Wednesday, 26 June 2013

The “Kaz” directional MW antenna

The Kaz gives a deep null in one direction.
I have always had a soft spot for Medium Wave and a couple of years ago I decided to take MW DXing a little more seriously. The goal was to hear some North American stations – it couldn't be that hard could it? Well, yes it seems it could!

The first season saw me using my Icom 756 Pro 3 and my usual 80m dipole antenna, but nothing of any significance was heard.

It seems the 756 Pro 3 is deliberately deaf on MW and you can't use the pre-amp. I also listened on a portable MW receiver but that was no better, even with a small 12-inch Tecsun passive loop. The next season I used an RF Space SDR-IQ, but the pickings were thin.

So last year I upgraded to a Perseus SDR and a Wellbrook ALA1530S loop so that I could record the whole of Medium Wave two minutes before the hour to two minutes past to aid with stations IDs. Now we were getting somewhere, with WBBR 1130 kHz (New York) and NBC 1510 kHz (Boston) being heard regularly, although I wasn't hearing anything like the DX other MW enthusiasts in the UK were reporting.

 I actually monitored WBBR every hour, every night for two months to compare reception alongside the daily DsT index, but I can't say I saw a correlation. Anyway, this coming winter I'm determined to try harder and so I need an antenna that will null or attenuate signals from the continent. I ended up choosing a passive design called a “Kaz”, named after its designer Neil Kazaross.

Very simply, the antenna is part of the Flag/Pennant terminated loop family. It is an isosceles triangle with a base of 40ft and the apex at 10ft. One corner (FB) is fed with an impedance transformer and the other corner (TB) is terminated with a resistor between the two legs.

It actually turned out to be really good.

Read the full review of the Kaz antenna.

Monday, 17 June 2013

The secret of the Hately Cross Field Loop antenna revealed

Now it can be told – how were they built and what was Maurice working on before he died?

Maurice Hately G3HAT (SK)
It was with regret that I learned that Maurice Hately GM3HAT (and latterly G3HAT) had passed away. It appears that he actually died in the spring of 2012, but there was no mention of it in the radio press.

My interest in Maurice's work stems from my enthusiasm for small and stealthy HF antennas. As one of the pioneers of the very controversial crossed field antenna (CFA) theory, Maurice used to make and sell small loops for everything from Top Band to 6m.

His adverts regularly appeared in RadCom and I was lucky enough back in 2002 to review some of them for the RSGB.

BUT! This was on the strict understanding that I didn't reveal how he had configured the matching circuitry. I even had to promise not to break the seals on the boxes.

This I duly did and the review was written and published.

But now that Maurice has died I feel I should reveal how the antenna was constructed and also release details of what he had been working on before his death -  a new form of crossed field antenna that used two loops.

All this information may be too important to be lost and it is presented here so that amateurs can continue experimenting with his ideas. Was he on to something? Did his antennas work as as he said and can we continue developing them?

Steve G0KYA
June 2013

Download a PDF with the details of how the CFLs were built and also Maurice's last secret antenna design.

Sunday, 9 June 2013

Practical Wireless 2m QRP contest

The 2m Moxon (arrowed as it is very small).
I don't have a permanent 2m horizontal antenna installed, but when I was first licenced back in the 80s I did spend hours using 2.5W from a Yaesu FT-290R into a 4-element quad in the loft.

I used to work around the UK, as far as Norway, the South of France. Germany and Switzerland. Ah - good old days!

So for the Practical Wireless 2m QRP contest in June I thought I would have a bit of fun. I put up my 2-element home-made Moxon beam at about 8m on a fishing pole and used a Yaesu FT-817 running 2.5W from my Norfolk QTH.

I took part for a couple of hours and managed to work as far as Holland, France, Sheffield and Ditchling Beacon near the south coast. Also worked a few locals and into Cambridgeshire and Lincolnshire. Heard another guy near Cheshire, but he went QRT before I could get him.

Considering the size of the antenna I was amazed to work anything. Conditions were reasonable at first - I could even hear the GB3VHF beacon on a vertical dipole, but the band seemed to get worse by lunchtime.

All good fun though and happy to give away a few points. Nice to hear 2m SSB being used.