A Song Fom Dexter ZL2DEX

From a post on on "ZL Amateur Radio & Friends,"  in response to a complaint about the lack of activity (with apologies to Paul Simon):  

'50 Ways':

"Get on the band, Stan,
Trigger the mic, Ike,
Tap your key, Lee,
Listen for me.
Paddle the bug, Doug,
Watch the waterfall, Paul,
Just QSO, Joe,
when conditions agree."

73

Dex, ZL2DEX

Chuck Adams K7QO's AMAZING Lab Notebook

Thanks to Tony G4WIF for alerting me to this amazing (and free!) e-book by QRP Master Builder Chuck Adams K7QO: 

https://www.k7qo.com/lab.pdf

There is a lot of wisdom and tribal knowledge in that .pdf.  

Thanks Chuck. 

Mars is BACK! 2020 Opposition! Don't Miss it!

2004 

Sometimes waking up a bit earlier when the sunrise is coming later leads you to some interesting things.  

It was quite humid in Northern Virginia on the morning of 25 August 2020, but the skies were surprisingly clear.  I stepped outside at about 0500 local time, coffee cup in hand.  Venus was blazing in the east.  Then I saw this big very bright red thing high in the southern sky.   It seemed almost too bright and too high in the sky to be Mars.  But a quick check with Stellarium showed that it was in fact the Red Planet.  I pulled out my six inch Dobsonian reflector telescope and soon had Mars in the eyepiece.  

For the first time in many years I could see surface features:  It is springtime in the southern hemisphere of Mars, but the Southern Polar Cap (which recedes in the summer) was still very prominent (in my eyepiece it was near the top, as in the GIF above) .  I could also see an albedo (dark on light) feature below the icecap.

I went out again on the morning of 26 August 2020.  Again the Southern Polar Cap was very visible.  Below it, near the center of the disc,  I could make out a large albedo feature.  I am pretty sure that is Mare Erythraeum.  

Above is what Stellarium presented as Mars as viewed from Earth this morning. The Southern Polar Cap is much more prominent in my telescope (you can see it in the upper right in the image above).  The large dark thing near the center of the disc is Erythraeum.  In the Stellarium image you can see the enormous Vallis Marinaris canyon shooting off to the lower right (sadly I could not see this in my telescope). 

The GIF at the top of this post gives a much better view than I get with my little six inch telescope.  The GIF gives a good idea of what the albedo features and the ice cap look like.  

This was a great time for me to see these things.  I'm almost done with the second book in Kim Stanley Robinson's Mars Trilogy -- much of the story takes place in sanctuaries carved under the Southern ice cap, and in Hellas (which Robinson's colonists are filling with water).  During the 2018 Earth-Mars opposition a big dust storm made it impossible for me  to see anything on Mars; a similar storm takes place during book one of Robinson's Trilogy. And right now the Perseverance rover is on its way to Mars.  

This 2020 opposition will be the best one until 2033.  So don't miss it. 



Here is a good article on observing Mars during the current opposition: 
https://www.skyatnightmagazine.com/advice/skills/how-to-observe-mars/

Here are technical details on the 2020 opposition: 
http://www.alpo-astronomy.org/jbeish/2020_MARS.htm

To see what side of Mars is facing us at any time, use Sky and Telescope's Mars Profiler: 
https://skyandtelescope.org/observing/interactive-sky-watching-tools/mars-which-side-is-visible/#

Here is a very informative video about the 2020 opposition: 



And remember:  The Elser-Mathes Cup has still not been won.  

Great Video on PC Board Techniques, with a Focus on Surface Mount

Wow, lots of wisdom in this video from Leo Fernekes.  Great hints and kinks on prototyping with copper clad boards. I need a Dremel just so that I can make Leo's board cutter.  And I can see that I need some of that liquid flux and isopropyl alcohol. Surf boards and headers! Who knew?  Teflon coating for the wires -- gotta get it. Glad to see that Leo is also a fan of copper tape.

His emphasis on the importance of stage-by-stage construction and testing is right on the mark.  

My only disagreement with Leo is about his use of steel wool.  I've found that steel wool will inevitably cause little tiny "Murphy Whiskers" to float around your workbench. They will eventually settle onto the most inconvenient and damaging place on your board.  So I have banished steel wool from my workshop.  Those green, non-metallic Scotch Brite pads work just as well and don't cause shorts. 

Three cheers for Leo. He is based in Thailand.  He has an interesting background and some really amazing projects and insights:  

http://www.luminati.aero/leofernekes

http://www.fernekes.com/blog/

https://www.youtube.com/channel/UCe1bjEcBichpiAMhExh0NiQ/videos

Thanks to Tore LB4RG for alerting us to Leo's video.  

Experimental Methods Book on Clearance sale -- $20

http://www.arrl.org/shop/Experimental-Methods-in-RF-Design-Classic-Reprint-Edition/

And it includes a .pdf copy of Solid State Design for the Radio Amateur. 

Video on the Strange Tuning of the Radio Shack DX-390 Receiver

I'm more of a single conversion guy myself, but in working with the DX-390 I came to appreciate the benefits (especially regarding image rejection) of the double conversion technique. 

While working on the DX-390, I discovered that the BFO control on the front panel DOES NOT change the BFO frequency.  It was fun to try to figure out why the designers did it this way.  It does make sense once you consider the limitation imposed by that PLL main tuning oscillator that only moves in 1 kHz steps. I hope the video explains things.  

Here is the drawing I used in the video: 

And here is a drawing that shows how a single conversion superhet with a fixed or switchable  (usually crystal-controlled) BFO works: 

Earlier this month  I did a blog post on my repair of a broken DX-390: 

https://soldersmoke.blogspot.com/2020/08/fixing-up-radio-shack-dx-390-aka.html

Mike WU2D's Great Drake TR-3 Refurb Video -- Part 2

Mike WU2D made another very nice video about his Drake TR-3 refurb. 

He cracked me up when he noticed that one of the calibration oscillators was 30 Hz off.  "Let's pretend we care," said Mike.  Indeed. But it was probably wise to tackle this problem, given how upset modern hams seem to get with 30 Hz discrepancies.  Mike noted that the problem was casued by "aging cystals." Yikes! Another thing to worry about, along with the Southern Magnetic Anomaly. 

Once again Mike has added a useful term to our lexicon:   "The Dribble Method" of signal injection (or extraction):  Just wrap a few turns of insulated wire around the tube or IF can and inject or measure away.

Neutralization! Now there's a blast from the Thermatron past.  I haven't done that in a long time. I liked Mike's "reverse neutralization" method. 

Mike's video featured some real Boatanchor eye candy.   That Heathkit HR-10 receiver caught my eye, as did that HP signal generator. 

Thanks Mike.  One hand behind your back OM.    

Very Cool Vosworx AZ-EL Satellite Tracker

When I was in the Dominican Republic working the RS satellites, MIR and the Space Shuttle, I didn't have an elevation rotator.  I could only move the antenna in the azimuth plane.  So I just aimed it about 45 degrees above the horizon, spun it around, and hoped for the best.  I also had no computer control of the azimuth heading -- I'd just watch the location of the satellite on my computer screen and operate the rotator control manually.  

This device is a big improvement. 

The Original Tuna Tin 2 (and the Mojo Transfer Ceremony with W1REX)

From the Amateur QRP Radio group on Facebook:‎

Brian Murrey‎to

 Amateur QRP Radio

The Original Tuna Tin II built by Doug DeMaw W1FB (SK)...Ed Hare W1RFI of the ARRL Lab, brought this to FDIM in 2001 and allowed us to borrow it for a night. It was so cool. The little guy was found at a hamfest somewhere on the east coast, and brought back to the ARRL. Bruce Muscolino W6TOY (SK) recieved it from the ARRL and he replaced missing parts and got the thing working again. It's in the museum at the ARRL HQ today. I think we made like 16 contacts using that for the transmitter, and a homebrew receiver from Diz W8DIZ that was part of the MultiPig Rig. Antenna was a dipole we had strung up out the window of the Ramada Inn (FDIM Central).
-----------------------------------
Here is my only encounter with the original Tuna Tin 2 -- In 2014 Rex W1REX conducted this solemn ceremony in which some of the TTT mojo was transferred to my homebrew BITX 17. 

The South Atlantic Anomaly in Earth's Magnetic Field

In case you've grown tired of worrying about infectious disease, here's another scientific problem for you to worry about:

https://www.youtube.com/watch?v=qpdQcw_52iM