Arnie Coro CO2KK
Hi amigos radioaficionados around the world and orbiting the Earth, because, yes, there are radio amateurs in space at this moment, and they do communicate with hams using 2 meters band equipment aboard the International Space Station... I am Arnie Coro , radio amateur CO2KK, host of this twice weekly program and someone that has had the unique opportunity of talking to cosmonauts orbiting the Earth... a unique experience amigos, and one of the more than 81 ways of enjoying our wonderful radio hobby: space amateur radio communications....
Item two: zero, zero, zero, one after the other is the result obtained by Solar Observatories around the world that monitor the number and characteristics of sunspots... Zero sunspots and a solar microwave flux of below 70 mean that high frequency bands from 20 megaHertz up are behaving like VHF bands as regards to ionospheric propagation. Simply there are not enough free electrons available at the ionosphere to send short wave signals back to Earth on frequencies above 20 megaHertz or so for 95 percent of the days... An occasional 15 meters amateur band opening does happen, and one can pick up an international broadcast station operating on the adjacent 13 meters band, but those band openings are very short lived.... We must be patient and wait until the next solar cycle starts and the daily sunspot number and solar flux go above no less than 20 for the sunspots and 80 to 90 for the solar flux, that are the required figures to bring back our much wanted higher frequency bands amigos...
Stay tuned for more radio hobby related information, coming to you from Havana , I'll be back with you in a few seconds , after a short break...
.....
This is Radio Havana Cuba, the name of the show is Dxers Unlimited, and yes amigos, we do QSL , we do verify reception reports with beautiful QSL cards... send your reception reports to arnie@rhc.cu , or VIA AIR MAIL to Arnie Coro, Radio Havana Cuba, Havana, Cuba... and here is now item three of the mid week edition of the program. Our technical topics section, that is rapidly competing with ASK ARNIE and the HF plus low band VHF Propagation update and forecast in listener's popularity... The technical topics today is about the design criteria for an optimized homebrew receiver, using the lowest parts count that is still consistent with good overall performance. I have been working on two such receivers during the past several weeks, as they will be part of the radio amateurs academy training program now in progress at my Plaza Radio Club here in Havana, where we have joined efforts with the nearby Cerro Radio Club to provide training for the newcomers to the radio amateur hobby that will soon be taking the ham radio license test,required to own and operate an amateur radio station.
Receiver prototype one, is an all solid state design, using locally available parts and components, and like in the case of receiver prototype two, that is a hybrid vacuum tubes and transistors radio, no attempt has been made to miniaturize the sets. A lot of nice open space where to work with the soldering iron, parts well separated from each other, and the printed circuit designs using wide strips of copper for interconnecting the components. This design philosophy leads to very easy to build by the newcomers radios... receivers that can be also easily modified to add new features, and the most important thing of all, these two prototypes provide very good reception within the frequency range from 500 kiloHertz all the way up to the 50 megaHertz or 6 meters amateur band. But again, no attempt was made to provide bandswitching using conventional multiposition switches to select the tuned circuits, instead a much more up to date switching arrangement using saturated transistors is used...
Prototype one, the all solid state receiver, follows a modular design criteria, that starts with the power supply, the first item that the newcomer assembles and tests under the supervision of the instructor. This power supply is based on a locally plentiful power transformer, and the voltage regulator used can provide up to 2.5 amperes at 13.8 volts, so that it can also be used, in the future, to power a QRP or low power amateur radio transmitter. Taking into consideration the locally available components, this power supply can be considered as a basic building block that the newcomer to the hobby can use both for operating his receivers and transceivers, as well as for doing a lot of experiments with different circuits. The power supply can be later modified to provide variable output voltage, as well as several lower voltages that may be required for other equipment like a CW keyer or an external audio filter.
The building blocks concept has proven to be a very nice approach, because during the radio and electronic lessons, we assemble one unit and test it in front of the class. For example, the input signal attenuator, bandpass tuneable filter and radio frequency amplifier module has become the de facto standard to add as an outboard accesory to portable solid state receivers, that lack adequate input selectivity.
Hi amigos radioaficionados around the world and orbiting the Earth, because, yes, there are radio amateurs in space at this moment, and they do communicate with hams using 2 meters band equipment aboard the International Space Station... I am Arnie Coro , radio amateur CO2KK, host of this twice weekly program and someone that has had the unique opportunity of talking to cosmonauts orbiting the Earth... a unique experience amigos, and one of the more than 81 ways of enjoying our wonderful radio hobby: space amateur radio communications....
Item two: zero, zero, zero, one after the other is the result obtained by Solar Observatories around the world that monitor the number and characteristics of sunspots... Zero sunspots and a solar microwave flux of below 70 mean that high frequency bands from 20 megaHertz up are behaving like VHF bands as regards to ionospheric propagation. Simply there are not enough free electrons available at the ionosphere to send short wave signals back to Earth on frequencies above 20 megaHertz or so for 95 percent of the days... An occasional 15 meters amateur band opening does happen, and one can pick up an international broadcast station operating on the adjacent 13 meters band, but those band openings are very short lived.... We must be patient and wait until the next solar cycle starts and the daily sunspot number and solar flux go above no less than 20 for the sunspots and 80 to 90 for the solar flux, that are the required figures to bring back our much wanted higher frequency bands amigos...
Stay tuned for more radio hobby related information, coming to you from Havana , I'll be back with you in a few seconds , after a short break...
.....
This is Radio Havana Cuba, the name of the show is Dxers Unlimited, and yes amigos, we do QSL , we do verify reception reports with beautiful QSL cards... send your reception reports to arnie@rhc.cu , or VIA AIR MAIL to Arnie Coro, Radio Havana Cuba, Havana, Cuba... and here is now item three of the mid week edition of the program. Our technical topics section, that is rapidly competing with ASK ARNIE and the HF plus low band VHF Propagation update and forecast in listener's popularity... The technical topics today is about the design criteria for an optimized homebrew receiver, using the lowest parts count that is still consistent with good overall performance. I have been working on two such receivers during the past several weeks, as they will be part of the radio amateurs academy training program now in progress at my Plaza Radio Club here in Havana, where we have joined efforts with the nearby Cerro Radio Club to provide training for the newcomers to the radio amateur hobby that will soon be taking the ham radio license test,required to own and operate an amateur radio station.
Receiver prototype one, is an all solid state design, using locally available parts and components, and like in the case of receiver prototype two, that is a hybrid vacuum tubes and transistors radio, no attempt has been made to miniaturize the sets. A lot of nice open space where to work with the soldering iron, parts well separated from each other, and the printed circuit designs using wide strips of copper for interconnecting the components. This design philosophy leads to very easy to build by the newcomers radios... receivers that can be also easily modified to add new features, and the most important thing of all, these two prototypes provide very good reception within the frequency range from 500 kiloHertz all the way up to the 50 megaHertz or 6 meters amateur band. But again, no attempt was made to provide bandswitching using conventional multiposition switches to select the tuned circuits, instead a much more up to date switching arrangement using saturated transistors is used...
Prototype one, the all solid state receiver, follows a modular design criteria, that starts with the power supply, the first item that the newcomer assembles and tests under the supervision of the instructor. This power supply is based on a locally plentiful power transformer, and the voltage regulator used can provide up to 2.5 amperes at 13.8 volts, so that it can also be used, in the future, to power a QRP or low power amateur radio transmitter. Taking into consideration the locally available components, this power supply can be considered as a basic building block that the newcomer to the hobby can use both for operating his receivers and transceivers, as well as for doing a lot of experiments with different circuits. The power supply can be later modified to provide variable output voltage, as well as several lower voltages that may be required for other equipment like a CW keyer or an external audio filter.
The building blocks concept has proven to be a very nice approach, because during the radio and electronic lessons, we assemble one unit and test it in front of the class. For example, the input signal attenuator, bandpass tuneable filter and radio frequency amplifier module has become the de facto standard to add as an outboard accesory to portable solid state receivers, that lack adequate input selectivity.
A simple demonstration of the improvement to a Sony ICF7600 D receiver to which the prototype RF input module was connected by means of a short length of 50 ohms coaxial cable showed a great improvement in reception , especially within the frequency range of 5 to 12 megaHertz, where at this particular phase of the solar cycle are the most used . The presence of super power international broadcast stations is one of the problems that makes reception difficult with those radio receivers that have a very poor front end design. And, just to provide a bit more of information, the use of the basic RF signal attenuator, bandpass tuneable filter and RF amplifier module with a more sophisticated receiver, also proved to be worthwhile, because the tendency by designers is to use fixed tuned input filters that are switched when the bands are changed, in contrast with my receiver prototype that offers the user the possibility of having a sharply selective tuneable input filter .
In an upcoming edition I will be describing the third module of the solid state receiver prototype, the double balanced broadband mixer and first local oscillator.
Now Dxers Unlimited's mid week edition will continue with another popular section of the program; Antenna Topics, coming up in a few seconds ...
..........
You are listening to Radio Havana Cuba's twice weekly radio hobby program, and here is now our Antenna Topics section that today will be devoted to feedback from listeners that are experimenting with the double spiral loaded dipoles , following the design ideas of Petlowany and Tektorian... Spiral end loading of antennas is nothing new at all, and it has been used by low frequency stations that for obvious reasons could not make use of the extremely high masts or towers required to achieve resonance at the quarter wave of a wavelength.
By adding simple top capacitive loading , the so called UMBRELLA antennas have made possible rather efficient radiators at frequencies as low as the long wave AM broadcast band still used in Europe, Africa and Asia, but that was never brought into use in the Americas.
The spiral top loading is a stept further, that adds both capacitive and inductive loading to the antenna, but that does require a rather complex mechanical arrangement... But until very recently that type of loading was not experimented with dipole antennas. The latest version of these spirals end loaded dipoles is the so called TAK ANTENNA, that according to its designer is able to achieve a very high radiation efficiency with a very short horizontal length .A 40 meters band TAK Antenna is claimed to have more than 80 percent of the efficiency of a full size antenna, while requiring only about three meters of horizontal space for its installation.
Reviews by top antenna experts are very favorable to both the Petlowany and TAK spiral end loaded antennas, but there is just one objetion about their use, and that is that they are narrow band systems, in other words they provide a reasonable good match at a center operating frequency, and then if you need to move up or down in frequency, the standing wave ratio goes up very fast.
Nevertheless these spiral loaded antennas are an excellent option for radio amateurs that are very short of space to install their antenna systems, and are of particular interest at this phase of the solar cycle when the higher frequency bands, where smaller antennas can be used, are absolutely useless due to the extremely low solar activity.
The basic spiral loaded dipole uses two large diameter wire spirals that have a bit more than a quarter wavelength of wire wound in about 7 to 10 turns with proper spacing between turns. The matching is done on site, on an experimental basis, by moving a feed wire along the spirals to find the lowest possible standing wave ratio...
Again these are narrowband antennas, but you can understand how useful they are, when you realize that a 40 meters band TAK TENNA is less than three meters long, as compared to the 20 meters length required by a full size wire dipole !!!
.......
Now here is ASK ARNIE, la numero uno, the most popular section of Dxers Unlimited according to your e-mail messages, letters, postcards and phone calls amigos... Today I will be answering a question sent by listener Claire from Indiana, USA. Claire wants to know why she can't listen to an otherwise strong and in the clear
short wave signal when she is using her hair dryer.... and she even adds that she has borrowed one from a neighbor and exactly the same type of buzzing noise erase the short wave station she was listening to. The answer amiga Claire, is that hair dryers, and blenders, as well as fish tank pumps, and many other home appliances generate wide band radio frequency noise that interferes with short wave reception.
The hair dryers, kitchen mixers and blenders are particularly noisy because they use a type of electric motor that use carbon brushes to feed electricity to the motor's rotor, and very small sparks jump across causing the generation of radio frequency energy, exactly as it was done by the first primitive radio telegraph transmitters, the so called SPARK TRANSMITTERS, that had to be banned because they generated wide band noise all over the radio frequency spectrum !!!
.....
And now amigos as always at the end of the program when I am here in Havana, get ready to copy Arnie Coro's HF plus low band VHF propagation update and forecast.. Solar activity continues at extremely low levels, with the effective sunspot numer ESN at just four units Tuesday at 15 hours UTC. The geomagnetic field is also extremely quiet too, and the maximum useable frequency curve is a very slow starter after local sunrise, reaching only about 18 to 20 megaHertz at the best times of the day... According to solar scientists we will have to wait at least one more year to see a significant improvement on short wave propagation conditions amigos !!!
Hope to have you all listening next Saturday and Sunday UTC days to the weekend edition of Dxers Unlimited !!! Same time, same short wave frequencies, same world wide web connection, same satellite feed you are picking us up
(Arnie Coro)
In an upcoming edition I will be describing the third module of the solid state receiver prototype, the double balanced broadband mixer and first local oscillator.
Now Dxers Unlimited's mid week edition will continue with another popular section of the program; Antenna Topics, coming up in a few seconds ...
..........
You are listening to Radio Havana Cuba's twice weekly radio hobby program, and here is now our Antenna Topics section that today will be devoted to feedback from listeners that are experimenting with the double spiral loaded dipoles , following the design ideas of Petlowany and Tektorian... Spiral end loading of antennas is nothing new at all, and it has been used by low frequency stations that for obvious reasons could not make use of the extremely high masts or towers required to achieve resonance at the quarter wave of a wavelength.
By adding simple top capacitive loading , the so called UMBRELLA antennas have made possible rather efficient radiators at frequencies as low as the long wave AM broadcast band still used in Europe, Africa and Asia, but that was never brought into use in the Americas.
The spiral top loading is a stept further, that adds both capacitive and inductive loading to the antenna, but that does require a rather complex mechanical arrangement... But until very recently that type of loading was not experimented with dipole antennas. The latest version of these spirals end loaded dipoles is the so called TAK ANTENNA, that according to its designer is able to achieve a very high radiation efficiency with a very short horizontal length .A 40 meters band TAK Antenna is claimed to have more than 80 percent of the efficiency of a full size antenna, while requiring only about three meters of horizontal space for its installation.
Reviews by top antenna experts are very favorable to both the Petlowany and TAK spiral end loaded antennas, but there is just one objetion about their use, and that is that they are narrow band systems, in other words they provide a reasonable good match at a center operating frequency, and then if you need to move up or down in frequency, the standing wave ratio goes up very fast.
Nevertheless these spiral loaded antennas are an excellent option for radio amateurs that are very short of space to install their antenna systems, and are of particular interest at this phase of the solar cycle when the higher frequency bands, where smaller antennas can be used, are absolutely useless due to the extremely low solar activity.
The basic spiral loaded dipole uses two large diameter wire spirals that have a bit more than a quarter wavelength of wire wound in about 7 to 10 turns with proper spacing between turns. The matching is done on site, on an experimental basis, by moving a feed wire along the spirals to find the lowest possible standing wave ratio...
Again these are narrowband antennas, but you can understand how useful they are, when you realize that a 40 meters band TAK TENNA is less than three meters long, as compared to the 20 meters length required by a full size wire dipole !!!
.......
Now here is ASK ARNIE, la numero uno, the most popular section of Dxers Unlimited according to your e-mail messages, letters, postcards and phone calls amigos... Today I will be answering a question sent by listener Claire from Indiana, USA. Claire wants to know why she can't listen to an otherwise strong and in the clear
short wave signal when she is using her hair dryer.... and she even adds that she has borrowed one from a neighbor and exactly the same type of buzzing noise erase the short wave station she was listening to. The answer amiga Claire, is that hair dryers, and blenders, as well as fish tank pumps, and many other home appliances generate wide band radio frequency noise that interferes with short wave reception.
The hair dryers, kitchen mixers and blenders are particularly noisy because they use a type of electric motor that use carbon brushes to feed electricity to the motor's rotor, and very small sparks jump across causing the generation of radio frequency energy, exactly as it was done by the first primitive radio telegraph transmitters, the so called SPARK TRANSMITTERS, that had to be banned because they generated wide band noise all over the radio frequency spectrum !!!
.....
And now amigos as always at the end of the program when I am here in Havana, get ready to copy Arnie Coro's HF plus low band VHF propagation update and forecast.. Solar activity continues at extremely low levels, with the effective sunspot numer ESN at just four units Tuesday at 15 hours UTC. The geomagnetic field is also extremely quiet too, and the maximum useable frequency curve is a very slow starter after local sunrise, reaching only about 18 to 20 megaHertz at the best times of the day... According to solar scientists we will have to wait at least one more year to see a significant improvement on short wave propagation conditions amigos !!!
Hope to have you all listening next Saturday and Sunday UTC days to the weekend edition of Dxers Unlimited !!! Same time, same short wave frequencies, same world wide web connection, same satellite feed you are picking us up
(Arnie Coro)
