Wednesday, July 18, 2018

Portable in OZ and meeting the OZFF team

Usually I spend my summer holidays in the south of Europe. This year however we opted for a trip north to OZ for a stay of three weeks on two campites. 

So far - a couple of days on our first campsite - we have been blessed with Mediterranean weather and a view over the sea (Kattegat).

View over the Kattegat (IR photo)

As always I managed to squeeze some radio gear, wires and an antenna pole between all the camping stuff (amazing how many items it takes to transform a family of four into happy campers). 

I have decided not to set up my station on the camping itself for various reasons. For one I am not a fan of digital modes (and living in a tent, phone is not an option) and the OZ campsites are far more organised than I am used to with neatly arranged places so that it would be impossible to keep the station low profile, especially as there are no trees around - only hedges.

Instead I will go out portable for a good number of hours at least once from each campsite. I am aiming to activate two OZFF nature reserves each time - so at least four in total. One will be on the shore of a body of salt water. I am curious if that will help me get my signal out.

Discussing my ideas with the OZFF coordinator and longtime fellow WWFF-er Jakob OZ7AEI, it turned out his holiday plans meant we would be relatively close together on two occasions. So we aimed for a radio-active meet-up.

Getting more specific we have planned a joint operation on Sunday evening July 22 from OZFF-0098. It looks like another member of the OZFF team - Finn OZ3FI - will join as well.
I will start off activating a nearby nature reserve first (OZFF-0100) in the afternoon.

Looking forward to meeting these fellow WWFF enthusiasts and adding OZ to my activity list.

Thursday, April 26, 2018

PACC 2018: we did it again

Today the results of the PACC contest came in. Amazingly my fellow team members of YNOMY and me managed to score a hat-trick: we secured the first place for the third year in a row using the call PG55G this time.

The recipe has been the same these three years: using an empty campground we set up wire antennas on Friday for 40, 80 and 160, adding a portable hexbeam on Saturday morning and then have radio fun for 24h using a well prepared plan constantly updated by live experiences of the band conditions. The two phone operators get a few hours of sleep while our poor cw operator only gets a few opportunities to nap when the phone operators are going.

We are always looking for improvements but this year the only upgrade was the coax we used (as we ran into problems with the coax we used last year). It gets harder and harder to squeeze out more while maintaining our field day concept. 

Tried and trusted hexbeam for 20m (and 2 QSO on 15m)

Wednesday, April 11, 2018

Preparing for a dxpedition to HB0

Last year May I went to LX with PD7YY and PG8M for a weekend to activate 7 different LXFF nature reserves. With the help of the LXFF coordinator we managed to get hold of a nice special call LX44FF.

Perfect conditions @LX in 2017
We were blessed with perfect weather and some Es conditions on 20m. We had a great time that weekend and managed to log far more contacts than we anticipated. We were thinking along the lines of the PACC contest (24h) - 1700 QSO or so - but we ended up with over 2100 QSOs. 

With this experience we of course discussed going on tour again this year. Moving up the DXCC wanted list we considered Bouvet for a moment and had a good look at Scarborough Reef but settled for Liechtenstein.

Picture of the hotel in HB0 - I hope the weather will be like that for us
We will be staying up in the mountains in a nice looking hotel - an upgrade from the caravan we occupied last year - and we will have a bit more time as we are traveling on Friday and Monday. The weather is a big unknown as are the conditions. In general the conditions on HF are poor but that was the case last year as well. We can only hope we will have some Es conditions (bringing a 2m and 6m antenna just in case). Then there is the influence of the mountains that will be a new one for us. Some of the locations we will be active from are on a mountain side. That will undoubtedly influence the signals in some directions.

HB0 is very strict in giving out callsigns so we will not have the benefit we had in LX of a nice short special call. Instead we will be using HB0/PG8M and HB0/PH0NO (switching between those when we move from park to park). Like last time we will be making special awards available for our chasers (details here:

Preparations are ongoing. Several ham radio news sites / letters have been informed and we are checking and completing our gear. We will be taking three radios (one specifically for VHF) with batteries for one day and a whole bunch of different antennas including end fed wires, dipoles, a hexbeam and a VHF yagi with the necessary masts. We will have one mobile amplifier for the HF phone station with its own fat battery.

Now we will have to figure out how to fit all of that and three operators in one car...

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 used four stakes in the corners of the plate I constructed. They were of different size and mostly too 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.