Re: [HCDX] Dxers Unlimited's mid week edition 5-6 December 2006

["Prof. Arnaldo Coro Antich" <coro@xxxxxxx>]

Dxers Unlimited

Dxers Unlimited's mid week edition for August 1-2 2006

By Arnie Coro

radio amateur CO2KK


Hi amigos radioaficionados, with our now traditional salute, half in 
English, half in Spanish, I am opening up the mid week edition of Dxers 
Unlimited, your favorite radio hobby program. My name is Arnaldo, but 
everyone in the radio world knows me as Arnie, and as always it's my 
pleasure to share with you about seventeen minutes of on the air and on 
the world wide web time... Here is item one: Fresh direct and from the 
source, BIG SOLAR FLARE.... an unexpected X9

type flare, yes , you heard it right, and the active region that 
generated this really big solar eruption is still at the Sun's limb, so 
it will have to transit right trough the solar disk for about two weeks, 
before it turns around , and in the meantime we may be seeing some very 
interesting fireworks from the Sun... As of now the expected solar flux 
may cross the critical 100 units mark maybe by tomorrow...do remember 
that the the July 2006 monthly solar report that my good friend Angel 
Gonzalez Coroas, Cuba's most experienced solar optical observer sent me 
showed that the WOLF number for the month of July was 16, and that the 
highest number of sunspots registered on a single day during the whole 
month was 36... Other details about this very elaborate solar report 
show what in my opinion is the most relevant data... NO sunspots from 
cycle 24 have yet been seen , despite the fact that Angel is doubling 
the number of his daily comprehensive solar optical observations, aiming 
at trying to find the higher solar disk latitude sunspot group that will 
signal the start up of cycle 24. So, if we follow the Cuban expert's 
point of view

the two small reverse magnetic configuration sunspots observed 
previously may be attributed to chance rather than to the actual 
beginning of cycle 24.

In comments sent together with his report, the Cuban scientist explains 
that he is now changing his estimate for the beginning of cycle 24 
further away , probably by the end or next year... If this becomes a 
reality, then poor HF propagation conditions on the higher frequencies 
are going to last longer than expected.

But, I must now ask him about this new big sunspot that is already 
producing X level type solar flares...

Item two: Monitoring civil aviation traffic on the VHF short range band 
between 118 and 136 megaHertz is not only very interesting, but also 
sometimes provides with highly stressful moments, especially when bad 
weather makes aircraft operations much more difficult. Among the popular 
radio receivers that do have the capability of AIR BAND monitoring is 
the now classic SONY ICF2010, but you can also monitor the 110 to 136 
megaHertz segment of the VHF spectrum with a home brew solid state 
converter connected ahead of your standard AM short wave broadcast 
receiver... All I can tell you is that it's pretty fascinating listening 
amigos !!!

Stay tuned for more radio hobby related information , and don't forget 
to look around for paper , pencil or pen , ready to write my e-mail and 
also my postal address ...

I am Arnie Coro in Havana, back with you in a few seconds

.....

Your radio is tuned to Radio Havana Cuba, on one of our short wave 
broadcast bands frequencies. At present we are using 6060 kiloHertz on 
the 49 meters international broadcast band in English from 0500 to 0700 
hours UTC... beaming to Eastern North America, but also reaching at 
times, when propagation is good up to the United Kingdom, Scandinavia 
and Germany. We are also using 11760 kiloHertz in English from 0500 to 
0700 UTC with an omnidirectional 6 dB gain antenna, and are receiving 
now some nice reports from Australia and New Zealand....and the new 6180 
kiloHertz with our 340 degrees azimuth curtain array is beaming to 
Central North America, from 01 to 07 hours UTC too. Now here is item 
four of the mid week edition of Dxers Unlimited amigos... Lack of 
amateur radio activity on open bands, providing at a specific moment 
excellent propagation, is worrying hams all over the world, because this 
may lead to actually using some segments of the amateur bands to other 
users of the radio frequency spectrum. According to a very recent 
research project aiming at finding out about the activity levels 
observed on several amateur bands during times of the day when they are 
supposed to provide good communications , fewer amateurs are now on the 
air at any given time than five, ten or even fifteeen years ago. The 
reason for this lack of motivation to go on the air seems to be related 
to the fatal attraction of the Internet, as a leading amateur radio 
official of a national ham radio organization told me recently , but he 
also added that the trend seems to be taking a reverse path now, as some 
newcomers to the amateur radio hobby are becoming very active on the air 
using the digital communications modes that link ham radio and computers 
in such a nice way...

Item five: A visit to Arnie's workshop, where a homebrew type power 
supply is laying on top of one of the tables, still unrepaired. This 
linear supply is rated for 20 amperes at 13,8 volts continuos service, 
and up to 25 amps intermittent, but it was generatinga very bad hum on 
the transmitted audio when running a 100 Watt HFtransceiver, so 
something is really wrong with it.

I talked on 2 meters with my long time friend Luis Rodriguez, CO2LR, and 
we discussed possible causes of the poor regulation of the supply. Among 
the suspected causes I have yet to give a clean bill of health to the 
big electrolytic filter capacitor , because those capacitors show a 
marked tendency to loose their capacitance after 10 or more years of 
service.

Luis advised to just go ahead and replace the big 68000 microfarads at 
50 volts DC capacitor , when I told him that the supply was now about 20 
years old.

Other components to check carefully are the two big series pass NPN 
power transistors, each rated for 25 amperes of collector current. As 
always when doing this kind of major repair work, I look at the 
possibility of doing improvements to the original circuit 
design,because, like in many other instances this supply was designed 
perhaps more than a quarter century ago, something that is easy to 
appreciate when you look at the printed circuit board that contains the 
actual voltage regulator circuit.. it is an all discrete components 
board, with individual transistors, capacitors and resistors, and 
without any integrated circuits of any type.

Talking to CO2LR, we both came to the conclusion that because this is 
not a collectors item, the performance of the supply could be improved 
substantially by modernizing its voltage regulator circuit and keeping 
the big , husky, well built components . Maybe by the time this edition 
of Dxers Unlimited is on the air for its first airing at 21 hours UTC on 
Tuesday, the power supply will be providing 13.8 volts at 20 amperes to 
my HF rig when I run it at the high power setting, that requires about 
18 amperes.

......

 From Havana, coming to you via short wave and from 05 to 07 UTC via 
Internet , this is the English language program of Radio Havana Cuba, 
the name of the show is Dxers Unlimited and here is item six: Powering 
your radios from batteries is sometimes the only solution available to 
downtown city dwellers that receive a lot of radio frequency noise via 
the AC power lines, even after installing very good quality filters with 
the corresponding low inductance ground connections.

A good practical example of how reception improves when using battery 
power is seen at my QTH here in Havana, where I can operate my short 
wave radios with external antennas even when the 21 inch TV set is in 
use just tree meters or about 10 feet away from the radio . If I 
disconnect the batteries and connect the receiver to the well built, 
fully regulated power supply,the noise level starting at the low end of 
the AM broadcast band and moving well into past the 6 megaHertz 49 
meters band, is so high that only very powerful stations can be picked 
up. Switching the radio back to the 7 ampere hours 12 volts GEL Cell , 
the noise level drops dramatically, a clear indication that the noise 
was coming into the receiver's circuits not by the antenna , but by 
means of the AC power line. All experiments done to try to clean up

the radio frequency waveforms that reach the AC power line from the TV 
set and the computers switched mode power

supplies have met with total failure... So , I was left with just one 
option, build a nice , efficient battery charger, and buy a brand new 
GEL CELL 12 volts DC at 7 ampere hours accumulator, a quite standard 
component of house electronic alarm systems. Running my homebrew solid 
state receiver, the fully charged battery lasted almost a week of heavy 
service, but the same doesn't hold when powering the power hungry YAESU 
FT-817, and otherwise excellent low power or QRP transceiver, that has 
served me well for the past four years without any breakdowns...The FT 
817 is a power hungry transceiver when in the receive position, so the 
external 12 volts lead acid gel cell accumulator , even after a full 
charge, will be completely discharged after about one or two days of 
operation in the receive mode, and of course , much faster when in the 
transmit mode.

In contrast to the power hungry FT-817, my own design HF single band 10 
Watt transceiver , the Hurricane One, runs many more operating hours 
from the same GEL CELL 7 ampere hours accumulator , despite the fact 
that it delivers twice the power to the antenna...

......


ASK ARNIE.... Preguntaselo a ARNIE in Spanish for you to practice your 
Spanish amigos... ASK Arnie is the most popular section of the show, 
because radio hobby related questions sent to my e-mail address are 
answered with a very fast

turnaround ... Today's question came from a listener in Canada that is 
enjoying our new antenna beamed to Central North America on 6180 
kiloHertz .Amigo Luigi from Toronto asks what he can do to deal with big 
birds using his VHF and UHF Yagi beam and log periodic antennas as 
parking places. Well, yours is a problem that is shared with a great 
number of both amateur and professional radio and TV operators... Big 
birds cause lots of problems to TV and FM stations, when their droppings 
, that are very aggressive from a chemical point of view cause severe 
corrosion to critical parts of the antennas.

One practical and very easy to implement solution to reducing the number 
of birds that use your antennas to make short of long term stopovers is 
to install a mockup bird of prey atop the masts.. A plastic full size 
OWL or a FALCON works wonders according to those who have tried that 
idea !!!

Be sure that the fake bird has all the characteristics of the real one, 
including the colors of the feathers, as smaller birds seem to have good 
visual recognition that helps them to determine if the bird sitting on 
top of your mast or tower is the real thing or not... And in order to 
survive, if they suspect that the big bird may be the real thing, they 
do keep away from the antennas !!!

And now amigos after this final item about the protection of your 
antennas from birds capable of breaking up the elements of VHF beams, 
here is now Arnie Coro's Dxers Unlimited's HF plus low band VHF 
propagation update and forecast...

BIG , really BIG sunspot still growing and now moving into a much more 
geoeffective position,from where it may be sending high intensity 
streams of charged particles towards the Earth during the next several 
days...Solar flux has moved up to near 100 units now, and we do expect 
some very exciting days ahead regarding HF propagation conditions...So 
be ont he alert for possible short wave fadeouts and blackouts, abnormal 
propagation conditions to the South on the AM broadcast band, and 
possible 10 and 6 meter bands openings... Exciting for sure, as we are 
supposed to be going trough the lower activity part of the solar cycle !!!


So , be on the lookout for abnormal propagation conditions on the AM 
medium wave broadcast band, especially at higher latitudes, and also 
don't expect a lot of DX to be heard on the HF bands from 6 to 18 
megahertz or so, until the disturbance comes to an end, something that I 
expect to happen in about two or perhaps three more days... AND, don't 
forget to send me your signal reports, comments about the program and 
radio hobby related questions via e-mail to arnie@xxxxxx or VIA AIR 
MAIL, send a postcard or letter to Arnie Coro, Radio Havana Cuba, 
Havana, Cuba

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