Posts Tagged ‘NA-034’
Originally, my wife Sharon and I were going to spend the full day “playing tourist” together on our last day of the trip, and I hadn’t planned on doing any additional radio operations. However, things changed and since Sharon had plans with her Mom, I decided to head back to South Lido Beach for one more day of operating. I got a much earlier start than the previous days, and set up in the same place that I did before, operating from inside the car. I was on the air at just around noon local time, but I got off to a very slow start, with only three contacts in that first half-hour. However, thanks to the magic of the packet cluster network, once I got spotted (initially by N8ZI, thanks!) things got a lot busier, and with more spots there were a lot more stations calling, who in turn spotted me again which brought another wave of stations calling. For that afternoon, ignoring the initial “slow start”, I wound working a station about every 2 minutes over the next 2 1/2 hours. Considering that in a few cases (one of which I’ll mention specifically) I stopped and chatted for several minutes, I was extremely pleased with that rate.
Unlike the previous days, the final day of operation went very smoothly, with no hitches at all. I operated entirely on 15m, and aside from some fairly deep QSB (fading) that was problematic from time to time, propagation seemed to be very good into central Europe as well as both the northeast and western United States.
One of the more memorable contacts I made was with Budd, W3FF. Budd is the “Budd” in Buddipole, and while we’ve emailed back and forth on several occasions, this was the first time we’d ever had a contact on the radio. When he first called me I had some trouble hearing him due to the previously mentioned QSB. He’d tried to work me on the previous day while “pedestrian portable” (that’s walking around with an HF radio and antenna), but I wasn’t able to hear him. For this contact, he was working from his home station, and he had to turn on his amplifier so that I could hear him more clearly. It was fun getting to speak to Budd, and after a while we finished and I went on to work more stations.
After returning home, a little quick analysis of my log showed the I made 119 contacts with 116 different stations (I worked 3 stations twice each) located in 24 different countries. As of the time that I’m writing this, I had 33 of those contacts confirmed via Logbook of The World and another dozen who send me QSL cards directly through the mail, including 3 DX stations. (I won’t see any bureau cards for at least another 6 to 12 months). With the help of my son Brett who did the design work, I was able to print out the cards needed to confirm those contacts, making sure to include both the IOTA number and island name as part of the card. (This is a requirement of the IOTA programme and and I wanted to ensure that the folks who got a card for me were able to use it for confirmation of their contact with NA-034.)
All in all, I had a great time operating, and I look forward to doing it again.
Here’s the list of countries that I contacted:
|DL||Federal Republic of Germany|
|K||United States of America|
This is part 2 of this series. You might want to read Part 1 first if you haven’t already done so.
When I woke up for the second day of my operation, for some reason I had a feeling that I hadn’t remembered to pack up all my equipment the day before. I was sure that I had the radio, the antenna, and the mast, but I didn’t remember actually packing the tent stakes and guy lines. I was hoping that I’d forgotten and done that anyway, but I headed to the car to check the equipment, and found that I had indeed forgotten those small but important items. I did have some spare line with me, so the only thing I’d need to do is to figure out how to anchor that line, possibly with some rocks. I decided that I’d head to where I’d set up and figure out if maybe the missing items were still there. If not, I’d try to find a local store that sold what I needed.
When I arrived at the location where I’d set up the day before, I discovered the good news and the bad news: The good news was that the line and carabiners were lying on the ground. The bad news was that the bright-yellow tents stakes were gone. I took the line and carabiners and decided to have lunch while I mulled my options.
As I’ve done in the past, I headed to my favorite place for lunch, The Old Salty Dog, located just a few minutes away. As I was waiting for my blackened Grouper “Firecracker Wrap”, I used my iPhone to try to find a place that sold camping supplies. There was nothing at all nearby, with the closest place, a Wal-Mart, being over 10 miles away. I live in northern New Jersey and I’m used to traffic, but Sarasota County in the middle of the day during tourist season is awful. I figured that the amount of time that it would have taken to get the stakes and back just wasn’t worth the effort, so I tried to figure out an alternative. Thinking about how I’d set up on the first day, out in the direct sunlight, I realized that ideally I’d be able to set up where I could get a little shade. There was a section of the park where I’d set up on the previous trips that was shaded, but with the park being much busier than in the past, I couldn’t use that location. I then figured out that I could use a couple of bungee cords that I had with me to lash the mast to a fence that bordered the parking lot. I found a suitable location in the lot, with the only drawback being that there was no shade and no place to sit. (This second location is marked in green on the map in my first post of this series.)
Although not as nice as sitting outside, I figured that I could set up the radio and logging computer inside the car, and with the doors open to help get a little air circulating through the car, it was pretty warm, but tolerable. To stay out of the sun, I wound up sitting in the back seat which also let me stretch out a bit. There was room for the radio on the console between the front seats, and by setting up the iPad (used for logging) and the keyboard carefully, I was able to log relatively easily while operating.
With the logistics out of the way, I decided to concentrate on 15m since the propagation seemed to be cooperating and the antenna was tuning up nicely on that band. Things started off fairly slowly, but after about an hour of operating I got spotted on the packet cluster by a few stations in Europe, and that brought in a lot more callers. Most of the time, the stations were far enough in between that I had a chance to chat a little bit with folks, but occasionally, usually after getting spotted, I’d have 3 or 4 stations call in at once. While hardly a pileup by most standards, I really enjoy working hard to pull individual callsigns out to work the stations. What was particularly enjoyable for me was being able to help out stations who needed NA-034 either for an “all-time” new IOTA entity, or to increase their scores for the IOTA Marathon event sponsored by Radio Society of Great Britain.
Unfortunately, because of the time spent trying to figure out how to set things up, (and of course the all-important lunch), I only wound up being on the air for about 90 minutes that day. I made about 35 contacts during that time, so for a lightweight, low-power operation I was very happy.
I’m back from my short trip to Florida where I operated from Lido Key, located just to the west of Sarasota, in west central Florida. I was very pleased with the operation this time, despite a minor glitch after the first day (which I’ll talk about later). I wound up operating from the same general area that I did on my last trip, which is from South Lido Park at the very southern tip of Lido Key. As with each trip, I learned things that I hope will help make things better for the next time, but fortunately, unlike my last trip, I didn’t run into any significant issues that had a major impact on my ability to operate. (If you’re interested, you can read the whole saga of my last trip starting with this post; there are links to the rest of the series at the end of that one.)
View K2DBK @ South Lido Park in a larger map
As with past operations from NA-034, my radio activities took place in the afternoon which allowed me time to spend some time with my wife’s family in the mornings and evenings as well as giving me some time to have lunch at my favorite restaurant in the area, The Old Salty Dog, before setting up for the afternoon.
As I mentioned during my preparations a few weeks ago, the idea was to operate using the Buddipole on top of the 8-foot shock-corded mast, using some tent stakes, line, and some small S carabiners to guy the mast. As long as the wind wasn’t too strong, I felt that the setup should work just fine, and it did. The setup here was very similar to what I’d done in the past, but I wound up having to drag the picnic table over to where it was close enough to the car so that I could run the power cables to the battery. On the first day, I wound up having a very late breakfast so I decided to skip lunch and headed right for South Lido Park. The first difference from previous years was that although it was almost the exact same days as previously, this year, there were a lot more people in the park, which meant it was a lot harder to get to my “favorite” operating position. On the map here, I’ve put a red marker on the spot, which is just off the south end of the parking lot.
There was a reason why there were more people this year: It was quite a bit warmer than in the past. In fact, the weather was absolutely beautiful, with temperatures in the mid-80s under a beautiful blue sky with just a few clouds on the horizon.That warm weather led to my first small problem: As with my trip to Costa Rica, I was using my iPad with the Hamlog logging software to log my contacts. (Just a quick side note about Hamlog, Nick, N3WG, has done some great upgrades to recently, including the ability to save your log to a cloud server. Very slick stuff.) The one big difference is that when in Costa Rica, even when it wasn’t raining, I was usually operating in the shade, not in direct sunlight. When operating from the table you see in the picture, I was in direct sunlight. After a few minutes of having the iPad set up, it shut itself down due to the heat. What I wound up doing was to use the backpack bag from my radio to shield the iPad which kept the temperature down to a point were it was no longer shutting off. Lesson learned for next time.
I initially set up to operate on 21.260Mhz and although I did make a contact with Vasily, ER4DX in Moldova who was CQing a bit above that frequency, I wasn’t getting any “takers” so I decided to switch to the main IOTA frequency of 14.260Mhz. I started calling CQ there and after a few minutes, George, KC2GLG, who had read my previous posting about the IOTA activation, heard me and answered. We had a nice chat, and I then moved on and worked about a dozen other stations that day.
I did have a bit of an issue with the antenna on 20m, though I was able to work some DX (Sweden and the UK). With the configuration I was using, it was very tough to get a good SWR and I seemed to be getting some RF back into the radio. Scott, NE1RD, wrote me and suggested that I set up for 20m in a vertical configuration, but unfortunately I didn’t have time to test that configuration before I left home. Even though I had Scott’s excellent Buddipole In The Field [PDF] book with me on my iPad which has a cookbook section to help set things like this up, by the time I decided to try this I was hot, tired, and it was getting late so I decided to call it quits for the day. So that takeaway lesson from that was “try everything before you leave”.
In just over a week, I’ll be heading down to Florida to visit family, and, as I’ve done on previous trips, I plan to be operating from Lido Key, IOTA # NA-034 from March 21 to 23. My current plans are to be on the air during my local afternoon between around 1700 – 2200 GMT, on 14.260 or 21.260 (the standard IOTA frequencies), phone only. This is very much a “holiday style” operation, so those operating times may vary, and depending on band conditions, I might set up elsewhere.
For this trip, I’ll be taking my Buddipole and using it on top of the same 8-foot mast that I used last summer in Costa Rica. When I was in Costa Rica, I was able to bungee cord the mast to the railing of the balcony, but since I’m not sure that I’ll be able to do the same with the picnic tables at the park where I’m planning to operate, I figured out how to guy the mast using some lightweight tent stakes, some line, and some small carabiners that I picked up at a local outdoor store. The folks who sell the Buddipole do make a guying kit, but I thought it would be nice to see if I could make something myself.
As I’ve learned, I always try out any new setup before I travel, leaving at least a little less chance for last minute problems. Yesterday afternoon, I set up everything in the backyard as a test. What I did was to run some line through the holes on the Versatee to use as an attachment point. I then used 3 lengths of line and made a taut-line hitch on one end of each which I to put onto the tent stake. On the other end, I connected a very small S carabiner which I used to clip onto the lines on the Versatee. This was a lot easier than trying to tie line-to-line.
Because I learned the hard way that it’s pretty easy to break a whip if the antenna isn’t supported properly, I first made sure that I could connect the Versatee to the mast (without the arms or whips), attach the lines to that, then stand it up and tension the guys so that the mast seemed stable. I realized that I needed to keep the guy lines probably a bit closer than I would have liked to the mast or I wouldn’t be able to reach the hitch knots to adjust them. While I could have used adjustable knots to connect to the carabiners, in use those would be at the top of the mast and would be unreachable. As it turned out, it worked out pretty well the way I set it up. I had to first roughly estimate the 120 degree separation between the stakes around the mast, and I got lucky on my first try.
After seeing that this seemed to be pretty stable once I put some tension on the guy lines, I took it down and screwed in the antenna arms, coils, and whips, though I left the whips fully collapsed. I raised it back up, tightened up the guys (actually I just had to tighten one guy because of the way I’d lowered things), and it still seemed pretty stable, so I lowered everything once again, extended the whips (I’d already connected the wander leads to the proper location on the coils) and raised everything up. (If you’re viewing this on my blog page, you can click on the pictures to see a bit more detail, which is particularly helpful for the one showing the antenna fully deployed).
I connected the feedline to my radio (I’d brought my Icom 706MkIIG and a small power supply outside) and the built-in SWR meter in the’706 showed good SWR over the phone portion of 15 meters. I tuned around to see if I could find a station to work and I came across was Pedro, EC8AUZ. We had a nice little chat and he told me that my setup was working well, which was all that I could ask for.
At only 8 feet above ground, I know that the pattern for the antenna is going to be distorted. As I was set up with the broad side of the antenna roughly aligned Northeast/Southwest, it was good to know that I could make a 3500 mile contact due east with that setup.
I still have a few things to do before leaving, but it looks like I should be all set as far as the antenna goes. I hope to work some of you while I’m in Florida. If you’re in the Sarasota area, drop me and email and maybe we can get together for a bit while I’m there.
Well, I was wrong. Or was I?
When I got home after my NA-034 operation, I wanted to try to understand what happened. I was sure that I’d operated solely off a car battery in the past and as long as I was connected directly to the battery I hadn’t had any problems. Based on some testing that I did, I discovered that I may have been mistaken. The short version is that I discovered that by using the battery in my car without the engine running, I was able to reproduce the “strange noise in headset” that I recently wrote about, and that by running the car engine, that problem went away. There’s a bit more to it though. Read on if you’re interested.
I needed to have some way to measure the voltage from the battery and the amount of current that it was drawing while the radio was transmitting. While I could do this with a couple of meters when I was home, based on some recommendations that I got from W3FF, K8EAB, and NE1RD, I picked up a Super Whattmeter from Astroflight for around $50 plus shipping. These devices are used by folks who fly electric model airplanes because you really don’t want your battery to die when it’s up in the air. As it turns out, they are well-suited for monitoring your power when operating portable. Of course, they work fine too in the home shack, though my power supply has meters so it’s not needed. The picture here shows it hooked up that way for testing, and you can see that the Astron supply is supplying 13.8v.
As a side note, I started using quick-disconnect connectors made by Workman Electronic quite a number of years ago, before Anderson Powerpoles became popular. I was looking for some kind of quick disconnect power connector and found patch cables similar to the ones in the picture at a hamfest. I typically cut them in half and crimp them onto whatever I need to, be it battery clamps, the power cord for a radio, and so on. The good part is that I’ve been able to find them surplus at hamfests (though I’ve seen from a number of places online that they are now discontinued) but the bad news is that they don’t match what most other folks use. I keep meaning to make myself a set of adapters to connect to Powerpoles.
I crimped a set of the quick disconnects onto the Whattmeter and did a test with the power supply and radio in the shack to ensure that the meter was working and found that it worked perfectly. The shack power supply was putting out just over 13.8 volts with the Icom 756 Pro II drawing around 3 amps while receiving. (Interestingly, this is about 0.6A below what the ARRL reported in their testing, but I’ve had some repair work done on the radio and it’s possible that some of the newer components draw less than the originals.) The next step was to reproduce what I’d set up while in Florida.
As luck would have it, the weather was beautiful this weekend, and as we had no plans on Sunday, I took the 706, the Buddistick, the Whattmeter, the antenna analyzer, and a length of coax outside. I set up the Buddistick on the front lawn (I just had it on the mini-tripod sitting on the lawn, though I did put the radial over a couple of plastic lawn chairs to keep it off the ground) which while not optimal for DX, took me all of 5 minutes to set up with a good match to the radio, as verified by the antenna analyzer. I connected the radio to the antenna then connected the power cables to the car battery, with the Whattmeter in-line. My thoughts were to do a few tests with the engine off, fully expecting that I wouldn’t have any issues, then turn the engine on to see what kind of difference it made. I found an empty frequency on 20m and started testing. As soon as I transmitted, without looking at the meter, I knew that, to my surprise, I’d reproduced the problem: That nasty noise in the headphones was back.
What I figured I’d do was to collect data using various levels of transmit power to see the effect on the voltage and current draw. The meter itself also shows power in watts, though of course that’s trivial to calculate if you already have current and voltage. (From Ohm’s law, P=I×E). I quickly discovered that the car battery wasn’t able to supply sufficient voltage unless I was transmitting with about 10 watts or less. The specification for the 706 MkIIG is that it requires 13.8vdc ± 15% meaning the minimum allowable voltage is 11.73vdc. With the car engine turned off, I measured 11.68v with the radio drawing 5.79A when transmitting using 10w. At 40w (the next step I measured; when I was in Florida I was able to “get away” with 40w when testing with KH6ITY), I measured 11.52v while drawing 8.23A. At 60w transmit power and up, the voltage dropped to about 11.4v but the radio was simply unable to draw the current needed.
With the car running, it was a completely different situation. Even at full transmit power (100w), the voltage supplied to the radio was 13.24volts at 14.77A. (I’m not sure why my current draw measurement at that power was different from the specifications for the radio, which were also pretty close to what the ARRL measured). I took the results and plotted it out in transmit power vs. watts consumed for both the case with the engine on and the engine off, and it’s pretty clear that with the engine off, the battery simply isn’t able to supply the required power. (You may need to click on that chart to have it display in a readable size. If you’re reading this via email and that doesn’t work for you, go to the web version of this post at k2dbk.blogspot.com and it should work from there.)
You can see from the chart that not only couldn’t the battery supply sufficient power for the transmit needs, it was only able to supply less as the radio tried to use more, presumably because the battery simply couldn’t “keep up”. So all my empirical testing seemed to prove that with the setup that I was using, I simply couldn’t operation at full power using just a car battery with the engine running.
However, similar to bees who simply don’t know that they can’t fly, so they do, apparently my radio didn’t know that it didn’t have enough power to operate, at least during my 2004 and 2006 operations from NA-034, so it worked just fine. During those operations I know that I did not have the car running, yet I had no issues with power. The key for me know will be to find out what has changed. I am using the same power cables and the same radio (the antenna was different, but that shouldn’t matter), yet something has changed. The next thing I am going to do is to see if perhaps there is a problem with the power cables that may have occurred over the years.
Although I attempted to measure the resistance in the power cables and came up with a measured 0.1 Ohms, my meter is probably fairly inaccurate at such low resistance, so I did a calculation instead assuming that I’ve got all 12 AWG wire in place. (Part of it is actually 10AWG, but I’m using 12 to account for any losses due to connectors and splices.) Using a 12v supply with a load of 15A (matching what I saw when the engine was running) and a length of 20 feet, the voltage drop calculator that I used shows an estimated voltage drop of around 8%. Allowing a bit of wiggle room for the length, it appears that the voltage drop would be somewhere between around 6% and 10% which corresponds to a voltage at the load (radio) of between 11.3v and 10.8v. Even the highest end of that range is too low for the radio to operate properly. Dropping the transmit power to 40w results in the voltage to the radio of about 11.5v which is a bit below spec but probably would allow operation, with some minor distortion. That seems to match what I had experienced.
The other factor that I haven’t played around with much is temperature, and I’ll leave that as an exercise for the reader. At this point, I think the best thing to do is to shorten the power cable as much as I reasonably can, replacing the section that is currently 12AWG wire with 10AWG wire. I suspect that will help ensure sufficient current flow while minimizing voltage drop.
I would be very interested in any feedback from anyone who can shed a bit more light on these issues, as I know that there are other factors that may come into play, such as the battery chemistry and perhaps other parts of the car’s electrical system.
As I mentioned previously, once I got the power problem figured out I was able to easily make contacts with other stations, which is what I’d planned to do in the first place. In the first half-hour of operating, I made contact with about 25 stations. Compared to rare DX stations this is very slow, but my operation was very low-key and I’d often spend a bit of time to briefly chat with the other operators, so this was far from the typical “K2DBK you are 59 thanks QR Zed” that you hear in those operations. I was having a great time working stations, and after a while I started to hear folks in Europe calling me, but they were covered up by the US callers. I figured that I’d try to work as many folks outside North America as I could, so I asked for only stations outside of North America, and worked 9 stations in as many minutes, all outside the US. I worked folks in Italy, Poland, Spain, and Belarus all in fairly quick succession. Thanks very much to the folks in North America who very politely stood by while I worked the other stations. Not one single person from North America called when I was asking for the other folks. (By way of explanation, it is an unfortunate fact of life that all-too-often hams will “call out of turn” and ignore requests from contacts from specific areas. When they do that, it just slows down the process.)
After I had contacted the folks outside North America, I went back to working any station that was calling me, and I picked up a mix of both US stations and some more DX from Italy, Serbia, and Belgium. I had a couple of other chats during a few lulls with Larry, KH6ITY, and finally shut down for the day at around 4:45PM local time to head back to have dinner with the Sharon in St. Armands.
|The Legendary Salty Dog|
The following day I got somewhat of a later start than expected, but I did want to stop at The Old Salty Dog again, this time to have what is one of the most delicious and presumably most unhealthy foods in existence: Their signature “Salty Dog”. A Salty Dog is a jumbo hot dog dipped in beer batter and deep fried. It is indescribably delicious. Of course, it must be washed down with a nice cold bevarage (a Bass Ale for me, thanks).
When I arrived at the park, the parking spot I’d had the first day was taken, and I was having trouble finding a place to park where I could be close enough to be able to set up on a picnic table, but as I was walking around (I’d parked temporarily “out of range”) someone left and I was able to pull in close to a different table, this time right out in the sun. The only downside to this location was there there wasn’t another table nearby so that I could set up the antenna on a different table, but I was able to set up the antenna on one end of the table and operate from the other without any issues. Well, not at first.
|Buddistick set up for 20m with counterpoise thrown|
over a tree branch
I started off working stations on 20 meters and worked a number of US and Canadian stations, as well as a station from Slovakia and one from Hungary. I’d been trying to set up a contact with Scott, NE1RD, who was now operating from the island of St. Thomas (as KP2/NE1RD) on and off for a while by this point. I emailed Scott from my BlackBerry that I was currently on 14.260Mhz and Scott quickly threw together an antenna for 20m, but by the time he got on the air, I’d lost the frequency that I was using and we didn’t make the contact. “Losing” the frequency means that I was using it to make contacts, but due to the way that propagation works, sometimes two (or more) stations will be using the same frequency, both unable to hear each other until the conditions change, then usually one of the stations will wind up “taking over” the frequency. This is what happened in my case, and I “lost”.
As it turned out, Scott had already built a 2 element beam for 15 meters using the Buddipole gear that he’d brought, which would provide a much better signal to me. I reconfigured my antenna for 15m (very easy to do), and coordinating once again via email we were able to contact each other. Neither Scott nor I consider ourselves as “rag-chewers”, which are folks who prefer to get on the radio and have a nice long chat with someone. I’ve certainly done that in the past, but most of my current interest is in working DX stations and contesting, both of which require very brief, specific exchanges of information. However, Scott and I found that we had a lot to talk about, so the contact was not a brief one. About 10 or 15 minutes into our conversation, I got another visit from Mr. Murphy.
As we were talking on the radio, I thought that I noticed the odd sound in my headset that I’d heard previously. This didn’t make any sense, since the car was still running (as you’ll recall, the battery alone was unable to provide sufficient power to transmit at full power). Scott then commented that he could hear my signal starting to distort, so it sounded like the problem was returning. We both tried to figure out what might be going wrong, and while trying to figure out what could have “broken” while operating (nothing had been touched since I originally got on the air that day), I thought that perhaps our relatively long chat had caused the power cables to heat, which in turn would increase the resistance in the cables, reducing the power available to the radio. I felt along the length of the cable but didn’t feel any warm spots. I was about to rule out the wire heating up when I realized that I’d closed the hood on the car almost all the way and when I opened it, obviously (in hindsight) the portion of the power cable that was closest to the battery, and under the hood, was quite warm. It hadn’t heated up solely from transmitting, but also because it was a warm day and with the engine running and the hood closed, the engine compartment was quite hot. The solution to the problem was now quite simple: Leave the hood of the car open.
After just a minute or two, the power cables cooled enough to allow enough power to flow so that my radio was again transmitting normally. Scott and I finished our chat, and I decided to stay on 15m where I worked stations from Puerto Rico, Italy, Portugal, and the US, finally finishing up with a nice chat with Andy, AE6Y who was operating from Aruba as P49Y, having just arrived there prior to the WPX Contest that was coming up. When I finished with Andy, it was time to shut the station down to head back for a final family dinner, since we were leaving for home the next day.
In all, despite losing a day of operating due to the power problem, I would rate this as a successful operation for a number of reasons. First, I did finally get on the air and made contact with 16 different DXCC entities (countries) and at least 10 different states. (It was almost certainly more than that, but I didn’t always get the name of the state for the station that I was talking to.) Second, I was able to give back a bit to the hobby by talking to, and with Larry, KH6ITY’s class. If even one of his students goes on to get his ham license that would really be a wonderful extra benefit. Third, I’ve made a number of new friends both as the result of both my operation on the air and the attempts to troubleshoot with the wonderful folks from the Buddipole Users Group. Fourth, I’ve learned a bit more than I already knew about troubleshooting this type of problem. Finally, and perhaps most important, despite the issues that I ran into, I had a really good time doing this.
I have really enjoyed writing this series, and I want to thank those of you who’ve commented about how you’ve enjoyed it as well. There is a bit more information that I want to share that I’m going to write as an epilogue to this series, please look for that soon.
Update: I’ve posted the epilogue.
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.