Tuesday, April 27, 2010

Today's silver lining

Today's bad news is that the toothache that I'd had for about a week hadn't gone away this morning, and after my dentist took a look yesterday and tried one thing to fix it that didn't work, this morning I made an appointment with an endodontist to see if I needed to have a root canal on that tooth. The folks in his office were nice and managed to get me a late-morning appointment, which meant that I'd work from home in the morning (the endodontist's office is only about 10 minutes from home, so going all the way to work in Secaucus and coming back made no sense) then head to the appointment. (The other bad news is that I did indeed have the root canal procedure done. The procedure itself wasn't so bad, but now that the anesthetic has worn off it's pretty uncomfortable.)

As usual,  when I work from home I usually leave that packet cluster up and running, and this morning was no exception. I saw a spot for Charlie, VR2XMT in Hong Kong on 20m, which is another entity that I still needed to work. I've heard Charlie before and even tried working him but hadn't had any success. While working on some emails for work on my laptop, I tuned to the spot frequency and heard Charlie's very strong signal. I called him several times but wasn't able to get through, so I turned down the volume a bit and kept listening while working. After a while it seemed that there weren't as many callers, and in fact it got to the point where there seemed to be nobody calling at all, so I gave my callsign a few times in response to Charlie's "CQ", and he responded to "the station ending in Echo Bravo Kilo". I figured that he might have been calling me so I called phonetically a few more times and sure enough, he was calling me. We exchanged 5x5 signal reports, I thanked him, and I had a new one in the log!

Unfortunately, Charlie doesn't participate in Logbook of the World, but since this is an all-time new entity I would have been sending for a paper QSL card anyway, which I will get in the mail very soon. It's always great to work a new DXCC entity, and it was especially great to have worked my 2nd new one this year within less than a week of working the previous one.


Saturday, April 24, 2010

My first new entity for 2010

Yesterday morning, I got a nice surprise. I was working from home in the morning and chatting on the computer with Larry, N4VA. He was also at home and told me that Jimmy, BX5AA was coming in very strong on 20 meters. Jimmy is located in Taiwan, and that's a DXCC entity that I'd never worked before, so I was anxious to try to make a contact. I tuned to the frequency and at first, I only heard a very weak station, which I assumed was Jimmy, and figured that I wasn't going to have a chance to work him. It wasn't surprising that he'd be louder to Larry, since he's got a beam on his tower instead of just a G5RV (wire) up in the air.

However, it turns out that I was hearing a local station that Jimmy was working, and when it was Jimmy's turn to transmit I heard him very well. (I had heard him and tried to work him in the past, but the signals were much weaker.) Although he had a pretty good pileup, he heard part of my callsign (the "BK" part always seems to get through), and he asked just for the "Bravo Kilo" station. It took a few tries, but he was patient and eventually he got the complete and correct callsign, and gave me a 5x5 signal report. (I gave him a 5x9). That was that, and he moved on to working other stations.

I noticed on his website that he uses Logbook of The World, so that night I uploaded my contact with him, and to my surprise I found that he'd already uploaded his contacts and there was a confirmed QSL record generated. The time from contact to confirmation was probably under 12 hours. Not bad for a station from Taiwan!

I'll be sending for a paper card anyway, as while I think LoTW is fantastic, there's nothing like having an old-fashioned QSL card to look at.

Saturday, April 17, 2010

The new ARRL website is disappointing

I'm going to stray a bit from my normal topics to discuss the newly updated ARRL website which after several attempts finally went live this week. My overall response was one of disappointment. I am well aware that any it's often difficult to get pretty much anything right in Information Technology  the first time. (In fact, I was commenting to one of my colleagues at work that if you think you've gotten something right on the first try, you have overlooked something). My fellow bloggers Dan, KB6NU and David, K2DSL have written posts describing some of the flaws, and I suggest you read them for the details.

David in particular enumerated a lot of the different issues, and while I'm not going to add anything to his list, I will mention that in particular, the two things that are particularly annoying are the fact that it seems that even with the "favorites" feature, nearly everything requires a lot more clicks to get to (which is one of the main things you don't want to do if you want people to keep visiting your site) and that you no longer remain logged in for very long. (It looks like they may have adjusted this value since David wrote his blog, but in any case, it should allow you to remain logged in for at least a few weeks minimum; this isn't a banking site.)

I want to make clear that I am a big fan of the ARRL, and that I really appreciate the advocacy they provide for our hobby. I know that an undertaking of this magnitude must have been quite difficult, but I think that they should have allowed ARRL members "preview" access much earlier in the process. (Yes, I'm aware that there was an article in QST, but static images are not the same as actually using the site.) I suspect that the reason for not doing so was a concern over the flood of input that they may would have received, but when you are developing something that is supposed to provide service to your members, you need to take their feedback into account.

I sincerely hope that the ARRL will listen to those of us who have been sending in feedback and will be able to make the changes to make the website at least as useful as it was before the changes. I also hope that we, the members, don't hear that "it's too far along in the process to change things".

Monday, April 05, 2010

The NA-034 operation that almost wasn't: Epilogue

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.

Friday, April 02, 2010

The NA-034 operation that almost wasn't, Part IV

If you haven't read Part I , Part II and Part III first, you might want to do that.

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.

Until then,
David, K2DBK

Update: I've posted the epilogue.