Dxers UnlimitedDxers Unlimited’s mid week edition 23-24 January 2007
By Arnie Coro-CO2KK
Hi amigos radioaficionados , its nice to have you all listening to this mid week edition of this radio program that is entirely , absolutely devoted not to one specific aspect of the hobby, but to all the more than 80 ways that you and I enjoy it !
I am Arnie Coro, radio amateur CO2KK , your host here in sunny Havana and here is today’s menu: 7040 kiloHertz,yes write it down, because 7040 kiloHertz is the QRP spot frequency where low power enthusiasts gather to challenge operator’s skills while running extremely low power transmitters on the 40 meters amateur band, the one that does remain open during the local evening hours.
Then moving ed up a bit to the 41 meters international broadcast band, sure enough ! several nice DX stations provide armchair copy too. And by the way, late in the evening listening or operating HF ham radio equipment is also much better due to a general reduction in man made noise !!!
Item Two: Monitoring the low band TV channels provides very early warning of an Sporadic E event in progress and do remember that sporadic E events may happen at anytime, not just during the two peak seasons .
Item Three: One of the main topics discussed by Cuban hams is “Amateur radio operations during emergency situations”, and there are some very interesting comments from Cuban amateurs that have had first hand experience keeping communications operating even during the middle of a category four hurricane... Now as the hurricane season approaches, Cuban radio amateurs are getting ready to participate in a nation wide emergency drill, in order to test the readiness of our stations to handle weather related and emergency traffic in case we are hit by a storm.Next item coming up: Yes, I won’t forget of including ASK ARNIE in every Dxers Unlimited that goes on the air, because, according to your e-mail messages and letters, it is certainly the most popular section of the program closely followed by Arnie Coro’s Dxers Unlimited’s HF plus low band VHF propagation updates and forecast..
If time permits, I will also include today our tips and techniques section, as it is becoming quite popular too..Standby for more radio hobby related information, coming to you from Havana…I’ll be back in just a few seconds … I am Arnie Coro in Havana...….You are listening to Radio Havana Cuba, the name of the show is Dxers Unlimited, and yes, we do encourage listener’s feedback, as a very effective way of improving this program, send your comments, opinions, and ideas on how to make Dxers Unlimited better directly to my computer … send mail to
arnie@rhc.cu, again, slowly and phonetically,
arnie@rhc.cu, and if you are not yet in cyberspace, just drop me a postcard to Arnie Coro, Radio Havana Cuba, Havana, Cuba.Now here is ASK ARNIE… THE most popular section of this show.
Today ‘s first question came from England.. listener Pat wants to know if he can adapt a discarded cellphone for amateur radio use. Well amigo Patrick, thanks for a very nice question, as first, second and third generation cellular phones are now becoming an environmental problem in many countries, because technology evolves into much more sophisticated systems that require different cellphones to operate with them. The only amateur radio band that is near to the older and still in use cellphone band around 900 megaHertz is not authorized by telecommunications administrations at a worldwide scale, as a matter of fact, only a few countries authorize their amateur radio operators to use the 900 megaHert band, the one that is close enough to the first cellphone band to make a conversion practical. According to what I have seen inside discarded cellphone sets, the only possible approach for converting them into ham radio transceivers for the 900 megaHertz band is by means of software access to the programming of the cellphone set, and apparently some radio amateurs have already achieved positive results with some specific types of older technology cellphones… By the way amigo Pat, a much easier conversion from new information and communications technologies professional equipment to amateur radio applications can be achieved with the so called WI-FI wireless networking equipment, that can be easily adapted for ham radio use !!!
Question number two: Came from Norway, where listener Olaf is picking up our 6000 kiloHertz and 6180 kiloHertz transmissions just after midnight his local time.Olaf wants to know why is it possible to pick up Tropical Band stations from Latin America at his QTH near Oslo with such good signals, and he mentions picking up Radio Rebelde on 5025 kiloHertz very clearly after the station installed its new transmitter and antenna. Well amigo Olaf, Tropical Band signals will continue to propagate better and better as solar activity continues to move down towards the end of solar cycle 23. When solar flux figures between 70 and 80 units prevail for many days, ionospheric absorption is at a minimum and that will certainly help signals below 5 or 6 megaHertz propagate much better. Another important factor regarding low frequency propagation is the connection between geomagnetic latitude and signal attenuation, something that has puzzled scientists for many years. So, the good news for you up North, is that lower solar activity will improve your reception of Tropical Band stations for at least the next three or four years amigo !!! When old man Sol comes back into high activity, ionospheric absorption will increase and Tropical Band signals will not propagate so well during solar maximum years . Closely following the pattern seen on the 60 meters Tropical Band, international shortwave broadcast stations operating on the 6 megaHertz or 49 meters band will be achivieng much better coverage during the local evening hours, and all along the night path from their location.
Question number three: This one came from Kansas, USA, listener Barry ASKs ARNIE about static electricity charging his antenna all the time, and the problems associated with sudden sparks coming from the antenna even when its disconnected… Well amigo Barry, here is my advice… install a good ground system at your location, even a single ground rod , well driven into the soil of the garden will work, and then buy a pair of 10 kiloOHms two watt carbon resistors and connect them between the antenna and ground… The 5 kiloOhm effective resistance will continuosly drain the static electricity picked up by your antenna to ground, saving your radio receiver’s front end solid state devices from a quick death, caused by the static discharging trough the radio, as it has unfortunately happened to you already… My advice is that you connect the antenna to the radio only when you are using it, and at any signs of even a far away thunderstorm or the presence of CUMULUS NIMBUS type of storm clouds, disconnect the radio and start reading or assembling your new homebrew radio project !!!Static electricity discharging to ground trough your radio’s very delicate solid state devices will burn them up, as many solid state receiver users have learned the hard way. My latest HURRICANE TWO ham radio transceiver, intended to operate during emergencies has a unique front end protection, provided by the use of a vacuum tube radio frequency amplifier stage, that is much more immune to static damages than solid state transistors of any type.Although the vacuum tube stage requires an additional 24 volts DC power supply, the protection provided is well worth the additional components required !!!By the way amigos, don’t forget that specially during the summer thundestorm season,and at anytime, it is always a very good practice to keep all your radio and electronic equipment disconnected from the antennas, ground systems and power line when they are not in use, and as I said a while earlier, it is also extremely good practice to disconnect all radio equipment whenever a thunderstorm is approaching !!!…
.TIPS and TECHNNIQUES is fast becoming popular among Dxers Unlimited’s worldwide audience and cybersurfers that read my scripts via the INTERNET… so, I am trying to include this section in almost every program.
Today’s Tip : When you are going to use any radio equipment connecting it to an automobile or truck electrical system as a power source, STOP, STOP, STOP, before doing it, and build yourself or ask an electronic hobbyst friend to assemble for you a well protected interface… I have seen too many radios, handie talkies, cellphones and CD portable players killed by connecting them directly to automotive electric systems that may generate , under the worst case scenario conditions, voltages as high as 17 or even 20 volts from alternators that are not properly regulated…
The typical automotive electric system goes normally up to 15 or 16 volts to be able to charge the battery, so any electronic device that is not properly protected against such high voltage will simply be killed sooner or later by the overvoltage damage.Before connecting any radio or electronic equipment to a car, truck , airplane or boat electric system run a very exhaustive check of the system while it is operating and be sure that your equipment is capable of handling the highest voltages that are generated by the particular system. My practical solution to this problem for the typical 12 to 14 volts required by amateur radio equipment , is to assemble an interface that provides both reverse polarity and overvoltage protection , and install such interface in the car, truck, mobile home, boat or aircraft, so that the radios are always safe from both reverse polarity connection and overvoltage accidents !!!And now amigos, here is my exclusive, at the end of the show Arnie Coro’s HF plus low band VHF propagation update and forecast…
Very quiet geomagnetic field now, with very low solar activity prevailing for the next several days…Solar flux is expected to stay very near 80 units, and the effective sunspot number is 20 …I do Hope to see you all at the upcoming edition of Dxers Unlimited amigos !!! And don't forget to send your signal reports, comments about the program and radio hobby related questions to
arnie@rhc.cu or VIA AIR MAIL to Arnie Coro, Radio Havana Cuba, Havana, Cuba
(Arnie Coro/R Havana)
