Thursday, October 25, 2012

Getting ready for CQWW phone

Once again we are at the end of October, synonymous for many hams around the globe with CQWW SSB, a festival of contacts on the air for 48 hours.

For the fifth year running, I will be taking part in the multi-single team at ED5T with my friends Victor EA5KV, Elías EB5KT, Jose EA5GS, and Juan Carlos EA5UF.

In order for all of this to happen, there has been a lot of preparatory work going on behind the scenes, and apart from the above mentioned, we have counted on the multiple skills of Juan EA5GIE and the helping hands of Belar EA5YI.

This year, we decided to concentrate our pre-contest efforts on an area where we could do with making some improvement and which, if successful, will give a boost to our score. I'm talking about antenna improvements on 80 metres.

Our mainstay antenna at ED5T for many years has been a bazooka, held up in an inverted V from tower 1. In last years CQWW, the antenna failed on us in the middle of the night and was replaced by a half wave dipole which appears to work just as well. In the past, and in an effort to try to improve over the bazooka, we tried a single full size vertical, a two element full size vertical, and a vertically polarized delta loop. None of those antennas worked better than the bazooka.

Based on that experience, we decided to build a rotatable dipole, on the basis that a) the ends would be higher off the ground and in theory perform better and b) we would be able to rotate it to be broadside to wherever we want it.

The design chosen was a helical winding on fibreglass and aluminium tips for tuning. The antenna is 24 metres long. Part of the reason for choosing this design was that we already had a lot of the material available. The drawback is that since it is physically smaller than a full size, it will not be as efficient, and also will have limited bandwith. Also, the use of fibreglass makes proper guying obligatory due to it being extremely flexible.

The antenna was assembled and tested on the ground and looked good. However installing the antenna was not easy and when finally up, the resonance had risen 200KHz. It took another day and a lot of hands to get it to a more reasonable point and to get it back up in the air. In this photo you can see Juan and Victor finalising assembly.

As you can see, it was already dark by the time we finished. Again....

How does it work? Ahhhh, can't tell you that! You'll have to wait until after the contest to find out! :)

Tomorrow, setup of all the gear, including beverages in the forest courtesy of "Magic" Andreu, EC5AA. And at 0000 utc saturday..... CQ CONTEST!

Sunday, October 21, 2012


Today I finally managed to get round to doing the second part of the experiment with the vertical beams which I started last month.

After the limited success with the 2 element model, I decided to continue with the model suggested by Dave HK1A and make the 2 element into a 4 element by adding two directors. Director number one was tuned for 29.640 and director number 2 for 29.930. Element spacing was 2.07m approx between each element.

Having already done the 2 element version, making the next two elements was a breeze and pretty soon the antenna was up and playing. SWR with the 4 elements gave a good curve although resonated a bit high up the band at around 28.7 MHz.

As in the previous experiment, I did A/B testing with the same reference antenna as before, the quarter wave vertical on the car. Today, the band was mostly open to the states and I worked numerous stations who were kind enough to give me reports on the two antennas. In the previous tests, stateside stations were mostly a bit better on the quarter wave. Today, the stations closer in (east coast) did not notice much difference, some giving a slight edge to the quarter wave and most noting no difference or the beam one S unit better. On the midwest to west coast stations, there was generally more difference in favour of the beam, up to 2 S units in some cases. When N6HD in Los Angeles suggested that propagation was strange and he was getting EU best over 90 degrees instead of the normal 30, I moved the antenna a bit further south and signals improved very slightly on that path.

In summary, the 4 element antenna did not give the improvement I had hoped for, but it was not worse.

There was one case which had me particularly curious and to which I don't have an easy answer. I was called by EA5KV when he was beaming south. I was beaming east, at 90 degrees to him and he logically heard me better on my quarterwave than on my beam. On my receive I noted the same. However when he called in a bit later, with his beam pointing at me (north) there was a very considerable difference in favour of my beam. Does anyone have an explanation for this? He was located about 15km from me and using a horizontal ultrabeam.

The final test will be to use the four elements in a 2 x 2 phased array to see if this gives an improvement over the straight 4 element vertical yagi. Stay tuned!

Thursday, October 18, 2012


This week, I received another couple of those cards I was waiting for, for long forgotten contacts:

And today, in spite of my misgivings about being able to work the T30PY expedition to West Kiribati, all of a sudden today, the unheard of happened: crossing over 14.195 I heard what sounded like a french station working them on simplex. They completed the contact, I called, in spite of hearing them at not more than a whisper, and got a 55 right back! Right after that, I heard Julen EB2AM (owner of the EE2W contest station) work them too. The way things are with the propagation, I think I can count myself very lucky.

Saturday, October 06, 2012

It's been a quiet couple of weeks for me on the radio. This week, I had the misfortune to have my car break down, and since I had a business trip during the week, wasn't able to pick it up from the garage until late on friday afternoon. I had hoped to do a bit more vertical testing on friday, but it wasn't to be....

Regarding the vertical testing, the previous friday was impossible too. We had the wettest and windiest conditions in a long time and no way to even consider any tests. So, let's hope third time lucky and next week I can see about getting the 4 element for 10 working. Watch this space!

The good news is that I was at least able to work 3D2C on Conway reef on 10m and 17m, for country number 303 from the car.