Wednesday, July 29, 2009
Wednesday, July 22, 2009
Welcome to Handiham World!
We are back again after a vacation week. Our family spent a week on the North Shore of Lake Superior, and I found out some interesting things about operating from the hotel via the Internet. As you might expect, one typically operates a notebook computer at such a location via a wireless connection to the hotel's wireless router. This particular hotel, which was really more like rental condominiums, had an unsecured wireless router. This may seem unusual, but we were so far north "in the sticks" that I imagine security concerns don't crop up all that much. One advantage for the hotel is that there are fewer tech support calls from guests having trouble logging on to the system. So far, so good. It was easy to connect to the hotel Internet system, and there were no annoying login screens like the ones typically encountered at major hotel chains. Sometimes security software and firewalls get in the way of ham radio operation via the Internet, so a test of the system is always in order. Most of us who have operated EchoLink are familiar with firewall issues, and when I am traveling I assume that I am going to have to operate EchoLink through a proxy in order to bypass firewalls at hotels and coffee shops. Of course you can always run a simple test with EchoLink in the normal (non-proxy) mode to see what happens. You should see a station list, and if you are often dealing with firewall issues like me, you probably have the EchoLink test server already bookmarked in your favorites. You need to try a test connection to the EchoLink test server. If it fails, the next step is to select a proxy from the public proxy list and try the test server again. If it works, you are good to go!
The interesting thing that I encountered -- something I had never seen before -- was that the connection through a proxy was successfully made and allowed perfectly normal reception. The oddity came when I transmitted and got reports that everything I said was vastly speeded up, although the pitch of my voice was not changed. "Dead air" punctuated the speeded up speech. This was most interesting; it was certainly nothing I had ever experienced before in using EchoLink. It certainly wasn't caused by the proxy, which is my own WA0TDA proxy running on a high-speed Internet connection. It wasn't the Dell netbook computer, which I had used many times for successful EchoLink QSO's. It pretty much had to be the hotel wireless system, which was delaying packets and then dumping them out all at once. Still, it seemed odd that this only happened on transmit and audio was perfectly normal while receiving. One would certainly think that the phenomenon would be the same in both directions. I would be interested in hearing from any of our readers and listeners who can shed some light on this strange EchoLink behavior.
That EchoLink problem prevented me from getting on the handiham net, but I still had the handiham remote base software installed on the Dell along with Skype, so I decided to check into PICONET, a daily HF net on 3.925 MHz. Interestingly enough, the rig control software behaved perfectly normally and I was able to easily control the Kenwood TS-480 transceiver at Courage North. Skype transported the audio as expected, delivering both excellent reception and good reports on transmission. Clearly Skype and EchoLink are very different applications and route audio packets differently over the Internet. Although it is possible to operate a remote base station using EchoLink, this only served to confirm that we made the correct decision to choose Skype as the audio transport system for the handiham remote base instead of EchoLink. Skype is much more likely to work the first time without a need to worry about firewalls, proxies, port forwarding, and all the rest.
Now, as we get closer to the release date of Windows 7, we need to continue testing to determine how the handiham remote base software and EchoLink will work in this new operating system that will ultimately replace Windows XP and Windows Vista. If anyone has experience with testing using the Windows 7 beta or the current Windows 7 release candidate, let me know so that we can compare notes. We want to make sure that the handiham remote base is reliable and accessible for all users, whether they are operating from a hotel room or from their home Internet connection.
Photo: Lightning destroyed this fiberglass antenna at Handiham headquarters several years ago. The antenna literally blew apart, but gas-discharge arrestors protected the station equipment.
Before we move on to Avery's QTH, I want to remind you that it is thunderstorm season in much of the northern hemisphere. Yesterday afternoon I went out for a walk, my typical 2 mile trek through the local park. When I left the house, I stepped into bright sunshine. Halfway through the walk, cumulus clouds had grown quickly, getting darker and larger, and thunder was evident. When conditions are right, thunderstorms can sprout quickly as the strong sunlight causes air to warm and rise. And there I was, a mile from home with no umbrella, and no protection from lightning, wind, or hail!
Well, I hoofed it back home as quickly as I could, with the thunder getting louder and the sky getting even darker. I wasn't all that worried about getting wet, but lightning scares me, and I knew that I needed to be under shelter as soon as possible. Besides, all of my station's antennas were still connected, putting my radios at risk.
As it happened, I made it home without getting rained on, the station was unscathed, and the storm moved off. Later that evening, I heard on the news that a 14 year old girl in a nearby city, only about 12 miles away, had been struck by lightning and killed. She had been playing outside in the rain when the tree she was under was struck.
Lightning is unpredictable, and it is more dangerous than the wind and rain. Lightning has been known to strike 10 to 15 miles from the storm cloud! I was lucky this time, but it does serve as a reminder to check the weather radar before going outdoors for an extended period during these unsettled summer weather conditions. This wouldn't be a bad time to check your ham shack's grounding and lightning protection systems, too! Remember, summer is the time when the day can dawn bright and clear, but thunderstorms can pop up suddenly, drawing massive energy from the hot sun. Disconnect those antennas unless you are actually using your station, just to be on the safe side.
Wednesday, July 08, 2009
Welcome to Handiham World!
Did you miss us last week? Well, after all, it is summertime here in Minnesota and we have to take a few days off to enjoy the fine weather. Next week will also be a "vacation week" for your weekly e-letter and audio lectures, but this week it's business as usual. In case you suspect that we are inordinately lazy in the summer, I think I should point out in our defense that this is typically the slowest time of year in the office, so it is the best time for staff to enjoy some time off without affecting our service to members all that much. Other organizations, including our friends at TIPSNET, take a summer break, as do many radio clubs. Once ARRL Field Day is over, the pace of ham radio slows considerably.
Not, mind you, that there are not things to do on the bands and around the ham shack!
I've been slowly collecting the materials for a new 160 meter wire antenna. This will be a random-wire job, and I'm going to tune it right at the feedpoint with an LDG autotuner. I've always wanted to try this kind of antenna arrangement, and the little LDG tuner is just the ticket. A random-wire antenna is really just an end-fed wire of more or less whatever length fits in a given space, and I have a nice, deep back yard, so there is no problem at all running the wire out at least 125 feet. If I cared to put a bend in it, I could easily make it 200. The problem with 160 meters, and the reason so few hams actually use that band, is that the antennas needed to operate on a frequency like 1.9 MHz are very long and thus very difficult to fit into a typical urban property. Let's take a moment to calculate the length of a half-wave dipole at 1.9 MHz, shall we?
Start with the formula: 468 divided by the frequency in MHz = the length of a half-wave in feet.
468 divided by 1.9 = 246.3 feet. That's a long dipole antenna! In fact, many operators barely have space for a 40 meter dipole that requires only about 65 feet. A vertical antenna might be a consideration, but for 160 meters, it could easily top 120 feet for a quarter-wave. I think folks in my neighborhood might notice something that tall in the back yard!
So consider the beauty of the end-fed Marconi wire. Like the vertical antenna, it is fed at the base, with the antenna's radiator near the ground and a counterpoise of radials or other conducting material serving to cut current losses in the ground near the feedpoint. The wire radiator goes up for whatever distance is practical, near the roofline of my house in this case, and then the wire continues out into the long back yard to make up the rest of the required length. If I use an antenna tuner right near the feedpoint, the tuner can decide if the radiating length is too long, in which case it will add a bit of capacitance to electrically shorten the antenna, and if the radiating length is too short for a given frequency, the tuner will add a bit of inductance to electrically lengthen the wire. I love letting an antenna tuner do the work - it's so much easier and more practical than cutting the antenna wire to exactly the right length, which is always time-consuming and problematic. If you cut off too much wire, the antenna tunes too high in frequency, and then you are stuck. There is an old joke about "reaching into your toolkit and pulling out the wire-stretcher", but that mythical tool has never been in any toolkit I've ever owned.
A Marconi antenna works best with an extensive radial system, but I'm not going to worry too much about that. I'll use the house's copper water pipe system, which is also near the antenna's feed point, as well as a galvanized metal window well that is conveniently located at the basement egress window near the feedpoint. I figure I can always add a radial or two if that isn't enough. Even shorter radials will act to reduce ground losses near the feedpoint, which is where most of the current flows anyway.
The 160 meter band is more useful than you might think. Even during a sunspot minimum, 160 meters remains reliably "open" during evening and nighttime hours. Although it can be difficult to use in the summer thunderstorm season when static levels rise, the 160 meter band always has some nighttime activity. My local radio club hosts an evening net on or around 1.9 MHz at 20:00 United States Central Time. You can find the SARA net nightly except Tuesday & Thursday. SARA, the Stillwater Amateur Radio Association, is a Handiham affiliate.
My goal is to get my wire antenna up & running before winter - antenna work is one ham radio activity that is best done in the summertime! For anyone out there looking for "bonus points", convert the length of an end-fed wire 1/4-wave at 1.9 MHz to meters.