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Re: [HCDX] Dxers Unlimited´s script for mid week edition 17-18 June 2008
Radio Havana Cuba
Dxers Unlimited
Dxers Unlimited mid week edition for 17-18 June 2008
By Arnie Coro
Radio amateur CO2KK
Hi amigos radioaficionados, welcome to the mid week edition of Dxers
Unlimited at a moment when the 2750 megaHertz solar flux is very near to
the lowest ever recorded levels since 1947, when Professor Arthur
Covington of Canada started to monitor the Sun at microwave frequencies
on a daily basis. Solar flux was at 65 units , a value very close to
the minimum ever recorded. So, as may realize the daytime maximum
useable frequency curve is showing a very slow build up, and is peaking
at extremely low values, with the typical highest possible frequency
propagating via the F2 layer not reaching higher than about 20 to 24
megaHertz and that´s for very short periods of time.
More about the very low solar activity and how it may be actually
enhancing sporadic E layer propagation at the end of the program.
Item two: Handling the daily influx of e-mail sent by Dxers Unlimited
listeners around the world is quite a task amigos ! But I do enjoy it a
lot, because some very interesting topics are suggested, questions asked
allow me to provide useful answers not only for the person or persons
who sent the question, but also for many other listeners of the
program... You can send your signal reports , QSL requests for station
verification of reception radio hobby related questions , and comments
about the show. Send them to inforhc at enet.cu
<mailto:inforhc%20at%20enet.cu>, again inforhc at enet.cu
<mailto:inforhc@xxxxxxx>... Or VIA AIR MAIL, send your postcards and
letters to Arnie Coro, Radio Havana Cuba, Havana, Cuba.
Now here is item three of the mid week edition for Tuesday June 17 and
Wednesday June 18^th UTC days...Software defined radios are now becoming
more and more both builder and user friendly... Several kits now
available provide prospective homebrewers with a much faster way of
assembling a software defined radio than what may be possible by
attempting to buy or ask for all the required electronic components to
make a Software Defined receiver or transceiver... For advanced radio
hobbysts familiar with assembling electronic projects, I think that
experimenting with software defined radios will provide a lot of very
interesting results, and open up new ways of enjoying our hobby.
Item four: Indoor antennas are useful when there is bad weather and you
do need to communicate. More about indoor antennas for emergency
communications in just a few seconds, when Dxers Unlimited´s mid week
edition continues after a station ID.
I am Arnie Coro, radio amateur CO2KK in Havana...
........
Si amigos ! You are listening to the mid week edition of your favorite
radio hobby program, Dxers Unlimited with yours truly Arnie Coro ...
Here is now our technical topics section on indoor antennas for
emergency communications .
Indoor antennas are no match to well installed outdoor ones, but under
some very special circumstances, your only option for providing the
antenna required by your radios may be to carefully select the best
location inside a building and proceed to install an indoor antenna system.
I have seen extremely well designed indoor antennas that provide those
who use them with very effective reception and transmission. In order to
make this description a bit more flexible, my concept of an indoors
antenna system includes those that are installed in balconies and
attached to balcony rails.
At CO2KK , my amateur radio station, there are not one, but five
different indoor antennas that see almost constant daily use.
Let me describe them for you in detail:
Number one :The telescopic whips used on my three portable multi-band
receivers...
Number two: A dual band 2 meters and seventy centimeters vertical
monopole antenna that is used for monitoring the two local 2 meters FM
repeaters, and also to make local contacts on that band and on 70
centimeters.
The number three indoor antenna is a MOXON rectangle for the two meters
band that is installed , when needed, on a camera tripod so that it can
be aimed in the direction of the station or repeater I want to contact.
Number four indoor antenna is a one meter diameter 19 millimeters tubing
copper loop...Yes, it is tuneable magnetic loop that covers from 10 to
30 megaHertz for reception and that
Allows transmission on the 30, 20, 17,15 , 12 and 10 meters band, so
this is in my opinion the most compact six band antenna that one can
imagine. It is manually tuned, and YES, you have to retune it everytime
that you need to shift frequency by even a few kiloHertz , but it allows
me to be on the air , especially on 10 meters when the band is open and
I don´t want to connect the outdoor beam because the presence of thunder
clouds in the sky.
Finally my fifth but not less important indoor antenna is another
magnetic loop optimized for the 6 meters or 50 megaHertz band and that
is kept close to a picture window. I use this smaller loop to monitor
for possible 6 meters DX during the sporadic E season, that here in Cuba
happens to coincide with the peak of the summer thunderstorm season....
An interesting fact about the use of indoor antennas is that their
performance is very much related to the type of material used for
building your home. An antenna located inside an attic that is high
above the ground and has no metal elements inside its walls, will show a
much better performance than an identical system that is installed
inside a room of a house built with brick walls and a reinforced
concrete roof. Signals , both the ones to be received and those
transmitted will suffer from severe attenuation , reaching values of
many decibels as compared with an identcial antenna inside the wooden
wall and roof attic !!!
Please remember that just a small antenna is better than a telescopic
whip or a rubber duck helically loaded whip... something that applies
for both short wave and VHF operation.
Even a short length of hookup wire attached to your portable radio´s
antenna and placed as near as possible to a window, or even just dropped
from the window or balcony will make quite a difference , although
careful placement of the indoor or semi-indoor antenna is necessary in
order to reduce the pick up of interference from home appliances of all
types...
If you need advice on installing an indoor antenna , just drop me an
e-mail and I´ll try to provide you with advice according to
the frequencies involved and the type of building .
......
This is Dxers Unlimited´s mid week edition and now here is ASK ARNIE, la
numero UNO, the number one most popular section of the program...
Listener Gabriel from Atlanta , Georgia, USA, wants to know what´s the
best time or times of the day to pick up Sporadic E skip signals... He
says in his e-mail: Arnie, I agree with you that HF , that is short wave
propagation is worst than ever... Having listened to international
broadcasts for the past 30 years, I have never before experienced such
poor propagation conditions. Recently I became interested in FM
broadcast band Dxing, one of those 84 ways of enjoying the radio hobby
that you have described. And Gabe continues his e-mail describing his
nice vintage Scott FM tuner that has an ECC88 cascode RF amplifier and
outperforms his two other solid state FM receivers in a very significant
way... Gabe says that he is using two antennas for FM Dxing, one is a
commercial log periodic fed with 300 ohms low loss foam dielectric line,
and the other antenna was built following instructions provided in one
of my articles about the TTFD published by CQ-VHF Magazine many years ago.
Gabe ends his nice e-mail message with the question that I repeat now ¨¨
Arnie, what are the best times for Sporadic E summer DX ¨¨... Well amigo
Gabriel,or Gabe as you like to be called, it is an interesting fact that
Sporadic E propagation events can happen at anytime of the day, but they
do show ,during the summer months a much higher probability of happening
from about 9 in the morning or a little earlier local time, to about an
hour before noon, and again, there is another period of higher
probability of E skip from about three to four o´clock in the afternoon
to just after sunset, again, I am talking about local time...
But be aware that in my more than 50 years of Dxing via sporadic E skip,
I have made two way contacts on the 10 and 6 meter bands at two or three
o´clock in the morning, as well as at one o´clock in the afternoon, when
normally you don´t see E skip happening... By the way , we may soon be
loosing one of the best sources of early warning of Sporadic E skip
events , at least here in the Caribbean, and the USA, when next year the
analog TV stations in the United States of America will shut down, and
be replaced by digital technology signals !!! so for those Dxers, both
TV and amateur radio VHF enthusiasts that don´t have bought a digital TV
or a converter box, the familiar pattern of venetian blinds atop a
fringe area TV channel two or even a local powerhouse when the band is
really open will be a thing of the past...
That´s why amigo Gabe, amateur radio 10 and 6 meter band beacons will
become much more important for us to learn when E skip is present !!! I
hope that this reply answers your question and congratulations on your
nice FM broadcast band Dxing setup amigo !!!
FM broadcast band Dxing is quite a challenge for people living in
metropolitan areas where cross modulation problems are a tremendous
problem... but those of you living away from the big cities and having a
good receiver or FM tuner can still enjoy FM broadcast band DX events
both via tropospheric ducting or Sporadic E.
...............
Technical Tips, yes Technical Tips here at Dxers Unlimited´s mid week
edition... For your radio hobby enjoyment... Here is the first one:
Whenever you buy or get a free piece of old equipment, be it full of
vacuum tubes or solid state devices... NEVER, , again NEVER connect it
to the power line if it is an AC operated radio, before making a very
detailed visual inspection INSIDE... Look for electrolytic capacitors
that may be leaking , signs of overheated transformers, and in the case
of equipment in long storage signs of mildew and humidity damage.
After the visual inspection, if no signs of those typical problems are
found, then phase two of a start up procedure for gear in long term
storage will be to carefully test all the electrolytic capacitors using
an Equivalent Series Resistance or ESR meter... go one by one, be
patient and you will be rewarded usually with the detection of one or
more capacitors that will need to be replaced... Proceed to replace
them, and when powering up the equipment use a variable voltage
autotransformer to carefully provide AC to the radio... I usually start
with 25 volts and leave it there for a number of hours... jump then to
50 volts and monitor the AC current drawn by the radio under the revival
process...after about a day at 50 volts, it will be usually safe to
raise the voltage o 100 volts and watch for any signs of overheating or
excessive current drawn from the variable
voltage transformer ...Just before I forget... in older vacuum tube
radios, it will always a good idea to replace all the paper dielectric
bypass capacitors too... a time consuming procedure, but one that will
save you from having to replace much more expensive and hard to find
components !!!...
And now as always at the end of the show, here is Arnie Coro´s Dxers
Unlimited´s HF plus low band VHF propagation update and forecast....
Bottom low solar activity, extremely low F2 layer maximum useable
frequencies, while plenty of E skip events are happening over North
America, the Caribbean, Central America and Europe with some unique DX
on 6 meters from half way around the world coming to the surprise of
long time operators on the so called MAGIC BAND---The effective sunspot
number at 15 hours UTC Tuesday was an extremely low ZERO TWO <... A
close look at the Sun shows we still have the remains of old sunspot
998, but we have are seeing a sunspot group, 999. This one is almost
on the sun's equator and like 998 has a a clear cycle 23 magnetic
signature. The flux has dropped to a bottom low level of 65 units and
the K index was lower at just 4, units at around 14 UTC Tuesday with
the solar wind well over 700 kilometers per second but it's unlikely
we'll have auroral conditions in the near future. Due to the higher
solar wind there may be some disturbance from minor geomagnetic
storming especially towards the poles.
One final note that is causing concern among solar scientists..
Unfortunately it looks like we have a lot further to go before we can
be certain that we have actually reached the minimum of cycle 23 yet !!!
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