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