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This site was last updated 4/13/2002.

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Mobile Computing
On our trip to Southern AZ

I am sitting here, cruising in the dark down I-10 south of El Paso, Texas. I am typing this on my 486 laptop, which I bought for $40, probably my best deal of the year. We are on the way home from visiting my grandparents in McNeal, Arizona, about 20 miles north of the Mexican border. Now let me start at the beginning.

I had the idea a few weeks ago. I wanted to run PSK31 mobile on the AZ trip, but this slow (66MHz) laptop doesn't have a working audio input. Another reason for a good computer in the van is for playing of MP3 files (another thing that this laptop won't do). We like to listen to books-on-tape during long trips, and we have recently been recording the meetings at church into MP3 format for archiving on CDs. All we had to do was record the books-on-tape into the computer and encode them into MP3 format. I thought to use my dad's laptop, a much newer Dell machine, with which we also do the audio recording. However, my dad does not want to run the risk of breaking the LCD screen (he broke one a few years ago), and when the screen is closed, the computer goes into "suspend" mode. Naturally, I thought to use a normal, full-size PC.

Of course, there isn't room for a monitor, and a keyboard is also fairly large. The control and display problem is easily solved with a program called RemoteAdministrator. ( It allows complete control of a remote machine over a network, including live (about 40 updates a second on this system) screen captures and display on another machine conected to the remote computer. I had tried it before and I really liked it. Since the 30-day evaluation period was up, I bought the program for the $35 registration fee.

Unfortunately for this application, my 700MHz Duron computer is in a full-tower case, which takes up a lot of space, even in our full-size van. A few days later, I had the idea to take my computer out of the case and put it in my cardboard box (we each have one of these to take on trips. Each one is like a single file-cabinet drawer, and when they are stacked in the back of the van they provide a nice way to get at anything quickly). I did this, reattached all the important things, and it worked. However, my dad pointed out that cooling in the back corner of the cardboard box would be very tough, and it would be easy to damage the machine.

I was not beat yet. We had a 486 machine that didn't work right, and the case wasn't too big. Although the case was not ATX, I decided I could modify it for my use. I stripped everything out of it, and the power supply holes lined up right for the ATX supply, so I screwed it right in. I then drilled mounting holes for the motherboard in the bottom front of the case, because the heatsink on the processor didn't fit under the power supply ( in the back). I made standoffs by cutting some small brass tubing, and soon I had the motherboard securely mounted in the case. Unfortunately, the motherboard now blocked the drive mounting slots. For then I just fed the power and data cables out the empty drive holes in the front of the case, and in that manner I connected the CD-ROM, hard drives (the 15.3GB HD that I normally used, and the 1.6GB HD that I was using because I didn't want to expose the big one with all of the important stuff to vibrations and shocks while driving), and floppy drive.

For a few days, I switched back and forth between hard drives, depending on wat I needed. I could surf the Internet and stop my different email forwarding from the 1.6GB hard drive, but for actually checking my email, I used the 15.3GB hard drive. I put everything I needed onto the 1.6GB hard drive. Through that week, my dad did a lot of the recording stuff, including the music that I am listening to right now. Then, on the Friday night a week before we were leaving (we left Thursday, Dec. 21), my 1.6GB hard drive died. I went to bed, and the next morning, I hooked up the 15.3GB hard drive. The BIOS didn't detect it! We could even hear the heads seeking, so it seemed really strange. I tried to get the drives working, but I didn't have any luck. I had one working hard drive left, a 270MB drive from the old 486 that I grabbed the case from. I knew that Win95 would fit, I have installed it in under 100MB. I didn't want to mess with fitting in Win98 and the few other programs I need.

I got Win95 installed, and it seemed to work okay. Since not enough of the MP3 files would fit on the 270MB hard drive, we decided to burn a CD with them and then just read them off of a CD drive. I spent a long time working on the case. I drilled mounting holes in the top cover for the hard drive, the ZIP drive (to store digital pictures), and the CD-ROM. Once I had the jumpers properly set on the drives it seemed to be going along fine, until I started having major BIOS problems. The CD drives (CD-RW and CD-ROM) were not being detected, and I was also having problems with Win95 (once when restarted all references to network stuff were gone!). Fortunately, I got a Pentium 90 in the mail on Monday or Tuesday, with a 630MB hard drive, so the CD drives were not needed although they are still hooked up. I needed a computer that I could trust to work every time. My dad had since figured out a key combination that would allow his computer to run even with the lid closed, but his computer is not as good for proving the remote control concept. (It has its own display, keyboard and mouse)

Since there were only about two days to work on it, I decided to just throw everything back in the tower case (there was NOTHING in it), because although I might not be able to take it, I did not want to take a computer that I would have to worry about. There was not a way to fix it on the trip, or even work on it at all. The remote control program only works in Windows, and therefore it is impossible to change the BIOS or get into Windows in safe mode. I got it working in the big case, and all of the problems with Windows and the BIOS were gone. My dad agreed to let me take it, but I had to put some of my clothes inside the empty portions of the case (there is a lot of air in a full tower case).

I packed in my clothes, along with the "radio bag" containing my 2 meter equipment for emergency use. I loaded everything in the van the night before we left, and hooked it up. It was about 15 deg. F, so I didn't bother testing the system. Let me explain the rest of it... I had the K2 hooked up next to the computer for PSK31 and SSB use. I had a PSK31 audio and keying adapter for the mic plug, and a cable for the audio input to the computer. We also had a small FM transmitter designed for use with a CD player, that transmits to the car radio. This was to be used for getting our MP3s to the speakers. I made a little audio switch cable to switch the coputer audio output between the FM transmitter and the K2 audio input (for PSK31). For the power distribution system, we had a 300W power inverter to run the computer and 4-port hub for the network. We ran two fused cables straight to the battery and hooked the ends to the inverter. Also connected to this wire-nut secured point were the 12V lines for the K2 supply, and the lighter plug to power my laptop supply. This comprised the primary power distribution system. It has only failed once, a couple hours ago (it is now 4:50 PM 12/31/00) when one of the wirenuts came off.

Ten minutes before we left home, I decided that it would be a good idea to start everything up and make sure that the system worked the way it was supposed to. I turned on the laptop, the K2, and the inverter. I looked at the hub to make sure that it was on. It wasn't! I took it inside, plugged it in, and it worked. I figured that the inverter output was not close enough to a sine-wave to please the switching supplies in the hub and computer, and I decided to work on it later, because we were about to leave. The first day I just used the laptop. I did write a neat little number guessing game in QBASIC, but as always the programming was more enjoyable than playing the game.

That night, we stopped at Wendy's for supper, and afterwards I got out to the van first to work on the computer system. I hooked up our extension light to the inverter, plugged it in, and it worked. Next, I plugged the hub into the jack in the light body. It worked! I next plugged in the computer, and it also worked. Since I needed to make the cable mess a little more manageable, I decided to wait until the next morning.

The next morning I got out to the van (we spent the night in a motel in Tulsa, OK) to warm it up, and got the computer and the hub connected to the inverter (the hub had to be connected on the end of the extension light because the power supply was built into the plug, and there wasn't room next to it on the inverter outlets for the computer plug). I fired it up, and it didn't work. I noticed that when I turned on the inverter, the power LED went immediately from red to green (a bi-color LED). I cycled power, and the light stayed red. This time the computer and hub came on. I finally solved the inverter problem.

When my dad came out, he found the FM transmitter and I hooked it into the system. We left the hotel, and I got the big computer running under remote control. I started playing a file, and turned on the transmitter. I had previously tuned it to the frequency of the radio. I could hear audio, but there was a lot of static. The transmitter didn't have enough power to make it to the antenna! Real QRP! We needed an extension cord for it, so that we could position the antenna in the front of the van. Later that day, I turned on the laptop to do something. The display didn't turn on! Additionally, it started to smell like it was burning.

I turned it off quickly, and took apart the computer. I tried to look and smell for smoke, but I couldn't find anything. I left it off and decided to wait until I could examine it properly. It seemed like a bad display, and I didn't have much hope for fixing it.

The next day was the last day of our drive out there. Since the laptop wasn't working, I decided to turn on the K2 to see what I could hear. I pulled it out and turned it on, but I couldn't hear anything from one end of the band to the other, with the audio cranked all the way up. I tuned up the 40m Hamstick with the K2 auto-tuner, and there wasn't much of an improvement. I tried tuning the antenna on other bands, but I didn't hear anything there either. I decided to fix it when we arrived at our destination and I had more time and space to work with. Now I had two things to fix!

While at my grandparent's place (a New Tribes Mission training and maintenance airport), I had a chance to demo the K2 to some other hams. They had never seen one before, and they were pretty impressed. One of the hams, N4PDR, lived next door to where we were staying, and he had a nice Cushcraft beam, which we hooked it up to. The K2 worked fine, so I knew that couldn't be the problem. I cleaned off the antenna mount on the van, which was really salty from all of the salty roads on the way there. I took apart the mount, wirebrushed it, and rinsed it off. When I reassembled it and hooked up the antenna, it seemed to work great! I was really excited, as I could hear signal all over the place.

On a short trip to Tucson, I turned on the K2 to see what I could here. Nothing! It was the same as before. I thought that maybe the increased performance was due to the metal carport that was about 50 feet long and only about 5 feet from the antenna mounted on the van. The next day was the day we were leaving, and N4PDR offered to help me troubleshoot the antenna with the help of an MFJ-259 SWR Analyzer borrowed from the avionics shop (which was really neat -- they had about six ham transceivers in the shop, and a long-wire coming from the top of the hangar which was tuned by an SGC auto-tuner. I also learned that IC-706s are being installed in the planes for HF communication and the control head can be remote-mounted, with the rest of the radio in the rear of the plane.) It was the first time I had actually used an MFJ-259, and it was pretty neat. The K2 said that the antenna SWR was about 1.1:1, so I didn't think that there was a problem with tuning of the antenna. We checked it out with the MFJ SWR Analyzer, and it agreed! Everything looked OK, so we tried out the K2 with one of the rigs in the avionics shop. Since the van was parked right under the long-wire, the overloading was terrible on both ends! I moved the van a few hundred feet away, and it sounded fine. We set up a schedule to try to contact each other every hour, and we set off in the van, bound for Las Cruces, NM. I tried several times throughout the ~5 hour drive. I heard N4PDR several times, very weakly, but he couldn't seem to hear me. I was really disappointed in the antenna installation. Since we got back, I haven't tried to figure it out, but I would really like to.

On the return trip the first day, we listened to several of the MP3 books-on-tape. However, my computer didn't work out because the power supply or something caused a lot of interference in the FM receiver that was hard on the ears. Also, we couldn't get the audio level high enough. We hooked the FM transmitter to my dad's laptop and it worked OK. He had figured out how to get it to not go into suspend mode when the cover was closed, so that was no problem... we just started it playing and closed the lid, and set it on top of my big machine under the seat. So, it turned out that we didn't use my big machine hardly at all, since it caused interferance to the FM transmitter and the K2 wasn't working for PSK31.

However, on the trip I learned a few things. I learned to always try something out completely before you leave home. This was a big mistake that I made in having to get everything going at the last minute. Also, I learned that it is great to have tools to repair things that go wrong (I took the laptop apart in the back seat of the van several times). I found out that it is good to have back-ups so that you can keep going even when one system fails. (I think I need an antenna on the other side of the bumper!) Overall, it was a great trip, and we all had a good time. I discovered how much of an adventure it can be to put together, test, and fix a mobile computer network and peripheral systems (such as the radio system). That part teaches a lot of patience, that is for sure. I thought that there wasn't much that could go wrong. I was really mistaken.

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This page last updated 4/13/2002.
© 2002 N8MX.