Dxers Unlimited’s middle of the week program for Tuesday 4 December 2018

By Arnie Coro
radio amateur CO2KK

Hola amigos radioaficionados all around the world and in space… this is the middle of the week edition of Dxers Unlimited, your favorite listener oriented radio hobby program covering regularly many of the more than 91 ways you and I are able to enjoy this wonderful hobby. This three days of December have brought us a very quiet Sun, with diminishing solar activity shown by solar flux levels that barely around 68 units…. 202 days of 2018 without sunspots is the best example of solar minimum in progress.

Last minute spaceweather alert received at 15 hours UTC Tuesday —  CME, coronal mass ejection — IMPACT POSSIBLE THIS WEEK: NOAA forecasters say there is a 45% chance of G1-class geomagnetc storms on Dec. 5th when a coronal mass ejection (CME) is expected to hit Earth’s magnetic field.

CMEs are rare during solar minimum because their usual launching pads — that is, sunspots–are absent. This one was produced not by a sunspot, but rather by a filament of magnetism erupting from the sun’s southern hemisphere.

The very low solar activity in progress has led to very nice AM Medium Wave Band and 160 meters amateur band night time propagation conditions that can be traced to much lower ionospheric absorption…  As you have just heard, weak solar cycle 24 is behaving exactly as the latest predictions had announced, to let me insist in the need for better low frequency bands antennas, and I suggest that all short wave listeners should consider building or buying a magnetic loop antenna capable of tuning from about 500 kiloHertz or 2 megaHertz all the way up to around 12 megaHertz — where most long distance signals are going to be heard all along the rest of 2018 and all along next yeaar.

I am Arnaldo, Arnie, Coro, radio amateur CO2KK, your host here at the middle of the week edition of Dxers Unlimited… You can send your radio hobby related questions to be answered on the air and also directly to your e’mail address… Send mail to inforhc at enet dot cu or VIA AIR MAIL to Arnie Coro, Radio Havana Cuba, Havana, Cuba.

Here is now the next news item of today’s show… It moves rather slowly ahead, but it is a fact that DRM , Digital Radio Mondiale continues to attract the attention of broadcasters that need to increase their quality of service and are expecting that soon at least several lower cost DRM capable receivers are going to become available at least in Asia. The already available new Indian DRM receiver is still very expensive for the average consumer, and according to the most recent reports is still away from achieving the expected features required for Digital Radio Mondiale reception.

Anyway it is considered by experts a good step forward that will attract the high end wealthy radio hobbyists interest and also that it may open the path towards a much more simple and lower cost DRM radio. Now let me add that savvy expert short wave listeners are capable of picking up DRM short wave broadcasts using computer software that works quite well…. The decoding software requires some time to familiarize with its features and operational characteristics, but once it is set up, signals from far away short wave broadcasters transmitting in DRM mode are very well decoded.

Here in Cuba a good friend of mine was able to pick up the New Zealand DRM short wave broadcasts, when propagation conditions are good. But, signal fading takes its toll, and it is very annoying to be listening to an interesting program when suddenly the signal drops out to zero, and nothing, absolutely nothing is heard, something in contrast with what happens with the traditional Amplitude Modulation Mode that slowly fades away and then recovers without a total loss of signal… DRM software apparently needs some kind of polishing to avoid those sudden dropouts that are very annoying to the listeners…

By the way, the United Nations specialized telecommunications agency, the ITU , has recommended and endorsed the use of DRM for local medium wave and FM broadcast bands, but so far , due to the lack of receivers, DRM implementation has kept at a so far experimental only transmission mode.

As a senior Cuban broadcast engineer and university professor recently stated at a technical meeting held here in Havana, Cuba…. DRM is an excellent choice to replace the obsolete AM medium wave broadcasting mode, and it is a viable alternative to FM broadcasts too… but until well designed and medium or low cost radios are available in large quantities, the future of DRM is questionable….

Another digital audio broadcast mode, formerly known as IBOC, or In Band on Channel, that has now changed its name to HD Radio, High definition radio, to make it more attractive to listeners is struggling to survive in the United States of America saturated media markets, and also in Mexico… HD Radio receivers are sold at prices that make them attractive to some medium income consumers, but so far sales have not picked up, as buyers prefer to spend their money on digital gadgets like high end mobile phones and tablet computers…. Stay tuned for more radio hobby related information coming from La Habana , I will be back in just a few seconds…

Si amigos, yes my friends, this is Radio Havana Cuba’s program on the air for the enjoyment of radio hobby fans all around the world… we have now entered into our 27th year on the air , something made possible by your support of this show sending e’mail messages, letters, postcards, fax and even stepping up at the door of our Infanta 105 Centro Habana building that we share with Radio Progreso National Network…

It is really nice to read what you write about some unique experiences, like monitoring the emergency traffic following a tornado, or keeping a close watch on a tropical hurricane as it approaches landfall, when amateur radio operators set up their extremely valuable emergency nets…. As a matter of fact the recent assignment of a 15 kiloHertz of extremely valuable five megaHertz band segment to the amateur radio service during the most recent world administrative radio conference held in Geneva at the end of 2015, is an excellent example of the high value that the world’s telecommunications authorities give to the amateur radio service…

Now item four:  Amazing as it may sound… I just saw a new regenerative radio circuit that uses a well known voltage regulator integrated circuit as its only active component… The TL431 is used by many switched mode  units , like those used to provide power to computers… But this is the first time that I have seen using that IC that only has three terminals as an active component. For those of you that enjoy exploring new circuits designs ideas, I saved the dot jpg circuit diagram and coil winding details that can be sent via e’mail because it is a small size file…

If you are interested in exploring the TL431 single IC regenerative receiver circuit, just send an e’mail to inforhc at enet dot, cu . Again inforhc at enet dot cu….

This is Dxers Unlimited’s middle of the week program, and now more about home building of radio receivers, one of the more than 91 ways of enjoying this wonderful hobby. At a recent radio club meeting that I attended, it was discussed how we could encourage new members to start building radios, and several of the participants agreed that the first construction project to accomplish should be a power supply…. It was further agreed that considering the large quantity of vacuum tubes still locally available… the best approach would be to design not one, but two well filtered and regulated power supplies, one for solid state only radios and the other one for hybrid or vacuum tubes only receivers….

The availability of zero cost silicon diodes recycled from the compact fluorescent light bulbs circuit boards led to a one ampere current capacity regulated supply that also uses a series pass transistor also supplied by recycling the CFL boards… The hard to find parts for this project are a step down transformer and a high value electrolytic capacitor . Old dead TV sets that used transformers are the source of those parts , and we ended up with a nice power supply unit for the solid state receivers and low power transmitters…

Si amigos, you can make your own radios and enjoy those special moments when signals are heard for the first time on a home built receiver !!! See you all at the weekend edition of Dxers Unlimited next Sunday and Monday UTC days… just after the top of the hour newscast…

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