By Arnie Coro-CO2KK
Hi long time amigos radioaficionados and those who are listening for the first time too... welcome to the midweek edition of Dxers Unlimited that is certainly a very special one, as at the time you are listening to the program, our nearest star the Sun has been inactive for a very long period, with the daily sunspot count at ZERO for many days.
Now a new sunspot active region is slowly rotating into view, and that will probably increase the solar flux above the extremely low 67 and 68 flux units that it has been hovering as of late. By the way, any solar flux figure below 70 units , automatically sends the sunspot count to ZERO.
Item two: Thank you amigos, to the many friends around the world that have already sent birthday greetings..ahead of time, as I will be celebrating my birthday Monday of next week. Some came in as early as yesterday evening, as it seems that some of my good friends have very well structured computerized data bases with their amigos birthdays records !!!
Item three: Listening Friday evening on the AM medium wave broadcast band to the recently upgraded Radio Reloj Pinar del Rio provincial relay, operating on 790 kiloHertz and running 20 kiloWatts, its another of the new solid state high technology transmitters that are replacing the old power hungry vacuum tube broadcast equipment, in an effort by Cuban broadcasting to make more efficient use of electricity by replacing the obsolete transmitting plant as financial resources become available.
Hi long time amigos radioaficionados and those who are listening for the first time too... welcome to the midweek edition of Dxers Unlimited that is certainly a very special one, as at the time you are listening to the program, our nearest star the Sun has been inactive for a very long period, with the daily sunspot count at ZERO for many days.
Now a new sunspot active region is slowly rotating into view, and that will probably increase the solar flux above the extremely low 67 and 68 flux units that it has been hovering as of late. By the way, any solar flux figure below 70 units , automatically sends the sunspot count to ZERO.
Item two: Thank you amigos, to the many friends around the world that have already sent birthday greetings..ahead of time, as I will be celebrating my birthday Monday of next week. Some came in as early as yesterday evening, as it seems that some of my good friends have very well structured computerized data bases with their amigos birthdays records !!!
Item three: Listening Friday evening on the AM medium wave broadcast band to the recently upgraded Radio Reloj Pinar del Rio provincial relay, operating on 790 kiloHertz and running 20 kiloWatts, its another of the new solid state high technology transmitters that are replacing the old power hungry vacuum tube broadcast equipment, in an effort by Cuban broadcasting to make more efficient use of electricity by replacing the obsolete transmitting plant as financial resources become available.
The new 20 kW 790 kHz transmitter is located on the outskirts of the city of Pinar del Rio , about 100 miles west of Havana, and tests done by RadioCuba engineers show that it has an overall conversion efficiency of around 80 percent... that meaning that the new Radio Reloj relay will save a lot of electricity while providing a much better service, because it is also capable of modulating the carrier wave on positive peaks up to 125 percent...
A similar 10 kiloWatt transmitter was recently installed by Radio Cuba for the Radio Reloj City of Havana station on 950 kiloHertz, something that has improved the coverage of Radio Reloj in three of the nation's western provinces. More radio hobby related information coming to you in just a few seconds as Dxers Unlimited's weekend edition continues...
Si amigos, wish you could join my modest birthday party next Monday afternoon... I will be meeting with family and friends for the celebration, with little Claudia, my youngest daughter now almost two and a half years old, Teresita, my elder daughter , Arnie Jr. and Roxana my wife having prepared a cake and ice cream party !!!
Now here is the next item of today's program: Just added a Light Emitting Diodes home brew lamp to act as the back light of my favorite 2 meters band FM transceiver that was constantly burning the very difficult to replace incandescent pilot lamp that illuminates the liquid crystal display. A white light emitting diode and a resistor did the job that , according to LED manufacturers specifications won't need to be replaced in a very long , long time.
I also did a similar incandescent light bulb replacement on my small portable, a Grundig FR200 " Recycle Power"radio.
On this radio I replaced the high intensity miniature incandescent lamp dash emergency light with a cluster of three high intensity white diodes, that give a lot of light and use less than half the electricity that the incandescent bulb requires to operate. Some time ago a long time Dxers Unlimited listeners sent me the photos of his modified Grundig FR200 receiver , to which he had changed the light bulb for three high intensity white Light Emitting Diodes with great success, and I just followed upon this nice idea.
The other modification that he made consists on an electronic band spread, that is a voltage variable silicon diode that was added to the local oscillator tuned circuit on the short wave bands, making tuning a lot easier than with the radio's original mechanical analog tuning. He told me that he could set the analog dial to a specific position on the blank calibration scale, and then tune the radio with the varicap diode. Another thing he did to this very special "emergency radio" was to add a beat frequency oscillator, so that single side band and CW stations could be picked up..The BFO is switched on and off by a miniature switch located on the back of the radio, right next to a second variable resistor to control the voltage to a second voltage variable or varicap diode.
One of the really nice features of the Grundig FR200 is that it uses up very little electricity to operate... as a matter of fact three standard double A cells will last for quite some time if you use the radio for casual listening.
Again, it's an excellent set to have around in case there is a power failure, and even if your batteries go dead, the Grundig FR 200 has a crank type Direct Current Generator that will charge a small nickel metal hydride battery pack, and even if the pack is in bad shape, the radio will keep working all the time that you are cranking the generator !!!
Si amigos, despite doomsday predictions that the radio hobby will just vanish due to the now everywhere Internet, it's just not happening, and what a paradox, the Internet is actually helping the radio hobby in the specific case of amateur radio.
The other modification that he made consists on an electronic band spread, that is a voltage variable silicon diode that was added to the local oscillator tuned circuit on the short wave bands, making tuning a lot easier than with the radio's original mechanical analog tuning. He told me that he could set the analog dial to a specific position on the blank calibration scale, and then tune the radio with the varicap diode. Another thing he did to this very special "emergency radio" was to add a beat frequency oscillator, so that single side band and CW stations could be picked up..The BFO is switched on and off by a miniature switch located on the back of the radio, right next to a second variable resistor to control the voltage to a second voltage variable or varicap diode.
One of the really nice features of the Grundig FR200 is that it uses up very little electricity to operate... as a matter of fact three standard double A cells will last for quite some time if you use the radio for casual listening.
Again, it's an excellent set to have around in case there is a power failure, and even if your batteries go dead, the Grundig FR 200 has a crank type Direct Current Generator that will charge a small nickel metal hydride battery pack, and even if the pack is in bad shape, the radio will keep working all the time that you are cranking the generator !!!
Si amigos, despite doomsday predictions that the radio hobby will just vanish due to the now everywhere Internet, it's just not happening, and what a paradox, the Internet is actually helping the radio hobby in the specific case of amateur radio.
Never before in the more than one hundred years of the existence of our wonderful hobby we have seen so much valuable information been made available freely... There are thousands and thousands of amateur radio websites, and the amount of technical information that can be downloaded is absolutely amazing...
There are websites that require many, many hours to just take a look at, like the super antenna site courtesy of W4RNL , Dr. L.B. Cebik, that can be found at http://www.cebik.com....
There are sites devoted to specific modes like the Dr. Oliver Phelp's digital communications mode website, and there are also lots of sites devoted to radio wave propagation, home brewing of radios, contests, antique radios... you name it, so again, we are seeing a very interesting thing happening in front of our eyes... the Internet, that was supposed to be the end of amateur radio and the radio hobby in general, is actually now helping more and more people enjoy the hobby in a much more plentiful and I must add also inexpensive way !!!
But be aware that some radio amateurs think different as regards to making their websites freely available to anyone, by demanding copyright privileges as if their websites were run as commercial operation... but fortunately those are just a few exceptions and the true amateur radio spirit of cooperation with anyone interested in the promotion and development of the radio hobby seems to prevail in at least a one hundred to one ratio in favor of freely available technical information.
Si amigos, yes my friends, thanks for joining me today on this mid weekk edition of Dxers Unlimited... And now here is the very popular antenna topics section of the show...devoted today to a peculiar antenna system that is known as " The DIPOLES NEST ", a very easy to home brew High end of the HF, low band VHF and high Band VHF antenna.
A few weeks ago I quickly assembled a NEST OF DIPOLES, to solve a friend's antenna problem... The system has a dipole cut for 28.4 megaHertz on the 10 meters band, his favorite HF band, another one cut for 50.3 megaHertz on 6 meters and yet another one cut from 145.000 megaHertz on 2 meters.
They are all fed using the single RG 58U 50 ohms coaxial cable that my friend had at hand, and as expected, I used a first balun choke coil for the two meters dipole, made by looping 6 turns of the cable on a 1.5 inch diameter PVC pipe coil form, followed by another air wound choke coil of 6 inches diameter aiming at decoupling the radio frequency of the 10 and 6 meters band from from flowing on the outside of the braid of the coaxial cable.
The dipoles were made with number 8 PVC insulated copper wire, something that required careful tuning of each dipole, because the dimensions of antennas using insulated wires are different from the ones using bare copper or aluminum wire.
They are all fed using the single RG 58U 50 ohms coaxial cable that my friend had at hand, and as expected, I used a first balun choke coil for the two meters dipole, made by looping 6 turns of the cable on a 1.5 inch diameter PVC pipe coil form, followed by another air wound choke coil of 6 inches diameter aiming at decoupling the radio frequency of the 10 and 6 meters band from from flowing on the outside of the braid of the coaxial cable.
The dipoles were made with number 8 PVC insulated copper wire, something that required careful tuning of each dipole, because the dimensions of antennas using insulated wires are different from the ones using bare copper or aluminum wire.
Anyway, the three dipoles are kept separated from each other by small lengths of polyethylene pipe, and in a second antenna, the separation between the dipoles was achieved with lengths of the center insulator of heavy duty RG17 coaxial cable, also an excellent HF, VHF and UHF insulating material.
The procedure to set up the antenna involved using a good quality HF standing wave ratio meter for tuning up the 10 meters band antenna first , and a similar VHF instrument for setting up the 6 and 2 meters bands dipoles in sequence. In this second version, as always, something new came to my mind, and we decided to include yet another dipole, a fourth one, tuned to the center of the aircraft VHF band...that for voice communications spans from 118 to 136 MHz, so we cut the dipole for 127 megaHertz. This antenna was not adjusted for transmission, because it will always be a receive only antenna as you may realize.
The four dipoles " Nest of Dipoles" HF, plus 3 VHF bands antenna works very well on 10 meters, 6 meters, the aircraft band and the ham two meters band.Installing the two antennas was a rather easy job, as they are quite compact... because the longest dipole, the one for 10 meters is just about 5 meters or 16 feet long. Both antennas were installed as 45 degrees tilted dipoles, a compromise to achieve good pick up and transmission of both vertical and horizontally polarized waves.
If you need to install these dipole nests at a distance longer than about 20 meters or 60 feet from your radio equipment, then please consider the need to change to more expensive and less loss coaxial cable types, like the RG-213 or RG-8, in order to reduce the signal loss typical of the RG58 type cables.
The procedure to set up the antenna involved using a good quality HF standing wave ratio meter for tuning up the 10 meters band antenna first , and a similar VHF instrument for setting up the 6 and 2 meters bands dipoles in sequence. In this second version, as always, something new came to my mind, and we decided to include yet another dipole, a fourth one, tuned to the center of the aircraft VHF band...that for voice communications spans from 118 to 136 MHz, so we cut the dipole for 127 megaHertz. This antenna was not adjusted for transmission, because it will always be a receive only antenna as you may realize.
The four dipoles " Nest of Dipoles" HF, plus 3 VHF bands antenna works very well on 10 meters, 6 meters, the aircraft band and the ham two meters band.Installing the two antennas was a rather easy job, as they are quite compact... because the longest dipole, the one for 10 meters is just about 5 meters or 16 feet long. Both antennas were installed as 45 degrees tilted dipoles, a compromise to achieve good pick up and transmission of both vertical and horizontally polarized waves.
If you need to install these dipole nests at a distance longer than about 20 meters or 60 feet from your radio equipment, then please consider the need to change to more expensive and less loss coaxial cable types, like the RG-213 or RG-8, in order to reduce the signal loss typical of the RG58 type cables.
By the way , a similar dipoles 'nest' can be built for other frequency ranges too... VHF-UHF radio amateurs can make a nice nest for 6 meters, 2 meters and 70 centimeters, and ideal system to carry on the backpack with one of the new ultracompact multi band amateur radio transceivers like the YAESU FT817 or the ICOM 706...These antennas are lightweight, easy to repair on the field, and will cost you next to nothing as compared with similar commercially built versions...But again, I insist that you will need to invest quite some time adjusting them for minimum standing wave ratio...
And now amigos, as always at the end of the show here is our exclusive and not copyrighted HF plus low band VHF propagation update and forecast... The latest forecast for the solar minimum is telling us that it may be actually happening right now , but other scientists believe that the tail end of solar cycle 23 will extend until the first half of 2008.
And now amigos, as always at the end of the show here is our exclusive and not copyrighted HF plus low band VHF propagation update and forecast... The latest forecast for the solar minimum is telling us that it may be actually happening right now , but other scientists believe that the tail end of solar cycle 23 will extend until the first half of 2008.
The latest solar data are simply typical of minimum solar activity with zero sunspot count, solar flux below 70 units and a very quiet geomagnetic field...the expected average sunspot number for June is expected to reach the rock bottom figure of 5... Expect also some really amazing sporadic E skip openings during the next several days ,with multiple hop E skip giving radio amateurs the unique opportunity of working transcontinental DX between Africa, Europe and the Americas. Don't forget to set aside a little of your valuable time to send me a signal report and your comments about the program, send them to arnie@rhc.cu, again arnie@rhc.cu and VIA AIR MAIL, send mail to Arnie Coro Radio Havana Cuba, Havana, Cuba . Hope to have you all listening to our weekend edition next Saturday and Sunday UTC days amigos !!!
(Arnie Coro CO2KK)
