Summer Fun – A Moxon Antenna for 6 metres

Six Meters is a great Amateur Radio band, and there are quite a few active operators,  but just about everyone I’ve talked to recently says something along the lines of “ Six Meters sounds great I’d love to be on it”,  or “I’d love to get on Six Meters but I don’t have an antenna” It seems it’s seen as more of a “summer only”  band in times of slow solar activity. Indeed, ‘ol Sol isn’t going to let you talk to England via the F2 layer with the current number of sunspots.

Even without big sunspot numbers,  Six meters is a lot of fun via Summer Sporadic “E” layer propagation. VK wide and VK-ZL paths are often a daily occurrence, and VK-Pacific regions, VK-Hawaii, VK-West Coast NA/SA are all a possibility. 

The fact that just about all modern Transceivers now include Six Meters as standard, and the demise of channel 0 and the accompanying TVI issues that went along with that, ( thanks digital TV!) means that “6” is now more useable than ever. 

Another plus with 6 metres is that getting a decent antenna up for the band isn’t difficult. For Sporadic E contacts, although a simple vertical or even a dipole will get you on the band, having a bit of gain and direction will often turn what would be a marginal contact on a vertical into a solid contact. This gain and direction is even more important when using weak signal modes like WSPR, FT8 and JT.

i have been on 6 metres off and on over the years with various antenna I’ve put together, from verticals to beams. This year I decided to put up something better than the 40M dipole tuned up on 6.

I’ve  always been aware of the Moxon antenna . I have often contemplated constructing one to use portable for the 20 metre band vertically polarised near salt water. It’s smaller size, small footprint 2 element design seemed ideal to sit on top of one my push-up masts at home.

One of the good things about building a Moxon is that at 50 MHz, it’s not a very big antenna at all and, is easily managed by one person. Lightweight construction methods and wire elements will work a treat.

Fortunately, there is a good deal of info on the internet about the antenna. There was a very good page called “ The Moxon Antenna Project” , but unfortunately it appears to be down at the moment. There was good information, and many build examples on that page, I hope it gets put back up soon. If working with aluminium tubing is your thing,  then DK7ZB has a dedicated section for the Moxon on his website.

Step one is to find a Moxon program, either a stand alone downloadable app or one of several online calculators…I went with this one. 

 

It really is as simple as putting in the frequency you want to build the antenna for, and letting the program do the work. you’ll be presented with a nice table with all the dimensions. Stick to them to the millimetre if you can, and I”ll bet you’ll be rewarded with a working antenna first pop. Pay special attention to the gap between the two sets of folded elements (measurement “C” in the table above), this dimension is critical to the correct operation of this antenna.

Ok, so on paper, we have all the information on the dimensions of the antenna, now we have to translate those lengths into an actual antenna. I found the best place to start was just googling “Moxon Antenna” and looking at a lot of the images and videos available on line. Everything you thought of (or didn’t), will come up and you’ll soon be inspired. Aluminium, wire, wood, steel, nylon, plastic, fiberglass and PVC are just some of the materials people have used in the construction of this antenna.

 

I decided to go with a Nylon chopping board from BigW for the baseplate. This is only going to be in the air for the summer, so longevity isn’t a priority. I used smaller short squidpole tubing from Haverfords as my spreaders. The spreaders had a 150mm length of wooden dowel inserted for strength, and were clamped to the chopping board with conduit clamps from the local plumbing supply house. The right angle bracket is a pergola fixing from Bunnings, drilled to accomodate the U bolts I used to suit my mounting mast. Simple!

 

I mounted a BNC socket through the chopping board and bought out the cable and sealed it with liquid electrical tape. I put a balun at this point also (yeah you should use one). I used an FT140-43 Toroid and wrapped 8 turns through it. I ended up hot gluing the balun assy to the nylon surface, seemed to be quite sturdy.

At this stage, I temporarily mounted the antenna after fitting the wire elements. Click on the pictures to enlarge them, you’ll see the pink brickies cord I used as element spacers. the second picture shows the short piece of 16mm PVC water pipe I used to guide the coax to the feed point. I used a two terminal piece of chocolate block electrical connector, hidden inside the far end of the pvc pipe to transition the coax to the elements feed point. I sealed up the ends with bluetack to keep any water or creepy crawlies out. Unfortunately I forgot to get a photo of this arrangement.

The wires were stretched out and attached with cable ties slipped over the end of the squid pole spreaders and secured with PVC electrical tape.

I used a super strong PVC jacketed, 7 strand copper clad steel, kevlar reinforced antenna wire that I had left over spare from a previous project, but you could use just about anything that can take a bit of tension. 1mm enamelled copper wire for the elements would work well and would be more than strong enough. Just tension everything so that its sits nice and taut across the spreaders.

The Moxon calculator must have got it right the first time, as I couldn’t measure any VSWR on my FT-817 at the design frequency of 50.110 Mhz . The antenna seemed to be working, a quick test with some local operators, Adrian VK5AW,  Rob VK5TRM, and Mal VK5MJ showed it was both getting out and had directivity. Conveniently, I was able to hear a couple of Six metre beacons from QLD as well. Turning the antenna to test the front to back ratio demonstrated a deep null in the pattern with the antenna driven element 180 degrees to the source, exactly as expected.

I decided to mount the antenna above my 8 ele 2/70 Quad, so it is about 13 metres above ground level. I’s rotated with an armstrong rotator, the mast for both antenna is strapped to the palm tree!

The antenna seems to be performing well, It’s only been up for around 10 days and I’ve already had several solid SSB and FT8 Sporadic E contacts so far this summer, exactly the reason I built it in the first place. I leave it on the 6M WSPR frequency all day and have spotted stations as far out as 3D2 Fiji and FK1 Vanuatu. So it hears great as well. It’s also small and light enough to pack it in the car and see if you can get some contacts from a park or summit on Six too.

So if you’re sick of hearing about Six metres and wish you could get on the band, then this simple antenna should be on your to-do list this weekend!

See you on Six

73

Andy, VK5LA

White Dam Conservation Park

On Sunday, 3rd of June, I headed of early to activate the White Dam Conservation Park VKFF-1122.

It was a very frosty -2.1 degrees when I got up to get ready to head out to the White Dam Conservation Park, VKFF-1122. First things first, COFFEE STOP!!! No affiliation, but Pit Stop in Barmera, SA is a favorite place of mine to grab a traveling caffeine fix when heading past…

The Park is located around 115Km from my home, just west of Morgan, on the Morgan -Burra Rd. It was a beautifully crisp and clear morning, perfect driving conditions for the 1 hour 20minute drive. I stopped at Waikerie to have a look at the low cloud/fog  in the river valley.

Then on to Morgan and across the ferry…

Then a short drive up the Goyder Hwy on the Burra Rd for about 14km until you get to the park…

The maps show the location of the park and my operating position just off of Powerline Rd, in the north west corner. This was one of the few places I could gain access to an area that looked suitable to set up. X marks the spot!

The Park is described in DEWNR website as such, and I quote:

“Habitat: The landscape is flat to gently undulating, with much of the park comprising low open woodland of Black Oak (Allocasuarina cristata) with an understorey dominated by Bluebush (Maireana sedifolia). Other understorey species present include spear grass (Austrostipa sp.), Emubush (Eremophila sp.), Bullock Bush (Alectryon oleifolium), False Sandalwood (Myoporum platycarpum), Quondong (Santalum acuminatum), and Nitrebush (Nitraria billardierei).”

I will now give you the description in layman’s terms:

“Hard Sand. Small, dead looking bushes . The few short trees look like they will die soon, and it’s too cold for Kangaroo’s or birds!

This is harsh country. The Park is intersected by the Goyder highway and there a a set of ruins in visible from the road in about the middle of the park on the northern side. It’s quite obvious that the park hasn’t seen a decent drop of rain for many, many months.

It was still quite fresh when I parked the car and began to set up the station. I decided to run the 80M End Fed Half Wave (EFHW) again, as I have had good luck with it so far, and wanted to give any VK5 operators a chance to work me, as the close in propagation isn’t working too well at the moment on 40 M. Rob, VK5TRM was the first in the log, and I soon had the park qualified on 80M. I went to the 40M band after about 22 contacts in the log on 80M.

40M was quite busy with the usual suspects calling me.

These stations made it P2P, most on several bands.

VK2JNG/P, VKFF-1165

VK4HNS/P, VKFF-1675

VK4AAC/3, VKFF-0622

VK3ZPF/3, VKFF-0622

The big surprise for me was 20M. The 80M EFHW Antenna is 2 wavelengths on this band and seems to work well. I had several contacts this activation and some quite close in VK3, not what I’m used to.

I finished the day with 55 contacts across 80,40 and 20M in the log.

As it was a beautiful day I decided to stop again in Morgan for lunch. Last weekend, in between activating 2 parks, I went to the Terminus Hotel.

This week, I thought Id try the pub directly opposite…The Commercial Hotel…Not Bad!!!

 

 

I recently received my Murray River Parks Award 10 as an activator. This is a great motivator for me to get out and add to the tally. I am enjoying the activating in this nice weather, lets hope it lasts!

Thanks for reading,

Andy VK5LA

 

Two Park Sunday… VK5LA

On Sunday the 27th, I decided to head out early and spend the day activating 2 parks for the WWFF program.
The 1st park was Hogwash Bend Conservation Park VKFF-0892. This park is located on the River Murray, near the town of Cadell, in the Riverland region of S.A. It is approximately 75 Km from my home and I arrived at around 9:00am.

 

 

I travelled along the western boundary, it was well signposted but all the access gates were either locked or fenced off. I ended up walking in to the park after parking my car at the end of Hogwash Rd, near the entrance to the walking track. The red dot shows my operating position

 

The Wikipedia page has a good description of the park and the reasons for its existence https://en.m.wikipedia.org/wiki/Hogwash_Bend_Conservation_Park

The park is adjacent to the popular “Hogwash” camp ground that is a Mecca for skiers and day trippers. The place is also packed at Easter and most long weekends. (when the water is churned to foam by so many boats)

I set up my station just inside the park boundary, a few metres from the information bay in a clearing to the right of the walking track. You can just see my table set up on the right of the picture.

 

The weather loomed ominous, with threatening clouds, but any rain around either held of or missed me.

For the antenna, I set up the End Fed Half Wave I have been experimenting with. This antenna is approximately 40 metres long making it a 1/2 wave on 80M, 1 wave on 40M and 2 waves on 20m.

 

To match it I used a 3:24 turns ratio autotransformer to match the very high impedance of the end fed ~3000 ohms to 50 ohms our rigs like to see. I had the transformer at the base of the Squid pole and the 40m length of wire vertical for around 7M and the rest tied of to a distant tree above head height. at around 40M long its a large antenna.

A quick check showed the VSWR on 80, 40, 20 and 10 M to be below 1.5:1 on all bands. no tuner needed! This was a very pleasing result as I meant I wouldn’t have to touch the antenna to change bands.

On switching on the radio I tuned the 80m band and was pleased that the WIA Broadcast relay, via John, VK5NX (in beautiful uptown Surrey Downs) was coming through very nicely. It had actually been many years since I had called in on 80M. The radio was also seeing a very low VSWR at 80M, 1:1.2 with out the tuner engaged.

 

Come callback time John’s signal was S9 as were the other callers. Rob VK5TRM from Loxton was the strongest Riverlander with a terrific 59+15dB signal, all others were very strong as well. My signal was heard very well by all parties.

I then commenced my activation and spent the next 2 1/2 hours getting my 44+ contacts to qualify the park. I was able to swap between 80 and 40M effortlessly, very convenient!
I did pull the EFHW down with about 15 contacts to go and put up the Linked dipole to check if it was any better. I wasn’t seeing/hearing any stark improvement, in fact I reckon signals on 40 were about the same, but without the convenience of instant band changes I couldn’t tell on 80 or 20M.

 

The next step is to have both the Link dipole and the EFHW set up together so I can do a direct comparison with a switch, which I will do soon on another activation.

I managed 49 QSO’s across 80 and 40M, covering VK1,2,3,4 and 5.

I packed up after 50 contacts and headed to the town of Morgan, for a bite to eat before heading to the next park. I ended up at the historic Terminus Hotel for lunch, one of the two classic old Aussie pubs in Morgan.

 

I decided on a stone grilled rump from this classic county Pub. The meal was great and the super friendly publican was a good laugh!

After lunch it was of to park number 2, The Morgan Conservation Park, VKFF-0911.
This park is located south and east of the big bend in the river at Morgan, details here…https://www.environment.sa.gov.au/parks/find-a-park/Browse_by_region/Murray_River/morgan-conservation-park

After leaving the hotel and crossing the Ferry I turned hard left, which puts you in the park. I drove past the Park sign and followed the road down past the many shacks that dot the river, hoping to find a nice clear section with some river frontage to set up the antenna. Unfortunately the track tuned to sand and I didn’t want to risk getting my Falcon bogged, so I found a clear area of the old Cadel Rd in which to set up for the remainder of the afternoon. The red dot indicated my operating position.

 

 

At this location, I set up out the back of the car and used a tree stump to attach the squidpole. I used a different autotransformer, this one having a 2:14 turns ratio, and using an FT140-43 mix core material, rather than the unknown core from the original
Autotransformer (AT) I wound that was salvaged from a commercial broadband HF antenna. The only difference in the actual antenna deployment was instead of having the AT at ground level I attached it at around 1 metre off the ground. I felt that the antenna seemed to work slightly better in this configuration. Further research confirmed my thoughts, others have confirmed there are less ground losses when the feed point is elevated,. 

 

 

 

 

 

 

I was soon underway, activating 80/40/20 throughout the course of the afternoon, 20M did seem a little flat, but I did hear a VK6 Station calling CQ. I was chuffed to give Jason, VK6YTS a 55 report on a fairly flat band. He also reported he wasn’t hearing much, and gave me a 52.

 

I felt that the antenna seemed to work slightly better in this configuration, rather than with the Autotransformer/feedpoint at ground level. Further research confirmed my thoughts, others have confirmed there are less ground losses when the feed point is elevated,. 

Again, the convenience of not having to touch the antenna to change bands was a very handy thing, and made operating just that bit better.

I will have to conduct more experiments with the Autotransformers and EFHW wire, hopefully the next park will also be close to one of our lovely old country Hotels that do our state proud, even better if it’s lunchtime!

 

 

 

 

ANZAC Day Activation 25/04/2018

After a terrific start to ANZAC Day, attending a wonderful Dawn Service at the Loxton Cross Of Sacrifice then checking on my Grandfather and a couple friends at the Loxton Cemetery, I headed of to the QTH of Ivan VK5HS. The master plan was for Ivan VK5HS, Pete VK5PE, Andy VK5LA, and myself Danny VK5DW to all meet up at Ivan’s place and head off to a couple parks that had not yet been activated.

With us all loaded up into a couple vehicles we headed North (well Northish) up to Chowilla. Chowilla parks consist of the Chowilla Game Reserve VKFF-1697 and Chowilla Regional Reserve VKFF-1698. These parks incorporate the Chowilla Floodplain which contains the largest remaining natural river red gum forest in the Lower Murray and a range of diverse aquatic habitats. It is a part of the Chowilla Game and Regional Reserve as well as the Riverland Ramsar wetland of international importance. Chowilla is home to many iconic and endangered native species, including the Murray cod, regent parrot and the southern bell frog and is the traditional home of the First Peoples of the River Murray and Mallee region

For more info on the Chowilla Floodplain check out: Chowilla Fllodplain – DEWNR.

Our first place to activate was Chowilla Game Reserve which  is located adjacent to Murtho on the Northern side of the Murray River, North East of Renmark. Shown on the map here shaded blue.

We headed in on the Old Wentworth Rd, nice bit of track that in a 2WD tray top ute!!! Before turning into the Game Reserve back toward the Murray then following Chowilla Creek along to the Chowilla Regulator. Finding a nice little spot not far from the Regulator we set up a couple portable stations and got to work at about 0000z. Andy and Ivan fired up on 80m while Pete and I went to 40m.

This was a terrific spot along side the Chowilla Creek with great company and a swag of great and most appreciated contacts. The weather was mid 20 degrees a little overcast and a very light breeze. The site was as quiet as a mouse, QRM and people… we didn’t see anyone until we were leaving. Pete and I stayed on 40m for the duration of our activations while Andy and Ivan made their quotas on 80m and 30m. The ANZAC Day privilege of the ‘AX’ callsign certainly got a fair workout as well.

Ivan made 44 contacts, Andy 45, Pete 28, and I made 46. By this time we were all looking pretty pleased with ourselves.

While Andy was working his last couple Pete and Ivan fired up the BBQ and started to cook up a couple snags, onion and spuds.

After we fed the worms (had lunch) we headed off to our next location in the Chowilla Regional Reserve. Have a look over all our pics of Chowilla Game Reserve in this mosaic.

 

OK so now were on our way to the next site, Pete and I following Ivan and Andy in complete faith with only one little issue… what’s that… Ivan cracking a U-bolt?!?!? Ummm wrong way?

Anyway a little while latter we pulled into the Chowilla Regional Reserve and found ourselves a comfortable little spot under a bit of shade.

We went straight to work and set up a station and Andy got right into calling CQ Parks.

 

Pete kicked back and just enjoyed the surroundings while Ivan, Andy and I shared the mic passing back and forth. The constant changing of operators, callsigns, slipping the ‘AX’ prefix in, and the odd little pile up proved to make for a very entertaining time. Sorry to anyone that was getting confused. No fear we knew exactly what we were doing… that’s what we kept telling ourselves.

We were having a wow of a time and in no time at all we had over 10 contacts each. Satisfied we decided it was time to retire back to Ivan’s QTH, unpack and call it a very enjoyable day.

Here is a mosaic of the second Operating Location, Chowilla Regional Reserve VKFF-1698:

For a bunch of ratbag friends just having a fun time we think our contact counts are pretty cool:

• Ivan VK5HS / AX5HS
  • VKFF1697 – 44
  • VKFF1698 – 17
  • Park to Park – 14
• Andy VK5LA / AX5LA
  • VKFF1697 – 45
  • VKFF1698 – 18
  • Park to Park – 14
• Pete VK5PE / AX5PE
  • VKFF1697 – 28
  • Park to Park – 1
• Danny VK5DW / AX5DW
  • VKFF1697 – 46
  • VKFF1698 – 17
  • Park to Park – 12
• Totals:
  • VKFF1697 – 163
  • VKFF1698 – 54
    • Combined – 217
  • Park to Park – 41

Here are our 2 Operating Locations:

Thanks for reading. Please click ‘Like’ and/or leave a comment.

Cheers and 73’s,

Danny VK5DW

Update 27/04/2018 – A couple more pics in from Pete VK5PE: