RADIO HABANA CUBA
DXERS UNLIMITED
WEEKEND EDITION
SATURDAY, APRIL 7, 2001
By Arnie Coro CO2KKSend your comments, questions and ideas to: arnie@radiohc.org
Hi, amigos, welcome to the weekend edition of your favorite radio hobby show on short wave and on the world wide web. I am Arnie Coro, radio amateur CO2KK in Havana, and here are the headlines: Fireworks continue! Another X class solar flare has sent charged particles towards the Earth, and we may soon be watching the effects in the form of yet another geomagnetic disturbance...
Headline number two: If you followed my advice, then during the past two weeks you should have added quite a few of very interesting loggings to your records... Be ready for more unusal HF propagation during the next three weeks amigos....
Headline number three.... The huge solar flare, originally thought to be at an X17 level, was finally upgraded to an X22, the most powerful solar eruption ever registered by modern instruments... Planet Earth, and especially satellites in orbit around us, were very lucky that the huge solar flare erupted when the active sunspot region was not in a geoeffective position. Had the flare happened when region 9393 was looking right at us, then we would probably be still making the inventory of all the terrible effects it should had done!
Now stay tuned, in a few seconds more radio hobby-related information will follow, right on this same frequency. Margarita Delgado is my sound engineer and producer... I am Arnie Coro in Havana.
You are listening to the weekend edition of Dxers Unlimited, and if your reception is not very good today, the bands are noisy and there is QSB, blame it on the effects of two coronal mass ejections that have impacted one after the other, affecting the ionosphere signficantly....
Now item four: The very popular YOU have questions and Arnie tries to answer them: Here is today's first question: Arnie, when one of those huge solar flares sends a stream of charged particles towards Earth, what bands are affected first?
Well, amigo from Manitoba, Canada, the increase in ionospheric absorption hits the lower frequencies first... that's why professional communications systems that still operate on the HF region, from 3 to 30 megaHertz, have channels assigned on frequencies above 20 megaHertz, as above that frequency the effects of the disturbances are not so noticeable. BUT it's a completely different story when a radiation storm hits the earth... a radiation storm reaches the Earth's upper atmosphere in just a few minutes after the solar flare eruption, it takes about 8 minutes to reach us, and if it is powerful enough, we may be then witnessing a radio blackout.... the so-called Moss-Dillinger effect that is caused by a tremendous and sudden enhancement of the D layer of the ionosphere, just as happened last Friday to all of us who were in the sunlit hemisphere.
The X5 solar flare that erupted from the new powerful solar active region did just that -- it enhanced the D layer ionization to such a level that absolutely NO shortwave propagation was possible for a certain time period. So, amigo from Canada, I hope that you now have clear that there are two different effects brought by the solar flares, first the radiation storm, and later the geomagnetic disturbance that is caused when the stream of charged particles ejected from the solar corona reach the Earth's magnetosphere.
Now question number two: This one has to do with power line filtering, and I think that this is a very important question, as more and more radio hobbyists are deciding to install radio frequency interference filters at the power line service entrance of their homes, in an effort to clean up the tremendous amount of radio frequency noise that is coming in via the power lines. Well amigo from Texas who asked this question, installing a real brute force, full-protection, power line filter is no easy job... this is something that will require a very careful study, the installation of a very good ground system, and finally the installation of the brute force radio frequency filter itself. As I said, this is a job for an expert, and it must be done by a licensed electrician, because all the power used at your house will be passing through this filter.
There is no doubt that installing a brute force power line radio frequency interference filter is a once-in-a-lifetime investment.... but again, It must be done very carefully and by someone that really knows what she or he is doing! That's why, amigo from Texas, I prefer to use a smaller power line filter that is installed so that only the electricity that is going to your radio room is cleaned of radio frequency interference... I would say that this option provides about 75 percent effective filtering as compared to the full brute force filter at the service entrance. If we compare costs and how easy it is to install the smaller filter that protects just the line that goes to your radio room, then it is obvious that only in extreme cases it is worthwhile to go to the full brute force solution...
Many years ago, I designed two power line radio frequency interference filters that also provided additional surge protection against the nowadays so common, and terrible, power line spikes or transients. One is rated at a current of just 2 amperes, and is very convenient when you are using just a radio receiver or maybe two that do not draw too much current from the AC power line.
The other filter, rated at 6 amperes, will power the typical 100 watt amateur radio station, and provides full isolation from the power line, as it has a built-in bulky but very effective isolation transformer. Choke coils, capacitors and spike supressors, combined with the big, heavy isolation transformer and a good ground connection, to provide really clean power at a cost -- because, amigos, this is not an inexpensive project.... Imagine that you will need a transfomer rated at around 850 watts in order to provide 115 volts AC at 6 amperes of current, and calculating an efficiency of around 80 percent... This is a bulky transformer, but, it is worth every cent invested in it, as the isolation it provides makes your radio reception much nicer.
A properly designed line isolation transformer includes a Faraday Screen, shielding between the two windings, primary and secondary, something that provides additional isolation... Then, you add radio frequency filter chokes, bypass capacitors that operate at different frequencies and spike suppressors to complete the most reliable and effective line radio frequency interference filter that one can think of.... But, do not use it without a proper low impedance ground, because tying the filter's ground terminal to the power line neutral wire will destroy most of the filter's effectiveness...
If your radio reception is experiencing noise interference, at least part of that noise may be coming in via the power line that is feeding your radios... so follow Arnie Coro's advice, and try to test your reception under battery power.... if you have much better reception when using batteries, then it's time to start thinking about homebrewing a power line filter.
Any questions related to this topic are most welcome, and they will further promote talking about radio noise suppression here at Dxers Unlimited, send your questions via e-mail to arnie@radiohc.org and via airmail to Arnie Coro, Radio Havana Cuba, Havana Cuba...
This is the weekend edition of your favorite listener-oriented radio hobby show, Dxers Unlimited, coming to you from Havana. And here is item six: Forecasting short wave propagation conditions is no easy job... There are so many variables involved that many organizations that depend on HF radio communications use a very practical approach ... instead of spending a lot of time and effort working on forecasts, they operate networks of ionospheric oblique angle sounders, also known as chirp sounders, for their peculiar audio signature when they are heard on the radio.
Chirp sounders are often actually connected to the communications equipment in such a way that the radios change operating frequencies automatically as required when propagation changes... But chirp sounders are also a nuisance to other users of the spectrum, from 3 to 30 megaHertz in general, and especially from 5 to 18 megaHertz, where they seem to concentrate... Although they send out short bursts of radio frequency energy, chirp sounders do affect other users of the radio spectrum. That is why attempts are now underway to regulate the use of this type of equipment, and one solution is to try to assign them specific channels, allocated all along the HF spectrum, so that they will do their job without interference to other users.
Item seven: More about home brew radios... If you have built a radio receiver within the past two years and it is still working, why not share your results with other Dxers Unlimited listeners? Send your circuit diagrams in .jpg, or .gif formats and the description of your homebrew radio in text form to arnie@radiohc.org and I will then include it in my radio receiver projects database, which already has more than one hundred different regenerative receiver circuits, including the very high-performance regenerodynes... a combination of a super-heterodyne front end, with a high performance regenerative detector.
Share with other radio hobbyists your circuit diagrams and comments about them... You and only you who have built even the simplest of radios know that there is nothing like tuning the bands with a receiver that you built all by yourself.... I don't know if there is some magic involved, but there seems to be some very special sound coming out of the headphones or loudspeaker when the radio is a homebuilt set !!!
And now, amigos, with the solar flux very near 200, actually nearer to 190 than to 200 units, here is Arnie Coro's exclusive and not copyrighted HF propagation update and forecast: Solar activity still hovering between moderate and high; a big sunspot, about five times the size of the Earth is on sight... and it has already generated one X1 and one X5 flare, and according to scientists, its magnetic configuration is such that it may continue very active during the next several days. At the time that you are hearing this program, reception may not be very good, due to the fact that a geomagnetic disturbance may be in progress...
Be on the lookout for possible 10 and 6 meter amateur band rare DX conditions, and if you are located at a latitude above 40 degrees North, there is a good chance that AURORA BOREALIS will be seen tonight, too... Radio Aurora will send back signals on frequencies as high as 300 megaHertz, so have those 6 and 2 meter band transceivers ready to work via the auroral curtain reflection...
Solar cycle 23 has surprised everyone, and if during the next three solar rotations the Sun continues to be so active, then the solar peak of April 2000 solar might be exceeded by the March-April, 2001 activity....
See you on the amateur bands; I am usually on 28.500 plus or minus 5 kiloHertz on 10 meters, and when 10 is closed I hang around 21.300 on 15 meters or 14.200 on 20... See you there amigos, and be on the lookout for rare Dx during the ionospheric disturbances now in progress...
Transcription 07-Apr-2001 by NY Transfer News
Arnie Coro CO2KK
Havana, Cuba
7 April, 2001Postal address:
Arnie Coro, "Dxers Unlimited"
Radio Havana Cuba, Havana, CUBA
e-mail: arnie@radiohc.org
To Arnie Coro's Dxers Unlimited
Back to NY Transfer's RHC main page