15 Meter Homebrew SSB Rig As Heard in Mexico City

 19 August 2023. Ralph XE1RK recorded part of our QSO and played it back to me. Thanks Ralph!

I was running about 75 watts to a hex beam aimed Southwest.

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.  

More Ancient Technology Keeping Space Missions Alive

 https://www.bbc.com/future/article/20230815-the-ancient-tech-keeping-space-missions-alive

Three cheers for software.  Really. 

Working Indonesia and Chile with new 15-10 Homebrew Transceiver

Conditions were good this morning, and the Radio Gods continue to favor homebrew rigs.  I got on 15 meters SSB with the new 15-10 dual bander and quickly worked YH0AD in Jakarta (about 10,000 miles).  A few minutes later I talked to YB2MVD; he was a bit further east on Java.  I shot a video of the QSO with YB2MVD.  He said I was 59.  

I then switched to 10 meter SSB (same rig) and worked CE4PS in Chile (5,000 miles).   

TRGHS. 

The antenna for all these contacts was my K4KIO Hex Beam.  I was running about 75 watts from the .1kW CCI amplifier. 

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: 

https://www.qrz.com/db/VU2DGR 

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. 

You have heard of the International Geophysical Year (IGY). But have you heard of the IQSY?

 

International Quiet Sun Year.  1964-1965.  Yes, that was a thing.  

Voyager, Canopus, JPL, and 74xx Logic Chips from the early 1970s

"So somewhere out there in interstellar space beyond the boundary of the Solar System is a card frame full of 74 logic that’s been quietly keeping an eye on a star since the early 1970s, and the engineers from those far-off days at JPL are about to save the bacon of the current generation at NASA with their work. We hope that there are some old guys in Pasadena right now with a spring in their step."

https://hackaday.com/2023/07/31/just-how-is-voyager-2-going-to-sort-out-its-dish-then/

Understanding Maxwell's Equations (video)

And you should also look at the accompanying web site: 

https://www.maxwells-equations.com/m/index.php#maxwells

Writing about the equations, the author notes, "They are formidable to look at - so complicated that most electrical engineers and physicists don't even really know what they mean.  This leads to the reason for this website - an intuitive tutorial of Maxwell's Equations. I will avoid if at all possible the mathematical difficulties that arise, and instead describe what the equations mean. And don't be afraid - the math is so complicated that those who do understand complex vector calculus still cannot apply Maxwell's Equations in anything but the simplest scenarios. For this reason, intuitive knowledge of Maxwell's Equations is far superior than mathematical manipulation-based knowledge. To understand the world, you must understand what equations mean, and not just know mathematical constructs. I believe the accepted methods of teaching electromagnetics and Maxwell's Equations do not produce understanding. And with that, let's say something about these equations." 

Thanks to Armand WA1UQO for sending me the wonderful book about Faraday and Maxwell that put me -- once again -- on the path toward a deeper understanding of their work.  

https://www.amazon.com/Faraday-Maxwell-Electromagnetic-Field-Revolutionized/dp/1633886077/ref=sr_1_1?crid=1ZRPDYCCN9CGA&keywords=Faraday+and+Maxwell+Forbes+Mahon&qid=1690716355&s=books&sprefix=faraday+and+maxwell+forbes+mahon%2Cstripbooks%2C55&sr=1-1

Thanks also to Michael Rainey AA1TJ.  Several years ago he commented that he too wanted to get a better understanding of these equations. 

Phase Noise and the Radio Amateur

A weak signal disappears in the phase noise of the stronger signal.

The March 1988 QST provides a relatively clear explanation of what phase noise really is:

https://www.robkalmeijer.nl/techniek/electronica/radiotechniek/hambladen/qst/1988/03/page14/index.html

Highlights: 

Phase noise is an undesired variation in the phase of the signal. In this case, an oscilloscope shows that the time between zero crossings of the signal varies over time when compared to the zero crossings of an ideal sine wave. An exaggerated example of phase noise is shown above.

Phase noise on an oscillator signal has exactly the same effect as frequency modulating the oscillator with noise.

Whenever a carrier is passed through a mixer, the phase noise of the oscillator driving that mixer is added to the carrier.

Phase noise on a transmitted signal causes effects identical to phase noise generated in a receiver.

Any signal that reaches a mixer in the receiver is modulated by the phase noise in the local oscillator driving that mixer. As such, the signal appears to have at least as much phase noise as the local oscillator. Thus, sufficiently strong signals off the receiving frequency can degrade receiver sensitivity by raising the noise floor at the receiving frequency. Receiver dynamic range is reduced as the noise floor rises.

With a frequency-shift-keyed or- a phase-shift-keyed signal, the close-in phase noise limits the maximum bit error rate that the system can achieve. Both of these effects can be quantified once the communications system is defined. With an SSB voice signal, the effects are much harder to predict, but excessive phase noise does degrade SSB signal intelligibility to some extent.

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Receiver guru Rob Sherwood provides some very useful historical background on his web site:

http://www.sherweng.com/documents/TermsExplainedSherwoodTableofReceiverPerformance-RevF.pdf

Phase Noise: Old radios (Collins, Drake, Hammarlund, National) used a VFO or PTO and crystal oscillators to tune the bands. Any noise in the local oscillator (LO) chain was minimal. When synthesized radios came along in the 70s, the LO had noise on it. It is caused by phase jitter in the circuit, and puts significant noise sidebands on the LO. This can mix with a strong signal outside the passband of the radio and put noise on top of the weak signal you are trying to copy. This is a significant problem in some cases: You have a neighboring ham close by, during Field Day when there are multiple transmitters at the same site, and certainly in a multi-multi contest station. You would like the number to be better that 130 dBc / Hz at 10 kHz. A non-synthesized radio, such as a Drake or Collins, has so little local oscillator noise the measurements were made closer-in between 2 and 5 kHz.   

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Experimental Methods in RF Design (EMRFD) has this to say about phase noise:

"The local oscillator is a critical part of any communications system. Modern transceiver performance is often compromised by LO systems that suffer from excess phase noise, effectively limiting the receiver dynamic range. While quiet oscillators, those with low phase noise, can be built using traditional methods, these circuits often lack the thermal stability of a synthesizer.... Frequency synthesis is not, however, the answer to all the LO problems presented to the experimenter.  Some PLL synthesizers are burdened by excessive phase noise. Those using DDS, while quieter, emit spurious outputs, often in profusion.  Both use an excess of digital circuitry that can often corrupt a receiver environment."  page 4.1

   

"At first glance, phase noise sounds like an esoteric detail that probably has little impact on practical communications.  This is generally true." page 4.12 

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Hans Summers G0UPL analyzed and measured the phase noise of the Si5351a chip: 

http://qrp-labs.com/qcxp/phasenoise.html

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DC4KU appears to be using the crystal filter method used by Hans: 

https://dc4ku.darc.de/Transmitter-Sideband-Noise_DC4KU.pdf

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Martien PA3AKE has done a lot of great work on this topic.  See: 

https://martein.home.xs4all.nl/pa3ake/hmode/dds_pmnoise_intro.html

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Dean KK4DAS commented on the phase noise video of the IMSAI guy: 

Watching the video I was reminded of Segal's law roughly paraphrased as follows.:

A man with one spectrum analyzer knows his phase noise. A man with two is unsure.

First Contacts with 15-10 Rig -- Two Atlantic Crossings

 

I was just testing it, working (as usual at this stage) on final amplifier stability.   Then I heard ON5WO calling CQ.   I could not resist.  I worked him, but had to use a test lead to manually key the .1 kW amplifier.  Minutes later I worked OH6RM.  He very diplomatically said that I had "highly unusual audio."  This was probably due to earlier efforts to shift the carrier oscillator to improve carrier suppression. (I will fix this.)  

I will continue to work on the rig; It should look a bit better when I am done.  But hey, it works!  It has already crossed the Atlantic. Twice!  

"Onda Corta" ("Shortwave") -- A Short Film about Ham Radio in Venezuela (Please ID the Boatanchors!)

https://youtu.be/J1QlKykhR2M?t=583

I have it cued up to 9:43 -- at that point Ramon is in his ham shack.  

Lots of good stuff in there! 

Please ID the rigs/parts you see and list them in the comments below. 

This version has subtitles in English.  I like it -- a nice story.  And the whole film is only about 15 minutes. 

Going Down the Phase Noise Rabbit Hole with the IMSAI Guy (VIDEO) -- Is there a better way?

Chimera:  2.

a thing that is hoped or wished for but in fact is illusory or impossible to achieve.

(from the Oxford English Language Dictionary). 

Phase Noise.  We know what it is, but how do you measure it?  Pete N6QW and I went through this back when people were casting phase noise aspersions at (Pete's!) beloved Si5351.   More recently phase noise hate  has been focused on (my?) beloved Franklin oscillator.  When I asked a very technically proficient and guy at the VWS club if he could measure phase noise, I was surprised when he honestly said that he could not. 

And now we have the IMSAI guy saying, essentially, the same thing.  Wow, if the VWS guy and the IMSAI guy -- with all the spectrum analyzers at their disposal -- have trouble measuring phase noise, what hope do we ordinary hams have?  I mean, at best most of us have just an oscilloscope, a NanoVNA,  and a TinySA.  

Look, I know that phase noise is real and in certain circumstances, it is important.   But sometimes I suspect that its measurement is also a bit of a technical chimera:  If,  for whatever reason,  there is a circuit that you don't like, you can claim that the phase noise of that circuit is bad.  Or horrible. I think we see this sometimes with the Franklin oscillator.  Very few hams will be able to measure it and dispute the assertion that the phase noise is bad.    

For a perhaps painful walk down SoldeSmoke's "Phase Noise Memory Lane"  go here: 

https://soldersmoke.blogspot.com/search?q=Phase+Noise

Thanks to the IMSAI guy for a great video.   But let me ask:   Is there a better, simpler way to measure phase noise?  One that will avoid chimerical results and that could be used by hams with sort of standard ('scope, sig gen, NanoVNA, TinySA) test gear?