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Hi. I have been a ham since 1985. I used to write the "Ask Kaboom" column in 73 Magazine for many years, and I also wrote reviews and construction articles for them. The second edition of my book, "How to Diagnose and Fix Everything Electronic," was published recently by McGraw-Hill, and can be found on Amazon and at bookstores like Barnes & Noble.


Almost all of my gear is old, but it works well and I like it. My main rig is a Kenwood TS-940S/AT, and I also have a TS-50S and a Yaesu FT-747GX. Amp is an Ameritron AL-80B, and tuner is an old Murch roller-inductor type. Antenna farm is under construction, and will consist of a Cushcraft MA5B mini-beam, along with dipoles for 40 and 80.

About a year ago, I acquired a Yaesu FT-817ND, and have gotten into QRP in a big way. Yes, they really can hear you! I've modified the living heck out of this radio. It now has an internal 3000 mAh lithium battery, plus I can plug in a 4400 mAh external lithium pack I made from the pack of an old portable DVD player. Because the radio uses diodes to isolate the power sources, the two batteries can be used at the same time, and they track each other as their voltages decline. So, instead of the 1400 mAh of the original pack, my setup  has a total of 7400 mAh, while weighing hardly more than the original. And man does it work! I ran it all weekend for Field Day and still had plenty of power left.

The radio also has an original mod I developed to speed up the ALC time constant to track spoken syllables, providing speech compression without the cost or added current drain of installing a compressor. Plus, the radio has been goosed up to 10W output, and I replaced the stock mic with a homebrewed smaller one with a better-sounding dynamic cartridge. Because of the lithium batteries, the rig will do 10W on battery power, although it drops to 7-8W as the cells run down. Not even a KX3 will do 10W on the internal batteries! The result is that this radio gets heard on most calls I make, as long as I have a half-decent antenna. I have worked all over the world with it on SSB, and it has become one of my favorite pieces of ham gear. Here's a pic of me using it on Field Day, with my homebrewed Peanut Butter Loop, which is a tabletop magnetic loop for 40-6m I built into a plastic peanut butter jar. Note the external battery pack under the back of the radio. Pretty small for 4400 mAh! It weighs just a few ounces, too.

Since this pic was taken, I've added an antenna current meter to the Peanut Butter Loop. It really helps me tune for the best RF output. Here's a closeup of the improved PB Loop. One of these days, I'll get around to posting the inner workings of this thing. The matching capacitor on the left is homemade and especially interesting.

The Peanut Butter Loop is fun, but I have made something much smaller that actually seems to get out a little better. It won't go all the way down to 40m, but it handles 20-10m just fine, and the RF field from it is stronger than what I get from the PB Loop, even though the radiator is smaller and thinner. Plus, this new one is a lot easier to carry and deploy. I call it the Crazy Little Loop. Here are some pics:


Here it is on the rig. The second pic shows the size of the wire loop. By using banana plugs, I can swivel the loop so its edge points toward the desired station without my having to move the radio. I don't know of any other mag loops that can do that. It's really important, as these loops are highly bidirectional. Ya gotta point at the station you're trying to work, or the other op won't hear you.


Theory says this can't work much at all, given its thin #14 solid wire radiator, but it does! I've made several contacts beyond 1000 miles, with signal reports ranging from S5 to S9. I had a nice, long chat on 20m SSB with a guy 1500 miles away just the other day, and I was S9 to him. How about that? No, it's not as good as a full-sized dipole, but it does work and people hear me with it, without my having to string wires in trees. Now if only 10m would open up! I expect this loop to be considerably more efficient on 10 than on 20. Heck, I'd settle for decent propagation on 17m! How about it, sun??

QRP madness! I really dig my FT-817. Heck, if one can operate from a campsite, a mobile, a motel room, and so on, why not from the throne? This setup connects to my house antenna system (dipoles for now, a beam sometime soon), and I make contacts quite readily with it. I call it the "QRPooper." (OK, not on the air!) Can ya tell I'm single? ;)

Still more QRP madness!! For years, I've wanted to run HF on a bike. Why not? I've talked to other people who have done it. So, I set out to make a bicycle mobile system for the FT-817. It seemed simple enough, but it turned into a pretty big project.

The bike is a Giant Revive semi-recumbent. These are pretty rare. They don't make 'em anymore. I saw one a year ago and was infatuated. I snagged this blue beauty off craigslist and haven't seen another. I had a wider set of gears put on it, along with high-pressure tires. It's still no mountain bike, but it rides well and is the most comfortable bike I've ever been on. It turns heads, too, even without a big green antenna on the back!
My design goals for a bicycle mobile system were simple: it had to get out well, be as lightweight as possible, and pretty much disappear when I wanted to use the bike without the radio. The rig runs for quite awhile off its internal 3000 mAh lithium battery, so I didn't need to add a battery. The antenna system, described below, weighs only 13.5 ounces, including the mount. The radio, bag, mic and PTT switch bring the total to 3.69 lbs. I can't even tell it's on the bike.
Here's the rig in its form-fitting bag, angled for easy operation while riding. I got this bag at a hamfest and have no idea what it was used for originally. It fits the 817 perfectly for bicycle use. I added some Velcro to keep the flaps open. If it starts drizzling, I can zip it closed to protect the radio.

The curly thing hanging it from the handlebars is a piece of coat hanger wire inside some plastic tubing. It hooks through loops in the back of the bag. Those were already there. By using a curly shape, I'm able to get it on and off the handlebars without bending the wire.

On the back of the case, I hot-melt-glued foam that presses against the steering column, and a Velcro strap to keep everything from swinging around. This forms a shock-absorbing mount that holds the radio securely but cushions it from road bumps. Whoever invented hot-melt glue is one of my favorite people on the planet! That stuff holds many of my projects together!

The FT-817 uses a standard ethernet connector for its mic, so I cut up a spare ethernet cable and made an adapter for the headset and PTT setup. For receive audio, I just use the speaker in the radio, as I don't want loud sounds against my ears, and I want to be able to hear what's going on around me. For TX, I use a condenser mic on a stalk cannibalized from an old computer headset. To power it, there's a resistor in the adapter wiring by the ethernet plug, along with a capacitor to couple the audio to the radio. Bigger condenser mic cartridges sounded tubby and terrible, but this tiny one was just right for clear, clean transmit audio on the 817.

Here's a rather awful selfie showing the headset Velcroed to the helmet. The stalk can be swung up out of the way. The headset plugs into a mini jack on the front of the radio bag. That way, if I dismount the bike and forget to take off the headset, or (heaven forbid) I fall off, the plug will pop out without doing damage to the radio. It also makes it easy to get on and off the bike with the headset in place on the helmet. By the way, the antenna sticking up is not attached to the helmet. That's the resonator on top of the HF antenna behind me.

Here's the PTT switch, placed so I can press it with my thumb without moving my hand from its normal riding position. It, too, is Velcroed, with the fasteners held on by, you guessed it, hot-melt glue.

The heart of the whole system is the antenna, of course. Light weight was my prime consideration. The mast is a plastic garden stake that has a hollow stainless-steel tube inside. The middle of the tube is filled with the same green plastic that's on the outside. It is 6 feet long, quite stiff, and it weighs only 5 1/2 ounces. I jammed a Hustler threaded bolt into the top and secured it with a hose clamp. Onto that I can screw a standard Hustler mobile resonator. To connect it, I skinned off the plastic at the bottom of the mast so I could clamp on a large clip fed by the center conductor of the coax.

The mount is homemade. Again, light weight was the goal. It's made from 2 pieces of wood and a few inches of PVC. The mast just slides on in. I glued a washer to the mast so it couldn't go in too far. Push it in, clip on the coax clip, and that's it! It takes just a few seconds to put on or remove the antenna.

My initial test of the system showed that the mast tended to rotate in the wind, probably because the resonator wasn't perfectly straight. Given the low speed of a bicycle, that really surprised me. It wasn't good, because it turned the coax clip and could put stress on the cable. I added a nail bent into an L to the washer on the mast, and a hole for it in the top wood block. The nail fits into the hole as I insert the antenna into the mount, and the mast can't turn. Problem solved. These pics were taken before I added that.

The coax is RG-174 mini stuff, run through the frame in front (along with the brake and gear cables), and grounded at the back of the bike. Here's the ground connection, coated with my favorite substance to keep weather from oxidizing it. Soldering the ground wire to the braid of such tiny coax without melting the inner conductor's insulation was one of the hardest parts of the entire project! Not visible are several loops of the coax going through a slot between the frame and the rack, resulting in a few turns around the frame. (You can see them in the pic above this one.) The idea was to create an RF choke between the rig and the antenna to keep anything from crawling back up the cable. Is it effective? Well, I can only say that it's like the "No Elephants in the Butter" sign I put in my fridge: I don't know if it really works, but I sure haven't seen any!

As you can see, the antenna is rather tall. With the 6-foot mast, the mount being about 2 feet off the ground, and the resonator and whip on top, it's about 9 1/2 feet from tip to ground! I've already hit 3 tree limbs with it on my first ride. So far, no damage. It just bounced around for a few moments. Whew! Gotta watch out for those trees.

My experience with Hustler antennas in normal mobile operation has been wonderful. They get out like crazy, better than most of the fancy, expensive antenna systems available today. I had no idea if one would work on a bike, given that there's not much metal underneath to use as a counterpoise. I tuned up 20- and 17-meter resonators with my trusty MFJ-259 antenna analyzer, and they both tuned pretty close to how they do on my car, so I was hopeful. SWR was flat, and bandwidth was about the same as on the car.

So, does it work? Oh my, yes! On the bike's maiden voyage, I worked all over the country on 20m, coast to coast, and into Canada, with great signal and audio reports from pretty much everybody. I even worked QRP-to-QRP, chatting with a guy several states away who was running a KX3 into a dipole. It was quite something to be on the other end of a pileup for a change! Everybody wanted to work a QRP bicycle mobile. My thanks to all the stations who called me. It was a blast.

Next spring, keep an ear out for KB1UM QRP bicycle mobile! I plan to take this thing out as often as possible. There's no end to the fun things one can do with ham radio!

Here's my old home shack from when I lived in Seattle, in the cold basement. The Lava Lamp was the magic element that brought everything into resonance. I have a new shack here in Colorado, but no pics of it yet. It's based on the same equipment, along with some new additions. It's still in the basement, but this basement is a lot more comfortable, and the ham table is much bigger.

For a year, I was traveling. To get on HF, I bought an MFJ-935B magnetic loop tuner. Using my TS-50S and indoor loops, I worked Japan on 40m, and Europe and all over the U.S. on 20m-10m, with the loops 4 feet off the ground. All on SSB, not CW. If you're in an antenna-restricted QTH, check out magnetic loops. I am blown away by how well they work.

That's what got me into magnetic loops, and I continue to build and experiment with them, especially for portable use.

The pic shows all the loops in place, ready to be connected. They didn't bother each other! I could just unscrew one set of lugs and hook on the other as needed. The red wire was the 40m loop, draped around two window sills. It worked remarkably well, and I modified the tuner so it would resonate the 32-foot wire loop on 80m as well as on 40m. I got heard decently all up and down the west coast late at night with it, running 100W.

Loop sizes (circumference) and bands:

Inner loop: 4.75 ft, 10-15m (best on 10)

Middle loop: 7 ft, 15-20m (best on 15 and 17)

Outer loop: 13 ft, 20-30m

Red wire: 32 ft, 40-60m, 80m with extra capacitors added to tuner

Happy hamming and 73 from KB1UM

7658575 Last modified: 2016-10-27 06:35:50, 16091 bytes

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