Field Day 2008, wherein even a near-miss with a collapsing antenna can’t spoil the fun

Tuesday, July 1st, 2008

On Saturday this past weekend I did so many ham radio activities I had to split them across two blog posts. Yesterday I wrote about the 17 foot antenna I installed on top of my house. Today, I’ll regale you with tales from Field Day 2008.

Field Day is an annual 24-hour North American amateur radio event running from 2pm on Saturday to 2pm on Sunday. Amateur radio clubs and operators all across the nation set up stations off the grid as an emergency preparedness exercise and public outreach event. Contesting is a large part of it, with the goal being to make confirmed contacts with as many other Field Day stations as possible. So after finishing setting up our own antenna, and after grabbing a quick bite for dinner, my dad and I headed over to Montgomery Amateur Radio Club’s (W3EXP) Field Day location at the Montgomery College campus in Germantown, Maryland.

The Field Day setup was quite impressive. Antennas were everywhere. Many temporary masts, some guyed, some not, filled two different parking lots, a gravel area, and a field. Longwire antennas were strung between trees and in giant inverted-Vs off masts. Altogether the setup had eight separate antenna systems and at least fifteen towers/masts. Two gasoline generators provided electricity for all of the equipment. Three separate rental vans were set up as operating stations, with the radio stations inside of them shielded from the weather (they had a bad experience last year with the weather).

When we arrived, W3TDH was still working on setting up a 20m Yagi on a 50′ crank-up military mast made of aircraft-grade aluminum left over from the Korean War. Unfortunately, we never got that antenna up, because about an hour before dark a vicious thunderstorm blew in. Luckily, being at a ham radio station is about the best place to be when inclement weather is coming in, because everyone was kept apprised with up-to-the-minute weather information using the club’s repeater (it seemed like everyone there had a handheld VHF radio). I was also getting weather reports off the National Weather Service’s channels and the Blumont, Virginia ham radio repeater (147.300), which runs a SkyWarn net during inclement weather. As the storm came in, we shut off the transceivers and most of us headed into the nearest building on Montgomery College’s campus.

However, before I started to go inside, I had the immense “pleasure” of watching two guyed masts come down in the gale-force winds just forty feet away from me. Apparently they had been put up with only two guyed tiers (against W3TDH’s recommendation to use all three), and they came down quite quickly in the high-speed winds. It was a sight to see. The bottom sections of the masts, which were not secured to the ground, blew sideways, either coming undone from their locking joints or snapping right off. Then the entire masts toppled over sideways, straining against their guy anchors, many of which came ripping right out of the ground. Guy wires flew menacingly across the darkening sky. I was very fortunate not to be downwind of the masts when they blew over, because I was closer to them than they were tall. After this, I dithered no further outside.

After weathering out the storm inside the Science Building at Montgomery College until it was merely raining, we emerged to survey the extent of the damage. Those two masts were the only things that were damaged by the storm. Everything else survived just fine. Unfortunately in the meantime darkness had descended, and making progress on putting up that 20m Yagi became nearly impossible.

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Taking amateur radio to the next level

Monday, June 30th, 2008

This weekend was pretty awesome. Saturday was jam-packed with ham radio activities, from morning until midnight (and beyond). That’s right, an entire day of ham radio! I started off by installing the 17-foot antenna I bought awhile back on top of our house. That took a good four to five hours, many of them spent on top of a burning-hot roof forty feet in the air. But it was worth it! Here’s a close-up look at the antenna.

Don’t be fooled by the upwards-looking perspective; this antenna is a full 17′ tall. The mount also adds about two feet to the overall height. Altogether, the antenna is about 30′ in the air. That’s not bad considering we didn’t have to put up a tower or anything. The three spokes sticking out of the bottom of the antenna are the radials, which create the ground plane for the radio signals. And I should point out that this antenna is a marked improvement over my previous antenna, which was a 44-incher at ground level.

The two flanges of the mount are located off-center on the pressure-treated wood blocks. This was not intentional, but rather, a consequence of bad measurement and trying to get the darn thing straight up in the air. But don’t let its looks fool you: the mount itself is rock-solid. You could throw a grappling hook through the mount and ascend to the roof from the ground. Each wooden block is secured with four 4.5″ bolts to blocks of wood on the interior of the house that are screwed directly into the house’s frame.

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Antenna preparations for ARRL Field Day

Friday, June 20th, 2008

It’s been awhile since I’ve discussed non-computer-related construction projects on this blog, so to break the drought, here are some details on a shortly upcoming antenna project.

The Amateur Radio Relay League’s annual Field Day is coming up next weekend. Field Day is the largest weekend of the year for amateur radio operators. It includes of all sorts of outreach activities, as well as heavy contesting (racing to see who can make the most radio contacts over the weekend). Since I only became involved with amateur radio recently, it’ll be my first Field Day. Unfortunately, the only antenna I’m operational on right now is a 44″ magnetic mount 70cm/2m dual-band whip antenna. It’s decent for operating mobile, but its performance isn’t anything to write home about.

Luckily, I bought a 17-foot 70m/2m dual-band base station antenna at a hamfest in March. A 201.5″ antenna is a bit more impressive than a 44″ antenna, don’t you think? I haven’t actually gotten around to installing the antenna yet, but Field Day is as good a reason as any to finally get it done. I’ve already done all the prep work and assembled the mount, which you can see in the picture. The domestic house cat is for scale.

I bought all the parts from Home Depot at not-too-ridiculous prices. All of it is galvanized steel (and thus rustproof), except for the tee-junction, which this particular Home Depot seemed to be out of in galvi. I do have a can of clear gloss waterproofing spray paint laying around though — hopefully a couple layers should be enough to keep the tee-junction safe from the weather. Most of the piping is 1″ interior diameter.

As for how the mount works, it will be installed vertically just below the peak of the roof on the side of the house. The two flanges will be secured to the side of the house using four-inch-long bolt screws. The screws will, of course, be going into studs accessible from inside the attic. The aluminum tube you see attached to the top of the mounting assembly is the base of the antenna; the antenna itself simply drops right into it once the mount is attached to the house. As for the decision of the overall placement, I’m putting the mount on the side of the house instead of on top of it so I don’t have to drill any holes through the roof, which could potentially cause some leaking.

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An amazing 4X Yagi array

Monday, April 7th, 2008

This right here is the definition of want:

Yes, that’s right, it’s a 4X Yagi antenna array on an electronically controlled alt-azimuth mount. Oh man, what I wouldn’t do to have one of those. It’s amazing. It has four times the antennae of a simple Yagi beam, thus four times the gain (an increase of 6 dB). And the alt-azimuth mount gives you two full degrees of freedom, allowing you to track satellites. The one problem I see is that it looks like the Yagis are horizontally polarized (although it’s hard to tell from the YouTube video), whereas for space contact you’d want them to be cross-polarized to account for spinning satellites. It’s still an impressive show all around though.

Plus, you can’t deny how cool it is. It reminds me of a Death Star laser turret, only it’s used for peace, not war. You can’t claim to be a nerd if, after seeing a video of a 4X Yagi array on an electronically controlled alt-azimuth mouth, you have any thought other than “I want one of those”.

Attending my first hamfest

Sunday, March 30th, 2008

Earlier today I attended my first hamfest (amateur radio convention), the Greater Baltimore Hamboree and Computerfest in Timonium, Maryland. Having just started with ham radio less than a month ago, I’m definitely getting into it pretty quickly. The rate at which I’m blowing through money will attest to that.

Overall, I give the hamfest mixed reviews. I’ll start with the negatives first so we can end on a positive note. Most of the negatives stem from my misconceptions of what this hamfest was. I was expecting a convention where the main activity is chatting up fellow hams and checking out cool rigs, but this hamfest turned out to be basically a large flea market, with a good mix of professional and not-so-professional vendors. It had a $10 per head admission charge.

The computer part of the show was just outright crap. Most of the computers on sale looked like they were acquired by the pallet-load from public auction, and simply weren’t worth buying even at the low asking price of $100-$200. I swear, some of those computers were pushing ten years old. If you wanted cheap and/or used peripherals though, this was your place (yay for $5 three generation old non-scroll-wheel optical mice). And if you want to risk all of the rest of your expensive computer components on shady unmarked power supplies, this was your opportunity! In the end, I just couldn’t justify spending any money on the computer stuff, so I didn’t. I’ll take NewEgg any day of the year. The tailgating part was especially depressing; a bunch of people (some of them hucksters) were selling miscellaneous computer and electronics junk set up on cheap tables out in the parking lot. I saw electronics equipment that was decades old. Who wants this stuff?!

There were lots of vendors selling vacuum tubes of all shapes and sizes, tens of thousands of them. The average price was about $1.00 per tube, which my dad says is less than they used to cost decades ago when they were still widely used (and that’s not taking inflation into account). None of the tubes were manufactured in the past few decades either. It’s like the transistor exploded onto the electronics scene so quickly and so completely that the inventory of tubes the manufacturers happened to have on-hand at the time was more than enough to satisfy the entire lingering tube market in perpetuity.

A lot of the vendors were, and there’s no other way to put it, shady. I wouldn’t go so far as to accuse them of having outright stolen what they were selling, but a lot of it wasn’t on the level, starting with the fact that most people weren’t charging sales tax and probably weren’t even reporting their sales to the IRS. There was no way to verify if a lot of things that were on sale were actually working, and presumably no way to return them if they weren’t. I’m also not intimately familiar with most of the kinds of things that were on sale, and I would have no idea if I was getting a good deal or a bad deal.

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