Ferdy HB9DSP's 5 band Moxon -- The Moxhorn!

 

Click on the image for a clearer view

Wow, I couldn't even build a 2 band Moxon, but Ferdy has built a 5 band version.  He told me that he had to tweak the elements a lot to get acceptable SWR's on all the bands.  20 and 17 are especially tough, because they are so close in frequency.  

More info on his great QRZ page: https://www.qrz.com/db/HB9DSP

Thanks Ferdy! 

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! 

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. 

A Very Clever Way to Build a Moxon for 17 and 20 meters

Jim AB9CN sent us Dan Zimmerman N3OX's page in response to my plea for help in SolderSmoke #227.   I think this is a very clever and attractive way to cover both bands with a single Moxon.  

http://www.n3ox.net/projects/2017moxon/

Of course there are other ways to do this -- other listeners wrote in with confirmation that it is indeed possible to nest a 17 meter element inside a 20 meter Moxon (as is done routinely with Hex beams), but this requires a lot of cut-and-try tuning of both antennas.  More in this in future posts.  Thanks Jim, and thanks to all who wrote in. 

I kind of like the N3OX approach.  I think his design makes it more of a workbench electronic project, as opposed to a mere wire and coax antenna project. But hey, that's just me. 

Adding 10 kHz of Coverage to My BITX 17

 

Solar Cycle 25 is underway.  The Solar Flux Index and Sunspot numbers are up considerably.  I have dusted off my old BITX17 transceiver.  This time around I am using it in conjunction with a waterfall display provided online by NA5B's KiwiSDR receiver, which is located about 9 miles east of me. This SDR receiver allows me to see the entire 17 meter band.   It was this panoramic display that made me pay more attention to the fact that the Variable Crystal Oscillator (VXO) that I am using in this rig prevented me from tuning the lower 10 kHz of the 17 meter phone band (18.110 -- 18.120 MHz). 

I use two crystals switched by a relay to cover the band. One is at 23.149 MHz, the other at 23.166 MHz.  The crystal filter is at 5MHz.  With a coil and some caps I could move the frequencies of the oscillator enough to cover 18.120 to 18.168 MHz (top of the band). 

When I first built this thing, I kind of wrote off the lower 10 kHz of the phone band.  I couldn't get the oscillator to work that low, and I was already satisfied with the top 48 kHz.  But the NA5B waterfall often showed SSB stations in that lower part of the band.  I wanted to talk to them.  So I started thinking about how to do this.       

Looking at my schematic (above) I remembered that most of the frequency lowering was done by L1, a 3.2uH toroid.  I figured that to go a bit lower, I would just have to add inductance.  But I didn't want to lower the frequency provided by BOTH crystals -- I just wanted to bring the frequency with the lower crystal down a bit.  

In my junkbox I found a 1 uH coil.  I disconnected the lower lead of the 23.149 MHz crystal from its connection to the relay.  I soldered the 1 uH coil between the crystal and the relay (see picture above).  This moved the lower limit down to 18.087 MHz. 

Now crystal one provides 18.087 - 18.144 MHz 

         crystal two provides 18.137 - 18.167 MHz

So now I have the whole phone band.  Bob is my uncle. TRGHS. 

This was a very quick and satisfying little fix. As Pete says WYKSYCDS: when you know stuff you can do stuff.  Indeed.  And as I re-build and repair gear that I built years ago, I am often reminded that as time goes by, we learn more. We end up knowing more and being able to do more.   

I am also planning on rebuilding my 17 meter Moxon;  this time I will make it better and stronger.         

The Moxon Files from L.B. Cebik W4RNL

I had thought that the Cebik files were lost to us in some sort of legal copyright struggle.  But in my effort to better understand the Moxon antenna, I found a real treasure trove of Cebik's writing.  These should all be saved somewhere safe. 

I especially liked his description of the evolution of the Moxon antenna.  Les Moxon was apparently very unAmerican in his emphasis on reception (not transmit gain)  as the main benefit of the beam antenna.  He also sought to avoid superfluous luxuries like rotators, but Cebik hints that rotators have become an important part of our American way of life.   Indeed.   
Before I found these files I had been on the verge of giving up on efforts to replace my storm-damaged Moxon.  After all, solar minimum is still ahead of us.   But after reading OM Cebik's articles I have decided to build a 20 meter version and place it above the center point of a 130 foot doublet.  I will have the best of both worlds.  

http://www.antentop.org/w4rnl.001/mu0.html

http://www.antentop.org/w4rnl.001/mu2a.html

L. A. Moxon, in his HF Antennas for All Locations, provides the essential clue: "the main benefit [of a beam] accrues from the reduction of interference during reception, though the 4 to 6 dB gain provided by typical amateur beams is an important bonus and probably the reason which carries the most weight with the majority of amateurs."⁽²⁾Here is a theory of beam operation quite unAmerican is style: instead of gain, Moxon strives for front-to-back ratio as the most crucial aid to ham operation. His statement is an affirmation of the "good ears" theory of operation. Even more, it forms the basis for his rectangular improvement upon the VK2ABQ square.
...
 Moxon prefers matched elements, tuning each of them to optimum performance remotely. That way, he can reverse the beam and do away with expensive and maintenance-intensive rotators. However, rotators are a way of life in the U.S. (a TV rotator will likely handle a 3-band Moxon beam), and there are many uses for portable beams that are hand-rotated or fixed in the field. Thus, I decided to continue the exercise in unequal element lengths.

http://www.antentop.org/w4rnl.001/mox20.html

Finally, a treasure trove of Cebik's writing: 

http://www.antentop.org/w4rnl.001/radio.html

Understanding Antenna Directivity -- Help from Canada

I am in the process of repairing my beloved 17 meter fishing-pole Moxon.  It was taken out of service by the last Nor'easter of the winter.  This repair has caused me to review the theory behind antenna directivity.  I find there is a lot of "hand waving" in the explanations of how directivity happens:  "You put a reflector element next to the antenna.  And it REFLECTS!"   You are left wondering how that reflection happens.  

The Royal Canadian Air Force made a video that does a pretty good job of explaining how the reflector reflects.  See above.  Thanks Canada!  

While we are talking about antennas,  I wanted to alert readers to a really nice antenna modeling program that is available for free.  It is called 4nec2.  You can find it here: 
http://www.qsl.net/4nec2/   There is a bit of a learning curve, and I am still climbing it, but I can see how this software would be very useful.  It has an optimization feature that runs the antenna through many versions and tells you how to optimize for F/B,  gain,  SWR, or whatever you want to prioritize.  

I have discovered that my Moxon was resonant below the 17 meter band.  In other words, the antenna elements were too big.  About 3.6% too big according to my calculations.  This may be the result of my using insulated wire for the antenna elements.  Apparently the MOXGEN software assumes the use of uninsulated wire.  I'm thinking that an easy way to deal with this would be to use the frequency 3.6% above my target frequency and then use the dimensions given my the MOXGEN program.  Any thoughts on this plan? 

What a shame that Cebik's web sites have all disappeared.      

Moxon Destroyed

The north-east region of the U.S.  is experiencing a very strong winter storm.  These storms are called "Nor-Easters"- that describes their track up the coast.   Here, we had wind gusts at 71 mph -- that was around what we had with Hurricane Sandy.  But no rain or snow down here -- it is a different story in New England. 

I was on the air, having a nice chat with Ivo OP2A on 17 when suddenly my SWR went way up.  I knew immediately what had happened.  I stepped outside and saw what you see above. 

Oh well, we had a good run.  It went up there on July 20, 2014.  Not bad for some fiberglass poles from Amazon, some scrap lumber and some wire from Steve Silverman (thanks Steve).  

To tell you the truth I was kind of hoping this would happen.  I'll replace it with a Moxon or a Hex that covers at least 20 and 17.   

DL1YC's Flat Moxon with Armstrong Rotation

DL1YC Moxon

I had a very nice contact on 17 meters yesterday with Jan DL1YC.  It was a rare Moxon-to-Moxon contact, with homebrew 17 meter Moxons on either end.  Jan's is a bit cooler than mine:   His is flat, without the "blownout umbrella" support that we see in mine (below) and in the Hex Beams.  Jans told me that he achieved this flatness by starting out with very long telescoping fishing poles -- he discarded the the thin portions of the pole and used only the more rigid pieces.  (I used 16 foot, 5 piece Shakespeare Wonderpoles from Amazon.) I think he also used thin wire for the elements.  The crossbar that you see in the picture above is there to support a balun at the feed point -- without the cross bar the balun and the feedline would cause the balun to droop. 

I couldn't resist a little front to back testing.   Jan's antenna does not have a rotator -- he used the "Armstrong" method of antenna pointing.  I didn't want to make him go outside to spin the thing around by hand, so I just turned mine and asked him to take note of the difference front to back.  He saw 3 S units.  18 db.  Not bad.   

Jan said his antenna weighs about 8 pounds -- mine is very similar at 9 pounds.  Jan expressed some concern about UV deterioration of the fishing pole fiberglass.  Mine has been up there three years without any problems.  

Like me, Jan had considered "nesting" an element for another ban (perhaps 20 or 12) but -- like me-- had concluded that this would be too difficult. 

N2CQR Moxon

Les Moxon, G6XN

I was on 40 SB tonight talking to Don KC5YR. He is the creator of the web site known as the Moxon Antenna Project: http://www.moxonantennaproject.com/   That site had this great picture of OM Les Moxon, inventor of the wonderful antenna that bears his name.  I also found this old QSL card that shows some of Les's homebrew gear.  Les has been a Silent Key for many years now, but his legacy lives on.

Antennas and National Monuments

We started SolderSmoke 185 with a brief description of my recent ascent to the top of the Washington Monument.  A few days later I was visiting George K9GDT's wonderful web site
http://www.qsl.net/k9gdt/radio/radio.htm  and in the humor section came across the above Gil cartoon from 1959.  That is the general idea. 

Pete then sent me this:

Pete originally had a three element Yagi coming out of Teddy Roosevelt's head, but that just wasn't right.  I asked that it be changed to a 17 meter Moxon.  Thanks Pete.

I would like to note for the record that I have no intention of using the Washington Monument, the Statue of Liberty, Mount Rushmore or any other national monuments as supports for any Yagis, Moxons, Cubical Quads, Ray Guns, Lazy H's, Inverted L's or any other type of electromagnetic wave launcher.

Old Spark (But Thankfully Not Forever)

For the last couple of weeks I have been plagued by noise on the HF bands.  In spite of being in a very built-up area of Northern Virginia,  I usually have low noise levels.  But for the last couple of weeks I've had intermittent but frequent arcing noise.  It sounded like classic power line arcing. 

My 17 meter Moxon antenna provided a clue as to where it was coming from:  As I spun the antenna around, the noise was always a lot stronger to the North-North West.

On Wednesday morning on the way to work I noticed that the fire department and the power utility were working frantically on a pole about a mile from our house.  It had obviously been on fire -- it was still smoking when we went past.

When I got home I was pleasantly surprised to find the arcing noise gone.  It took me a few minutes to make the connection -- yes, the smoking power pole was to my North-North West. 

OBVIOUSLY THE RADIO GODS CAME TO MY ASSISTANCE!

This was a good demonstration of the fine front-to-back characteristic of the Moxon antenna.  And a reminder of what radio signals sounded like in the days of spark. 

The 9CS transmitter (from http://www.ontheshortwaves.com/EarlyAmateur.html)

  

Cutting Edge Regens! No, really.

Bill - 

Thanks so much for featuring The Sproutie on your blog. I heard through my friend Jason NT7S on Twitter that you had built a regen and we both did a double-take. Bill from Soldersmoke building a regen - and enjoying the experience? I was frantically pinching myself, as it just didn't seem likely, given your past bad karma with them but there it was - a lovely old set with that great brushed aluminum finish with the swirls on the front panel - and being worked on by Bill N2CQR. Wonderful!  I have been meaning to either e-mail you, or comment, perhaps below the post in which you featured the letter from Todd VE7BPO. I discovered recently that although we think of regens as being an established, and now stagnant technology, there are still people doing cutting edge research on them.  Some of the discussion was in the Yahoo regenrx Group, and much of the research is being done by a fellow from NJ with the username vladn. Concerning the phenomenon that we notice with our regens that, as we get close to the threshold of oscillation, the bandwidth narrows, and then as we advance into oscillation (as we do to receive SSB and CW), the bandwidth broadens out somewhat, I am going to quote verbatim a comment that was left on my blog by user qrp.gaijin,

This phenomenon has been deeply analyzed and explained (by user “vladn”) here:http://theradioboard.com/rb/viewtopic.php?f=1&t=4680&start=0 . It is, in fact, possible to completely eliminate this phenomenon; bandwidth can be controlled independently of oscillation amplitude (to choose a desired amount of selectivity), and oscillation amplitude can be controlled independently of bandwidth (to control how easy it is for the regen to lock on to the incoming signal: we want a low oscillation amplitude and easy locking for synchronous AM reception, whereas we want a high oscillation amplitude and no locking behavior when listening to SSB). Eliminating this phenomenon, i.e., separating control of bandwidth and oscillation amplitude, can be done by using an explicit amplitude limiter (i.e. a separate transistor/tube stage as part of the oscillator’s explicit amplitude stabilization control loop) that exhibits scale-independent gain compression. In other words, regardless of the oscillation amplitude, if the oscillator’s gain compression (amplitude limiting) behavior is scale-independent, then the final result of the repeated selective amplification (that defines the final regenerated Q and bandwidth) will be the same, regardless of the oscillation amplitude. See this video (by vladn) for a demonstration of independent control of oscillation amplitude and bandwidth: http://www.youtube.com/watch?v=UyqD99WGlss .

The fellow in NJ whose username is vladn has built a regen to test the above theory, and it works! You can see it in the video that is linked in the above quote. vladn has done other equally cutting edge research into regens, but I wanted to let you know that these little receivers are still being developed and improved by a few intrepid experimenters. Howard Armstrong would be so proud!

Best of luck building your regen Steve. With Bill Meara now a regen fan, the radio Gods are on your side!

73,

Dave
AA7EE

****************

Hi Bill and Dave,

The Soldersmoke blog post about the Sproutie super-regen radio by Dave got my soldering iron warm without even turning it on!  That National N Velvet Vernier dial really got my homebrew and radio nostalgia juices flowing with that beautiful nickel plating and the big shiny Bakelite knob.  Plus the use of modern semiconductors along with an Octal socket for the plug-in coils was almost too much to bare.

I immediately bought the National dial and the two variable caps on eBay and from the link Dave suggested in his post for the dial.  That custom chassis company, while in Nova Scotia, is quite close to me here in Maine, and I just might have to visit them to talk about the details of my proposed chassis. 

The obvious next step is a real PCB, but Dave's beautiful technique using the ME squares and pads is hard to argue with.  Those solder-friendly squares and pads are local to me too from good ol' Rex Harper.

Bill, many thanks for your post and link. Dave, thanks for the great design and implementation, as well as the amazing details and photos on your blog.  I think I see a HB super regen project in my immediate future. The parts are piling up!  Gary sold out of the N dials almost immediately.

73

Steve Silverman  KB3SII ... .. ..

**************

I'm really glad that Steve wrote in because his e-mail reminded me that I need to thank him again for the multiband dipole that he sent me a couple of years ago.  For a number of reasons I couldn't really use it in its original configuration, but the wire has been used in almost all my recent antenna projects, including the magnificent Moxon.  The black insulation was just what I needed for that essential stealth effect.  Thanks Steve. 

  

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Moonlight Moxon

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My Moxon on Hackaday!

I was really pleased to see my Moxon on Hackaday.  Their write-up was a lot of fun.

http://hackaday.com/2014/07/23/fishing-for-radio-signals-with-the-moxon-antenna/ 

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Moxon Aloft!

We put it up on the roof this afternoon.  I think it looks great!   The neighbors have not yet risen up in opposition to the new skyhook.   My family thinks it cool that I can spin it around.   I have it pointed at Europe and I notice a big difference.  I've worked F5LIW, OT4A, YL2BJ,  F5BBD.  Lots of fun. 

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Scrap wood, some wire, four fishing poles and an old tripod: Moxon Update

 

It is not up on the roof yet, but we are getting close.   Above you can see he center "hub" -- just some scrap plywood and 8 u bolts.



 

Here is how I handled the corners.  The coil thing is from the end of a bungee cord. It makes for easy disassembly. 

 

 

 

Here is how the mast connects to the hub.  I had some 1x1 scrap wood. The 1x1 will be U-bolted into the rotator.  



 

 

 

Made of wire and fishing poles, Moxons are not very photogenic.  But I think mine looks great.  The 17 meter version is quite small. 

 



 

A bit of a balun.  Just to keep RF currents off the outside of the braid.

 



 

That tripod was last aloft in the Dominican Republic (1992-1996!).  Two spray cans of flat black paint have been applied.  Stealth!  

 

Four 16 foot "crappie" telescoping fiberglass poles purchased from Amazon.   



 

The only thing holding me up at this point is a safety concern.  The roof has a somewhat steep pitch, and I am not at agile as I used to be.   So before I install this magnificent sky hook I'm getting one of those roof safety harness systems that roof workers are supposed to use (but rarely do).  This sill also benefit the poor fellow who comes to clean our gutters.  



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Latest Project: 17 Meter Moxon

17 Meter Moxon by AE6AC

That's what I have in mind.  I ordered four fiberglass "crappie" poles yesterday.  I have a tripod for the roof.   What should I use to spin this thing around?  A TV rotor is an obvious solution, but the last time I used one it didn't hold up too well.  There is always the Armstrong method...  

Here's AE6AC's site:

http://www.moxonantennaproject.com/ae6ac/ae6ac.htm


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