On the Web : September 2006

If you enjoy reading 'On the Web', your ham radio club can publish this column on an exchange basis with SJRA. Contact Ted, , for the exchange details.		Our contributions to the South Jersey Radio Association club bulletin "Harmonics" includes lengthy Web addresses. As the URL's can be difficult or a nuisance to type into your Web browser, the postings here should make it easier to get to the Web sites SJRA members are interested in. Look for the posting at w2xq.com at the time "Harmonics" is scheduled for delivery in the south Jersey area. Questions, suggestions or contributions are always welcome.
		Solar X-rays  Geomagnetic Field  N 3 K L

Greetings. Summer is gone, fall is upon us, and soon the cold weather — suitable for putting up antennas — will be upon us.

The ARRL offers an interesting service of mapping FCC amateur radio licensees to a map. A ZIP code query pulls a list of hams by call from the FCC databases and sends it to Yahoo! Maps to generate a interactive map. The Web address is www.arrl.org/fcc/hamszip.html?zip which is easy to use. Just enter a 5-digit ZIP code click on the "get" button. My apologies to Charlie Belavitz, WA2ONH, Jackson, for not acknowledging his e-mail tip sent earlier this year (I flagged the e-mail, but overlooked the flag in the ton of e-mail that drifts into our mailbox each day.) I tried this on my own 08088 ZIP, and the map omits me. (Because my writings published around the world, all mail goes to a post office box. And yes, I checked the expiration on W2XQ -- 2014.) Perhaps the omission is by design, to cast out meaningless map data, but one could argue the data set is flawed by not listing the entire ham population in a ZIP code area. Nevertheless, this is a neat trick to see who is close to you, splattering keyclicks up and down the band.

N4MC's Vanity HQ is an interesting ham radio Web site. Michael Carroll seemingly has all the information one would need to search out a vanity call sign of your choosing. There is an article offering guidance on the choice of a call, information on pending applications (345 in mid-July), and a listing of recent grants. An interesting statistic is updated regularly: of the almost 724 thousand licensees, about 90 percent have call signs representing their home QTH district and about 9 percent are vanity calls. There is a graphic map display to find hams in a ZIP code. And there is an e-mail scrambler: enter an e-mail address and the wheels spin to produce a "mail to" address that cannot be read by spam engines. Neat stuff at www.vanityhq.com. Have a look.

According to Dean Gibson, "An amateur's legal operating authority in the USA comes from the data in the FCC's ULS database (see FCC rules, Part 97.5(a) & 97.7(a)), and not from the paper license that the FCC prints and mails, which is just a legal notification of that data (although the paper license may be required by foreign governments if you travel outside the USA). In fact, the FCC provides a web page for printing a "reference" copy of any FCC license." Would you like a copy of your FCC license to frame that is better looking than the one provided by the FCC's ULS? Take a look at the colorful hi-res alternative designed by AE7Q: www.ae7q.net/Generate.html. And AE7Q, like N4MC, has an extensive vanity call database sliced into different perspectives. Have a look around the rest of the Web site.

Band Openings, Interference on VHF and UHF

During the morning commute to work, I often hear comments such as "there is another repeater on the frequency" or "someone is interfering with your transmission." What's going here? The answer may be simply be enhanced long distance reception due to tropospheric ducting. Areas have "the necessary atmospheric conditions to produce tropospheric bending of VHF, UHF and/or microwave radio waves. Tropospheric bending extends the range of radio & TV stations well beyond their normal limit and thus increases interference amongst stations as well." According to William Hepburn, tropo occurs when a temperature inversion (warmer air over cooler air) exists. Hepburn says an important factor is water vapor (humidity), and a warm dry air mass on top of a cooler humid air mass produces the best conditions; tropo is rare in mountains or in dry regions (deserts) of the world. Classification of tropo as enhancement or ducting is a rule of thumb: temperature inversions below 1500 feet (450m) are the former, and above 1500 feet are the latter. The layer of the troposphere below 1500 feet is called the "boundary layer" in meteorology.

There is a very interesting Web site that explains all of this in detail, and provides forecast maps for the next five days. A week's worth of historical maps are also available. Look at Tropospheric Ducting Forecasts at www.dxinfocentre.com/tropo.html and be prepared to spend some time reading all this information. And the top page also provides a link to Current Conditions: VHF Propagation at www.mountainlake.k12.mn.us/ham/aprs. These pages by Peter Loveall AE5PL make extensive use of current data from the APRS-IS (Automatic Packet Reporting System-Internet Service. Again, a very interesting read and useful no matter where in the world you're located.

Quickies

Dick Tyler, WA2EHL, has a repeater on 447.675 MHz (-5) (PL 103.5) in Burlington, NJ. There is an initial key-up delay of at least one second to access it. The repeater is local in coverage due to antenna height and some hilly terrain. You will probably need an outside antenna at points east of Mount Holly or south in the Medford and Mount Laurel areas. Dick advises that he runs the radio show Amateur Radio Newsline on Sunday mornings at 10 a.m. Eastern, and adds local area ham news. I think it is the only Burlington County repeater to carry ARN. More details are on wa2ehl.com and you can check the newly redesigned Web site for updates.

Most Internet users have found NASA's Astronomy Picture of the Day — apod.nasa.gov — but there is another "picture of the day" site at Space.com. If you grew up with Star Trek and like to wander around the universe, add Image of the Day — www.space.com/imageoftheday — to your travels. Look in the archive for 26 May 2006 for a spectacular picture of the plume of smoke out of the Cleveland volcano, in Alaska. The eruption lasted two hours before the smoke separated from the volcano, and that was long enough for the ISS (International Space Station) to make a pass overhead. By the way, before you leave NASA's site, check out 14 November 2002 for the sharpest view ever of the Sun; it is a spectacular look into a huge sunspot.

Do you design electrical circuits for your hobby or work? Would an electrical filter design and analysis program, highpass and lowpass circuits, or a helical-resonator filter circuit be helpful? Or a diplexing or PI-L network? How about a class E RF amplifier? Jim Tonne of Tonne Software has all this "stuff" on his Web site, and more. Do you listen to distant North American broadcast stations? Toone has a program to map antenna patterns of AM radio stations on a specified frequency. Looking for custom polar and rectangular projection maps of the world? Contact your probe to tonnesoftware.com and have a look. Yes, some of the programs cost a bit of money, but if your time is valuable... enuf said.

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Revised 12 September 2006

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