GRO Lauro 1735Z 10S W0CJV 1825Z Ft. Collins Gary 10s 2000Zish KK7TV Gary in Randy. Asked what software/microcontroller I was using. 10S KJ5MFF 2015Zish a middle school in New Mexico. KI5MFF control op sent picture

 

"The New Essential Guide to Electronics in Shenzhen" A Book Review by Jenny List (with a video from Shenzhen)

This new book looks really good.  Great electronics info, with lots of cultural and linguistic wisdom. 

https://hackaday.com/2024/03/13/review-the-new-essential-guide-to-electronics-in-shenzhen/#more-668397 

Jenny's review brought to mind an older SolderSmoke blog post about Shenzhen. In this 2012 video  Bunnie Huang in Singapore talks about getting parts in that city: https://soldersmoke.blogspot.com/2012/08/singapore-knack.html

Thanks to Jenny, Naomi, and Bunnie.  

Using the RF Power Amplifier of the BITX40 Module

 

PA shematic from the BITX 40 Module

Click on the diagram for a better view

C.F. Rockey W9SCH (who alerted us in SPRAT 22 to the chicken sacrifice option) spoke of transistors that exhibit "quantum mechanical necromancy."  Rockey explained that when this happens, "The transistor simply turns up its toes and dies. Not even an Atomic Physicist can tell you why!"  

This often (very often!) happens with homebrew power amplifiers.  So when we find a good one, many of us stick with it, using the same power amp circuit in rig after rig.  I have done this with the power amplifier from the BITX40 Module. 

Mythbuster (75 & 20 Meter) version (early)  

Click on image for a better view. 

https://soldersmoke.blogspot.com/2021/08/mythbuster-video-13-rf-power-amplifier.html

Same amplifier built into Version 2 of the 15-10 Transceiver 

Click on image for a better view. 

In the build for the 15-10 transceiver you can see some changes.  I used an RD06HHF1 instead of an IRF-510.  I used an 8.1 volt zener diode instead of the regulator chip. I set the bias at around 5.5 volts DC on the gate of the RD06.   I used a smaller, metal can driver transistor (it works fine). I changed the input/output physical configuration between the pre-driver and the driver stages (I think it was kind of goofy the way I had it in the Mythbuster).  Finally, you can see how I used a small piece of copper tape (with conductive adhesive) to shield the line going from the driver transformer to the gate of the RD06.  The wire was too small to use a bit of shielded coax, but I think the copper tape and the copper clad board beneath it work just as well. 

Farhan provided me with some fascinating background on this circuit: 

Bill,

I just saw your post on the bitx40 power amp. The credit must go to Wes for this, it is from the Lichen transceiver described in 6.9 of the EMRFD. I merely copied it with some modifications for it to work with junkbox components.

It bears mentioning that at that time I didn't have a way of generating two tone signal or measuring the IMDR. Those came later when I built my own spectrum analyzer based on Wes and Terry White's spectrum analyzer. It was sheer luck that I picked this power chain that already had careful gain distribution.

For the output, the original build used and LPF with inductors wound on a ballpen shell and TV baluns cores instead of toroids. Again, it was incredibly lucky that they worked at all. 

- f

Justin's Receiver -- A 40 meter Superhet from AC8LV

 

FB Justin!  I really like the board that you are using as a base for the project.  And you have some great mentors in Nick and Loren.  

It is wonderful that you have that receiver working.  But I would tweak and peak quite a bit before taking on the transmitter.  Get a decent outside antenna -- even a dipole or a 1/4 wave with counterpoise would be a big improvment.  Like this one:  

https://soldersmoke.blogspot.com/2023/03/an-antenna-for-high-school-direct.html

And try to square away the grounding on the board (maybe some copper tape from Amazon) and the power supply you are using (I hope it is not one of those noisy wall warts).  When  you are experimenting, it can be useful to power varous stages with 9V batteries -- this is a good way to find out where noise is coming from.  If your AF amp is squealing at 12 volts, you need to break the feedback loop that is leading to oscillation.  Often the feedback is through the power supply.  Finally, try to get that homewbrew crystal filter working -- if the bandpass is uneven, you just need some impedance matching at the input and output.  

Great work Justin!   Keep at it.  73  Bill 

Bill,

I am sending video and pictures of my 40m  superhet that I built. I have it on the floor in an extra room in the house. The antenna is a stock vhf dipole that came with my rtl sdr which I use as a spectrum analyzer. In one of the clips I am receiving RW7K. I have been working on the station for the past year with help from Loren Moline, WA7SKT through texts when I have a problem. The LO / VFO is from Nick Woods Videos.

Next, I will build an outdoor antenna and the transmitter section. I first started homebrewing at the beginning of the pandemic, but this is by far my largest accomplishment. I would like to thank you and Pete for the soldersmoke videos which have been a great inspiration.

I will send more updates when the transmitter section is finish along with a much longer description of the projects

Thank you

Justin Elliott
AC8LZ

Bill, Pete, and Dean 

Thank you for the compliment. Pete, I want you to know, I’m a huge fan and I enjoy the one-liner jokes. I enjoy your contributions to the videos when you’re on Dean. 

Here are pics / videos of my superhet. 

The bandpass filter is a homebrew version of qrp labs design for 40m, I had to add an extra capacitor to get the bandpass where I wanted it. It is 6.9mhz to 7.32mhz. 

Mixer / demods are ade-ask.

The rf amps are kits i bought online, assembled, then used the schematics to replicate. They are the W7OI created and which have been mentioned on the channel

The LO/VFO are arduino driven from Nick Woods (M0NTV) YouTube channel. I believe episode 26

The crystal filter was built for 9MHz, but when I swept it I found the bandpass was saw toothed, so I used a commercial filter that Loren Moline WA7SKT sent. 

The audio amplifiers are a Common Emitter Amp I found on YouTube, I can’t recall the channel and a commercial amplifier, which I can now reproduce as I have the schematics. 

The speaker is a 2W 8 ohm speaker. 

...

Justin Elliott

AC8LZ