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Tuesday, September 13, 2011

"Medium Wave DXING" By Victor Goonetilleke

Few days back responding to my request in Facebook a great and worldwide  respected Dxer from South Asia Mr. Victor Goonetilleke wrote this very useful article on Medium Wave Dxing. With prior permission from the writer I am publishing it here for the greater interest of DX community. (Curtsey: Indian DXing Corporation Forum in Facebook)




"Medium Wave DXING" 
 By Victor Goonetilleke 







PART-I


Medium Wave DX-ing: This is a huge subject too big to tackle in a post. But I am sure you can find a lot of supporting material on the Internet once you have some idea of the basic questions you want to know answers to. So let me try; I might fail badly!!


Long dx stations come in when there is darkness between the TX(transmitting station) and receiving point. So daytime you will hear local stations or within 500 kms or so depending on transmitter power used, as the D layer absorbs Low/MW frequencies. So as sun set approaches you start to hear stations coming on your receiver from the East of you as that area is now in darkness. Take a world map showing the darkness area and you can visualize possible/impossible areas to hear at any particular time. Look for sunrise-sunset maps.


Your local stations will usually block the weak DX signals you hear on MW as the stations are not beaming to foreign audiences, but some will broadcast to adjacent countries. Therefore you have to wait till your local stations close down if they are very strong, but depending on your country's use of the Medium Wave band you will have free spots without local stations.


To start dxing MW you do not have to bother about special antennas and receivers. I have heard even South America, Africa & Australia from Sri Lanka on my domestic set and just 25 feet of wire outside my window. Maybe this post is already too long. Part 2 to follow.



PART-II


The stations on Medium Wave you hear for the most part will not be as strong as on the shortwave international bands, other than those beaming to you eg: BBC 1413, DW 1548 and the very high power stations like Dhaka 693, Rajkot, VOA Thailand 1575 and maybe a dozen or more. Of course sometimes some signals will surprise you. The other stations will keep fading slowly up and down. If you are in Kolkata you might hear AIR North, South and East regional stations on the same freq as they share frequencies. If you stay on the frequency, to your amazement you will find suddenly the Northern station which has been the dominant signal, fading down and the Southerner coming up. That is typical of long range MW. So similarly you might hear an Iranian and Thai MW station on the same frequency. If you have a directional rotatable loop of course you can null out one and bring up the other.


The main problem for MW DXing today, for most of us, is the high electrical noise level in our urban homes. The weak signals will be below the noise level. So a visit to your village home, friend, or some rural location or when your power fails (I love power failures and power cuts, much to the disgust of the others!!) you will find a huge difference in what you can hear. Well a good ground/earth helps as is switching off some electrical appliances, TVs, tube lights even low energy bulbs will reduce the electrical noise. In addition resonant antennas, AC line filters, having your antenna away from the house and of course a good receiver will help. You can read tons of material on the Internet on various aspects of Medium Wave dxing.


So for starters, your existing radio even with just the telescopic whip will bring you a fairly good crop of stations after your local stations have closed down, if you patiently tune in and look around. This has been just an introductory piece & not a master-piece. Good luck with your MW DXing.!!



By- Victor Goonetilleke.



SOME ADDITIONAL COMMENTS FROM Mr. Bruce Jensen on MW DXING:



I would like to add that most ordinary domestic radios for MW will have a simple ferrite rod inside as the antenna. Many here will know that the rod is wound with many feet of wire, and the coil or wire has the radio current induced within it by the ferrite magnet. As small and simple as it is, it makes a super antenna as long as the case around it is not metal. When I lived in the country, I could easily hear MW AM stations from 3,000 miles distant with just the internal ferrite coil inside my transistor radio. Your radio may have this kind of antenna as well. If not, excellent simple coil antennas for MW, even antennas with simple tuners, can be made and attached to your radio antenna lugs.


In other respects, Victor is absolutely right - noise is your enemy, and reducing that noise by eliminating it or moving away from it will probably help a great deal.Something really interesting I found - if you have a domestic radio with a ferrite antenna inside, and you want stronger signals, just wrap a wire around the radio twice and connect the wire ends to a sky-wire and a ground. You'll be amazed at the extra strength signals you can get! Might overload your radio though, so must be careful.

I have a portable radio whose MW and 2-6 MHz band has the ferrite. It isn't good enough for the 2-6, but when I wrap that wire around it, the signals go crazy!!


(Edited and Compiled By: Prithwiraj Purkayastha)

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