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Re: [HCDX] Dxers Unlimited´s weekend edition script for24-25 May 2008
Radio Havana Cuba
Dxers Unlimited
Dxers Unlimited's weekend edition for 24-25 May 2008
By Arnie Coro
radio amateur CO2KK
Hi mis amigos radioaficionados around the world and those of you now
orbiting our planet!!! Welcome to the weekend edition of your favorite
listener oriented, and surely technically minded radio hobby program...
YES... you are listening to Dxers Unlimited, the one and only short wave
program devoted to each and every aspect of our wonderful passtime...not
just to boring lists of stations that can be heard only at a certain
specific location...
When you spend part of your spare time with your radios... you can, like
during this weekend enjoy the thrill of a two way ham radio contact half
way around the world using a very low power QRP transmitter in the
middle of one of the year´s most important CW contests,the CQ Magazine
sponsored WPX CW prefix contest, or you can have a lot of fun during a 2
meters band fox hunt at one of your city's parks... but that´s not all,
you can also spend many hours optimizing your new TV Dxing antenna
system now that sporadic E layer openings are happening every day....
SI AMIGOS, YES MY FRIENDS..OUI MES AMIS,.radio is unique in the sense
that there is always something to learn, to experiment with, and to
enjoy... I am Arnie Coro in Havana, my ham radio call sign isCO2KK, and
you can hear my amateur radio station often on the 40, 30 and 20 meter
bands CW segments using my new 2 Watt rig, connected to a wideband
antenna that is working very well indeed.
Now here is item one of today's Dxers Unlimited... As the summer
solstice is approaching, now less than a month away, we are seeing late
evening band openings on the 30 and 20 meter amateur bands, and very
good reception of international short wave broadcasts on the 31an 25
meter bands.
Item two: Many e-mail messages keep coming in to my inforhc@xxxxxxx
account every day, and it's really nice to see how Dxers Unlimited's
listeners worldwide continue to enjoy this program and bring in so many
new ideas, suggestions and questions for me to review. Among the most
recently revived ideas was to create at least one CD ROM disk with the
best of Dxers Unlimited for the past several years... and then make it
available to those interested... Sure it's a good idea that will require
a lot of work on my part, something I am just starting to do during this
weekend... Item three: Simple wire antennas
continue to fascinate many of you amigos, among them the ultra compact
two element QUAD antenna for the two meters amateur band, that can be
built in a few hours using standard PVC insulated wire used for
household installations and PVC plastic pipe and standard fittings for
it. But be aware of an interesting phenomenon... if you don't strip the
wire of its plastic insulation, the dimensions of the antenna will be
different than those coming from the standard two elements VHF QUAD
antenna formula... And also there is a very nice and easy to use
software program to calculate a VHF QUAGI antenna, a neat combination of
a two element QUAD and several linear parasitic director elements...
By the way that program, which is freeware, is available by just sending
me an e-mail message requesting the QUAGI antenna design program... send
your
request to inforhc@xxxxxxx, again inforhc@xxxxxxx, and I'll e-mail the
software to you as a small dot zip attachment attachment...
More radio hobby related items coming up right here after a short
break... I am your amigo Arnie Coro in Havana, and as always it's really
nice to share with you all about seventeen minutes of air time during
the weekend edition of Dxers Unlimited.
..........................................
This is Radio Havana Cuba, the name of the show is Dxers Unlimited, we
are on the air twice weekly, at several different times of the day, and
using also several different short wave frequencies, as well as our
streaming audio from http://rhc.cu, every day from 05 to 07 UTC at this
moment...
Here is now item four of today's show: A simple, rugged, flexible ,
roll up ,easy to transport solar photovoltaic panel, a lead acid gel
cell accumulator and a simple home brewed voltage regulator will power
up your low power amateur radio
station and your short wave receiver at anytime... The solar energy
option is excellent for your emergency communications kit, and you will
be pleasantly surprised how even in somewhat dark days, the silicon
solar cells
can provide enough energy to charge up the battery for nighttime use. A
five or ten watt power solar panel is ideal for this application, and
let me add that many ham radio contests have now special entry
categories that provide bonus points for stations using solar or wind
energy for powering the equipment during the contest. Amateur radio
contests participants . like the many hams involved during this weekend
worldwide CQ WPX CWprefixes contests, learn a lot about fast and
efficient communications procedures and field installations, something
that is extremely useful when actual emergencies come up to your
community .
Item five: The number of amateur radio stations in some countries is
extremely small. This is seen especially in the African continent, where
the presence of DX expeditions of people visiting from developed nations
is often the only possible source of a two way contact with that DX
entity. My
perception is that helping to develop amateur radio in Africa will be
extremely useful for the people of that continent, and this is an effort
that could be very well linked to already ongoing projects designed to
provide Internet access from remote locations using satellite
technology. Item six: Tropical
Band DX season is now, for all practical purpose over in our northern
hemisphere... high noise levels, typical of the summer months make Dxing
on the 120, 90 and 60 meters Tropical Broadcast Bands extremely
difficult during the evening hours. Nevertheless, very early morning
monitoring of the 4.6 to 5.1 megahertz segment of the short wave
spectrum will still make possible some nice catches, because at that
time there is minimal ionospheric absorption and the daily distribution
of thunderstorm activity is also at a minimum... One not too nice thing
happening to Tropical Band Dxers is that many of their favorite stations
are going off the air, due to many different reasons, among them the
rapid development of FM broadcast stations in areas forming served by
Tropical Band broadcasts, and the high cost to broadcasters of keeping
on the air old vacuum tube transmitters for which replacement parts are
more and more difficult to find, and when found are extremely expensive.
Cuba uses the Tropical 60 meters band for providing a nationwide service
to so called silence zones, especially nations four main mountain
regions, where night time AM and FM coverage is not as good as it should
be ...
In areas of mountains and especially in the valleys where AM and FM
broadcasts do not reach or provide a very
unreliable service, the Near Vertical Incidence Skywave tropical band
signals provide excellent service. That's whey the Cuban Broadcast
Institute now operates a
50 kilowatt high tech transmitter for broadcasting Radio Rebelde's
network national program on 5025 kilohertz, using a near vertical
incidence sky wave antenna system to provide optimum service up to a
distance of 1000 kilometers around the transmitter site... For Dxers
there is a bonus... the
antenna does have a small low angle lobe that makes possible listening
to Radio Rebelde in many far away places too!!!
......
Si amigos, we do QSL, we do verify reception reports and absolutely free
of charge... You may send your detailed reception reports and comments
about this and other RHC programs to inforhc@xxxxxxx ,again
inforhc@xxxxxxx , or VIA AIR MAIL send a postcard to Arnie Coro, Radio
Havana Cuba, Havana, Cuba... And now la numero uno, the number one most
popular section of Dxers Unlimited, ASK ARNIE is on the air... Today's
question sent by listener Dimitri from near St Petersburg, Russia.
Dimitri wants to know how he can find the equivalents of solid state
devices, so as to make a cross reference between Russian electronic
components and those made in Europe, the USA and Asia... Amigo Dimitri,
you are not alone , you are facing a huge problem and quite a
challenge... because the specification of, for example, bipolar
transistors for low signal levels are difficult to match between
manufacturers.
Fortunately, there are some general purpose devices that provide a high
degree of compatibility, for example I have used here Russian made KT315
NPN low signal transistors to replace many different types made in Japan
and Europe with excellent results... I also have created a database that
matches to the best possible degree the specifications of many Russian
vacuum tubes to their US, Japan and European equivalents...
Second QUESTION... Came from Canada, listener Alex from London, Ontario,
is asking about the possible efficiency for short wave reception of a
TTFD antenna that in his case,will need to be be only 10 meters or about
33 feet long, as that is all the space he has for his antenna system.
Well amigo Alex, here is an important piece of information regarding the
TTFD antenna design... the lower cutoff frequency for transmitting is
calculated very easily by simple arithmetic...
The TTFD length is calculated by dividing the wavelength by the number
three.. so your antenna only 10 meters in overall length will be good
for transmitting from 30 meters or 10 megaHertz up... In other words, if
you divide 30 meters by
3, your answer will be 10 meters, and that's the length of a TTFD that
will be useable for transmitting from 10 megaHertz up... But now the
good news, it is a fact of life and fully documented by many users of
the TTFD, including yours truly, that a 10 meters or 33 feet long TTFD
is certainly a quite useful receiving antenna down to about 5
megaHertz And when used with an antenna tuner it will also put out a
useable signal on the 40 meters band, but not as efficiently as the full
size half wave dipole antenna cut for that amateur band that has an
overall length of 20 meters or 66 feet!!!
So , summarizing, the answer to your question amigo Alex,is, SURE, go
ahead and build and then install your 10 meters long TTFD, as per the
building instructions that I sent to you sometime ago, and then after
using it for a while, please tell me and other Dxers Unlimited's fans
around the world about your results !!! AND remember that the TTFD
Antenna's most recent version requires a terminating resistor between
800 and 950 or even one thousand ohms, that it must be a non inductive
type of resistor and that it should be properly protected against the
weather elements. For transmitting, the TTFD terminating resistor must
be rated to a minimum dissipation of one fourth of the transmitter power
for average use, and a higher rating if you plan to use full carrier
modes like standard RADIO TELETYPE or PSK31 digital keyboard to keyboard
mode... My version of the TTFD uses ten 2 Watt 8200 ohms carbon non
inductive resistors connected in parallel, to achieve a total
termination resistance of near 820 ohms, and with that value, the
antenna has worked very well for several years using my 100 Watts
transceiver, without any signs of the terminating resistance changing
its value...
....
And now amigos just at the end of the program, as always here is our
exclusive and not copyrighted free for all radio hobby enthusiasts
worldwide ..Arnie Coro's Dxers Unlimited HF plus low band VHF
propagation update and forecast...The effective sunspot number, ESN,
continues to be at a dramatically below 10 units, while the actual
sunspot optical count was zero on Friday and Saturday, an indication of
the almost endless very low solar activity. The daytime maximum useable
frequency curve is barely reaching 18 megaHertz on the East-West daytime
paths, and as expected, best HF propagation conditions continue to be
available just after local sunset.
Expect a lot more sporadic E layer openings, with possible 12, 10 and 6
meters band openings. Atmospheric noise levels are at a pretty high
level, as typical of the northern hemisphere
summer months... Hope to have you all join me next Tuesday and Wednesday
UTC days for the mid week edition of Dxers Unlimited, and don't forget
to take a little time and send me your valuable comments and opinions
about this program, to help me make it better for you and all listeners
around the
world !!!
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