Hi amigos radioaficionados... around the world, and in space … welcome to the weekend edition of your favorite radio hobby program. I am your host here in sunny Havana, the beautiful capital city of Cuba, where we are beginning to feel the typical south wind that signals for us that spring is just around the corner... when the south winds blow for a while, we then see a shift to the north, and a cold front drifts all across Cuba.

That's the typical pattern until around mid March, when we see another weather change, the cold fronts just stay stationary, they don't move an at all for several days, for the enjoyment of radio amateurs that operate on the VHF and UHF bands as well as FM broadcast band and TV Dxers.

This type of temperature inversion generated propagation has nothing to do with the ionosphere... it is a tropospheric event, that happens at altitudes below two thousand meters above the earth and sea surface...

Item two: The sunspots are back... after four days of a totally blank Sun, there are now at least two active regions showing up very clearly and one of them was growing at a fast rate since Friday... The daily sunspot count jumped from zero to 31 in just one day !!! As we continue to approach the equinoctial DX season, the presence of sunspots is the best news I can give to HF bands Dxers all around the world. More about the short wave bands propagation conditions ,a always at the end of the show amigos …

Item three: Trying to repair an old piece of equipment, be it a vacuum tubes receiver of nineteen fifties vintage or a more modern hybrid or solid state amateur radio transceiver built twenty or twenty five years ago can turn into a nightmare... especially it you don't have the appropriate measuring or test instruments.

As a very good friend of mine that is a wizard repairing electronic equipment likes to say... after the nose and eyes inspection of the radio or other piece of equipment you want to repair takes place, you are left with the options that are provided by the test instruments at hand. Yes you heard it right... when I talked about the nose inspection... that is using your nose to sense the characteristic smell of overheated electronics...something that in many instances will take you right to the damaged part or parts, or to the general area where the smoke was generated.

Sometimes the fuses protecting the electronic gear will blow and stop the current flow before the smoke starts to come out of the equipment, but the smell of the overheated part or parts will stay there for a long time.

My electronics repair wizard friend has three different magnifiers, and uses some equipment borrowed from his wife who happens to be one of the dentists at our dental clinic, not far away from my home. Natalie, has provided amigo Jose with some very nice small mirrors placed at the end of a stainless steel probe.

The dental mirrors are placed at different angles and are small enough to make possible placing them at places where a direct eyes inspection is not possible. Using his magic dentist's mirrors , my friend showed me recently how he was able to locate a faulty connection that was producing the intermittent operation of a power supply.

Jose also uses a homebrew ESR meter, that is an equivalent series resistance meter, that he describes as the most useful repair person's test instrument after his professional digital voltmeter …

I will tell you more about how to repair old and not so old electronic gear in a few seconds when the weekend edition of Dxers Unlimited will continue on our short wave frequencies and also from our streaming audio available at www.radiohc.cu...

I am Arnie Coro , radio amateur CO2KK, your host in Havana

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Yes amigos you are listening to Radio Havana Cuba, soon to be celebrating our 49th year on the air... and YES, we are getting ready to celebrate next year, our 50th Anniversary , and now we have here a group of old timers and newer members of our radio family forming part of a 50th Anniversary Celebrations Committee... of which, I am very proud to form part too...

Now as promised more about the how to repair radios tips... Not too long ago , a friend knocked at my door and handed over a solid state portable radio that , as he explained , could not be repaired.

He had tried himself, and also had asked at least two other local electronic's fans that are very good technicians to try to repair it without success...” Cogelo para piezas “ that meaning, “just used for parts Coro”, he said, but as you may guess I didn't started immediately to take the portable radio apart to recycle the loudspeaker, ferrite rod and other parts …

I left the radio on top of the workbench for several days until I had some spare time to open it up... It took just a few minutes of a careful visual inspection done with very good high intensity light illumination to realize that a one hundred microfarads at 6 volts DC electrolytic capacitor was leaking … not too badly, but it was certainly in bad shape.

A quick glance at the position occupied by the capacitor gave me the hint that it was the coupling between the integrated circuit audio amplifier and the loudspeaker... Once the defective component was found, it was just a matter of minutes to connect the soldering iron, set up the big magnifying glass and look for a replacement capacitor at the parts storage bins...

Once the new , well tested with the ESR meter capacitor was soldered in place, I connected the radio to the workbench's variable voltage power supply, setting it to 5 volts … And guess what ?

The radio started to play with a very nice , clear audio...

I left it there , at the workbench for the rest of the day... while I was writing the script for a mid week edition of Dxers Unlimited.... Just before supper, the radio was checked again, and it was working perfectly, so I just replaced the back cover, not before cleaning the circuit board with a fine camel hair brush...

The next step was to call Francisco my friend, to tell him that his radio, the one he gave to me because no one could repair it, was alive again...

In this particular case, the detailed visual inspection with the big magnifying glass was what made the difference and helped to locate the defective component. Now let me add that electrolytic capacitors are the components that after several years of service show the highest failure rate...

There is one test instrument that in my humble opinion should form part of all radio and electronic experimenter's tool box... it is known as an EQUIVALENT SERIES RESISTANCE METER, and all I can say amigos is that it has helped yours truly to repair a large number of radios and other electronic equipment that otherwise would had gone to the recycler.

As a matter of policy, I fully agree with the radio hobby enthusiasts that devote to their time to repairing and putting back in service old vacuum tubes equipment … they all underscore the importance of before connecting those radios to the power line , one must replace ALL the electrolytic capacitors, and also all the paper dielectric bypass capacitors, as essential in order to avoid the failure of the very difficult to replace power transformers .

Si amigos, yes my friends , oui mes amis, you can save a lot of electronic equipment from going to the recycler or what is worse to the dumping sites.... by applying some of the aforementioned advice, and don't forget that your friend Arnie Coro, was the person who told you about the ESR , Equivalent Series Resistance Meter, the one electronic test instrument that you won't want to be without it after you use one for the first time...

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This is the weekend edition of Dxers Unlimited , coming to you from Havana... and here is our next radio hobby related item , don't be surprised if you hear news about still more amateur radio satellites to be launched... but, unfortunately, all the announcements I have seen and read about ham radio satellites make reference to what are known as LEOS, or Low Earth Orbit Satellites...

So far there is still no news about a possible high orbit satellite, be it of the Molnya or highly elliptical Earth orbit , or of the geosynchronous also known erroneously as geostationary satellites...

The last attempt to put into Earth Orbit a Molnya ellipticaly orbit type satellite , that was named OSCAR 40 ended in total failure, because the on board equipment suffered from an explosion caused by the malfunction of a fuel control valve...

It is quite clear to me that a high orbit amateur satellite is a very costly bird... but a geosynchronous may prove to be , paradoxically, much less expensive to the worlds amateur radio community, if and when, it can be carried as part of the payload of a commercial telecommunications geostationary satellite...The willingness of a professional commercial venture to accept a ham radio satellite to share space aboard seems now closer than ever, as the engineers realize that it could be possible to design an amateur radio satellite fully compatible with the one that will carry it on board. This is not day dreaming amigos, it may happen in a few years time, and maybe we one day could also see an active amateur radio repeater installed on the Moon too !!!

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QSL on the air, QSL on the air to the many ham radio operators that wrote saying thank you Arnie for the HF propagation update and forecast that is on the air always at the end of the show... Raul CO8ZZ, is a regular user , as well as Abel CO6XN, they both made a lot of contacts recently during the first openings to Europe and Africa of the 15 meters or 21 megaHertz band that they became aware about after reading the copy of the script of the show that I send them via e-mail …

And now amigos as always at the end of the program, here is Arnie Coro's Dxers Unlimited HF propagation update and forecast....

Solar activity once again moving UP...

Solar flux reaching ninety units and the daily sunspot count around 35... So, we will have quite a nice weekend on the amateur short wave bands above 20 meters, and for short wave listeners, the 19, 16 and even the 13 meters band will bring in nice signals with very good quality of reception as the ionosphere receives an influx of radiation that keeps the number of free electrons at a much higher level than a week ago ! Don't forget to send your signal reports and comments about the program to inforhc at enet dot cu or VIA AIR MAIL to Arnie Coro, Radio Havana Cuba, Havana, Cuba.