Archive for February, 2009

More posts coming soon

Wednesday, February 11th, 2009

Hi there. Yes, I’m alive, and I’ve actually been doing some interesting things to post about, I just haven’t made time to post. I hope to remedy that soon.

Most of my “interesting stuff” is ham and/or electronics related. I got a soldering iron for Christmas, and I’ve put together a few kits and I’m in the process of putting together a few more, including an SDR receiver and a Morse code transceiver. I’ve also started tinkering with AVR microcontrollers.

During the holidays Luke got in the habit of going to sleep really late. After the holidays, he kept it up. I’d guess than during January, his average bedtime was 10:30pm. That doesn’t leave much time for dad to play with his toys. Luckily, he’s been going to sleep around 9pm the last week or so. He slipped a little tonight, but I’m not too worried about him regressing.

In other sleep-related news, we had been letting Liam sleep in his swing for the past few months. We knew it was a bad habit to form, but he slept so well in it. He went from getting up 2-3 times a night to 0-1 times a night. This week we finally decided it was time to break the habit. The first few nights were rough, but last night he only got up once. Luke got up once until he was about 15 months old (Liam is only 6 months old), so I don’t guess we can ask for much more.

So, if the boys keep up their good sleeping routines, you should be seeing a lot more posted here.

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My “new” antenna

Wednesday, February 11th, 2009

Back in October I mentioned that my dad had come down to help me put up a ham radio antenna. I never got around to saying any more about it. Well, now I am.

The antenna he had come to help me put up was a Diamond X50NA. It’s a 2m/70cm antenna. 2 meters is a popular VHF ham band, and the local club has a 2m repeater. The club also has a 70cm repeater less than a mile from my house. I don’t currently have a radio that supports 70cm, but when I get one, I don’t have to worry about an antenna.

The X50NA is not a small antenna. It’s over five and a half feet tall. I needed a substantial support to install it on. Also, at VHF frequencies and above, propagation is essentially line of sight, meaning that height is very important.

Luckily, when my grandmother moved a few years ago, she didn’t need all of the tower her TV antenna was on. My dad had taken the parts she didn’t need and stored them for a “rainy day.” (God bless pack rats.) So the base of my antenna support would be two sections of what appear to be Rohn 25G. On top of that we mounted a 10′ section of 2″ pipe using muffler clamps. Inside that, we placed a 10′ section of 1 1/2″ pipe restrained using a hose clamp. And on top of all that went the antenna. I estimate the base of the antenna is up about 25 to 30 feet.

I feed it with around 60 ft. of LMR-400 (PDF), a low-loss coax. Coax tends to be pretty lossy at VHF frequencies, so I wanted to go with the good stuff. At 147.33 MHz, the frequency of the local repeater, LMR-400 has a loss of 1.52dB (29%) per 100ft. The next best stuff, RG-213, has a loss of 2.50dB (44%) per 100 ft.

As you may recall, the only radio I have at the moment (that’s put together anyway) is a Yaesu VX-170, a handheld 2m transceiver. To reliably talk on the local repeater I had to walk up on the hill behind my house. When the repeater was having a bad day, as it sometimes does, I would even have to hook it up to my quarter wave ground plane antenna that I built to get into the repeater.

Now I can reliably talk on the repeater, even with my radio turned down to low power (500mW). I can also talk on the Pontotoc and New Albany repeaters, though I’m told I’m a little scratchy on the New Albany one. I had hoped to be able to hit the Batesville, Mooreville, and maybe even the Grenada repeaters. I still feel like I ought to be able to hit the Batesville repeater, I but I don’t even receive it well here for some reason. The Mooreville repeater was always a little optimistic, as Mooreville is all the way on the other side of Tupelo, but it’s on a tall tower, and I can hit it from inside my car halfway between Pontotoc and Oxford.
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