Dxers Unlimited's mid week edition 23-24 February

Radio Havana Cuba
Dxers Unlimited
Dxers Unlimited's mid week edition for 23-24 February 2010

Hi amigos radioaficionados all around the world and in space.... welcome to the mid week edition of your favorite listener oriented and technically minded radio hobby program, the one and only covering the more than 85 ways that you and I enjoy this wonderful hobby... from home brewing ultra simple minimalist amateur radio transceivers to providing much needed emergency communications when disasters strike and conventional telecomms facilities can't handle the overloads.

You can also spend time learning more about radio astronomy and pick up the peculiar sounds of planet Jupiter from a backyard radio telescope, or maybe help a disabled person to become a radio amateur.


Yes amigos, our hobby not only provides enjoyment to us, but is also capable of helping others, and that certainly makes it quite different from other well known ones.

Now here is item one of today's program … Solar activity is dwindling, only a single weak sunspot active region is on sight, but, it is there and keeping the now long stretch of days with sunspots going on.

As a matter of fact amigos, only two days of the year 2010 have brought a zero sunspots count, quite a difference from last year's record breaking spotless days.

Item two: Radio hobby enthusiasts are able to accept quite amazing challenges... for example, there is an ongoing effort to design, build and operate ultra simple minimalist amateur radio transceivers.... something that has led to some really amazing results... Just imagine the last one I have just learned about... it uses a single field effect transistor and no more than 15 electronic components... it switches between receive and transmit with a mechanical four position double throw switch .

When operating a a short wave ham bands receiver, the field effect transistor acts as a regenerative detector , a well known and highly effective receiver.

When switched into the transmit mode, the same active device, that is the field effect transistor works as a crystal controlled highly stable oscillator that feeds the antenna. When connected to a well built half wave dipole antenna cut for the 40 meters band, several radio amateurs that have built this miniature ultra low power transceiver have made two way contacts with other local stations using Morse Code radiotelegraphy , that is CW continuos wave or A1A transmitting mode.

The ultra miniature transceiver provides excellent headphone volume when on receive, and the on the air transmit signal has a very nice clean keying. The power output achieved when operating the rig using a 12 volts battery is very low , but quite enough to be heard up to several miles away via ground wave, and capable of reaching longer distances when 40 meters band propagation conditions are good.

Total cost of the parts required to build the ultra-minimalist single field effect transistor transceiver is very low, and in my experimental setup, some of the components were provided by recycling broken compact fluorescent lightbulbs !!! As I have said it here many times before, amateur radio doesn't need to be an expensive hobby amigos... ham radio ingenuity, recycling and clever circuit designs make possible to build an amateur station and operate it while spending very little money !!!

Now, stay tuned for more radio hobby related information , that will follow after a short break for station ID. I am Arnie Coro, radio amateur CO2KK your host here in Havana.

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This is Radio Havana Cuba, the name of the program is Dxers Unlimited and here is now item four of this mid week edition...

QSL on the air, QSL on the air to listener Mark from Vancouver , Canada, that wrote about his excellent results achieved with the latest version of the broadband Tilted Terminated Folded Dipole antenna, that according to those using it , provides the best overall performance for short wave reception , if you happen to have space to install just one antenna.

According to amigo Mark, his TTFD was designed for a low cut off frequency of seven megaHertz, so that it could fit into the space he had available for installing it. The antenna is 14 meters long, and it slopes down at a 30 degrees angle from the only mast that he could place next to his home.

The same mast serves as a support structure for two ham radio antennas, a 2 meters band omnidirectional Super Jay and his broadband disc cone that provides reception of frequencies from 100 to 500 megaHertz, and that is also capable of transmitting on the 2 meters and 70 centimeters ham bands.

Going back to the the TTFD , Mark tells me in his e-mail that he uses a home brew balun , and feeds the antenna with 50 ohms RG8-X coaxial cable . The antenna provides very good reception from 7 megaHertz all the way up to 29 megaHertz, and Mark plans to use it in the near future also as a standby transmitting antenna for amateur HF bands operation. He also told me about his ongoing project …. home brewing a single band 40 meters transmitter- receiver, that is not a transceiver, as it doesn't share circuits on transmit and receive , except for the common power supply.

The receiver was designed around the REGENERODYNE circuit, using a 2000 to 2200 kiloHertz regenerative detector acting as a variable intermediate frequency... More about amigo Mark's transmitter- receiver project in an upcoming edition of Dxers Unlimited...


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This is Dxers Unlimited's mid week edition, and amigos, finding a clear spot where to operate your amateur radio station on the 40 meters band can be quite difficult...

Due to the ongoing propagation conditions 40 meters is pretty crowded during the local evening hours... and that's why CW low power or QRP operators have explored the band in search of a segment that is less crowded... Apparently it has been found... My own monitoring of the segment of 40 meters between 7100 and 7120 kiloHertz shows that it has less traffic, a lot less traffic than the lower part of the band.

From time to time you can pick up a short burst of digital signals between 7100 and 7105, but they do go off the air after a very short time, I have also picked up one international shortwave broadcast station that is still operating on 7110 kiloHertz, but so far it has not been possible to identify it.

The typical week days evening here in Havana show that between 7100 and 7120 kiloHertz QRM levels are really very low, and I can pick up many nice ongoing CW contacts between stations that tell about their operating conditions , describing their transmitters as QRP , or of 5 Watts or less...

Here is now a comment by Canadian radio amateur Earl Andrews, VE3AB , himself a QRP or low power station operator. Earl posted on the QRP-L Internet list the following message that I am now quoting here: I have been listening to this freq and 7103. 7104 cleared up and is now free and nice without a lot of the clutter around 7030 and 7040. I did put out some test calls and will continue to do so in the next few days when Im down in the shack.

Hopefully..qrpers will operate there without being muscled out by qro types who might start operating there too! Might be a good idea to suggest a qrp zone between 7100 and 7115 in an official band plan proposal of some sort.

Si amigos, as you have just heard, here in the Americas, and very possibly also in Europe and Africa too, the segment of 40 meters just above 7100 seems to be an ideal place for operating low power stations, free from the dreadful interference of high power rigs and digital modes..


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Yes, we do QSL, we do verify your signal reports and comments about our programs, send mail to inforhc at enet dot cu, or VIA AIR MAIL to Arnie Coro, Radio Havana Cuba, Havana, Cuba... and now here is our next section of the show...

DRM, Digital Radio Mondiale continues to call my attention regarding the way it is used by those broadcasters that have decided to invest their resources using that transmission mode.

I would like to ask each and everyone of the executives of those stations that are using part of their budget on DRM transmissions, if they have an idea of how many DRM capable receivers are in operation around the world.

My expectations are that if those who provide the station's with their operating budgets learn about the NON EXISTANCE, of DRM Digital Radio Mondiale capable receivers around the world , they will immediately take the logical and sound decision of bringing those broadcasts to a screeching tires halt...

At this moment, there is no reason to broadcast on DRM more than short experimental transmissions, and those stations that move their regular Amplitude Modulation short wave programming to DRM are for sure loosing more than ninety nine percent of their potential audience.

No amigos, I am not against DRM or the development of digital radio technology, but at this very moment, when there are practically no short wave receivers that are DRM capable available at a reasonable cost, broadcasting using DRM is a real waste of valuable resources.

The DRM Consortium hasn't even negotiated for a free software package that can be downloaded from a website by anyone interested in picking up the DRM short wave broadcasts , so that they can pick up the programs using a slightly modified receiver connected to a computer.

My last search for a free software package to decode the DRM short wave programs was a total failure... the only software package found was available only after paying a rather substantial amount of money...something that I don't think many short wave listeners are willing to do...

So here is once again my advice to those who are trying to promote the use of Digital Radio Mondiale for high frequency decametric bands broadcasting... do your homework, find out how many receivers are presently in use , and where they are located... then target your DRM transmissions to those areas of the world, while at the same time go into an all out effort to promote the design , assembly and sales of at least a medium priced DRM capable short wave radio, while at the same time making available as free and open source software a DRM decoding package …

And last but not least... to the station managers presently running DRM broadcasts on the short wave bands, please instruct your frequency managers to very carefully select the operating frequencies and also instruct your senior engineering staff to be sure that the DRM signals are not causing harmful interference to other stations using Amplitude Modulation standard transmissions on the internationally assigned short wave bands !!!

And now amigos, as always at the end of the show, here is your Arnie Coro's, Dxers Unlimited's HF propagation update and forecast...

Solar activity is now at very low levels, with a single sunspot active region transiting the solar disc and soon to turn around out of sight. The solar flux is still abov 80 units and as we continue to approach the equinox, propagation should improve despite the low sunspot count. If no new sunspot active regions show up, we may soon see spotless days... something that has only happened twice so far this year. Best bands for daytime DX , from 17 to 22 megaHertz, and at night the best conditions will be found between 6 and 12 megaHertz amigos !!!

Send your signal reports and comments to inforhc at enet dot cu, or VIA AIR MAIL to Arnie Coro, Radio Havana Cuba, and remember that we are a one hundred percent QSL station !!!