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Dxers Unlimited weekend editionsby Prof. Arnaldo Coro Antichradio amateur CO2KKRadio Habana Cuba
Radio Havana Cuba By Arnie Coro Hi amigos radioaficionados all over the world enjoying the best HF propagation conditions seen so far this winter ! I am Arnie Coro, radio amateur CO2KK , your host here at RHC's Dxers Unlimited radio hobby program... And in order to remind you of what is happening 93 million miles from Planet Earth, here are some valuable statistics about this unusual and highly temperamental solar cycle number 24... So far the highest official sunspot number of Cycle 24 occurred on fifth of May of this year 2010... when the sunspot count reached 77 ... The highest solar flux registered , obviously associated directly with an M8 dot 3 solar flare happened exactly on the same day when the flare blasted the Earth, and this was on the twelveth of February of this year... So, now it is clear that the recent Catania Astrophysical Observatory Wolf number of 70 was not the highest registered so far into the cycle, but I must add that because it has happened during the month of November, it is certainly the solar sunspot count that has had the highest impact on short wave propagation so far... Item two: 10 meters is opening up for DX on a daily basis, still not as many hours of wonderful F2 propagation as we all want, but , it is certainly a change for the better... I tried calling CQ DX on ten meters single side band when no one was heard, except a certain number of beacons, and YES, my CQ DX brought up some activity If everyone just listens on 10 meters and nobody calls CQ... it is next to impossible to make contacts amigos So follow your friend Arnie Coro's advice and as soon as you pick up the first CW beacon on 10 meters, don't wait one more second, and start calling CQ DX.... It has proven to be a very effective way of generating much needed amateur radio activity on the wonderful 10 meters band... Item three: Software defined radios are becoming more and more popular not only among radio amateurs, but also among professional users of the radio spectrum... SDR radios as they are known consist of a relatively simple radio frequency module that is connected to a fast computer . The SDR features are almost all related to the software installed to the computer, and all I can say is that an SDR receiver performance can be absolutely amazing Several Cuban radio amateurs are experimenting not only with SDR receivers, but also with transceivers that are capable of providing amazing performance on the amateur bands. Item four: A low cost and at the same time good performance antenna system for the 10 meters amateur band can be put up during a few hours using a single mast or tower that must be no less than 7 meters high . Yes, you heard it right... the single mast supports a set of between one and four half wave sloping dipoles , that will provide the required low take off angle of radiation for working DX on 10 meters. The single half wave sloper is the simplest possible approach, and according to my experience from previous solar cycles peaks... it is a very effective antenna, when it is aimed in the desired direction. Aiming a sloper is as simple as making it slope at a 45 degrees angle
from the mast in the direction that you want to work DX. For example at
my home QTH in downtown Havana I have at the present time two 10 meters
band half wave slopers... One is aiming at Europe, and by that I mean it is sloping into a 45 degrees azimuth... The other sloper is aiming at the center of South America, and that is 165 degrees azimuth from Havana. The two antennas are connected with equal lengths of RG8X coaxial cable to a relay that is at the base of the 8 meters high tower. I can switch between the two antennas at the flip of a switch located at the operation position of CO2KK. The antenna that is used more frequently is the one beaming to South America, so its coaxial cable feeder is connected to the resting position of the coaxial relay, then, when the relay is activated, the Europe antenna is connected to the main feeder that goes to the station. In the past I did some comparisons between a three element Yagi antenna and the 10 meters band slopers, and to my surprise , the simple wire sloping antenna's performance was only very marginally below the well designed and well built 3 elements Yagi. By the way, the Yagi antenna gain was measured with professional test
instruments to be 6.5 db over a half wave dipole, but unfortunately so
far, I have not measured the gain of the sloping dipole as compared to a
reference half wave horizontal dipole installed at the top the 8 meters
high tower.... This is something to be done in the near future, just to really know what is the real gain of the sloper, but I must say that when operating on 10 meters with the switched slopers , the difference of signal strength when switching between the two antennas is really amazing. Ideally I should had installed a third half wave sloper beaming into the Pacific , but that would require a three position remotely controlled coaxial switch that I don't have , or adding a second coax feeder for the antenna beaming to Japan, New Zealand, Australia and the Pacific Islands... By the way the half wave sloper minus 3 dB beamwidth pattern is quite broad , especially when you are looking at distances of more than four thousand kilometers ! Si amigos, yes my friends , oui mes amis... the humble , low cost ,
easy to install, easy to adjust to minimum standing wave ratio half wave
sloping dipole installed at a 45 degrees tilt angle is in my humble
opinion an antenna that every radio amateur should install... Now please standby as we are going into a station ID break, I am
Arnie Coro , radio amateur CO2KK back with you with more radio hobby
related information in a few seconds This is Radio Havana Cuba, the name of the show is Dxers Unlimited, and it is on the air Sundays and Mondays UTC days, just after the top of the hour Radio Havana Cuba's English language program newscast... We are also on the air with our mid week edition on Tuesdays and Wednesdays UTC days just after the half hour news . Now here is item five of today's show... Our most popular section of
this program... YOU have questions and Arnie tries to answer them as
soon as possible.... And I mean tries to answer, because some times the
questions sent by listeners are really difficult to reply and require
the help of experts, like my good amigo Professor Jose Angel Amador from
Havana's Technical University, who teaches at the Electrical Engineering
school's department of Telecommunications... After consulting several experts on this topic, it was quite clear to
me that so far it is almost impossible to assure a one hundred percent
protection against a direct hit by lightning, especially at
installations using high towers or located atop high rise buildings. The simple monitor is nothing more than a broadband receiver connected to a circuit that is set to fire an alarm when a certain level of static crashes are picked up by the system... It may sound quite primitive, but it has proven time and again to be pretty effective, and the fact is that anyone with a little know how of electronics can reproduce the circuit and install the device so that it may provide the required advanced warning about how near a thunderstorm may be located. Of course that it will not protect you against a direct him coming out of nowhere, and those lightning strikes do happen, but they are the exception rather than the rule... The circuit diagram of the lightning warning device is relatively simple if you go by the simplest approach, but a more sophisticated design can even include a static crashes digital counter display and even a microprocessor to determine the number of static crashes picked up per minute and also display that figure too... Again, let me emphasize this message... underscoring, your best low cost protection against lightning damage is to disconnect all equipment, including the AC power line and the ground system when it is not in use, and at the slightest probability of a nearby cumulus nimbus thunderstorm cloud, follow your friend Arnie Coro's advice... disconnect all the electronic equipment, including not only you radios but also desktop computer, TV sets, and DVD players And now, at the end of the program here is our HF propagation update Solar activity has stayed at much higher levels than during the month of November one year ago... and the increase in both sunspot count and solar flux , combined with the seasonal propagation peak due to the lower height of the F2 and F layers characteristic of November in the northern hemisphere are making the daytime maximum usable frequency curve moving up much faster after sunrise... So amigos, my advice is to wake up early and play a lot more with your radios... at last the Sun is waking up !!! See you all at the weekend edition of Dxers Unlimited next Sunday and Monday UTC days just at the end of the top of the hour newscast... and don΄t forget to send me your comments about the program , radio hobby related questions and your results with homebrew radios to inforhc at enet dot cu or via air mail to Arnie Coro, Radio Havana Cuba, Havana, Cuba Posted by Arnaldo Coro at 4:29 PM 0 comments Links to this post
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