Tuesday, March 30, 2010
As I mentioned previously, meeting Larry, KH6ITY on the air turned out to be a great stroke of luck for me, and the contact proved to be beneficial for both of us. Larry is a technology teacher at a high school in Texas, and when he responded to my call on the air, he was looking for a contact to speak with his class via ham radio as a demonstration. I was more than happy to do so, but what Larry told me was that while he could hear me, my audio was very distorted and I was extremely difficult to understand. Somehow, I managed to convey to him enough that he understood that I'd done some pretty extensive troubleshooting on the antenna system, so he suggested that I try to reduce the transmitter power to see if that would help. Since I'd connected the radio directly to the car battery, I figured that power wouldn't likely be the source of the problem, but given that nothing else I'd tried had worked, I figured I'd give it a shot.
I turned the power down to about 40% of the maximum and transmitted, asking Larry if my signal was any better. Before he even answered, I knew what the answer was: I was no longer hearing that odd noise in my headset, and Larry confirmed that indeed my signal had no issues. Although the signal strength was somewhat reduced, Larry was able to report that the audio artifacts were completely gone. He then asked me about what kind of radio I was using (an Icom 706 MKIIG), and when I told him that, I think that both he and I figured out the problem, both from similar past experiences. First, a little bit of background.
All electronic equipment requires a power supply that is capable of supplying a certain amount of electrical current at a voltage within a specified range. According to the manual, the 706 MKIIG draws up to 20 amps at 13.8 volts DC+/- 15%. Although the electrical system in a car is rated at 12 volts DC, it turns out that a charged car battery will provide somewhat more than 12 volts, and the battery is charged at somewhere between 13.2 to 14.4 volts. A running engine which is charging the battery should provide enough power for the radio, but what happens if the car isn't running? It turns out that in practice, there is some "give" in these numbers, but at some point, the radio doesn't function properly.
For those of you who have forgotten (or never knew), one of the most basic formulas in electricity is known as Ohm's Law. It states the relationship between voltage, current, and resistance. In order to try to keep my readers awake, I'll skip all the details and say that Ohms law explains that the length of the power cord, among other factors, affects the amount of actual power that the car battery is able to deliver to the radio. I'd used this exact same setup previously from at least two different vehicles without any issue. However, it seems that the battery in the rental car (a Mazda 5) that I had was a bit weaker than the others that I'd previously used and it just wasn't capable of delivering enough power to the radio.
The Icom 706 MkIIG is probably one of the most popular radios made in recent years. It is very portable, capable of transmitting on all the HF radio bands, (10m through 160m) and can also transmit on VHF (6m and 2m) and UHF bands (70 cm). This was the first HF radio that I ever bought, and it has served me very well for the almost 10 years that I've owned it. However, it does have one problem (perhaps common to other similar radios): When it doesn't get enough power to transmit properly, instead of simply shutting down or refusing to transmit, the transmitted audio gets distorted.
Both Larry and I had previous experiences where the radio wasn't supplied enough power and exhibited this problem. In my case, the very first time that I ever tried to operate from a car, I was parked outside a friend's vacation home in upstate New York, and figured that the accessory adapter (we called them cigarette lighters back then) looked like an easy way to hook up the radio. It turns out that the wiring for the lighter plug wasn't capable of carrying the 20amps at 13.8vdc that the radio requires to transmit at full power. My audio was distorted, and a helpful ham in Italy (I wish I'd made a note of his call) helped me to troubleshoot the problem. At the time, the solution was to simply connect the radio directly to the car battery, which did the trick.
Since I was already connected directly to the battery, the only other thing that I could do was to start the engine, hoping that the charging current provided by the car's alternator would provide enough power to the radio when transmitting at full power. I adjusted the transmitter output back to 100%, and Larry verified that my audio was still clear. Finally, I was on the air, and could start making contacts.
The antenna was mounted on a picnic table about 15 meters away, I was sitting underneath some trees, and I was able to make contact with other stations all around the world. This was what I'd planned to do.
However, Murphy still had one surprise in store for me, which didn't crop up until the next day.
The sage concludes with Part IV.
Sunday, March 28, 2010
During these tests, in addition to just hearing the odd noise in my headset, and on the radio speaker when I disconnected the headset, I was attempting to call some stations that I had been hearing all afternoon. The location that I had now moved
to was even better than my previous location, as there was water on 3 sides, which means I had an especially good path to Europe, South America, and the southwest US. Some of the stations that I'd tried to contact were extremely strong and should not have been difficult at all to contact. I was finally able to make a contact with S55OO so I knew that the radio was actually transmitting, though he was in the middle of working many other stations so I didn't have a chance to ask him for a signal report. At that point, I was confused and frustrated at not being able to locate the source of the problem, and given that it was getting late in the afternoon, I decided to break down and shut down for the evening.
After heading back home (well, not to NJ, to where we were saying), I sent an email the Buddipole Users Group to see if anyone there had any ideas what the problem might be. I got back responses from a number of folks within a few hours, most of them suggesting that I try most of the things I'd already tried (which of course they didn't know I'd done). A couple of folks suggested trying to use some ferrite beads in various places on power cable, microphone cable, and power cables. Unfortunately, I didn't have any with me, and they aren't the kind of thing that are stocked in a local hardware store or even Radio Shack. Budd, W3FF, and Scott, NE1RD pointed out that since I'd made one contact that the radio must be transmitting, but it did seem that there was still some problem.
The Old Salty Dog on nearby Siesta Key. I was still frustrated that I hadn't figured out what the problem was, but things always seem better after a beer and a fried Grouper sandwich. They probably would have seemed even better after two or three beers, but since I still had to drive back to the operating site I decided to stop after one.
When I arrived at South Lido Park, I found an even better location than on the previous day, where the operating position was under trees for shade and I was able to set up the antenna on a different table from the operating position, putting even more distance between the antenna, the radio, and the car. I made sure to have the RF choke in place as close as possible to the feedpoint, and wound up as much of the excess feedline into that choke to try to eliminate as much of the unwanted RF on the outside of the feedline as possible.
I was still hearing what I thought was RF in my headset (or from the radio speaker when I switched to the hand microphone), but I decided to call CQ anyway, hoping that perhaps someone would be able to hear me and perhaps let me know what my on-air signal sounded like. I finally got an answer back from Larry, KH6ITY who, as it turns out, was a technology teacher in Texas and was in the middle of demonstrating ham radio to his class. As it turned out, meeting Larry on the air was a wonderful stroke of luck.
Click here for Part III.
Friday, March 26, 2010
My plan was to head out to the parking lot of Lido Beach and set up there, as I've done in the past.This location is very easy to get to, and the parking lot has never been full when I've been there, so I can take up as much space as I need. For this portable operation, instead of using hamsticks (which are very straightforward to use but since they are nearly 2 meters long, are hard to ship), I decided to use my Buddistick vertical antenna. I've written about the Buddistick quite a bit here before, you can do a search from the search box on the right of the blog home page for "buddistick" to see all the references. Because Sharon and I didn't want to have to check baggage, I shipped the radio (my trusty Icom 706MkIIG), feedline, power cables, and Buddistick down to a relative a couple of days before we left NJ.
I set up the radio and initially mounted the antenna on the rear of the rental car, a Mazda 5, which seemed to be a good way to get it up fairly high and also allowed me to toss the counterpoise wire over a low tree branch. (It's a bit difficult to see, but you can view the counterpose wire just above the bottom of the picture, it's the very thin wire.) I set up the antenna, configured it for 20m, and checked it with the antenna analyzer, where I found that I had excellent SWR at my intended operating frequency of 14.260Mhz (one of the standard IOTA frequencies). I connected the antenna to the feedline, and used the built-in SWR testing in the radio to ensure that the SWR was still good (it was), found that my intended frequency was unoccupied, and started to call CQ. That's when I discovered that I had a pretty serious problem.
The problem was that when I keyed the radio and called CQ, I could hear a lot of what sounded like RF feedback in the headset. My assumption was that for some reason, the transmitted signal from the transmitted signal from the radio was being fed back into the radio, and causing the noise that I was hearing in my headset. As it turned out, I was wrong about the source of the problem, but I didn't find that out for another 24 hours. Working on that initial assumption, I tried to move the antenna to a slightly different location on the car, and even tried to use the very small Buddistick tripod to place the antenna on the ground much farther away from the car, but had no success. (By the way, that's a wonderful little tripod, but it's really not designed to work on a concrete parking lot surface where you can neither dig the legs in nor secure it to anything. All it took was a tiny breeze to knock over the antenna. Fortunately, no damage was done to the whip antenna, but I'll be a bit more careful about trying that again.)
At that point, I had to take a break from troubleshooting to join a conference call at work. (Yes, even though I was on vacation.) After the call and a follow-up call, about 90 minutes had passed. I tried a few more attempts to play with the radial height, move the location of the radio, and to create an RF choke by coiling some feedline at the feedpoint of the antenna, but was still having no success. I decided to try to find another operating location, hoping to find a park where I could mount the antenna on a picnic table much farther away from the radio, hoping that any RF problems coming from the antenna would be significantly reduced by the distance. I looked at the GPS I'd brought with me and it appear to show a park farther south on the island, so I put all the gear in the car, and headed south.
The saga continues in Part II.
Thursday, March 18, 2010
Most likely I'll only be on SSB for this short trip, and I'll stay close to the standard IOTA frequencies, primarily on 20m (14.260) and 15m (21.260), though I may move around if the bands cooperate.
If anyone is in the area (Sarasota, FL) and wants to get together during one of those afternoons, please drop me line.
Saturday, March 13, 2010
To support this bill, the ARRL says:
What S 1755 Does
If enacted into law, S 1755 - the Amateur Radio Emergency Communications Enhancement Act of 2009 - would instruct the Secretary of Homeland Security to undertake a study, and report its findings to Congress within 180 days, on the uses and capabilities of Amateur Radio communications in emergencies and disaster relief.
The study shall:
- Include recommendations for enhancements in the voluntary deployment of Amateur Radio licensees in disaster and emergency communications and disaster relief efforts;
- Include recommendations for improved integration of Amateur Radio operators in planning and in furtherance of the Department of Homeland Security initiatives;
- Identify unreasonable or unnecessary impediments to enhanced Amateur Radio communications, such as the effects of private land use regulations on residential antenna installations, and make recommendations regarding such impediments;
- Include an evaluation of section 207 of the Telecommunications Act of 1996 (Public Law 104-104, 110 Stat. 56 (1996)); and
- Recommend whether section 207 should be modified to prevent unreasonable private land use restrictions that impair the ability of amateurs to conduct, or prepare to conduct, emergency communications by means of effective outdoor antennas and support structures at reasonable heights and dimensions for the purpose, in residential areas.
Please contact Committee Chairman Henry Waxman (D-CA-30) and Ranking Member Joe Barton (R-TX-6), urging them to send this bipartisan bill to the House floor for adoption. A sample letter can be found here. Send your letters urging consideration of S 1755 by the House Committee on Energy and Commerce to Rep Waxman via fax at 202-225-2525, and to Rep Barton via fax at 202-225-1919. Also, please fax a copy of your letters to the ARRL's Washington representative, Chwat & Co at 703-684-7594.If you're like many of us and have free dialing to anywhere in the US and have a fax machine, this is a very easy and very inexpensive way to support amateur radio. Make sure that you sign the letter (which proves that this isn't just some kind of automated system sending it) and if you can, customize the letter or, better still, hand-write a letter which will draw even more attention. If you aren't able to edit the letter from the link, please post a comment to my blog and I can convert it to pretty much any format that you need.
Thanks for helping.
(Apologies to those of you outside the US for this US-specific posting).
Monday, March 01, 2010
Today is the 10th anniversary of me getting my first ham radio license, which was officially issued by the FCC on March 1, 2000. My original callsign as issued was KC2FZT, though I changed to the current vanity callsign (K2DBK) later that year, just before I upgraded to my General license. At the time I was licensed, I had to take both the old Novice and Technician written tests to receive a Technician class license. (Major license restructuring occurred on April 15, 2000, when they reduced the number of license classes from 6 to 3 (Technician, General, and Amateur Extra). I didn't take a Morse code test at the time (which would have given me "Technician Plus" privileges), but I did take a 5wpm test later that year as part of the General Exam. And no, I didn't have to go to the FCC office in New York City as used to be the process, I took my exams in Joyce, KA2ANF's basement from a dedicated group of Volunteer Examiners.
I first got interested in getting onto the HF bands after participating in Field Day that year. Alan, KG2MV, helped me work the 15m phone tent (and yes, the bands were a whole lot better then, so we were pretty busy) and I got hooked. In addition to friends in my radio club (the 10-70 Repeater Association), I also had a lot of encouragement from a co-worker Jim, WK8G, and of course from my good friend Larry, N4VA, who continues to encourage me today.
Reflecting back on 10 years as a ham, there are a number of things that I've come to realize are why I so enjoy the hobby. There is always something new to try, be it a new digital mode, a new contest, or operating from a new location, although you can always go back on something you already know well and with which you are comfortable. The hobby is there when I'm ready for it; I don't have to depend on good weather or some particular location. And of course, there are good friends and good times for those of us drawn together by a common avocation.