Dxers Unlimited
Dxers Unlimited´s weekend edition for 8-9 March 2008
By Arnie Coro
Radio amateur CO2KK
Hi amigos radioaficionados around the world and in space , you are all most welcome to the weekend program of Dxers Unlimited, coming to you when once again solar optical observations show a spotless solar disc !!! Zero sunspots during four of the past six days until March the seventh... and nevertheless I see reports of 10 meters band openings between Namibia, callsign prefix V51 and Southern Europe, something that can be explained by the typical enhancement of trans equatorial propagation that happens as we approach the spring equinox of the Northern Hemisphere. So, Saturday and Sunday I will be keeping a close watch on both 10 meters and 6 meters for South American stations that are surely going to be coming in to the Caribbean from Argentina, Uruguay, Paraguay, Chile , Bolivia and Brazil... TEP, or Transequatorial propagation is one of the most interesting modes of Ionospheric propagation that incidentally was discovered by radio amateurs more than 50 years ago...
Item two: Got a recent report of Radio Guama, the Pinar del Rio provincial network heard in Texas on 990 kiloHertz, their main station located near the city that has the same name of the province, Pinar del Rio. Radio Guama is also on the air on FM, so I expect to see reports of their FM broadcasts when the spring-summer sporadic E season starts...
Item three: Also about Cuban AM broadcast stations between 900 and 1000 kiloHertz, right in the middle of the classic AM analog radio´s dials... On 900 kiloHertz Radio Progreso´s 50 kiloWatts located in Holguin province can be usually heard in the Caribbean, Central America ,the USA and Canada by nulling the Mexican station on the same channel XEW, that according to some sources runs a very high power transmitter on that frequency. Many years ago, the Chief Engineer of Radio Progreso Cuban National Network, Carlos Estrada , visited Mexico City to attend an International Radio Broadcasting Conference, and he came back very impressed by the XEW 250 kilowWatt transmitter that used a Doherty type linear amplifier. Doherty and Terman-Woodyard linear amplifiers are now part of broadcast history, because practically all if not all of today´s new transmitters are built using solid state devices that operate with rather low voltages . The solid state power output stages are modular, so in case one of them fails the transmitter still stays on the air at reduced power output, something broadcasters appreciate very much...
More about AM broadcasting in a few seconds when Dxers Unlimited´s weekend edition continues. I am Arnie Coro , radio amateur CO2KK in Havana...
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Si amigos, sure, AM broadcast band Dx season for this winter is about to come to an end, but if just gives way to the spring equinoctial DX season that brings in some very nice openings too, especially at just after local sunset... With the extremely low solar flux that we are observing nowadays, I expect a very nice AM band spring equinox DX season to be starting up by next week… Now, more about Cuban AM stations in the 900 to 1000 kiloHertz segment of the AM broadcast band… on 910 kiloHertz here in Havana , we have Radio Metropolitana, a local capital city station that is on the air 24 hours , and on that same frequency 910 kiloHertz we also have Radio Cadena Agramonte from Camaguey city, that can be heard very well all over eastern Cuba due to its transmitter´s excellent location. And here in Havana, on 950 kiloHertz we have the 10 kiloWatt Radio Reloj, the easiest Cuban station to identify because it sends out the letters R R on CW many times every day… You will hear a one per second pulse and the RR on CW from all of Radio Reloj´s network stations… Cuba is now using its national fiber optics cables backbone distribution network, as well as the several microwave radio relay systems, so many times you will notice that Radio Reloj´s signals on different frequencies have a slight time delay due to the coding and decoding process of the digital systems used by the fiber optic equipment… By the way, this last item answers a question sent by listener Jeff, from Toronto, who asked why he could hear on two radios slightly different audio from Radio Reloj on 950 and 1020 kiloHertz...
Now here is our next item… a special or amateur radio operators that are getting ready for the spring equinox DX season… Don´t expect this season to be a record breaking one… solar cycle 24 has not shown any more signs of activity after the tiny high latitude sunspot, and cycle 23 continues to provide many, many days of zero sunspots… Anyway, during the spring equinox HF propagation conditions will certainly improve, and I expect that the 20 and 17 meter bands take a turn for the better starting in about a week or two from now...
Another news item for radio amateurs has to do with the 60 meters band, that is now slowly becoming available to ham radio operators in some countries, although the trend is to authorize the use of specific frequencies, in other words, that the telecoms administrations want to keep radio amateur operators on the 5 megaHertz region of the HF spectrum tied to channelized operation, in order to avoid conflicts with primary users of that very much sought band of frequencies. 60 meters should be particularly useful for handling emergency traffic when the 40 meters band closes up for near vertical incidence skywave propagation, the mode used to communicate at short distances on the HF bands during emergencies.
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You are listening to Dxers Unlimited´s weekend edition, coming to you from Havana. Now here is ASK ARNIE, la numero uno, the most popular section of the program according to your e-mail messages, letters, fax reports and when some of you visit here in Havana and have the opportunity to talk to us about our programming… ASK ARNIE today is answering the question sent by listeners in Canada, the USA , the UK and Germany about DRM , Digital Radio Mondiale, the digital system that several stations are using now on the international short wave bands.
Well amigos Mark, Charlie, Ian and Rudolph… DRM continues to be a source of controversial opinions among the world´s mass communications researchers, but there seems to be a consensus about the waste of resources that DRM is causing to the broadcast organizations, many of which are openly talking about severe budget limitations. It is quite contradictory to watch how an international broadcaster spends money in transmitting using DRM signals that have practically no listeners, while at the same time cutting back programs and language services that do have a well established audience, fully equipped with short wave radios that are working perfectly well... The worst thing that is happening now is that there are no DRM capable receivers available at a competitive cost… and event the DRM receivers that do exist are as hard to find as the proverbial extinct DODO bird… If DRM wants to really survive, it must find financing for producing a high quality low cost receiver that could flood the world marketplace… That should be the number one objective of the DRM Consortium if they really want DRM to be successful… Instead of encouraging broadcasters to waste their limited resources in buying new DRM capable transmitters and put them on the air for many hours every day with no listeners picking up those broadcasts at the other end… someone must advise the Consortium about both basic marketing and audience research...
Just recently a well known Cuban senior engineer and university professor commented to me that the DRM basic transmission mode for short wave was showing very poor performance even at what he described as ideal distances for HF broadcasting. Professor Jose Angel Amador played back to me recordings of DRM broadcasts from the Montsinery site of Radio France International , that showed frequent totally silent periods as propagation conditions changed abruptly between Montsinery and Havana, changing from single hop to double hop back and forth.
Professor Amador´s findings coincide very well with what I witnessed several years ago in South Africa when experimental DRM broadcasts from the Sines, Portugal site were sent beaming to Johannesburg… instead of the slow fading typical of such a long path multiple hops propagation observed with AM signals, the DRM was either heard with good quality or just vanished , making it impossible to follow the program content because of the silence periods… The Montsinery to Havana path studied by Professor Amador is just another solid evidence that even if and when receivers are available, DRM broadcasts on short wave are much less reliable and less user friendly than standard AM and even than Single Side Band suppressed carrier signals ! ! !
Your comments and opinions of DRM are invited... send them to
arnie@rhc.cu again arnie@rhc.cu and if you wish them to be put on the air just tell me in your e-mail. I do believe that it is about time that broadcasters that are testing DRM without listeners bring those tests to an end in order to save energy and reduce radio frequency pollution, as well as CO2 emissions that result from the generation of electricity that is wasted powering up those DRM transmitters...
My point of view is that if a station puts a signal on the air that can be heard somewhere, the energy and resources invested are well worth the effort… but why waste so much resources sending out DRM broadcasts that nobody can hear ?.
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This is Radio Havana Cuba, the name of the show is Dxers Unlimited and here is now our next item… our antenna topics section, that today will be devoted to folded vertical grounded monopole antenna as a small footprint option for radio amateurs wanting to operate their stations with a low take off angle antenna. My experiments with the folded vertical grounded monopoles started just recently after reviewing several technical papers about this type of antenna that is more and more becoming the de facto standard for AM broadcast band transmitting installations. It was quite clear from the conclusions of the technical papers that the folded vertical grounded monopole could become a very nice antenna for amateur stations , especially those operating on the 160 , 80 and 40 meters bands… I am now in the process of gathering the materials to build and install a folded vertical grounded monopole antenna for the 20 meters band, a sort of scale model to test how it works as compared to a standard quarter wave vertical antenna with elevated radials that is going to be used as a reference at the same site, at CO2KK my ham radio station… As soon as the new test antenna goes up and results can be analyzed, you will hear about them here at your favorite hobby program… Dxers Unlimited that is now coming to an end today with our HF plus low band VHF propagation update and forecast. Very low solar activity, zero sunspots, but due to the approaching spring equinox, we will be witnessing somewhat better propagation conditions especially around local sunset… See you all at the upcoming mid week edition of Dxers Unlimited next Tuesday and Wednesday UTC days amigos ! ! !
(via dxld ml)
