A recording of AO-51

There was a good AO-51 pass here earlier, and I managed to hook up my radio to the laptop and record some of it with my IOio antenna. This was about a 50 degree eastern pass for me, so it was one I could easily listen to from my living room. After picking it up around due east, I was able to follow it down to about 5 degrees of elevation and 350 degrees on the compass heading. I heard calls from CA, WA, AZ, UT, OR, TX, and one guy in Mexico, at the very end no less! Good stuff. I still haven't added coax to the 145 MHz element, so I'm not able to attempt QSOs, but I'm confident that it will work well for that when the time comes.

Click below to listen to my recording.

Ao-51_2-20-10

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Building an IOio satellite antenna

I've had this post on my to-do list for a couple of weeks, but I needed to wrap up the build and take some pictures before I could write a complete entry. 

It wasn't until after I got my license that I became fully aware of the fact that there are orbiting ham radio satellites which can be used to make QSOs with little more than a 5 watt radio and a directional antenna. Step one for me was to buy an HT, which I did as a Christmas present to myself back in December. I had hoped I would be able to make the occasional QSO using a Yaesu VX-7R and a Diamond SRH320A whip antenna, but after many fruitless attempts I concluded that I needed better "ears." I had been planning to buy an Arrow satellite antenna, but they're about $170 and I like home-brewing. Enter the IOio.

The IOio was designed by EA4CYQ as a home-brew portable satellite antenna that was easier to transport than the Arrow but had similar receive and transmit gain. He wanted something that was "two-dimensional" instead of "three-dimensional" (the Arrow is a pair of yagis at 90 degrees to each other), lightweight, and somewhat collapsible. You can read his original build instructions and such here (PDF format). They include a good diagram of how the antenna goes together. The IOio seemed like a simple place to start my quest for a better satellite antenna so, after familiarizing myself with the design I got together with my friend Nick, N1UBZ, and set to work.

My first stop was Nick's garage. His landlord is a charming old man who lives next door, and Nick's garage is filled with the detritus of a lifetime of handywork. Hose reel made out of a Mustang alloy rim? Check. Massive air compressor? Check. Overhead chain hoist? Check. It also has a wide variety of scrap metal, wood, and plastic. We found a nice piece of 1" PVC with thin walls, 51" long so more than enough for the antenna and some excess to hold onto. Then we headed off to Discount Builders' Supply. It's bigger than a hardware store, but smaller than a Home Depot or Lowes, so it has a big selection of stuff without you needing a map to find your way around.

The first thing we needed was something to use for the elements. EA4CYQ's instructions are a little light on details about what materials he used. For the elements he just mentions "steely wire." For more detail I turned to 2E0HTS, a ham from Northern England who likes to work the ham sats, builds his own antennas, blogs, and posts YouTube videos. He's made a few IOios, and his instructions here were enlightening, as he mentions using TIG welding wire. We headed for the welding section, and after a little poking around we found 1/8" diameter copper-coated steel welding rods, in pre-cut 36" lengths. Perfect! The steel will bend, but hold its shape better than solid copper, yet the copper outside will be a snap to solder to! We bought six rods at $0.69 each. A packet of 4" cable ties and a roll of 3/32" rosin core 40/60 plumbing solder rounded out our purchases.

Back at the ranch we got to work. The first step was making the 435 MHz driven and reflected elements. These were easy enough, since both are shorter than 36", so they could be made out of one rod each. The driven element is a rectangle, 4.25" by 9.37". The reflected element is just a straight rod, 13.25" long. 

Drill your first 1/8" diameter hole near one end of the PVC pipe and make sure it goes straight through! You don't want crooked elements later. Then cut your driven element to length, 27.25", and pass it through the first hole. Measure 8.95" from each end and make a 90 degree bend there. Now measure 4.25" down from each bend and make another 90 degree bend there. You should now have a nice straight rectangle; bend the ends out 90 degrees, parallel with the short sides, so that there is about a 1" gap between them. Drill a second hole in the PVC pipe for the ends of the element to fit into. Try to make it more of a slot than a hole, 1/8" by 1/2". Slide two of the shaft collars over each end of the element, and then wiggle it around until you hook each end into the slot you've drilled. You can lightly tighten the shaft collars for now, we'll set them up properly later.

Drill another 1/8" hole in the PVC, 2" below where the straight part of the driven element sits in its slot. Again, make sure it's straight and that it lines up with the others. Insert your reflected element into that, slide a shaft collar over each end and lightly tighten to hold it in place. Congratulations, you have a 435 MHz antenna!

The 145 MHz elements are harder to make, as both are longer than 36", and so will need to be made from two pieces of rod soldered together. The reflected element needs to be 39.5" long. Rather than taking one 36" rod and adding 3.5" to one side, we took two and cut 19.75" off of each, so the joint would be in the center. At first we tried just soldering the rods end to end, in a butt-joint, but it wasn't strong enough. Nick rummaged around in the garage and came up with a piece of scrap sheet copper. He cut a little 3/4" square out of it with tin snips, rolled it into a tube, and used it to sleeve the ends of each rod. Don't make the tube wider, because we want it to sit entirely inside the PVC. We clamped one rod, and I held the other steady, while Nick applied a torch and solder. On his first attempt he applied too much heat and ended up burning off the copper coating, so it wouldn't take solder anymore. We flipped the rod around and went a little easier on it for the second try, and it worked perfectly. 

The 145 MHz driven element is the hardest of the four to make. It's a rectangle 27.75" by 12.75", so that's 81" long. Since it's going to be open at one end anyway, just like the 435 MHz driven element was, we cheated a little bit. First, drill a 1/8" hole 4" down from the 435 reflected element. Again, try to keep it aligned with the holes you've already drilled so everything comes out straight at the end. Take one 36" rod and pass it through. Make two 90 degree bends in it at 4.12" (4 and 1/8") from the ends. Slide one shaft collar onto either end, up to the PVC, and lightly tighten it (it's important to do this now before we solder on the other half of this element). Take two more 36" rods and cut 22.5" off each. Make a 90 degree bend in each of those at 8.63" (8 and 5/8") from one end. Now solder each short side onto one end of the piece you installed earlier, making one large rectangle! As with the 435 MHz driven element, bend out the open ends of this rectangle 90 degrees, and then drill slots in the PVC for them to clip into.

To install the 145 MHz reflected element, drill another hole 6" down from the slot that the driven element snaps into. This hole will need to be a little larger than 1/8", to accommodate the solder joint, but try to keep it as small as possible to minimize wiggling of the element when you are pointing the antenna. Attach two more shaft collars and you're done with the construction!

All that's left to do now is solder a piece of coax to each driven element and connect it to a diplexer, or to your dual-band, dual-antenna rig if you have one (or, if there is such a thing). I only had one piece of scrap RG-6 coax handy (left behind by a cable TV installer), so we decided to solder that to the 435 MHz element temporarily, so we could test it and I could use it t
o practice listening to the sats. The braid of this coax turned out to be aluminum, so it wouldn't solder to the copper of the elements. Nick bodged it together by tying it on with a piece of desoldering braid, and then soldering the braid to the element. The center pin soldered up with no issues. I will say that Nick has a Metcal soldering station. I suspect that my cheap-o Weller would not have been able to cope with the amount of heatsink that the antenna elements provide.

Nick has an antenna analyzer, so we used it to check out the 435 MHz antenna. It's resonant at 443 MHz, and the VSWR at 435 is 1.58. That's pretty good for DIY, I'd say! I don't know if it will get any better when I switch to 50 ohm coax or not. You can see the output graph here.

The last step is to tighten up the shaft collars. In order for them to get a solid hold on the PVC, I used a pair of vise grips to lightly squeeze the pipe while I tightened the collars. Then when I released the grips, the pipe pressed against the collars snugly for a good grip. 

That's it! My main take-aways from the build experience were to be precise when drilling holes in the boom, so the elements don't wiggle around; have the shaft collars on hand before you start so you can put them on before you solder anything; and bend the rectangular elements after you insert the rod into the first mounting hole (so you can keep that hole small). If you look at the photos of the finished antenna you'll see that I used some zip ties to anchor the front end of the 145 MHz driven element to the 435 reflected element, because I couldn't fit the shaft collars on after we had soldered it up.

So far I have only used the antenna as a receiver, but it works really well for that. I've been able to listen to several passes of AO-51 just standing in my living room and pointing it towards my large east-facing windows. I haven't had a chance to take it outside for a full horizon-to-horizon test, but hopefully I will soon.

Many thanks to Nick for all his help with the construction, and to Rob, AK6L, for the coax. You can see some photos of the build process and completed product here. My next project will be to build a diplexer, so I can use the TX antenna and start making some QSOs.

Lengths of elements ("front to back"):

435 MHz driven element: 9.37" (9 and 3/8") by 4.25"
2" space
Reflected element: 13.25"
4" space
145 MHz driven element: 27.75" by 12.75"
6" space
Reflected element: 39.5"

Materials list:

175" of welding wire (McMaster Carr - 1 lb package)
36" or more of 1", thin-walled PVC pipe
A small amount of scrap copper sheet
4" cable/zip ties
12 set screw shaft collars with a 3/16" inner diameter (McMaster Carr)
3/32" rosin core 40/60 plumbing solder
Two pieces of coax, length and type (50 ohm preferred) of your choosing
Strong wire cutters or tin snips
Propane torch
Power drill and bits
Digital calipers (very helpful but not crucial)

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ɹǝpun uʍop sɹǝʇǝɯ oʍʇ uO

I figured that my recent trip to Australia would be a good opportunity to use my new HT a bit more, so I spent some time investigating what the laws are with regard to American hams operating there. The gist of it is that you get privileges pretty similar to those of your American license, you can operate for up to 30 days without having to get special permission, and you have to identify yourself with your call sign and a suffix of "/VK." Armed with that knowlege I packed the HT, along with its 6m rubber duck and 18" 2m/440 flexi-whip, into my backpack. I figured I would at least hop on a local repeater, and maybe even try to work a satellite pass if possible.

Unfortunately a combination of being very busy with wedding planning and, surprisingly, a bit of mic stage fright at times, kept me from diving in. I did scan around for a bit and found a local 2m system that seemed reasonably active. Finally I found a spare half hour, gritted my teeth, and said, "This is KJ6AKQ/VK, that's kilo juliet six, alpha kilo quebec slash VK, visiting from America and monitoring." I've never heard of a pile-on happening on a 2m repeater, but I think the response I got can safely be described that way. 

I only had time to work one station, Ian/VK3VIG. We talked about what I was doing in Australia, how I liked it, what rig I was using, what we did for New Year's, and then I asked if there were any other repeaters around that I should know about. Ian told me about one in particular, VK3RHF. It's a four-way system that simulcasts on 23cm, 70cm, 6m and 10m. He said I might be able to get some DX on it if the 10m conditions were any good. An Aussie ham in #hamradio had told me that he heard someone in Melbourne, distant to him, on 10m via a repeater matching this description. I figured this must be it.

Sadly, I wasn't able to get another chance to get on the air and try it. I'll be back in Melbourne in March for my wedding, but I'm not sure my marriage will last very long if I try and bring the HT on that trip.

I did manage to break out the radio on one other occasion, though not for accessing a repeater. I saw that there were going to be two successive satellite passes, one by AO-51 with an 89 degree max angle, and one by SO-50 with a 33 degree max angle. I was able to hear the AO-51 pass as it was right overhead, but only for a couple of seconds! I thought it would last a lot longer than that. The SO-50 pass later on lasted a lot longer before I lost it. Considering I was waving my antenna around in the blind, with nothing more than a keychain compass and the knowledge that the bird was due west at 33 degrees, I was pleased. But even then, the audio was too garbled for me to really copy anything like a call sign. I just heard some quieting, and voices.

Now that I'm back home, I'm hoping to get to work on my micro diplexer and handheld satellite antenna this weekend. With any luck that'll be the subject of my next couple of posts.

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Obligatory shack tour

To paraphrase Chris Burger, the author of the excellent "How to make a Morse Code QSO," any discussion of ham radio must commence with a discussion of tools. The "shack tour" is a staple of many ham web sites and blogs, and since we are nothing without our equipment, I figured I might as well start there.

First, my transceiver. My main area of interest with regard to ham radio is DXing, so I've been focusing my attention on learning Morse code and working the HF bands. Wanting to get started right away after I got my license, I borrowed a Norcal 40A QRP radio from my friend Nick, N1UBZ. The Norcal can put out about 2 watts and is confined to 40 meters, so I wasn't expecting much from it, but I figured it was enough to get me started.

After a period of having no luck making QSOs with just the QRP power of the Norcal, a local guy I had met on the #hamradio IRC channel, Rob/AK6L, offered to loan me his Tokyo Hypower HL-45B amplifier, which he wasn't using. The Norcal can easily drive this to more than the 15 watt limit of my antenna tuner, so I keep it scaled back to that level. The amp is meant to be used with a Yaesu FT-817 transmitter, and has an accessory plug for that radio to tell the amp what band it's set to and when the transmitter has been keyed. In order to make it work with the Norcal we needed to build some kind of RF carrier detect switch to trigger the amp during transmissions. Rob came up with a basic design and supplied me with RF connectors and a project box, and then Nick helped us refine it and I put it together. Connected in the RF chain between the transmitter and the amp, it senses when the TX is keyed and turns the amp on at the same moment. Then it lags behind by a second or two before turning it off.

For an antenna, Nick helped me string up a simple 40 meter dipole on the roof of my apartment building. I live on the second floor of a three story building, and there's a fair amount of metal on the roof, so we fed it with RG-8x coax. In its first incarnation, I didn't have much of anything to attach the antenna elements to, so it was suspended pretty close to the roof itself and held up in the center by a three foot PVC pipe stump attached to a vent pipe. In spite of a lot of tinkering, the only QSO I was able to get with that setup was with someone about 35 miles away. With frustration setting in, I resolved to get my antenna up higher. Thanks to a brilliant suggestion from Rob's girlfriend, I bought a couple of patio umbrella bases to support two Radio Shack steel TV antenna masts. The umbrella bases are made of plastic, and can be filled with water for ballast. They support the middle and one end of the antenna up about 10'. The other end is guyed to a hook in the adjacent building, which is 1 story taller than mine, so the whole antenna is roughly level at 10' up. It's oriented from corner to corner of my building, radiating east/west, but because there's not quite enough roof space, the last 4-6 feet of each end is folded downward. This has improved things dramatically, and I've now had three QSOs with this setup, one with someone in Arizona and two with people in southern California.

The other two components of my HF setup currently are an Alinco DM-330MV power supply and an Emtech ZM-2 tuner which I built from a kit.

In addition to HF DX, two other aspects of ham radio that interest me are emergency communications and ham radio satellites. Living in earthquake country, the emcomm thing is kind of a no-brainer. In the aftermath of a major earthquake one needs to be able to be self-sufficient for a couple of days and, if possible, volunteer in any search and rescue efforts that might need to happen. There are countless examples of ordinary people saving lives after the 1989 Loma Prieta quake in San Francisco, and it pays to be prepared for situations like that. As for the ham satellites, most of them have an FM 2m/440MHz repeater on board. If you want to work through those, you need a radio that can put out a few watts at 145 MHz and receive at 435 MHz at or nearly at the same time.

To both of these ends, I decided to buy an HT. To some people this stands for "handheld transceiver," but I prefer the much nerdier-sounding "handie-talkie." After a bit of research, I settled on the Yaesu VX-7R, and bought it (along with a hand mic and an upgraded antenna) for myself as a Christmas present. So far I have just used it to chat on the local repeaters a little bit. I've tried a couple of times to hear passing ham satellites, but haven't had any luck so far. This will lead us to a post on "future projects," but I'll save that for later.

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It begins

I decided to create a blog where I can write about my interest in ham radio. I passed my Technician and General license tests on the same day in June of this year. I've ramped up very slowly in the intervening time, owing variously to lack of free time, lack of a good location to put up an HF antenna, and other such things. More to come in a future post.

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