Dxers Unlimited

Dxers Unlimited's mid week edition for 18-19 May 2004

By Arnie Coro

Radio amateur CO2KK




Hi amigos radioaficionados , its nice to have you all listening to the 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 77 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: If you followed your's truly advice during our last
several programs, I am sure that you have enjoyed listening under excellent propagation conditions
late in the evening local time. Tuesday , May 18th just after 0500 hours UTC I did a bandscan, and
was able to pick up very nice DX on the 20 meters amateur band, clear signals on the CW segment,
around 14060 kiloHertz, the QRP spot frequency where low power enthusiasts gather to challenge
operator's skills while running extremely low power transmitters. Then I moved up a bit to the 19
meters international broadcast band, and sure enough ! several nice DX stations provided armchair
copy too. So, again, whenever your having a hard time falling asleep during the next several weeks,
remember that summer propagation conditions on the HF bands are much better after local sunset,
because during the daytime, ionospheric thermal expansion sends the maximum useable frequency way
down !!! And by the way, very 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: Sporadic E season is now
well under way, and I am writing this script at just after nine thirty in the morning local time,
while keeping my TV set tuned to channel 2, and my 6 meter band transceiver tuned to 50.125
kiloHertz , the calling frequency for the North America and Caribbean regions. Monitoring the low
band TV channels provides very early warning of an Sporadic E event in progress. Item three: At the
upcoming Cuban Federation of Radio Amateurs Convention to be held at the end of the month in Santa
Clara, one of the main topics is going to be "Amateur radio operations during emergency situations",
and I expect some interesting comments from Cuban amateurs that have had first hand experience
keeping communications operating even during the middle of a category four hurricane. Item four:
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 after a brief musical intercut..

..

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 New
York, USA.. listener Randolph wants to know if he can adapt a discarded cellphone for amateur radio
use. Well amigo Randolph, thanks for a very nice question, as first, second and third generation
cellphones are now becoming an environmental problem in many countries, as 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 Randolph, 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 11760 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.

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 150 volts DC power supply, the protection
provided is well worth the additional components required !!!

By the way amigos, don't forget that we are now into the summer thundestorm season, so 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, as always at the end of the program, here is Arnie Coro's HF plus low band VHF
propagation update and forecast. Solar flux is moving UP, and the Sun is exhibiting a lot of
sunspots at this moment, as a matter of fact , the number of sunspots has gone up to 148 on Sunday
and Monday. Solar active sunspot region 609 may generate class M solar flares during the next 48 to
72 hours, and the solar flux is now aound 110 units. I expect that this will be the peak activity of
the present solar rotation. Sporadic E events are highly probable during the next 10 days, so be on
the lookout for this unique propagation mode that sends the maximum useable frequency curve shooting
up even as high as 150 megahertz at times !!!

See you all at the weekend edition of Dxers Unlimited amigos !!!