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Kiwa Mediumwave Loop Experiences

by John Plimmer

I imported a new Kiwa Loop from Craig of Kiwa in the USA direct by airmail to South Africa at a cost of $250 around 1988. It arrived in good order well packed and was quickly put into operation. Performance was disappointingly dismal as it hardly compared with my modest 17 meter WINDOM longwire outside antenna. Some correspondence with Craig of Kiwa did not improve matters, so in disgust this expensive loop was packed away in a cupboard to gather dust.

Some years later it was taken out of storage and taken on a DXpedition to the remote settlement of Copperton (near Prieska) in the central area of South Africa in a very sparsely populated part of the country. Again, performance was dismal and on return to Johannesburg it was discovered that the Kiwa loop had a malfunction. Craig of Kiwa was superb and soon diagnosed the problem as some small part in the loop having been blown. He sent replacement parts and a local techie soon had it working again, but still with poor performance. The best that could be deduced was that one of the very long wire beverage antenna's on the DXpedition must have touched the Kiwa loop's windings and a spark of static from this very dry semi desert area must have caused the blowout.

Kiwa MW LoopAfter some years I was able to analyse why this Kiwa loop was not performing. As pointed out by Mark Connelly, loops do not like the proximity of all the gear in a typical shack: computers, stereos, radios, antenna and mains cabling and anything metal. In addition, a typical city suburban South African house has an iron roof, metal windows and metal heavy burglar bars over the windows. This is like trying to operate the Kiwa loop in a Faraday cage, and these factors all mitigate against any decent performance by the loop in my suburban house in Johannesburg.

However, things improved dramatically when I retired and moved house Southwards to the Western Cape Province. Again, the Kiwa did not perform very well in the new shack, for the same reasons as listed above, but when I took it to a seaside cottage at the ocean, things took a dramatic turn for the better.

Typically, these Cape seaside cottages are made of wood with wooden windows and roof's. They also have a minimal amount of electrical wiring, so the Kiwa loop came into it's own and I started getting DX results that were quite awe inspiring. A few examples of catches over recent years follow: (all on a Drake R8B RX)

1080 Khz, Gunnedah NSW, Australia, 11,000 Km's 2,000 watts
1430 Khz, KTBZ, Tulsa OK, USA, 14,300 Km's 5,000 watts
1520 Khz, R. Cristal, Cristalandia, Pocantins Prov, Brazil. 7244 Km's 250 watts
1593 Khz, Nigata, Japan, 13,650 Km's 10,000 watts
1620 Khz, WDHP, Fredericksted, St. Croix, US Virgin Isl. 10,430 Km's 1,000 watts
1630 Khz, Universidad Mexicali, Mexicali, Baja California, Mex, 16,060 Km's 1,000 watts

On a DXpedition to Jongensgat in September 2004 it was possible to compare results with other DXers who had strung out well placed 300m/1000 ft beverage longwire antennas. These results show that the Kiwa loop got as many long distance low power stations as did the longwire beverages. There were some strange differences though; the Kiwa only came to light after full darkness, whilst the beverage antennas were starting to get good far distant DX even before the sun had fully set. But once full darkness had set in, the Kiwa really performed with the best of the wire beverages.

For me, one of the main considerations in using the Kiwa loop is its portability. It is packed for transport in a medium sized suitcase and has been carted to many DX locations with no problem and no damage. It is dismantled, packed, then reassembled in literally seconds. Then, I can choose any convenient cottage or bungalow right on the sea, and there are many of these. The number of places where you can find a site to lay out 300m/1000 ft beverage antennas by the sea is getting more and more severely limited as coastal property developments blossom. So the Kiwa is easily portable and I can find numerous seaside cottages with ease, whereas after years of looking, I have only found one site where it is possible to lay out beverage longwires, and that only on our East Indian Ocean coast. This is a big advantage.

A Google search will reveal much written about MW loops, and the Kiwa MW Loop in particular, over the years. Much has been made of the MW loops ability to null out signals that may be masking DX stations that are of more interest to you. However, I have found this feature to be quite useless here in South Africa. Firstly, the Kiwa does not null out a powerful transmitter completely. At best, it may reduce its signal strength by 20 or even 30 dB, but this still leaves a powerful signal remaining which still masks a weaker signal you may be looking for.

Then there is its supposed directionality. In practice I find that even with the weak far distant stations listed above, you can swing the Kiwa loop at least 45 degrees either side of the peak and still have a readable signal. So my own experience over many years is that the loop is not very directional on receiving weak stations, as they can be adequately heard over quite a large arc.

There is also the ability to tilt the loop, but I find that in all cases the faint far off signals can only be heard in the fully vertical position. Even a slight tilting will rapidly loose the signal.

An example of this is reception of R. St. Helena in the Atlantic Ocean on 1548 Khz. This is masked by the 10 Kw R. Islam near Johannesburg. Although these two stations diverge by over 90 degrees from my DX site, it is not possible on the Kiwa loop to null out R. Islam and get St Helena. My experience of nulling out other stations over the years has been equally fruitless.

I have never DXed in N. America or Europe, but there must be substantial differences, as in these countries there are literally thousands upon thousands of MW transmitters, whereas here in Southern Africa there are only a handful of TX's by comparison. So that may account for the diverging opinions on loops that exist between my account and that of Mark Connelly and Werner Funkenhauser, peers whose opinions I value.

The regenerative feature of the Kiwa MW Loop is also worth mentioning, as it substantially peaks the signal, and as you can see above, allows a signal boost sufficient to capture even the faintest and rarest of far off DX.

Regrettably, Craig of Kiwa already discontinued manufacture of these loops some years ago, but they are still actively traded on eBay where they fetch astonishing prices. (several went for around the $600 mark)


On the July 2005 Seefontein DXpedition (PDF file) I took much more trouble to compare my Kiwa against a 300 meter/1000 foot beverage. Most of the time the Kiwa was better to much better than the beverage, which was well set, nice and straight and elevated on average of about four foot/1.2 meters above ground. The unterminated beverage was aligned to Australia and "over the shoulder" to central U.S.A., whilst the Kiwa favoured an alignment pointing to Florida, U.S.A.

Although the Kiwa was overall better, there were some notable exceptions when the beverage was spectacularly better. It was possible with the spectrum scope on the Icom 756 PRO III to analyse why the Kiwa was better. A notable example analysed was 555 Khz St. Kitts, Virgin Islands. This weak station was badly affected by splatter from a local station, 567 Cape Talk Radio. Another DXer's Drake R8A was badly affected by this splatter over the weak St. Kitt's, but my Icom was not. Analysis on the Icom spectrum scope showed that the fault was with the 567 TX splatter coming in on the beverage antenna, but when the Kiwa was switched in and the regenerative circuit optimised, then the splatter was greatly reduced and St. Kitt's much more readable as a result.

Another experiment was listening to the low power TX from Mauritius relaying BBC on 1575. It was much clearer on the Kiwa as the spectrum scope showed the ability of the Kiwa to reduce the static coming in on the beverage which was making the signal barely readable. The Kiwa was able to reduce the static and the regenerative circuit was able to enhance the signal to an acceptable readability. "No!" said my fellow DXer's, the Kiwa is able to optimise the direction better than the beverage, so to satisfy them I set the Kiwa on the same bearing as the beverage and the Kiwa was still hands down more readable and better.

So in most situations the Kiwa rendered a clearer more readable signal on a direct A/B comparison over three days of DXing.

- Very portable
- Easy to setup in any convenient seaside wooden cottage
- Tremendous clean-cut quiet amplification of very faint DX
- Performance equals a well laid out 300m/1000 ft longwire beverage antenna
- Extremely well made and very convenient to use
- Not very directional
- Nulling not very effective
- Does not like any iron or electrical devices near it
- Does not require large open spaces like wire antennas do

On various occasions I have had the use of different home brew aircore MW loops. One was of similar design and size to the Kiwa loop, others, huge ungainly things, were the more traditional one meter loops. Although they performed reasonably, they all lacked build quality. Bits and pieces would come off or they would fall apart with continuous use, and they were inconvenient and ungainly to use. They were not transportable and were never seen on DXpeditions. I noticed that after a while they all ended up gathering dust in their owners garages.

I have not gone into technical details here as a Google search will reveal a wealth of information on the Kiwa MW Loop, as also will the Kiwa website.

Published on DXing.info on March 22, 2005 (edited on August 9, 2005)

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