Tuesday, November 21, 2017

Looking at a VDA as a portable antenna (theory)

Always looking for more effective antennas for working DX while /P, I have been investigating the two element VDA (vertical directional array).


VDA design

Stories about the VDA
On the web there are some different stories about this antenna. Everyone seems to agree that this antenna is a great antenna for the expedition to a coastline where the antenna can be put very near to salt water. As with all antennas, the salt water with its high conductivity improves the antenna radiation as the ground losses decrease.

Only so much of our world is coastline, so what happens when you use the VDA over "normal ground"?

Some say it becomes useless. This is however only in comparison to the performance over salt water. In this comparison a lot of antennas are useless over normal ground. We know ground conductivity impacts the antenna radiation pattern, but it is quite another thing to say that you should forget about specific antennas because they perform better over salt water.

The backdrop - what is my reference?
My reference antenna and the one I have used most often, is the vertical end fed half wave dipole. It is very easy to set up (down to 40m - when you go lower other factors come into consideration) and its performance is quite good. Any antenna has to beat this setup to be worth my attention.

I have also used inverted V's and sloping wires. These antennas are definitely better on shorter skip (high angle radiation) but do not increase DX performance. My portable hexbeam beats all of the other antennas but is considerably more work to set up, does not fit everywhere (exp. in a forest), and is only a solution down to 20m. 

My default mast is the 18m high Spiderbeam HD fiberglass pole. I have a higher one (26m) but I consider taking that one as extra effort. I also have a aluminum mast for my portable hexbeam but that is also quite some work to setup. Note that for the end fed vertical a much more compact 12m pole suffices down to 20m.

Looking at it from a portable operator, there are a couple of constraints you have to deal with that limit the antenna performance you can achieve. Winning a couple of dB on low angle radiation is quite a challenge without adding a lot extra complexity.

Over to the VDA model
Okay, so we are looking for a portable antenna with DX specs that are better than those of an end fed half wave set up vertically, without adding too much complexity.

Would the VDA be an option?

Before building anything, I usually model the antenna to see what it will theoretically do. Using 4nec2 the performance of the VDA varies a bit depending on the dimensions you choose for the elements and their distance. I modeled four versions I found documented on the web over ground conditions found in the area I live in (no salt water I'm afraid). The versions are by: PA3FYM (blue pattern below), OH1TV (red pattern), OZ1CX (green pattern) and F4BKV (pink pattern). You can see some design choices with OH1TV opting for higher gain and a lower F/B ratio. They all achieve maximum gain around 20 degrees radiation angle - a good angle for DX.


Four different versions of one antenna

Now how does this compare to my tried and trusted end fed vertical?
The 20m end fed vertical can be set up using a 12m pole, but I would most often use my 18m pole.  So I compared the OH1TV version of the VDA (highest gain) to an half wave end fed with its top at 12m and one at 18m.



The angle of maximum gain is approximately the same - and all in the low range of 15-20 degrees (good for DX-ing). The VDA at approximately the same height as the end fed (12m high), gives a considerable gain of 4dB. All things equal this would mean you would need 2.5x the amount of power to get the same signal at the DX station.
Now when the end fed vertical goes up, the gain increases. The difference is now down to 1.4 dB - corresponding to a power increase of 1.4x 

There is a bit more to say than just these maximum gain figures. With the VDA you lose the omni-directionality that is very convenient when you are not working someone in particular - e.g. when activating a nature reserve. But another factor (for me) is that I am testing this on 20m with the intention to make one for 40m later. In that case the reference end fed antenna is not as high (relatively) as I can get it on 20m, so the difference will be bigger in favour of the VDA. 

All in all this does trigger my curiosity sufficiently to build one. I am planning to make one for 20m first and test the real life performance differences using my WSPRLite beacons. To be continued...

Monday, November 20, 2017

Portable at PAFF-0117

Last week I had a rare opportunity to go out again /P for a longer stretch of time. I decided to head to the south of the country to activate a nature reserve I had not visited yet: Weerter- en Budelerbergen & Ringselven.

Because I had some time on my hands and I had not been on the radio for weeks, I went for the "full monty" - taking a hexbeam for the higher bands and a delta loop for 40m. I was not going to let the conditions ruin my day.

When I arrived at a lake in the nature reserve I was suprised to find a nice sturdy gate - placed by a local fishing organisation to corner off a piece of the lake. This made setting up the hexbeam a bit easier.

Alu mast nicely supported by a fence

There was some old metal pole a bit further away that was helpful for keeping my Spiderbeam 18m mast up. This mast was holding the full size delta loop for 40m. I had not used that in the field apart from some initial testing.

When the antennas were up I first collected J5 on two bands (atno for me) and TO2 on a new band. Then it was time to wake up the WWFF chasers.

Hexbeam at about 10m/30ft

I started on 40m as the higher bands were still rather quiet. QRM was manageable and the flow of chasers was quite constant - logging 116 calls in the first hour.

Then it was time to try 20m with the hexbeam pointing east. The first contact was a nice surprise: a VU2 who commented on my signal level - being 9+10dB at his end. I worked VU only a couple of times before so I was thrilled that he came to say hello and even more so that signals were that good. He was followed by a number of EU chasers. As the earth kept turning North America woke up. K1RO was the first one to make it across. It was time to turn the hex that way. Signals were never very strong but QRM was low on 20m, allowing me to work 23 stations from 15 US states and 4 VE provinces. Not bad at all.

In the meantime I was visited by a member of the local fishing club who wanted to know what I was doing. He made a minor point about me using their gate as a support but was satisfied after a short explanation of my intentions.

After a while I did not get any response on my CQs anymore and dusk was setting in. So I decided to take down the hex while I could still see what I was doing and continue on 40m until I had to leave. Before doing that, I called TI2 and logged him on a new band (17m).

Taking down the hex at dusk

Sadly 40m had turned into a very noisy band. It was hard to copy anyone at signal levels under s9. I did seem to put out a nice signal though as I saw a spot on the cluster from W3 and an OM from A7 (Qatar) came by to ask me what the heck my setup was, as I was that strong. The delta loop has made it into my favourite set of antennas. I logged another 60 chasers through the QRM.

In just under 4h radio time I logged 254 calls from 44 DXCC, 15 US states and 4 VE provinces. ODX was TI2 at 9100km.

Tnx to all the chasers that came by.

Friday, October 27, 2017

Test: End fed wire versus AlexLoop on 20m

Recently I did some tests with my two WSPRLite beacons. I started testing my AlexLoop against a 20m long end fed wire on 40m. The wire beat the loop quite dramatically.

One of the comments I got was that the loop should do relatively better on higher bands. That is why I ran a test on 20m as well. I collected the data about 2 weeks ago but due to other commitments I only got around to analysing it today. 

So what was the set-up? As in the previous article, I set up the AlexLoop in the garden with the center of the loop at about 2 meters high. The end fed wire this time was 10 meters long and ran from the back of my house into the garden sloping from about 7m high to about 2,5m high. I ran the beacons on 200mW for 2 consecutive days. 

The WSPR data shows:

  • 514 spots from 49 spotters were received for the beacon on the wire 
  • 436 spots from 29 spotters were received for the beacon on the loop 

This already gives you some impression about the difference. More stations were able to pick up the signal from the wire. 

Looking at the spot map below (distance in km vs SNR) you can see the orange profile of the wire is slightly shifted to the right (higher SNR) as compared to the blue profile of the loop. It is not as big a difference as on 40m though. 
More prominently you can see that the odx is again much higher for the wire as the signal was picked up across the pond in East Coast US (orange spots on the top).


This time the overlap is bigger, which makes it interesting to zoom in on a single spotter to see the actual signal strength over time. I selected one spotter that generated the most spots (EA8) but did check if the profile was any different at other spotters. This seems like a good sample for those stations that heard both. The orange line shows the SNR of the end fed wire, while the blue one shows the loop. On average (also looking at other spotters) the loop is 3 dB down across EU.


There are not enough spotters to make further assumptions about performance differences at specific distances or directions. What you can see is that for DX the signal from the wire is received within a 6dB range of SNR. The loop is not reaching the lowest end of that SNR. So it seems the wire is beating the loop everywhere but more so on DX.

Sunday, October 15, 2017

One man set-up for the 26m Spiderbeam pole

In January of this year I received the Spiderbeam 26m HD fiberglas pole. It is the tallest they have and afaik the tallest you can get. Cool for low band antennas with little compromise.
I used it only a few times as I can normally get all the antennas I have on my 18m pole (or on my aluminum mast) and I simply did not have the time to build and test low band antennas.

When I did bring the mast out I was reminded of its size and weight - 2m when collapsed and an interesting 18kg. If you have a good support - like the one I build that I attach to my car, or some strong fixed pole you can tie the mast to - it is possible to set this up on your own. Otherwise you need more people. When we used it in the open field during the PACC, we need 3 people.

A few months ago I build a simple support system for my 18m pole that allowed me to set this mast up in the open field without any hassle. I have been using this more often and started to think if I could make something for the 26m mast as well. I wanted to use a bigger surface this time, but use a different structure because it would become too bulky if I just enlarged the 18m version.

Walking around in a DIY store I stumbled upon a flat roof vent. The inner diameter is just over 110mm allowing the 26m pole to slip through with the end cap on.




Now picture this thing pressed between 2 layers of wood with holes on each corner for stakes / pegs. I could just see this working. So I took this home and started working on the two layers of wood.



I chose plywood and cut two pieces approx 60 x 60 cm. I chose the bottom layer a bit thicker so I could sink the bolts I was going to use into the wood (and that way keep an even surface). In the picture you can see that I already cut a hole in the middle with the largest hole saw I have. That saw is only 83mm so I next I enlarged the hole.


Enlarger the center hole
The intermediate result - starts looking like what I had in mind

I added 4 bolts though both plywood layers and the metal, made 4 large holes (25mm diameter) near the corners and glued the two layers of wood together. Another thing I did (like with the 18m pole) is to add a fixed ring on the top of the lower segment of the 26m pole and add three guy rings to it.


(sunk) bolts through the wood and metal


Fixed guy rings

I finished the work yesterday, so today I could make good use of the brilliant weather we have at the moment to go out and see if my construction works.

Just for a comparison of size I put the 26m and 18m poles side by side with the two mast supports.

I then started setting up the 26m pole. I four stakes in the corners of the plate I constructed. They were of different size and mostly to long as you can see. However, they still do the job.



As I hoped, the collapsed pole slipped in nicely and stayed upright - even before I guyed it. That is very convenient as it allows you to add the guy lines one by one and adjust the tension of each one until the pole is fixated and completely vertical. 



I then pushed the segments out with my 20m long end fed wire attached to the upper segment (while I was there I might as well make some contacts). I was lazy and only wanted to assess if my idea worked so I did not guy the pole on any other level. 



As you can see the pole was not completely vertical. This was due to a lack of tension in the guy lines (will put on more tension next time) and of course due to the lack of guy lines higher up. It stayed up though and I was able to make a couple of WWFF contacts in the half hour I was there.

It is easy to set up and break down the way it works now, so I am pleased. The one thing I do need to add is a small step or something else that allows me to stand a bit taller. I am 2m tall but still the pushing out of the last segments is heavy work.


Saturday, October 14, 2017

Test: End fed wire versus AlexLoop on 40m

Recently I acquired two WSPRLite beacons. I want to use them to test various antennas to find out which ones are most effective /P. I have built a number of different antennas and I still have a few projects planned. Modelling antennas gives you an impression what to expect but you only find out in the field what the real performance is. Actually, you need (more or less) parallel reports to account for changing conditions and WSPR is a nice system to get these reports accurately. 


Two identical 200mW WSPR beacons
I started using the beacons at home testing the performance of my AlexLoop against my default antenna - an end fed wire. At home I use 20m of wire that is resonant on 10, 20 and 40m. That wire runs from the back of my house at approx 8m high to a corner of my garden and then still a couple of meters along the far end of the garden - sort of an L-shape. It ends at approx. 1.5m high. Nothing special - not your DX killer.

Although this is a convenient test for me to do at home, the comparison is not that exotic as both a low hanging and sloping end fed wire and a portable loop are realistic /P antenna options.

The first tests I used the AlexLoop in the attic on 20m, 30m and 40m. It turns out that although the loop is higher there, the attic itself attenuates the signal too much. It is just not picked up while I do get spots from the end fed wire. So I moved the loop to the garden at a height you would put it at when going /P - the center at about 2m high.


AlexLoop in the garden
I tuned the loop to 40m. Now spots were coming in for the AlexLoop. Running both beacons for 24h on 40m I can get a good picture of the difference between the AlexLoop and the (low) sloping end fed wire. 

Comparing the spots of the two antennas from the same RX stations, I find that the loop is mostly 10dB or more down from the end fed wire. That is an enormous difference. There is no advantage to be found on any distance for the loop.

Odx for the AlexLoop was EA8 with 3000km (2 spots from EA8) with 39 different spotters over the measurement period.
Odx for the end fed wire was N8 with 6500km (14 spots from W) with 110 different spotters over the measurement period.



The graph above shows the spots for the end fed wire (blue) and the AlexLoop (orange) on 40m over the same measurement period. The distance to the receiving station (in km) is on the vertical axis and the signal strength (in dB) reported by the receiving station on the horizontal axis. 

Apart from the two orange dots at 3000km (EA8) the AlexLoop does not reach much further than 1000km. You can also see that the end fed wire gets better signal reports - with significantly more dots to the right. 

So, my first test of the beacons worked out well and I have my first bit of data on two antennas. My idea is to create a separate section on this website dedicated to antenna performance based on future experiments with the beacons.



Wednesday, September 27, 2017

Projects - 4m slim jim antenna

As I wrote before I now have a working 4m set-up using the 4m transverter kit from DF2FQ (XV4-40). I also have a compact 2/4/6 meter beam that I will describe in more detail in a future post.

Although the beam is compact, I cannot use it at home as it is too large. How can that be? Well, I don't have a fixed mast - all my antennas start from my attic. I use a 20 meters long sloping end fed wire from my attic into the garden in an L shape for 80m-10m (resonant on 40/20/10m - works OK for 40-30-20). For 6m I use a vertical end fed wire that I put on a fiberglass pole in the attic and then push up through an attic window (I sometimes use this construction for lower bands as well). For 2m I have a compact 4 element beam that I can just push through the same attic window. I attach that one to an aluminium push up mast.

The 2/4/6m beam is just too large to fit through the attic window. So for working Es - one of my favourite sub hobbies - I needed a solution for 4m (having 6m and 2m covered). With Es you can get good results even with a "simple" vertical - as I have already experienced using my end fed wire for 6m. So, it was time to create a 4m vertical. Using a bit of ladder line PG8M had lying around and a nice online calculator by M0UKD (with construction tips), I created a slim jim for 4m.


Ladder line as the basis for the Slim Jim antenna

The online calculator and all the other info on John's page give you a good starting point but then you are tasked with finding the exact feed point position. As John M0UKD notes, it is important to perform the final tuning in a set-up that resembles your target situation. I stuck the ladder line to my fiberglass pole in the garden and pushed that up a couple of meters to make sure the antenna was away from obstacles (as I will be using it when I push it out from my attic). I tried different feed point positions, each time making measurements with my VNA.


Locating the feed point
Finding the feed point position is a trial and error process. This is slightly complicated by the wires being insulated. I didn't like the idea of having to remove the insulation on a large stretch to find the right spot, so I used the set-up in the picture above: two needles connected to my VNA. That way I could try different points and check the effect on the antenna SWR curve.




Finally I added a W2DU style current choke on approx 1m of coax (soldered to the feed point) that conveniently terminates with a SO-239 connector: ready to go.

The end result gives me an antenna with an SWR of 1:1.6 on 70.200. I might improve that a bit more by tweaking the stub length in the future but as it is I am pleased to know I am ready for next year's Es season.

Saturday, June 24, 2017

First 4m QSO - getting a transverter kit working

Almost a year ago I bought a 4m transverter kit from DF2FQ (XV4-40). I have basic understanding of electronics, acquired in part through the hobby but building a project like this was new to me. With my mechanical engineering background I am more confident in building robust stuff like antennas, masts, supports, baluns, etc. Soldering loads of tiny components on a board seemed challenging. 

However the level of documentation provided by DF2FQ and some motivating words by PG8M - who was already using the transverter - pushed me to the point that I ordered the kit. When I received the package I must admit it looked daunting. 



Lots of parts..
..and rather tiny

I started building the kit sometime in August last year. I tried to work as meticulous as I could (a challenge when you are as impatient as I am). When I had completed the kit and ran the first tests, I found that I received 70 Mhz signals with the radio tuned to 29Mhz. Hurray!

However, when I tried to transmit, the transverter appeared to be dead as a dodo. No LED, no signal. A very disappointing result. I did some tests (as far my knowledge goes) and could not find the cause of the failure. So the kit went back in the box it was shipped in. Time for other projects.


The Es season is rather good this year and I have enjoyed the effects on 6m but 4m was open a lot of times as well. I really had to get back to the abandoned transverter project. PG8M had already kindly offered to help me months ago and today I took him up on his offer. We went through the error checking process step by step, finding and fixing four major issues. It turned out I had made two soldering errors and two of the smd resistors were faulty. Whatever happened to these resistors I really don't know.



PG8M trying to locate the next error

The good news is that we ended up with a transverter that delivered up to 35W on 4m with 5W drive on 10m. 

There was no one around to do an on air test so back home I hooked up the transverter and put my tri-band yagi on a pole @2m high in the garden. PG8M was QRV 30km away with his 4 ele beam pointing in my direction. That is when I made my first 4m QSO.

DK7ZB tri-band beam in action twice this week

It is a bit late in the Es season but I am sure I will get back to this band in the future. The next thing I need is an antenna I can set up quickly at home in case of any high MUF situations. For 6m I use an end fed wire that I can attach to a pole that I push through the attic window. For 4m I am going to try a slim jim vertical. More on that later.


Friday, June 23, 2017

Playing with 6m Es - compact beam versus vertical

Some time ago I built a compact beam for 6/4/2m aimed at /P operations. It is a design by DK7ZB featuring 3 elements on 2m, 2 elements on 4m and 2 elements on 6m. I tested it when I finished building it and SWR was good on all bands.

I followed the design of DK7ZB (link) with a few changes to make this a /P antenna:
  • I use wing nuts on the 4m elements and the 6m reflector to be able to remove them easily for transport
  • I split the 6m driven dipole in a short center piece connected to the boom and removable parts on both ends of the dipole
  • I added spacers for the dipoles to keep them at the right distance from each other (refer to picture below)
Spacer for the dipole elements

Apart from a short appearance in LX (2 QSOs), I had not used the beam on the air. For 6m I use an end fed half wave vertically - both when I am /P as well as at home.
It is amazing how effective a vertical wire is in Es conditions. I have worked stations all over Europe with that antenna using 100w. I was curious how the beam would perform in comparison.

We are in the Es season at the moment and there was a 6m contest on last weekend. So I decided to go out /P and test the beam properly against the end fed wire. I used one of my Spiderbeam poles with the end fed wire in the top (feedpoint about 12m high) and the beam a bit lower at about 8m high.


I used an antenna switch to be able to quickly switch between the two antennas. You need quick switching as the signals themselves vary constantly under Es conditions. The difference was significant most of the time. Of course the heading of the beam is a factor that influences the difference. With the beam heading the right way, the signal strength on rx differed multiple s-points. On the low end this meant there were stations I could only copy on the beam. I recorded a view video's while switching between the antennas. One of them is on YouTube:


With PG8M - who lives just under 30km from where I was /P - I tested the characteristics of the beam via ground wave. We found a difference of 2 s-points front to back and 5 s-points front to side.

All in all this shows me that this beam is definitely an interesting antenna to use in the field for 6m. It is light, easy to set up and relatively easy to transport. As the 6m reflector is rather long for easy transportation I am thinking of splitting the reflector in two or three parts.

While I was testing this setup I logged 25 stations, collecting 10 new grid squares on the go.

Sunday, May 14, 2017

Projects - Inverted V antennas for the low(er) bands

Choosing a /P antenna for 80m

My favourite antenna when working /P is the end fed half wave, set up vertically. It is easy to set up and works well with reasonable DX performance. It will not beat my portable hexbeam when working DX but that one requires more time, material and open space to set up.

The EFHW vertical becomes a challenge however on the lower bands. Now I did get myself the largest Spiderbeam pole - so a vertical half wave for 40m is an option - but there is a limit and 80m will definitely not fit.

One option then is to use a quarterwave vertical. However this requires radials if you want the majority of your signal to be radiated above ground. I developed a quarter wave for 80m with four elevated radials and it works but is quite a hassle to set up. Working /P you don't always have room for four elevated radials.


Another option is to use the EFHW sloping. That is a good option and I have used it on numerous occasions. If the support is tall enough to allow for an angle around 45 degrees the antenna still has a low angle of radiation but also a lobe at a high angle. That makes it a versatile antenna. It has some directivity - in the direction of the slope. 

The challenge on 80m is that the EFHW sloping still requires a tall support for a reasonable (steep) sloping angle otherwise you will end up with only the high angle radiation. 


Inverted V antenna

Another option - using a single support - is to use an inverted V dipole antenna. For 80m I find it a convenient antenna to set up and it comes with a unidirectional radiation pattern (in the horizontal plane) that fits my needs when I am "being chased" with chasers from all directions.
The inverted V has a high angle of radiation. On my 18m pole it very much resembles a sloping half wave dipole of the same length. The main difference is that the sloping wire will have 6dB F/B ratio while the inverted V is omnidirectional. It is very much up to what you are looking for.

Practically when working on 60m or 80m (or 160m) - for more than a few QSOs - I choose the inverted V antenna. When my tallest support still was only 12m I also chose the inverted V as my default antenna for 40m.  


For my inverted V antennas I developed a universal center connector that fits on the fiberglass poles I use. It is a simple component made from 40mm PVC that allows me to connect various wires to a SO-239 connector. The reason I designed it with changeable wires is that it allows me to make different combinations like 40m and 80m inverted V's on one pole fed by one coax cable. 




The tie wraps on the sides are used to keep the cable tension away from the soldered cable shoes - otherwise the shoe will certainly break in due course. The hole through the center allows it to slip over the top segment of my fiberglass poles.

I developed a couple of these center connectors so I can set up different antennas at the same time. We use them for example with the YNOMY DX Group during the PACC contest when we set up three different inverted V's (40/80/160). We then have the 80m and 160m on the tallest mast together, being fed from one coax cable.

For each inverted V I have two separate dipole legs. Each dipole leg is cut to the right size and features a cable shoe as visible in the first picture. To hold the wire I have constructed a cable spool consisting of a piece of PVC (40mm) with two end caps. On each end caps I have glued a piece of wood and through the end caps and wood I have put a piece of threaded wire. 


40m wire spool (one leg)
This spool holds the antenna wire plus a long enough end of tension string. I find it works rather conveniently in that I can just stick the spool in the ground (slightly under an angle) where it unreels while I extend the mast. Once I am happy with the position of the mast and antenna I push the spool further into the ground, stopping it from turning. This way I do not need pegs or anything else to set up this antenna. 

Below you see an impression of the antenna with four legs - dipoles for 80m and 160m - ready to be deployed.



I just stick the spools in the ground in the direction I want the leg to go. Then I extend the fiberglass pole with the spools unreeling until the mast is fully extended. Then I pick up each spool and place it where I want the end point to be. The advantage of the spool unreeling is that there is only a slim chance the legs get entangled even when you have two dipoles on one mast - the wires are kept under some tension the whole time. 

Sunday, May 7, 2017

Projects - 18m pole set-up improvements

I use a variety of antennas and poles/masts when /P. The 12m HD Spiderbeam is the most compact one I have and is easy to set up in the field without any supporting structures. The bigger ones I normally attach to the car one way or another or to any suitable construction I can find around the place I am going to be active from. My favourite and most versatile antenna pole is the Spiderbeam 18 HD fiberglass pole. I use it almost every /P activity. Preparing for a tour through LX I decided to implement some improvements that make the pole even more portable.

Guying the 18m Spiderbeam pole
I have twice set up the 18m HD Spiderbeam pole on my own using an ingenious structure with all the 6 guy lines extending while I pushed out the segments. That took quite a bit of time so I looked for another option. When I set up the pole using the car or a supporting structure I find that I do not use any of the supplied guy lines - so it should be possible to find a much simpler configuration to set up this pole in the field.

I decided to try and set it up with only the lower segment guyed. That would allow me to simply set up the pole while it is still collapsed and then push out the segments without worrying about any other guying arrangement.

Borrowing from the idea behind the clamps Spiderbeam supplies for keeping the segments extended, I bought a hose clamp and applied rubber lint that I crimped in place. I cut some of the rubber away so I could add three rings. So now I have a permanent feature on my Spiderbeam pole: fixed guy rings. 


Securing the base
You also need the bottom part to stay put. Before I would use a large peg with some soft (insulation) material around it. I would just position the pole over this peg. However I have found this is not a very solid construction - e.g. it does not allow you to keep the pole standing while it is still collapsed. With the set up I just came up with, I need the collapsed pole to stay upright while I attach the lower guy lines. So I replaced the peg with this:


The center hole fits around the pole while the other holes can hold pegs that secure this little box in its place. Trying it in the field it turned out to work well - the Spiderbeam pole kept upright while I attached the lower guys.

With these two changes I can set up the pole in no time without needing any supporting structure, like so:


I used this a couple of hours with the pole extended 18m holding an efhw wire. Granted, it was not very windy that day. I will have to see if this is strong enough in higher winds.

Practical segment clamps
One last adjustment I made to the configuration is a replacement of the clamps that hold the segments in place when extended. The default clamps provided by Spiderbeam require a spanner or wrench to open and close. That is inconvenient and so I really did not use them often. I either extended the segments to the point that they stuck (with the risk that the antenna would collapse during a QSO) or I would use duct tape (that is quick to apply but not so easy to take off). 

So I bought clamps that have butterfly tightening tabs. I added rubber strip on the inside that I crimped on the clamps to protect the pole (like with the original clamps). I tried them and they work well.


Wednesday, April 26, 2017

Finding PE4BAS

Fellow blogger and radio addict Bas, PE4BAS is on holiday. To keep his followers busy he created a little puzzle to solve: where am I?

I am always in for solving puzzles.. so here goes.

As he is a WSPR user (I think our first conversation was about visualising WSPR contacts), he can of course be found in the database. 

He is being spotted as we speak:
2017-04-26 12:26 OZ/PE4BAS 7.040044 -2 0 JO56jl 5 OH2EAT KP20xw 1003 54

So, Bas is in OZ and in JO56jl to be more precisely.  That square is not that big and there is not a lot going on there. So I sneaked around and took a picture of his place while he was not looking:

OZ/PE4BAS


Looks familiar?

I had a look around (I hope Bas doesn't mind) and it indeed is a cosy place.

Cosy place Bas has chosen as temporay QTH
I left him alone again to enjoy the rest of his holidays. Thanks for the puzzle Bas & have fun!

Monday, April 17, 2017

Spending a lot of time at PAFF-0097

Just got home from a nice activity at PAFF-0097 as PC44FF. I brought my hexbeam but the parking I had in mind when planning the activity was too crowded. Driving around I was lucky to find a nice open space to set it up. There were some rain and hail clouds around and I was just in time setting up the beam to stay dry.

/P DX antennaThe skies cleared later on
I started out on 20m with the hexbeam pointing to NA. The band was not in a very good shape so the going was slow but I did copy a lot of NA stations (relatively). I tried a sked with VK4FW but the band was just not good enough. After 2 hours mostly on 20m - I tried 17m but that was no fun - I had logged 106 QSOs. 36 of those were with NA stations from 14 US states and 3 VE provinces. Quite a lot of familiar NA chasers in the meantime.

Personally I am OK with an activity once I reach 100 QSOs. However, as 20m was rather slow and I had not copied a lot of the familiar EU chasers, I decided to stay a little longer to try 40m. I took down the hexbeam and set up a 40m vertical (EFHW) on my 18m Spiderbeam pole. In about 45 minutes I was good to go again.

18m Spiderbeam pole with an EFHW for 40m

40m was very noisy where I was. It was due to splatter (a combination of a good rx antenna and poor filters in my FT857d) but also QRN. I changed frequencies a few times but then decided I would have to just bear the noise. It was really busy though. As signals were rather strong I could copy a lot of stations above all the noise. As chasers kept on calling there was no way for me to leave. It was getting dark and far past my negotiated return time but you can't just ignore a pile-up of chasers (well, I can't).

After 2 hours the pile up thinned and the signals dropped below the QRM level. By then I had logged 238 QSOs on 40m - apart from 4Z and SU all of them EU chasers. This makes for a total of 344 QSOs for this activity with 6 park to park contacts. A lot more than I had anticipated. 

Driving home in the dark I saw a lot of huge bonfires and remembered that in this part of the country it is tradition to make large Easter fires. It made it a magical drive home with my ears still buzzing from all the noise.


Magical views driving home

Sunday, April 9, 2017

YNOMY LX-pedition planned for May

In preparation of our expedition to BS7 or P5 sometime in the future, YNOMY DX group has planned its first group expedition. So far we have all been active from various places outside of PA individually. As a contest team we have shown to be able to work together for a couple of years already with rather acceptable results.

So now we are off to our first team expedition on May 20 and 21. We chose LX as a convenient location and we chose WWFF as the focus of our operation. Working together with the LXFF coordinator, Mill LX1CC, we have made some draft plans and acquired a special callsign to be used for this expedition: LX44FF.



Our goal is to work as many chasers as we can from Saturday morning till Sunday evening using multiple stations both on phone and CW on whatever band is open between 80m - 2m. We will also issue an award to the most active chasers - check out: LX44FF Award

Really looking forward to a whole weekend of LXFF. Let's hope conditions are acceptable or better.

Project - Mast support for heavy masts


For my portable endeavors I have built an aluminum push up mast and I have bought various fiberglass poles from Spiderbeam. I actually started out with a 10m pole from Spieth. That was rather thin, so I went for the 12m HD version from Spiderbeam.
To get my inverted v's for the low bands up higher I then bought the 18m version and recently I went even further and got myself the tallest pole they sell - 26m.  

Heavy masts present a challenge when working /P. I can manage to set up the 18m pole in the open field on my own but it is quite a bit of work and it would be a really daunting task with the aluminum mast and the 26m pole.

When I built the aluminum mast I went looking for a proper mast support that I could use with my car. Typically this would mean a drive-on support. The ones I found on the internet however were too light for my sturdy (and heavy) mast.

Not having any welding tools available to me at the time (I now have an arc welding machine), I decided to build something myself out of wood. After some experimentation I went for a design where I attach the support to the wheel using lashing strap, instead of driving on the support.

If you are reading this to try something yourself, keep in mind this design only works if you have spoke rims on your car.

I never got around to write something about this support, even though I got questions about the design. After buying the 26m pole I had to build a new support - for a much larger diameter mast - so I decided to take some pictures in the process.

The end result looks something like this (showing my first version):

The tried and trusted version from different angles - note the rubber pads that go between the support and the car tire:

I constructed the old one for my aluminum mast that has a diameter of [--- mm]. It can also hold the 18m Spiderbeam fiberglass pole. Conveniently the tall vertical wooden beams are the same width as the bottom segment of the mast. This means that the only spacing that is critical when you build it, is the spacing between the two vertical wooden beams.

Now for the 26m I built the same support but I could not find wooden beams of the desired width, so I used the nearest (smaller) width and added planks to end up with the correct width - as you can see in the picture below.


Wooden parts cut to desired lengths 
Now that the vertical beams are of the correct width, the only spacing you have to worry about is the one between the two vertical wooden beams. I used the bottom segment of the Spiderbeam pole to define the space, as shown below.



The length of the horizontal wooden beams is not critical. They define the space between the car tire and the mast / pole. I use [--- mm] to leave enough room for my shoes - so that I can use the support to position myself higher when I push out the mast segments.

The height of the upper horizontal beam is critical in the sense that you need to make sure it stays within the height of the car tire (more about that later).

Once all the horizontal beams have been added the support looks something like this:


What is left, is adding the frame that you can tie to your car rim. I use 44x44mm wooden beam for this frame. The height and width for this last rectangular frame have already been defined by the structure you have created so far. It is therefore important that the upper horizontal beam I referred to earlier, is positioned at a height that puts the top of the frame we are now going to add right against the rubber of your car tire.





When I completed this stage I took two more steps: a piece of (ply)wood on the bottom of the support - this keeps the mast / pole from getting stuck in the ground (e.g. in case of a muddy underground). And I add pieces of rubber that go between the car tire and the wooden frame (refer to the pictures above of the old version).

Now you have the lower support for your mast. This might be enough to keep your mast straight up. In my case I added a second support on the roof of the car. This helps keep the heavier masts (like my aluminum mast and the 26m Spiderbeam pole) straight up without guying. 

This roof support is nothing magical. It is simply a wooden beam (44x44mm) that is longer than the width of your car + the distance to the mast. At one end I add two pieces of wood at a distance that equals the width of the mast. Through these pieces of wood I put a threaded rod (M8). This rod is positioned at such a distance that it keeps the mast in place. I use some pvc pipe to keep the keep the sharpish threads from damaging my mast / pole. This roof support looks like this:



I use lashing strap to attach the support to a roof rack on my car.