Cuba: Dxers Unlimited's mid week edition 8-9 September 2009

Tuesday, September 8, 2009   Radio Havana Cuba Dxers Unlimited's mid week edition for 8-9 September 2009 By Arnie Coro Radio Amateur CO2KK Hi amigos radioaficionados all around the world... Your radio is now tuned to Radio Havana Cuba's Dxers Unlimited's mid week edition coming to you from sunny Havana,the capital city of Cuba, where its more than 850 radio amateur are well prepared to deal with the second half of this year's tropical hurricane season. The members of the Cuban Federation of Radio Amateurs participate in our national emergency nets that are capable of providing communications links even under the most difficult circumstances, something that is very much appreciated by the Cuba Civil Defense System. By the way this is going to be one or main topics to be discussed at our Seventh National Convention that will take place in Camaguey city, with the participation of more than 250 Cuban radio amateurs and about 50 guests from government agencies and the Civil Defense national command. I am Arnie Coro,radio amateur CO2KK,your friend in Havana, and here is our next news item of today's program.... Zero sunspots once again, with 200 days of this year 2009 registered as absolutely spotless, something that is having a very bad impact on high frequency short wave bands propagation conditions. This sounds like we may be heading for another Maunder Minimum, and it has surely caught solar researchers by surprise, because they didn't expect that solar cycle 23 would last so long !!! According to the opinions of several well known solar scientists, magnetic fields that generate sunspots just have proven to be extremely weak, as a a matter of fact they are showing a trend to become weaker and weaker during the past several years !!! The last long stretch of spotless days came just one day short of what happened during the summer of 2008, when cycle 23's record of 52 days without sunspots happened. Again, the total number of days of this year 2009 without a single sunspot seen has now added up to two hundred, equaling seventy nine percent 2009 that have gone by without sunspots. I'll be back with more radio hobby related information in just a few seconds I am Arnie Coro , radio amateur CO2KK in Havana. ......................................... This is Radio Havana Cuba, the name of the program is Dxers Unlimited, and here is our next item: Early morning, pre-sunrise propagation conditions on the lower frequency bands continue to provide unique opportunities to pick up DX stations... The AM medium wave broadcast band is going through a period when the QRN, the QR Nancy or radio noise levels are much lower than during the rest of the day... It is quite evident here at our tropical latitude of 23 degrees North, that weather systems still belong to the summer season, so the high noise levels generated by static crashes from thunderstorms are still making reception of low frequency signals rather difficult. But , as said earlier, just before sunrise local time, the QRN generated by the atmospheric noise level goes down, because the number of thunderstorms at that time of the day is lower than at any other period. Pre-sunrise propagation conditions also provide much better propagation to the West and Northwest of your location, a fact that must be taken into account . Although North-South and South-North propagation paths do open up also during the pre-sunrise period, it is quite clear that signals coming from due West or from the North West are several dB's better . Monday evening I tried my new T type antenna on 160 meters, having to battle with big static crashes from not too distant thunderstorms, nevertheless I was able to make several nice two-way contacts using single side band voice , and one CW Morse code radiotelegraphy QSO. As we enter more and more into the autumn equinoctial DX season, propagation conditions on frequencies between 500 kiloHertz and eight megaHertz will improve , making possible for radio amateurs to enjoy a short period of much better DX possibilities !!! ............................ At the request of several listeners , I am going to give a short glance at the ultra weak signal digital mode, that is known by its acronym ... WSPR, but that amateur radio operators using it are renaming as WHISPER. Again this is a digital radio communications program that ranks as one of the most remarkable contributions to amateur radio software in recent times.... it is certainly a nice interesting example of how well written computer code is able to optimize the use of computers processing power in order to boost the reception of extremely weak signals. WHISPER , or WSPR is another good example of the ULTRA NARROWBAND digital modes that are opening a totally different scenario to weak signal communications. I am talking here about the very small bandwidth digital modes, that use just a few cycles of radio frequency spectrum WSPR, the WHISPER, makes possible to operate with very low transmitter power output and still obtain good results !!! Although the most popular and most used today easy to learn digital communications mode preferred by hams worldwide is PSK31, this keyboard to keyboard mode can be used even with older computers,.PSK31is also pretty easy to set up, and one can become quite familiar with the PSK31 mode operating procedures in just a few hours. Now amigos, here is now our next radio hobby related item for your enjoyment. Homebrewing of simple easy to build solid state radio receivers is a very rewarding experience .... Yes amigos. Even the most simple radio, built around a tuned circuit, plus a crystal diode and a one transistor audio amplifier can provide excellent performance when properly designed and built. Just recently I tried out an AM broadcast band receiver circuit that uses a minimum of electronic components, while still providing excellent selectivity , that is the ability of the radio to separate between stations. The secret of this very simple receiver lies in the use of a very well designed input tuned circuit... It uses a large diameter , high Q coil and an air spaced 365 picoFarads variable capacitor. The high Q coil is coupled to a second matching coil that is designed to optimize the match between the antenna and the radio. I wound the big coil on a three inch or 75 millimeters diameter length of PVC white pipe. The wire used is number 18 enamel insulated , and the coil has 70 turns, with taps from the bottom up every 10 turns. By using a hand picked germanium crystal diode, the radio's sensitivity is much higher that what is normally achieved on this simple circuit when one uses any diode that is available without running into the trouble of measuring the diode's forward conduction voltage, in order to be able to select the one with the lowest value. In order to provide the maximum possible amplification that can be achieved from the single stage audio amplifier, I measured the amplification provided by no less than fifteen transistors of the same type, and then using the one with the highest gain and lower internal noise. This little radio was built as part of a training program at our Amateur Radio Academy that is made available to persons interested in becoming radio amateur operators. The little radio uses a matching output transformer, so that the easy to find low impedance headphones can be used. This transformer matches the transistor's collector impedance to 16 ohms, so power transformer to the headphones is very good. Parts count was intentionally kept to a minimum and the radio is battery powered . In actual practice it works quite well with just 3 volts DC coming from a pair of series connected AA type cells, but audio output is much higher when it is fed with 9 or 12 volts. Tests using a 9 volts battery were very rewarding, as I was able to pick our own Radio Havana Cuba's six thousand one hundred and forty kiloHertz 49 meters band frequency using a wire antenna that is about 10 meters or a bit less than 35 feet long. If you want to know more about this weekend project that can be assembled in just a couple of hours , just send an e-mail to inforch@enet.cu, again inforhc@enet.cu... or send a postcard or letter to Arnie Coro, Radio Havana Cuba, Havana, Cuba. ............................ You are listening to the mid week edition of Dxers Unlimited, and here is now, once again, a quick reminder for long time listeners and also good news for those of you that are enjoying this program for the first time.... Yes, we here at Radio Havana Cuba do QSL, we do verify your reception reports with a nice QSL card, and your comments about this and other Radio Havana Cuba programs are most welcome... Send your radio hobby related questions , that will be answered direct via e-mail and also on the air . Send mail to inforhc at enet dot cu, or VIA AIR MAIL to Arnie Coro, Radio Havana Cuba, Havana, Cuba. And now amigos, as always,when I am here in Havana and can compile all the required information ... here is at the end of the program Arnie Coro's exclusive Dxers Unlimited's HF plus low band VHF propagation update and forecasts. Solar activity at rock bottom levels, solar flux at 68 units, and there are no active sunspot regions in sight... The daily sunspot number is zero. Again ,once again an update, we are already enjoying the enhanced autumn equinox propagation conditions, reports that are reaching me from Dxers Unlimited's listeners around the world confirm that since early September , propagation conditions have taken a turn for the better , especially on the 40 , 30 and 20 meters amateur bands, and the 25, 22 and 19 meters international shortwave broadcast bands... Hope to have you all listening to the weekend edition of Dxers Unlimited that will be on the air and on the WEB next Saturday and Sunday UTC days, amigos, and don't forget to send me your comments about today's program to inforhc at enet dot cu or VIA AIR MAIL to Arnie Coro, Radio Havana Cuba, Havana , Cuba... They sure help me to make the next edition of Dxers Unlimited better for you all !!!   via Yimber Gaviria, Noticias de la Radio