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radio amateur CO2KK
Hi amigos radioaficionados around the world, continuing to enjoy the revival of short wave good propagation conditions for DX … I am your host here in Havana... Arnie Coro, radio amateur CO2KK now ready to share with you about seventeen minutes of on the air and on the WEB time, streaming the audio from http://www.radiohc.cu
Yes my friends, the Sun continues to be active, with now two sunspots active regions in sight, and one just about to turn around... The solar "numbers" for Friday looked like this:
SOLAR INDICES FOR 5 March 2010
WOLF NUMBER CATANIA observatory optical count : 036 as counted by experienced observer Enrico Catinoto, who shows in his report three active sunspot regions .
10CM SOLAR FLUX measured by the Canadian reference observatory : 080
ESTIMATED AP , that's the 24 hours planetary geomagnetic disturbance indicar … it was at a nice and quiet : 004,
Finally the so called ESTIMATED ISN or international sunspot number was 23, BASED ON observations made at 11 STATIONS.
The NOAA Sunspot number for 5-Mar-2010 was:
35
Most recent five days before March 5 (oldest first):
13
36
39
39
40
36
The SSN or effective sunspot number, a very practical measuring stick , is at 22, and we are seeing here in Havana, during our early morning Saturday observations , that the maximum useable frequency curve at 13 hours UTC is clearly passing the 20 megaHertz mark, so 15 meters band openings are about to begin as I write the script of the show...
So, I should hurry up and finish writing to be able to enjoy the nice opening on the 17 and 15 meter bands !
Stay tuned for more radio hobby related information coming to you from sunny Havana,
…...............
You are listening to Radio Havana Cuba's radio hobby program, Dxers Unlimited, with yours truly
Arnie Coro at the microphone... and here is item two of today's program amigos ...
A long, long time ago, I repaired a Phillips of Holland audio amplifier that was used in
a record player + radio housed in a beautiful wood cabinet.
It had very rare 800 ohms impedance loudspeakers and sounded really good !!!
I have lost one of my notebooks in a move... there I had copied a circuit of a simple OTL circuit, that is a vacuum tubes output transformerless stage, that if I remember well could be used with 8 ohms impedance loudspeakers ...
For your information, as the technical secretary of my radio club, I am now in charge of a very nice development project for our club members in general, but focused in particular for the newcomers to our radio hobby...
My latest home brew project now in progress , is a Regenerodyne receiver for the "newbies" at our radio club. It is designed around the plentifully available locally vacuum tubes - that are freely available at zero cost .
I use a "flexible" audio module design, so that my students can build their radio with the vacuum tubest types that they have at hand...
For example , the 6SJ7 - 6V6 module is built using the Russian equivalent tubes, and "borrowing" the output transformer from a TV set.
The modules can be built also with a triode-pentode or triode-tetrode built into the same glass envelope. The Russian 6F5 ( actually 6PHI5 ) works quite well , and I have tested the TV set's vertical output transformer as the audio output transformer, and there is no detectable difference between using it and using the audio output transformer from the same TV set !
My REGENERODYNE receiver , is a modular radio...
It has a crystal controlled converter at the input... feeding the regenerative detector that works as a variable frequency IF, and feeds the audio to the above mentioned module.
The power supply runs at between 140 and 160 volts well filtered, has a + 75 volts regulated output coming from a VR75 glow discharge tube, and the filament supply has two outputs, one is AC , and the other one is regulated DC that is used for feeding the filaments of the regenerative detector tube ( 6AK5 pentode in Hartley circuit configuration with screen grid control of regeneration ) and in some receivers, the regulated 6.0 volts is used to feed the filaments of the first audio tube ( in this case I use a 6AU6 or similar pentode as the audio preamp , feeding a 6AQ5, EL84 or similar tube.
The REGENERODYNE has a tunable bandpass input filter and a resistive step attenuator at the input. The bands are tuned in either a 200 kiloHertz or a 1 megaHertz segments ...selected at the regenerative detector bandspread configuration.
For example, with a 5 megaHertz crystal, the IF is at 2.0 megaHertz for tuning the 40 meters ham band... In position A " bandspread " the regenerative detector tunes from 7000 to 7200 kiloHertz, while in position B, the receiver tunes from 7000 to 8000 kiloHertz...
I have also experimented the option of leaving the regenerative detector operating at 2.0 megaHertz, and replacing the crystal oscillator at the front end with a good quality stable VFO...so there is no need to find quartz crystals, but this does require a very well built VFO !!! For the "newbies" if a quartz crystal can be found that will "mix" to the wanted receive frequency range... it is certainly the best option as it provides the most simple approach for a frequency stable receiver.
The REGENERODYNE circuit when built with care, is a very sensitive and selective low cost homebrew radio receiver, and one nice way to save vacuum tubes from going
to the recycler's glass and metal crunching machines !!!
And for those of you not familiar with vacuum tubes technology , let me add that a solid state version of the REGENERODYNE can also be designed and built, but it will not be as easy to make it work. For several good reasons, vacuum tubes seem to be ideally suited for the regenerative detector circuit, and making a solid state regenerative operate with the sensitivity and selectivity of a vacuum tube equivalent is quite a challenge. I have learned about two succesful solid state regenerative receivers, the Desert Rat designed by my good friend from New Mexico , Paul Harden NA5N, and the Kitchin , yes Kitchin, with an I and not Kitchen with an e... the Kitchin regenerative receiver, of which the most recent version was published by CQ Radio Amateur Magazine on its February 2010 issue...
…...........................
Si amigos, collecting QSL cards is one of the many ways that you and I enjoy our hobby... and this line reminds me about a recent request by the President of our Cuban DX Group , my good amigo Winston CO2WF... at a recent meeting he asked me to sit down and write the complete list of countries or DX entities that I have worked and for which I have received QSL cards...
This is quite a challenge, as there are several box fulls of QSL cards to be reviewed...
The Cuban DX Group, Grupo DX de Cuba offers a collection of beautiful full color diplomas for radio amateurs that submit their QSL cards for the different awards.
There is the Cuba Diploma... for showing proof of having made two way contacts with stations in all of the Cuban amateur radio districts... Instructions in how to apply for the different awards given by the Cuban DX group can be found at the Cuban Federation of Radio Amateurs Website, or by writing a letter to CO2WF Cuban DX Group, PO BOX 1 , Havana Cuba . Collecting amateur radio awards is also known among oldtimers in our radio hobby as " Colleting wallpaper " , and it always nice to visit an amateur radio station shack with the walls decorated with nice diplomas !!!
By the way, this is something to be included in my long list of to do's at my new garage radio hobby center !!!
Item five: During the year 2008 , Cuba was struck by not one , but three powerful tropical hurricanes, that required a lot of dedication on the part of our nation's amateur radio operators.
Among the many things done before, during and after the emergencies generated by hurricanes Gustav, Ike and Paloma, hams had to be able to contact disaster relief centers from difficult sites, like water reservoirs, shelters behind mountains and coastal towns that had to be evacuated to prevent loss of life caused by the huge storm surge that usually comes with the huge hurricanes.
Among the things done by 2 meters band operators to increase the range of their portable handie talkie FM transceivers, there was one that picked up my attention, because it was improvised independently by several operators.
They used TV sets rabbit ears telescopic antennas to improvise a full size 2 meters band half wave dipole antenna, and in some cases even added a reflector element recovered from a damaged TV antenna. ( See the photo at the top of this posting... where you can see my prototype antenna using that rabbit ears telescopic whips + a linear reflector element.
The 2 elements YAGI provided much better transmission and reception than the helically loaded vertical monopole antenna used by the HT or handheld FM 2 meters band transceivers, making possible to reach the disaster relief command posts while running the rigs on the low power settings.
This was very important at some locations, where it wasn't possible to recharge the batteries...
For some amateurs in Camaguey province , where hurricanes Ike and Paloma hit the area withing a few days of each other, the use of the makeshift two element Yagi antennas built with the TV sets telescopic whip made possible to achieve a reliable link to relay vitally important information , like the instructions to begin evacuation procedures from the coastal towns where the Cuban weather service was expecting a very significant storm surge.
Si amigos, yes my friends, oui mes amis...amateur radio operator's ingenuity and creativity shows up especially during emergencies, and the just mentioned example of the improvised two meter band two element Yagi antennas made from TV set's rabbit ears proves my point !!!
…...........
And now amigos, just before going QRT , here is Arnie Coro's Dxers Unlimited's short wave propagation update and forecast. Solar activity is expected to stay at very low levels for the next two days, with daily solar flux figures around 80 units.and a bit lower..
But soon we may see a jump in solar activity, as active sunspot regions now behind the solar disc rotate into view.
As we continue to approach the spring equinox, propagation conditions during local daytime hours will improve, providing amateur radio operators with nice opportunities to work DX on the 17, 15, 12 and even the 10 meters band. Do remember that due to the still large number of users of the 27 megaHertz or 11 meters so called Citizens Band, tuning around 27 megaHertz is a very effective way of detecting possible 12 and 10 meters amateur band openings.
Don't forget to send your signal reports and comments about this and other editions of Dxers Unlimited, send e-mail reports to inforhc at enet dot cu and VIA AIR MAIL, send a postcard or letter directly to Arnie Coro , Radio Havana Cuba , Havana, Cuba... there is no need to include the PO BOX number, as my good friends at Correos de Cuba will place your postcard or letter in our mailbox as soon as they see the station's name on it !!!
Yes my friends, the Sun continues to be active, with now two sunspots active regions in sight, and one just about to turn around... The solar "numbers" for Friday looked like this:
SOLAR INDICES FOR 5 March 2010
WOLF NUMBER CATANIA observatory optical count : 036 as counted by experienced observer Enrico Catinoto, who shows in his report three active sunspot regions .
10CM SOLAR FLUX measured by the Canadian reference observatory : 080
ESTIMATED AP , that's the 24 hours planetary geomagnetic disturbance indicar … it was at a nice and quiet : 004,
Finally the so called ESTIMATED ISN or international sunspot number was 23, BASED ON observations made at 11 STATIONS.
The NOAA Sunspot number for 5-Mar-2010 was:
35
Most recent five days before March 5 (oldest first):
13
36
39
39
40
36
The SSN or effective sunspot number, a very practical measuring stick , is at 22, and we are seeing here in Havana, during our early morning Saturday observations , that the maximum useable frequency curve at 13 hours UTC is clearly passing the 20 megaHertz mark, so 15 meters band openings are about to begin as I write the script of the show...
So, I should hurry up and finish writing to be able to enjoy the nice opening on the 17 and 15 meter bands !
Stay tuned for more radio hobby related information coming to you from sunny Havana,
…...............
You are listening to Radio Havana Cuba's radio hobby program, Dxers Unlimited, with yours truly
Arnie Coro at the microphone... and here is item two of today's program amigos ...
A long, long time ago, I repaired a Phillips of Holland audio amplifier that was used in
a record player + radio housed in a beautiful wood cabinet.
It had very rare 800 ohms impedance loudspeakers and sounded really good !!!
I have lost one of my notebooks in a move... there I had copied a circuit of a simple OTL circuit, that is a vacuum tubes output transformerless stage, that if I remember well could be used with 8 ohms impedance loudspeakers ...
For your information, as the technical secretary of my radio club, I am now in charge of a very nice development project for our club members in general, but focused in particular for the newcomers to our radio hobby...
My latest home brew project now in progress , is a Regenerodyne receiver for the "newbies" at our radio club. It is designed around the plentifully available locally vacuum tubes - that are freely available at zero cost .
I use a "flexible" audio module design, so that my students can build their radio with the vacuum tubest types that they have at hand...
For example , the 6SJ7 - 6V6 module is built using the Russian equivalent tubes, and "borrowing" the output transformer from a TV set.
The modules can be built also with a triode-pentode or triode-tetrode built into the same glass envelope. The Russian 6F5 ( actually 6PHI5 ) works quite well , and I have tested the TV set's vertical output transformer as the audio output transformer, and there is no detectable difference between using it and using the audio output transformer from the same TV set !
My REGENERODYNE receiver , is a modular radio...
It has a crystal controlled converter at the input... feeding the regenerative detector that works as a variable frequency IF, and feeds the audio to the above mentioned module.
The power supply runs at between 140 and 160 volts well filtered, has a + 75 volts regulated output coming from a VR75 glow discharge tube, and the filament supply has two outputs, one is AC , and the other one is regulated DC that is used for feeding the filaments of the regenerative detector tube ( 6AK5 pentode in Hartley circuit configuration with screen grid control of regeneration ) and in some receivers, the regulated 6.0 volts is used to feed the filaments of the first audio tube ( in this case I use a 6AU6 or similar pentode as the audio preamp , feeding a 6AQ5, EL84 or similar tube.
The REGENERODYNE has a tunable bandpass input filter and a resistive step attenuator at the input. The bands are tuned in either a 200 kiloHertz or a 1 megaHertz segments ...selected at the regenerative detector bandspread configuration.
For example, with a 5 megaHertz crystal, the IF is at 2.0 megaHertz for tuning the 40 meters ham band... In position A " bandspread " the regenerative detector tunes from 7000 to 7200 kiloHertz, while in position B, the receiver tunes from 7000 to 8000 kiloHertz...
I have also experimented the option of leaving the regenerative detector operating at 2.0 megaHertz, and replacing the crystal oscillator at the front end with a good quality stable VFO...so there is no need to find quartz crystals, but this does require a very well built VFO !!! For the "newbies" if a quartz crystal can be found that will "mix" to the wanted receive frequency range... it is certainly the best option as it provides the most simple approach for a frequency stable receiver.
The REGENERODYNE circuit when built with care, is a very sensitive and selective low cost homebrew radio receiver, and one nice way to save vacuum tubes from going
to the recycler's glass and metal crunching machines !!!
And for those of you not familiar with vacuum tubes technology , let me add that a solid state version of the REGENERODYNE can also be designed and built, but it will not be as easy to make it work. For several good reasons, vacuum tubes seem to be ideally suited for the regenerative detector circuit, and making a solid state regenerative operate with the sensitivity and selectivity of a vacuum tube equivalent is quite a challenge. I have learned about two succesful solid state regenerative receivers, the Desert Rat designed by my good friend from New Mexico , Paul Harden NA5N, and the Kitchin , yes Kitchin, with an I and not Kitchen with an e... the Kitchin regenerative receiver, of which the most recent version was published by CQ Radio Amateur Magazine on its February 2010 issue...
…...........................
Si amigos, collecting QSL cards is one of the many ways that you and I enjoy our hobby... and this line reminds me about a recent request by the President of our Cuban DX Group , my good amigo Winston CO2WF... at a recent meeting he asked me to sit down and write the complete list of countries or DX entities that I have worked and for which I have received QSL cards...
This is quite a challenge, as there are several box fulls of QSL cards to be reviewed...
The Cuban DX Group, Grupo DX de Cuba offers a collection of beautiful full color diplomas for radio amateurs that submit their QSL cards for the different awards.
There is the Cuba Diploma... for showing proof of having made two way contacts with stations in all of the Cuban amateur radio districts... Instructions in how to apply for the different awards given by the Cuban DX group can be found at the Cuban Federation of Radio Amateurs Website, or by writing a letter to CO2WF Cuban DX Group, PO BOX 1 , Havana Cuba . Collecting amateur radio awards is also known among oldtimers in our radio hobby as " Colleting wallpaper " , and it always nice to visit an amateur radio station shack with the walls decorated with nice diplomas !!!
By the way, this is something to be included in my long list of to do's at my new garage radio hobby center !!!
Item five: During the year 2008 , Cuba was struck by not one , but three powerful tropical hurricanes, that required a lot of dedication on the part of our nation's amateur radio operators.
Among the many things done before, during and after the emergencies generated by hurricanes Gustav, Ike and Paloma, hams had to be able to contact disaster relief centers from difficult sites, like water reservoirs, shelters behind mountains and coastal towns that had to be evacuated to prevent loss of life caused by the huge storm surge that usually comes with the huge hurricanes.
Among the things done by 2 meters band operators to increase the range of their portable handie talkie FM transceivers, there was one that picked up my attention, because it was improvised independently by several operators.
They used TV sets rabbit ears telescopic antennas to improvise a full size 2 meters band half wave dipole antenna, and in some cases even added a reflector element recovered from a damaged TV antenna. ( See the photo at the top of this posting... where you can see my prototype antenna using that rabbit ears telescopic whips + a linear reflector element.
The 2 elements YAGI provided much better transmission and reception than the helically loaded vertical monopole antenna used by the HT or handheld FM 2 meters band transceivers, making possible to reach the disaster relief command posts while running the rigs on the low power settings.
This was very important at some locations, where it wasn't possible to recharge the batteries...
For some amateurs in Camaguey province , where hurricanes Ike and Paloma hit the area withing a few days of each other, the use of the makeshift two element Yagi antennas built with the TV sets telescopic whip made possible to achieve a reliable link to relay vitally important information , like the instructions to begin evacuation procedures from the coastal towns where the Cuban weather service was expecting a very significant storm surge.
Si amigos, yes my friends, oui mes amis...amateur radio operator's ingenuity and creativity shows up especially during emergencies, and the just mentioned example of the improvised two meter band two element Yagi antennas made from TV set's rabbit ears proves my point !!!
…...........
And now amigos, just before going QRT , here is Arnie Coro's Dxers Unlimited's short wave propagation update and forecast. Solar activity is expected to stay at very low levels for the next two days, with daily solar flux figures around 80 units.and a bit lower..
But soon we may see a jump in solar activity, as active sunspot regions now behind the solar disc rotate into view.
As we continue to approach the spring equinox, propagation conditions during local daytime hours will improve, providing amateur radio operators with nice opportunities to work DX on the 17, 15, 12 and even the 10 meters band. Do remember that due to the still large number of users of the 27 megaHertz or 11 meters so called Citizens Band, tuning around 27 megaHertz is a very effective way of detecting possible 12 and 10 meters amateur band openings.
Don't forget to send your signal reports and comments about this and other editions of Dxers Unlimited, send e-mail reports to inforhc at enet dot cu and VIA AIR MAIL, send a postcard or letter directly to Arnie Coro , Radio Havana Cuba , Havana, Cuba... there is no need to include the PO BOX number, as my good friends at Correos de Cuba will place your postcard or letter in our mailbox as soon as they see the station's name on it !!!
Source: http://bit.ly/9fxQAB
Via Yimber Gaviria, Colombia
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