Radio Habana Cuba: Dxers Unlimited mid-week edition for October 17, 2000
By Arnie Coro, radio amateur CO2KK
HI amigos, hello from Havana. YES, HF propagation conditions are really nice, just as Dxers Unlimited's weekend edition had told you!!! Solar and ionospheric parameters have combined nicely to offer us some really interesting opportunities to work DX... A few examples will follow in a few minutes.
Item two: Mobile ham radio, yet another one of the more than 50 ways of enjoying the hobby, and for some, 10 meter band mobile operation gives the unique opportunity of working DX too.
Item three: Arnie Coro's broadband 10 to 30 megaHertz Spider Web dipole antenna, the one I use most of the time on the 20, 17, 15, 12 and 10 meter bands will be, once again, at the request of many listeners described here in detail... All this and maybe enough airtime for QSL on the air, and a short visit to my workbench will complete the menu of today's Dxers Unlimited. Margarita Delgado is my sound engineer and producer, the programs audio bandwidth is intentionally restricted to 3.4 kiloHertz in order to provide better reception....Stay tuned, I'll be back in just a few seconds.
This is Radio Havana Cuba, the name of the show is Dxers Unlimited, and if you have any radio hobby related questions just send them via Internet e-mail to arnie@radiohc.org, or via Air Mail to Arnie Coro, Radio Havana Cuba, Havana, Cuba....
Here is item two in detail, enjoying amateur mobile radio: Now that the 10 meter ham band is open for many hours every day, I make a point of answering calls coming from mobile hams. Here is the result of a very simple survey I did during the past 5 days: the typical 10 meter mobile is running always 100 watts or less, with about 75 percent of the mobile stations running 25 watts to the very popular ex Citizen Band radios... The typical antenna system is a quarter-wave magnetic mount antenna, and some stations deliver an excellent signal when using even shorter antennas, which are just about one meter -- that's about 3.2 feet long. These helically loaded, 10 meter band antennas are very efficient, and when the band is open the minus one or minus 2 dB losses that they exhibit are really not significant at all.
For many of the amateur operators running mobile 10 meter rigs, the excellent band openings are a blessing, as they are able to work stations halfway around the world right from the driver's seat. Some hams who cannot operate from their homes due to antenna installation restrictions keep active by using the mobile stations during the morning drive in, or the late afternoon return trip to their homes, if they have to commute. The fact is that others go out during the weekends, find a nice clear spot near the ocean, in a park or even in an empty parking lot, and play with their radios, having a nice time... This past week I talked to a ham in Virginia; he is a very busy medical doctor, a physician, but Tony finds time to go out to the shore of the Chesapeake bay, park his car and work some DX during the weekends. By the way, he told me that there is a very definite improvement both in reception and transmission when he drives his car right to the very edge of the shoreline, something to be expected due to the very high conductivity of salt water.
Some mobile hams have two radios installed, one for the popular short range 2 meters and 70 centimeter bands, to work via repeaters, and another radio for HF, which for many is a low cost single band 10 meter radio, because many amateurs are afraid of losing a very expensive multi-band transceiver to burglars... Anyway, if you have never tried 10 meter band mobiling, give it a try; the newer low cost single band 10 meter radios are easy to install, provide about 25 watts power output and are small enough to be easily removed from the car, if you do wish to keep them away from possible theft.... Antennas for 10 meters mobiling include the ever-popular 2.5 meters (or about 8 feet) long whip, which some hams consider just too big, so many nowadays prefer to use shorter versions which are equipped with a magnetic mount, so you can install and remove them withouy msking holes in the car's body. Arnie Coro's extended range forecast calls for a nice 10 meter DX season extending all the way from NOW till the end of April of next year, so many of you will have the chance to even work DXCC, the 100 DX countries award, while operating mobile on 10 meters from NOW until the end of April....
QSL's, yes we QSL here one hundred percent, that's part of short wave radio,right? So, if you are just starting in this wonderful hobby, send for your Radio Havana Cuba QSL card and verification letter, include a simple signal report and some comments about the programming and send via AIR MAIL to Arnie Coro, Radio Havana Cuba, Havana Cuba...
Now item three... at the request of many radio amateurs whom I have contacted recently on both the 15 and 10 meter bands, here is a detailed explanation of Arnie Coro's 10 to 30 megaHertz broadband spider web dipole antenna which, by the way, seems to work on 6 meters too. Essentially the antenna is just a dipole that, instead of having a single wire on each leg, has 5 wires on each leg. The wires are 6 meters long each, and they fan out away from the center insulator, forming a web like structure. Each of the wires is terminated by two egg insulators, and then a dacron line ties to the mast. The 5 wires are separated in such a way that they are tied to the supporting mast, forming a triangle of which two sides are 6 meters long and the other side is 3 meters long.... If you draw the antenna you will realize why it is so broadbanded, as the effective area of the dipole's legs is very large.
I feed the antenna either with open wire line, windowed 450 ohm line, or using two 75 ohm coaxial cables as a balanced shielded 150 ohm line. The transmission line is taken to a 4-to-1 balun, and from there a single 75 coaxial run goes to the station's antenna tuner.... The antenna spans between two masts, which are about 15 meters or some 50 feet from each other, and the lowest wire should be at least 3 meters or 10 feet from the ground. This is a broadband 5-wire-per-leg fan dipole, and with the 6 meter long legs, the antenna tunes very nicely from 10 megaHertz all the way up to the top of the 10 meter band -- that is almost 30 megaHertz. This is a very easy-to-build-yourself antenna, requires no special materials, and you can make it using no.14 copper wire which, by the way, is the smallest diameter allowed by the Electrical Code for external antennas that comply with it. You can obtain no.14 bare copper wire from an electrician's supply store, or you can just remove the insulation from no.14 PVC insulated wire used for household installations, something that will require a very sharp knife and a lot of patience!!!
I have built several of these antennas, and in some cases I have used PVC pipe insulators with excellent results, both for the center insulator and for the 20 insulators required for the ends of the wires. As you may realize, using two insulators at the end of each wire is only required when you are going to run more than 100 watts of RF power to the antenna, so for reception and for low power, 100 watts or below operation, you will only need 10 insulators for the Broadband 10 to 30 megaHertz Arnie's SPIDER WEB antenna!!! Any doubts, any questions, just send me an e-mail, to arnie@radiohc.org, and I will be very happy to send you an illustration of this nice antenna which, by the way, makes an excellent receiving antenna for short wave listening from the 31 meter band all the way up to the 11 meters international short wave broadcast band, and it is still useable on the 41 and 49 meter bands, too... If you do not have e-mail capability, just send a postcard to Arnie Coro, Radio Havana Cuba, Havana, Cuba, and I will be glad to send you a hard copy of the illustration and a printed file with the detailed information on how to build this nice, low-cost broadband antenna for both reception and transmission....
Sorry, but no time today for the workbench or QSL on the air, but I cannot end the show without telling the many hams that I have worked on 10 meters during the past three or four days how enjoyable those two-way QSO's with Dxers Unlimited's listeners are. Si amigos, yes my friends, it is certainly nice to hear your voices telling me how much you like the show, and giving such wonderful advice on how to improve it!!!
And now, as always at the end of the show, here is Arnie Coro's HF plus 6 meters propagation update and forecast. Solar activity should continue to move UP; we may see more flares, and their associated geomagnetic disturbances during the next few days. If big solar active region number 9169 returns in good shape, it will receive a new number, and we may see some big solar fireworks coming from it, too.... Expect very early morning high maximum useable frequencies; 6 meter openings will coincide with periods of high geomagnetic activity, especially when the K index is at 3 or higher. The 10 meter band will be open during the daylight hours from early sunrise, and will continue to be open even after sunset. Both the 15 and 17 meter bands are going to be in excellent shape for DX once the MUF goes down to about 22 megaHertz.
Look for me on 10 meters, I try to stay at or very near to 28.500 kiloHertz when the band is open, right where many of you have found me during the past few days... Try listening to Radio Havana Cuba's SSB broadcasts on 11705 kiloHertz and send me a signal report to arnie@radiohc.org, or via Air Mail, a postcard will do, to Arnie Coro, Radio Havana Cuba, Havana Cuba.
Arnie Coro CO2KK
Havana, Cuba
October 17, 2000Postal address:
Arnie Coro, "Dxers Unlimited"
Radio Havana Cuba, Havana, CUBA
e-mail: arnie@radiohc.org
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