By Arnie Coro
Radio amateur CO2KK
Hi amigos radioaficionados !... You are certainly most welcome to the
> mid week edition of Dxers Unlimited, our stationīs radio hobby program
> that is on the air twice weekly . I am Arnaldo, Arnie, Coro , radio
> amateur CO2KK and here is item one of todayīs show: Scientists
> continue to try to forecast when the peak of solar cycle 24 is going
> to happen, and they are also trying hard to forecast the actual value
> of the period of maximum activity , that is the smoothed sunspot
> number for the six months that will be considered to be the most
> active of cycle 24. So far one only hears disagreements among the
> worldīs most prestigious heliophycisists ... and that difficult to
> pronounce word, is the one used to call the solar scientists... In the
> meantime , rumors are rumbling that already cycle 23, the present one
> has achieved the unique characteristic of been a very long cycle by
> all standards.
>
> The tail end of cycle 23 has produced about the worst propagation
> conditions on the HF bands remembered since the very low activity
> cycle that took place during the first years of World War Two...
>
> Second news item: The contest ionosphere booster effect worked once
> again, and participants of the CQ Radio Amateur Magazine world
> prefixes contest observed with big surprise how stations on the 10
> meters band could be worked during the contest, when just a few days
> before and with higher solar activity 10 meters was totally dead.
> Sure, contests generate a lot of activity on the amateur bands , and
> that activity in turns makes possible two way contacts on frequencies
> that are little used during the solar minimum years. To me, the
> presence of 10 meter band stations during the WPX contest period
> didnīt produce a big surprise amigos, that was something that I was
> expecting ...
>
> Item three: A barebones ultra simple amateur radio station under test
> at CO2KK , my ham radio station , has so far made possible several
> nice DX contacts... The design philosophy of the barebones station was
> to keep the parts count to a minimum, while not compromising its
> performance. The group of Cuban radio amateurs that came together to
> work on the project agreed that the simple station must be reaching at
> least 10 watts , with a receiver sensitivity of one microvolt... The
> station is to be used by beginners, that will be told how to install
> an efficient 40 meters band antenna too... With the parts locally
> available, the designers have done a good job, having to face the
> difficulties derived from the lack of some specialized components,
> cleverly replaced by recycled parts...
>
> Stay right on this frequency or world wide web connection
>
> ss Dxers Unlimited continues in just a few seconds after a short
>
> station ID
>
> ..................................
>
> This is Radio Havana Cuba, the name of the program is Dxers Unlimited
> and now, letīs continue with the description of the ultra simple
> amateur radio station. This is a modular station, with the
> transmitter, receiver and power supply modules built and tested
>
> Individually, before putting the station together. The best approach
> is to start by building and testing the power supply, then moving to
> the receiver, and finally assembling the transmitter.
>
> The modular construction allows the builder to test upgrades to a
> specific module, be it the transmitter, the receiver or the power supply.
>
> You can even build separate modules, for example two or three
> different transmitter configurations, that can be powered from the
> same supply... by means of a simple interconnecting set of cable.
>
> My favorite modular station setup at this moment uses the single band
> approach, to keep things simple and easy ... The decision regarding
> which band should be selected for best all around operation moves very
> much in favor of 40 meters, with 20 meters in my opinion a good second
> choice .
>
> 40 meters is normally open for DX during local evenings, when most
> radio amateurs have time to operate, and at the present phase of the
> solar cycle, 20 meters dies down just around sunset.
>
> The receiver of this modular station is a rather straightforward
> design, without any fancy additions, in order to use the least
> possible number of parts. A single conversion superheterodyne receiver
> with an intermediate frequency between 2 and 5 megaHertz seems to be
> the most reliable and easy to build design.
>
> The availability of low cost quartz crystals used for computer clocks
> and other applications that have required mass production of crystals
> of the same operating frequency, lends itself to the homebrewing of
> some excellent bandpass ladder type crystal filters that show an
> excellent performance. Adding a simple audio filter module further
> enhances the performance of the receiver.
>
> The first transmitter used in the modular station was originally
> designed for CW operation only, but the second one had capability to
> operate on double sideband too. A third upgrade now in operation is
> capable of single sideband voice operation too.
>
> Finally the power supply can be connected to the domestic home power
> lines, and it also has the capability to act as an interphase with
> full reverse polarity and overvoltage protection when connected to a
> car, boat or any other 12 to 14 volts direct current system that may
> be available.
>
> No, this is not a miniature , compact ham radio
> transmitter-receiver... it is in fact a very rugged, reliable, easy to
> fix in case of breakdowns radio station that is capable of providing
> excellent performance for both fixed and portable operation, and it is
> specially suited for deployment during emergencies.
>
> Maybe in the future, I will upgrade this design to a two band station,
> keeping in mind that it is a very useful radio to have at hand during
> the hurricane season here, because it is very economical on the
> batteries, and has a much lower number of electronic components that
> may break down , as compared to a factory built multiband transceiver.
>
> Your comments , with ideas on how to improve Arnie Coroīs Emergency
> Portable Amateur Station are most welcome amigos, send them to inforhc
> at enet dot cu, again inforhc at enet dot cu or Via Air Mail to Arnie
> Coro, Radio Havana Cuba, Havana, Cuba.
>
> ......
>
> You are listening to the mid week program of Dxers Unlimited, when
> solar activity is moving down again, as the three sunspot active
> regions continue to move across the solar disc and no new sunspots are
> in sight... Now here is our next section of the program, itīs the
> Technical Topics, the number three most popular among listeners, after
> ASK ARNIE, la numero uno
>
> And the HF propagation update and forecast that is always in second
> place according to your e-mail message and letters...
>
> Todayīs technical topic will be dealing with the repair of solid state
> amateur radio transceivers, something that is becoming more and more
> difficult, and almost next to impossible as manufacturers continue to
> use more and more surface mounted devices ... As a matter of fact, the
> repair of practically all of the amateur radio transceivers built
> after 1990 or so, is only possible by sending the equipment to the
> original manufacturerīs authorized dealerships, and even in that case,
> many are returned to their owners not repaired or even more damaged
> than when they were sent to be fixed. My personal opinion is that the
> only way to fix the latest models of amateur radio transceivers is by
> changing complete circuit boards, and essentially sending to the trash
> can the boards that are removed. Transceivers built earlier in the
> days of solid state devices history, are much easier to repair,
> especially if you have previous knowledge of similar breakdowns... as
> for example, the typical receiver failure of very poor sensitivity,
> that can usually be traced to a bad front end active device, like the
> dual gate MOSFET used for the RF amplifier stage of rigs like the
> Kenwood TS520, 820 and 830 , just to give you an example. The MOSFET
> devices , even when protected by internal diodes, fail after a nearby
> lightning strike, that doesnīt necessarily has to be right next to
> your property.
>
> Loss of receiver sensitivity is quite evident, and replacing the
> MOSFET is a quite straightforward repair job, except that nowadays the
> exact replacement parts are becoming quite difficult to find...
> Amigos, let me add that homebrewing your receivers, transmitters and
> transceivers , as well as amateur station accessories is not only a
> very nice aspect of our hobby, but it also provides immunization
> against expensive equipment breakdowns that simply canīt be repaired !!!
>
> ..................
>
>
>
> Now, here is nice news for the VHF and UHF radio amateur enthusiasts,
> station T42UJC, a special even station will be on the air on six and
> two meters plus 70 centimeters, from atop a 12 story high building
> very near the northern coast of Cuba . The special event station will
> also be active on the 20 meters HF band. Here is now the announcement
> sent by CO2OJ, Oscar Morales Junior, who will be in charge of this
> interesting ham radio activity, Oscar tell me ..Our VHF Group will
> activate an special station (T42UJC) from april 3 to april 5. The
> station will be here in Habana, in a 12 floor building, just in front
> of the Ave. Malecon, a little more than 50 meters from the shore with
> more than 120 degrees free view over the Golf. T42UJC will be active
> on 6m, 2m and 70 cms ssb. 100 watts in 6 and 2m and 25w in 70 cms.
> Vertical antemna in 6m, a 12 elements yagi in 2m and a 17 elements
> yagi in 70 cms. Will be active also in 40m and 20m. In 20m mostly in
> RTTY and PSK31. So there you are, a good chance to add a new prefix to
> your collection, and for many of the newcomers to amateur radio,
> working Cuba on 6 and 2 meters is also very nice too... So be on the
> lookout for T42UJC, from April 3 to April 5, and send your QSL
> requests to T42UJC Post Office Box One, Havana, Cuba...
>
> And now amigos as always at the end of the program when I am here in
> Havana and can make the solar optical and radio observations here is
> Arnie Coroīs exclusive and not copyrighted HF plus low band VHF
> propagation update and forecast... Solar flux now moving down again,
> and the period of better HF propagation is just coming to an end...
> Sunspot count now below 20 and the solar flux again below 80 units, so
> the daytime maximum useable frequency curve will again show a very
> slow rise and will be reaching a much smaller peak... I expect some
> nice tropospheric ducting across the Gulf of Mexico during the next
> several days, an excellent opportunity for radio amateurs in Mexico
> and the South of the USA to work the special event VHF and UHF station
> T42UJC starting Thursday and until Saturday.
>
> I hope to have have enjoyed this program and will be listening to our
> weekend edition Saturday and Sunday UTC days amigos ...And donīt
> forget to provide me with your valuable opinions about the program ,
> any radio hobby related questions you may have for our ASK ARNIE
> section of the show, and your QSL requests... send mail to inforhc at
> enet dot cu, or VIA AIR MAIL to Arnie Coro, Radio Havana Cuba ,
> Havana, Cuba
