DXers Unlimited
Radio Havana Cuba
By Arnie Coro, CO2KK
Hi mis amigos radioaficionados around the world and those of you now orbiting our planet!!! Welcome to the weekend edition of your favorite listener oriented, and surely technically minded radio hobby program... YES... you are listening to Dxers Unlimited, the one and only short wave program devoted to each and every aspect of our wonderful passtime...not just to boring lists of stations that can be heard only at a certain specific location...
When you spend part of your spare time with your radios... you can, like during this weekend enjoy the thrill of a two way ham radio contact half way around the world using a very low power QRP transmitter in the middle of one of the year´s most important CW contests,the CQ Magazine sponsored WPX CW prefix contest, or you can have a lot of fun during a 2 meters band fox hunt at one of your city's parks... but that´s not all, you can also spend many hours optimizing your new TV Dxing antenna system now that sporadic E layer openings are happening every day....
By Arnie Coro, CO2KK
Hi mis amigos radioaficionados around the world and those of you now orbiting our planet!!! Welcome to the weekend edition of your favorite listener oriented, and surely technically minded radio hobby program... YES... you are listening to Dxers Unlimited, the one and only short wave program devoted to each and every aspect of our wonderful passtime...not just to boring lists of stations that can be heard only at a certain specific location...
When you spend part of your spare time with your radios... you can, like during this weekend enjoy the thrill of a two way ham radio contact half way around the world using a very low power QRP transmitter in the middle of one of the year´s most important CW contests,the CQ Magazine sponsored WPX CW prefix contest, or you can have a lot of fun during a 2 meters band fox hunt at one of your city's parks... but that´s not all, you can also spend many hours optimizing your new TV Dxing antenna system now that sporadic E layer openings are happening every day....
SI AMIGOS, YES MY FRIENDS..OUI MES AMIS,.radio is unique in the sense that there is always something to learn, to experiment with, and to enjoy... I am Arnie Coro in Havana, my ham radio call sign isCO2KK, and you can hear my amateur radio station often on the 40, 30 and 20 meter bands CW segments using my new 2 Watt rig, connected to a wideband antenna that is working very well indeed.
Now here is item one of today's Dxers Unlimited... As the summersolstice is approaching, now less than a month away, we are seeing late evening band openings on the 30 and 20 meter amateur bands, and very good reception of international short wave broadcasts on the 31an 25 meter bands.
Item Two: Many e-mail messages keep coming in to my inforhc@enet.cu account every day, and it's really nice to see how Dxers Unlimited's listeners worldwide continue to enjoy this program and bring in so many new ideas, suggestions and questions for me to review. Among the most recently revived ideas was to create at least one CD ROM disk with the best of Dxers Unlimited for the past several years... and then make it available to those interested... Sure it's a good idea that will require a lot of work on my part, something I am just starting to do during this weekend...
Item Three: Simple wire antennas continue to fascinate many of you amigos, among them the ultra compact two element QUAD antenna for the two meters amateur band, that can be built in a few hours using standard PVC insulated wire used for household installations and PVC plastic pipe and standard fittings for it. But be aware of an interesting phenomenon... if you don't strip the wire of its plastic insulation, the dimensions of the antenna will be different than those coming from the standard two elements VHF QUAD antenna formula... And also there is a very nice and easy to use software program to calculate a VHF QUAGI antenna, a neat ombination of a two element QUAD and several linear parasitic director elements...
Now here is item one of today's Dxers Unlimited... As the summersolstice is approaching, now less than a month away, we are seeing late evening band openings on the 30 and 20 meter amateur bands, and very good reception of international short wave broadcasts on the 31an 25 meter bands.
Item Two: Many e-mail messages keep coming in to my inforhc@enet.cu account every day, and it's really nice to see how Dxers Unlimited's listeners worldwide continue to enjoy this program and bring in so many new ideas, suggestions and questions for me to review. Among the most recently revived ideas was to create at least one CD ROM disk with the best of Dxers Unlimited for the past several years... and then make it available to those interested... Sure it's a good idea that will require a lot of work on my part, something I am just starting to do during this weekend...
Item Three: Simple wire antennas continue to fascinate many of you amigos, among them the ultra compact two element QUAD antenna for the two meters amateur band, that can be built in a few hours using standard PVC insulated wire used for household installations and PVC plastic pipe and standard fittings for it. But be aware of an interesting phenomenon... if you don't strip the wire of its plastic insulation, the dimensions of the antenna will be different than those coming from the standard two elements VHF QUAD antenna formula... And also there is a very nice and easy to use software program to calculate a VHF QUAGI antenna, a neat ombination of a two element QUAD and several linear parasitic director elements...
By the way that program, which is freeware, is available by just sending me an e-mail message requesting the QUAGI antenna design program... send your request to inforhc@enet.cu , again inforhc@enet.cu , and I'll e-mail the software to you as a small dot zip attachment attachment...
Item Four: A simple, rugged, flexible, roll up ,easy to transport solar photovoltaic panel, a lead acid gel cell accumulator and a simple home brewed voltage regulator will power up your low power amateur radio station and your short wave receiver at anytime... The solar energy option is excellent for your emergency communications kit, and you will be pleasantly surprised how even in somewhat dark days, the silicon solar cells can provide enough energy to charge up the battery for nighttime use.
A five or ten watt power solar panel is ideal for this application, and let me add that many ham radio contests have now special entry categories that provide bonus points for stations using solar or wind energy for powering the equipment during the contest. Amateur radio contests participants . like the many hams involved during this weekend worldwide CQ WPX CW prefixes ontests, learn a lot about fast and efficient communications procedures and field installations, something that is extremely useful when actual emergencies come up to your community .
Item Five: The number of amateur radio stations in some countries is extremely small. This is seen especially in the African continent, where the presence of DX expeditions of people visiting from developed nations is often the only possible source of a two way contact with that DX entity. My perception is that helping to develop amateur radio in Africa will be extremely useful for the people of that continent, and this is an effort that could be very well linked to already ongoing projects designed to provide Internet access from remote locations using satellite
technology.
Item Six: Tropical Band DX season is now, for all practical purpose over in our northern hemisphere... high noise levels, typical of the summer months make Dxing on the 120, 90 and 60 meters Tropical Broadcast Bands extremely difficult during the evening hours. Nevertheless, very early morning monitoring of the 4.6 to 5.1 megahertz segment of the short wave spectrum will still make possible some nice catches, because at that time there is minimal ionospheric absorption and the daily distribution of thunderstorm activity is also at a minimum...
Item Five: The number of amateur radio stations in some countries is extremely small. This is seen especially in the African continent, where the presence of DX expeditions of people visiting from developed nations is often the only possible source of a two way contact with that DX entity. My perception is that helping to develop amateur radio in Africa will be extremely useful for the people of that continent, and this is an effort that could be very well linked to already ongoing projects designed to provide Internet access from remote locations using satellite
technology.
Item Six: Tropical Band DX season is now, for all practical purpose over in our northern hemisphere... high noise levels, typical of the summer months make Dxing on the 120, 90 and 60 meters Tropical Broadcast Bands extremely difficult during the evening hours. Nevertheless, very early morning monitoring of the 4.6 to 5.1 megahertz segment of the short wave spectrum will still make possible some nice catches, because at that time there is minimal ionospheric absorption and the daily distribution of thunderstorm activity is also at a minimum...
One not too nice thing happening to Tropical Band Dxers is that many of their favorite stations
are going off the air, due to many different reasons, among them the rapid velopment of FM broadcast stations in areas forming served by Tropical Band broadcasts, and the high cost to broadcasters of keeping on the air old vacuum tube transmitters for which replacement parts are more and more difficult to find, and when found are extremely expensive. Cuba uses the Tropical 60 meters band for providing a nationwide service to so called silence zones, especially nations four main mountain regions, where night time AM and FM coverage is not as good as it should be ...
In areas of mountains and especially in the valleys where AM and FM broadcasts do not reach or provide a very unreliable service, the Near Vertical Incidence Skywave tropical band signals provide excellent service. That's whey the Cuban Broadcast Institute now operates a 50 kilowatt high tech transmitter for broadcasting Radio Rebelde's network national program on 5025 kilohertz, using a near verticalncidence sky wave antenna system to provide optimum service up to a distance of 1000 kilometers around the transmitter site...
For Dxers there is a bonus... thantenna does have a small low angle lobe that makes possible listening to Radio Rebelde in many far away places too!!!
......
Si amigos, we do QSL, we do verify reception reports and absolutely free of harge... You may send your detailed reception reports and comments about this and other RHC programs to inforhc@enet.cu ,again inforhc@enet.cu , or VIA AIR MAIL send a postcard to Arnie Coro, Radio Havana Cuba, Havana, Cuba... And now la numero uno, the number one most popular section of Dxers Unlimited, ASK ARNIE is on the air...
Today's question sent by listener Dimitri from near St Petersburg, Russia.Dimitri wants to know how he can find the equivalents of solid state devices, so as to make a cross reference between Russian electronic components and those made in Europe, the USA and Asia... Amigo Dimitri, you are not alone , you are facing a huge problem and quite a challenge... because the specification of, for example, bipolar transistors for low signal levels are difficult to match between manufacturers.
Fortunately, there are some general purpose devices that provide a high degree of compatibility, for example I have used here Russian made KT315 NPN low signal transistors to replace many different types made in Japan and Europe with excellent results... I also have created a database that matches to the best possible degree the specifications of many Russian vacuum tubes to their US, Japan and European equivalents...
Second QUESTION... Came from Canada, listener Alex from London, Ontario, is asking about the possible efficiency for short wave reception of a TTFD antenna that in his case,will need to be be only 10 meters or about 33 feet long, as that is all the space he has for his antenna system. Well amigo Alex, here is an important piece of information regarding the TTFD antenna design... the lower cutoff frequency for transmitting is calculated very easily by simple arithmetic...
The TTFD length is calculated by dividing the wavelength by the number three.. so your antenna only 10 meters in overall length will be good for transmitting from 30 meters or 10 megaHertz up... In other words, if you divide 30 meters by 3, your answer will be 10 meters, and that's the length of a TTFD that will be useable for transmitting from 10 megaHertz up... But now the good news, it is a fact of life and fully documented by many users of the TTFD, including yours truly, that a 10 meters or 33 feet long TTFD is certainly a quite useful receiving antenna down to about 5 megaHertz And when used with an antenna tuner it will also put out a useable signal on the 40 meters band, but not as efficiently as the full size half wave dipole antenna cut for that amateur band that has an overall length of 20 meters or 66 feet!!!
So , summarizing, the answer to your question amigo Alex,is, SURE, go ahead and build and then install your 10 meters long TTFD, as per the building instructions that I sent to you sometime ago, and then after using it for a while, please tell me and other Dxers Unlimited's fans around the world about your results !!!
are going off the air, due to many different reasons, among them the rapid velopment of FM broadcast stations in areas forming served by Tropical Band broadcasts, and the high cost to broadcasters of keeping on the air old vacuum tube transmitters for which replacement parts are more and more difficult to find, and when found are extremely expensive. Cuba uses the Tropical 60 meters band for providing a nationwide service to so called silence zones, especially nations four main mountain regions, where night time AM and FM coverage is not as good as it should be ...
In areas of mountains and especially in the valleys where AM and FM broadcasts do not reach or provide a very unreliable service, the Near Vertical Incidence Skywave tropical band signals provide excellent service. That's whey the Cuban Broadcast Institute now operates a 50 kilowatt high tech transmitter for broadcasting Radio Rebelde's network national program on 5025 kilohertz, using a near verticalncidence sky wave antenna system to provide optimum service up to a distance of 1000 kilometers around the transmitter site...
For Dxers there is a bonus... thantenna does have a small low angle lobe that makes possible listening to Radio Rebelde in many far away places too!!!
......
Si amigos, we do QSL, we do verify reception reports and absolutely free of harge... You may send your detailed reception reports and comments about this and other RHC programs to inforhc@enet.cu ,again inforhc@enet.cu , or VIA AIR MAIL send a postcard to Arnie Coro, Radio Havana Cuba, Havana, Cuba... And now la numero uno, the number one most popular section of Dxers Unlimited, ASK ARNIE is on the air...
Today's question sent by listener Dimitri from near St Petersburg, Russia.Dimitri wants to know how he can find the equivalents of solid state devices, so as to make a cross reference between Russian electronic components and those made in Europe, the USA and Asia... Amigo Dimitri, you are not alone , you are facing a huge problem and quite a challenge... because the specification of, for example, bipolar transistors for low signal levels are difficult to match between manufacturers.
Fortunately, there are some general purpose devices that provide a high degree of compatibility, for example I have used here Russian made KT315 NPN low signal transistors to replace many different types made in Japan and Europe with excellent results... I also have created a database that matches to the best possible degree the specifications of many Russian vacuum tubes to their US, Japan and European equivalents...
Second QUESTION... Came from Canada, listener Alex from London, Ontario, is asking about the possible efficiency for short wave reception of a TTFD antenna that in his case,will need to be be only 10 meters or about 33 feet long, as that is all the space he has for his antenna system. Well amigo Alex, here is an important piece of information regarding the TTFD antenna design... the lower cutoff frequency for transmitting is calculated very easily by simple arithmetic...
The TTFD length is calculated by dividing the wavelength by the number three.. so your antenna only 10 meters in overall length will be good for transmitting from 30 meters or 10 megaHertz up... In other words, if you divide 30 meters by 3, your answer will be 10 meters, and that's the length of a TTFD that will be useable for transmitting from 10 megaHertz up... But now the good news, it is a fact of life and fully documented by many users of the TTFD, including yours truly, that a 10 meters or 33 feet long TTFD is certainly a quite useful receiving antenna down to about 5 megaHertz And when used with an antenna tuner it will also put out a useable signal on the 40 meters band, but not as efficiently as the full size half wave dipole antenna cut for that amateur band that has an overall length of 20 meters or 66 feet!!!
So , summarizing, the answer to your question amigo Alex,is, SURE, go ahead and build and then install your 10 meters long TTFD, as per the building instructions that I sent to you sometime ago, and then after using it for a while, please tell me and other Dxers Unlimited's fans around the world about your results !!!
AND remember that the TTFD Antenna's most recent version requires a terminating resistor between 800 and 950 or even one thousand ohms, that it must be a non inductive type of resistor and that it should be properly protected against the weather elements. For transmitting, the TTFD terminating resistor must be rated to a minimum dissipation of one fourth of the transmitter power for average use, and a higher rating if you plan to use full carrier modes like standard RADIO TELETYPE or PSK31 digital keyboard to keyboard mode... My version of the TTFD uses ten 2 Watt 8200 ohms carbon non inductive resistors connected in parallel, to achieve a total termination resistance of near 820 ohms, and with that value, the antenna has worked very well for several years using my 100 Watts transceiver, without any signs of the terminating resistance changing its value...
....
And now amigos just at the end of the program, as always here is our exclusive and not copyrighted free for all radio hobby enthusiasts worldwide ..Arnie Coro's Dxers Unlimited HF plus low band VHF propagation update and forecast...The effective sunspot number, ESN, continues to be at a dramatically below 10 units, while the actual sunspot optical count was zero on Friday and Saturday, an indication of the almost endless very low solar activity. The daytime maximum useable frequency curve is barely reaching 18 megaHertz on the East-West daytime paths, and as expected, best HF propagation conditions continue to be available just after local sunset.
Expect a lot more sporadic E layer openings, with possible 12, 10 and 6 meters band openings. Atmospheric noise levels are at a pretty high level, as typical of the northern hemisphere summer months... Hope to have you all join me next Tuesday and Wednesday UTC days for the mid week edition of Dxers Unlimited, and don't forget to take a little time and send me your valuable comments and opinions about this program, to help me make it better for you and all listeners around the world !!!
(R Havana Cuba)
....
And now amigos just at the end of the program, as always here is our exclusive and not copyrighted free for all radio hobby enthusiasts worldwide ..Arnie Coro's Dxers Unlimited HF plus low band VHF propagation update and forecast...The effective sunspot number, ESN, continues to be at a dramatically below 10 units, while the actual sunspot optical count was zero on Friday and Saturday, an indication of the almost endless very low solar activity. The daytime maximum useable frequency curve is barely reaching 18 megaHertz on the East-West daytime paths, and as expected, best HF propagation conditions continue to be available just after local sunset.
Expect a lot more sporadic E layer openings, with possible 12, 10 and 6 meters band openings. Atmospheric noise levels are at a pretty high level, as typical of the northern hemisphere summer months... Hope to have you all join me next Tuesday and Wednesday UTC days for the mid week edition of Dxers Unlimited, and don't forget to take a little time and send me your valuable comments and opinions about this program, to help me make it better for you and all listeners around the world !!!
(R Havana Cuba)
