10/15 Trap Dipole

10/15 meter Trap dipole mounted below the 11 ele 2 meter yagi.

For the SDARS Field Day I built two resonant, have wave, end fed vertical antenna. One was a single band antenna for 10 meters and the other, a trap vertical for 20/15 and 17 meters. I was very pleased with the results from both antenna while in the electrically quiet environment of the countryside but at the home QTH they were prone to picking up too much domestic QRN.

10 Meters has been wide open at this period of the Sun Spot Cycle and rather than miss the DX I decided to build a mono band dipole. However, as usual I tend to get carried away and as I had already built 2 coaxial traps for 10 meters decided to incorporate those into the design. I have mentioned building coaxial traps before so I won't repeat myself here. 

I built a standard dipole with a normal centre "T" piece that accepts a PL259 terminated feeder. The 10 meter elements were added using the formula 468/F in feet. The coaxial traps were soldered onto the ends of the elements and short pieces of wire added for 15 meter elements.

The fun came when I started to tune the antenna and it took much adjusting to get both bands resonant in the CW frequencies that I was interested in. The 10 meter elements were too long so rather than unsolder and cut them I just folded back 3 inches of wire and held it in place with cable ties. The 15 meter elements were easier to trim and I managed to achieve an SWR of 1:1 on both bands.

Then came the problem of where to erect it. As a sloper it was cumbersome, looked untidy and it was too close to the house so I decided to make it into a rotary dipole. I cut a piece of teak that was in the shed down to a semi-circle with a radius of 7 inches. I drilled 2 holes to accept a "U" bolt to fix it to the mast. I then screwed the centre "T" piece to the block. To hold the wire elements out straight I used 2 bamboo garden canes that were just a bit too short but where needs must! I decided on a shallow "V" configuration for the elements partly to reduce the turning circle and partly to give better perceived DX performance for a single element antenna. So 2 holes were drilled into the wooden block, each at an approximate 25 degree angle, and the bamboo canes fitted snugly into them. I threaded the canes through the 10 meter traps and just simply cable tied the wire to the bamboo. About 6" of the 15 meter elements hung off the ends of the supports.

Up in the air the SWR remained 1:1 at the CW part of both bands so it looked like I was in business. I don't expect it will last forever but it was cheap and if it does break the wire will prevent it falling very far.

Results have been very good with a distinct null at 90 degrees to where the signals peak. It was also a lot quieter when compared directly to the vertical antenna with signals standing out from the noise very prominently. The first contact was with D44AC in Cape Verde on 15 meters. He had quite a pile up so I was pleased to work him at my first attempt. So far 10 meters has given me several USA stations which are new for me on 10.

I am glad that I made the effort to get on 10 meters before the Solar Cycle ends rather than just moan afterwards about what I had missed because I didn't have a proper antenna.

The Dipole centre piece cost me £4 at the SDARS rally and the rest of the components came from the shed so for the outlay I am very pleased. The turning radius of the antenna is similar to the UHF antenna so should not cause any visual problems either.

160 meter Club Calls AFS Contest

I must confess that I only venture onto top band very rarely. The problem is one of a suitable antenna. Last year I made a shortened Dipole (100 feet total length) with a fairly hefty Inductance coils in the centre of each leg. It does work quite well but it has a very narrow bandwidth. Even with my little LDG AT100Pro autotuner I can only work about 30 Hz of the band without going outside, lowering the ends and folding over some length of the wire. It is supported in the centre at 10 meters agl and the ends slope down to 3 meters agl. I only have room for the one antenna so it has to replace the 80/40 trap dipole.

In the run up to the Contest I did play around with a 9:1 UnUn, end feeding a 60 feet piece of wire but it was no better and much noisier than my shortened dipole so did not finish it.

This year I decided to try and find a run frequency and call CQ and see what developed. This is normally quite a difficult thing to do in HF Contests as the QRM can be severe. Fortunately the power limit is a modest 32 watts on 160 meters so I wasn't bothered by powerful adjacent stations very much at all.

I was using N1MM to log the contest but discovered a scoring problem with it. Working an RSGB HQ station is supposed to attract a bonus of 50 points but N1MM only scored it as a normal Club station with an extra 25 points. With no way of editing the score on the required Cabrillo file I just noted the problem in the soapbox and hoped for the best.

The first 5 minutes of the Contest were very slow and I was beginning to wonder if my antenna was working at all. But things soon warmed up and I received some nice reports. Of course, all reports on HF Contests are 59 but I did get some favourable comments on my signal and audio which was very satisfying.

I finished with a total of 74 QSO's and a grand total of 1102 points (I think!). A huge improvement on previous years.

It was great to work the SDARS Club Station, GX4DSP and also fellow Club members; M1MHZ, M1CDL and G4ODA who all managed to find me in the mellay. 

I must confess that I will be pleased to get the 80/40 meter dipole back up but there is another top band contest next week using CW so I will be retuning the shortened dipole to the lower end of the band so that I can have a go at that. Then it will be back to normal operations again with the pipe and slippers put into storage until next year.

Thanks to all stations for points and I hope that you all enjoyed the Contest.

73 de Jim G0HGH.

Marconi CW contest

The 2 meter CW Marconi Contest took place on 2nd and 3rd November 2013.

The Marconi is the longest of the VHF CW Championship events and runs for 24 hours. Last year I dabbled in it but was never going to be a serious contender. As I have entered into all of the VHF CW Championship events on 4 meters and 6 meters this year I was determined to have a better shot at it.

Bob, G1ZJP, very generously and diligently supplied the station so that I could go /P. The antennas alone were very impressive. Bob had fixed up a huge array of 4 X 12 element M2 yagis. Antenna always look bigger on the ground and he shot a photo of me being dwarfed by set up. They are colossal on the ground!

 Dwarfed by the huge 4 X 12 ele array

Weather forecasts indicated that we could expect very high winds and heavy rain over night and, for once, they were not wrong. At their highest the antenna were up at 23 meters agl. Well over twice the height that I could manage with my single 11 ele. on a pneumatic mast at my home QTH.

Antenna at full height seen across the fields.

The contest started at 14.00 z on Saturday and radio conditions were not very good. Working Europe was not very easy especially  considering the Continentals were working the contest as well. Most of them only turned their antennas to G land as a last resort so they were a bit thin on the ground. The UK activity level was not very high either. Maybe the promise of stormy conditions kept antennas lowered in readiness.

As night fell, Bob took on the duties of safety officer as the weather conditions outside deteriorated. The wind strengthened and, more importantly, got more gusty so he was outside in the riving rain lowering the mast to about half height. I ventured out a couple of times during the evening to get some air and seeing those antenna being buffeted by the wind was rather scary. 

The run rate in these events is never as high as during the UK AC Contests that I am more used to operating in, and 24 hours is a long time with very little activity. At 23.45 with only 1 qso in the previous hour I decided to get some sleep. I drove home and was amazed to get a few hours of shut eye despite consuming large quantities of coffee and still hearing CW ringing in my ears. Up bright and early on Sunday I was back on the key by 7.45 the next morning. In total I managed just over 16 hours of intensive CW operation in the 24 hours available.

Using the rotataor controls to peak the Continentals!

Last year I worked 30 other stations, this years tally was a more respectable 80 qso's. Upon analysis there was one dupe and one other non-scoring contact so that dropped to 78 contacts.

I must admit that I was quite relieved to see 14.00 z come around on Sunday. Concentrating on mainly weak CW signals for long periods is exhausting. CW decoders are virtually useless in these conditions so it was all reading by ear and sending was with the aid of a memory keyer and some manual sending to break the boredom.

The best DX worked was DK9IP at 759 Km and the average distance per QSO was 324 Km. 80 contacts in 24 hours is mind numbingly slow but the difficulty level was quite high so that kept me alert for most of the time. As I had been wearing headphones for all of the contest, my ears were plastered to the side of my head. As I write this they are just starting to get back to normal.

One of the most satisfying QSO's was with M1CDL. John is one of the members of our CW beginners group at Spalding and District Amateur Radio Society (SDARS). I could hear his nerves but he completed the contact in   a very proficient manner. Well done John.

I am not a very fast CW operator and the contest exchange is quite long in the Marconi, RST, Serial Number and Locator so maximum speed for me was about 17 wpm. Most other stations came back to my CQ calls at roughly the same speed, maybe a bit faster. I cease to be very accurate above 22 wpm and there was loads of time so I did not see any point in rushing contacts and jeopardising points. 

It was great fun but I was pleased when the end came. I left Bob to dismantle the antennas and get ready for his next contest on Tuesday. A huge thank you to him for all of the work he put in so that I could indulge myself in the 2013 Marconi VHF CW Contest.

Mni tnx fer qso and pts 73 es gl de G0HGH/P

Tower flexing in the wind - it got a lot stronger!

Thanks to Bob, G1ZJP, for the photographs.