Friday, September 4, 2009

Finally Have An HF Radio

I've been a licensed amateur radio operator in the United States since 2000. I upgraded to the General class license last year with the intention of getting in to HF communication. The license requires studying and $12, but where the hobby really gets you is the equipment costs. Starting from nothing, you could spend as much as $1000 to get on the air with moderately recent radio equipment. So, getting a radio has taken a back seat to other things.

But all that changed the other day. I've been following eBay auctions for radios and finally found one I liked and was able to get it for $415. It's an Icom IC-706 (the original 706 model, not the Mk II and not the Mk IIg), which is maybe around 10 years old now, maybe less. However, it falls with the price point, age, size, and capabilities that I'm looking for.

The radio was offered on eBay by an amateur radio operator in Japan. He shipped it yesterday and I've been following it on the Japan Post English tracking site.

Aside from the radio and assuming the radio is actually functional, I have a number of other things that I need before I can actually get on the air. For example:
  • An antenna tuner. Looking at the LDG Z-11 Pro and Z-100Plus.
  • A DC power supply rated at least at 20 amps continuous. Astron makes one that fits this category and it also has cool meters on it.
  • An antenna to use the VHF part of the 706. While I have a perfectly usable HT that does VHF, I'd like to at least hook up the 706 for that because I may want to use it. The 706 only does 10 watts on VHF, which is twice what the HT does. The VHF/UHF rig in my car does 50/35.
  • An HF antenna. This is going to be the most complicated part because of where I live.
And then there's the fluff (none of this is critical, but would be fun to have):
  • West Mountain Radio RIGblaster for digital mode interfacing.
  • External speaker. I'm usually fine with the speakers in radios.
  • Headphones.
  • Fancy mic with DTMF keypad (buttons that beep).
  • SSB filters for the 706 (assuming it comes with none).
  • DSP filter for the 706 (also assuming it lacks this).
  • The whole setup mounted in a box for portable operation.
  • A generator (I can't run one here anyway).
  • West Mountain Radio RIGrunner on the assumption that I may get more than one radio at home.
That list can go on forever. The tuner and power supply are more or less picked out. Just need to buy them. The VHF antenna is pretty simple. I can use a magmount Diamond mobile or J-pole or something like that. The concern I have is with the HF antenna.

Enter my limited knowledge of HF antennas. First some basic theory. The speed of light equals frequency (in Hertz) times the wavelength (in meters). We usually talk about megahertz (1 million Hertz) or kilohertz (1 thousand Hertz), so keep that in mind for the formula.

Given one we can calculate the other. And very quickly you'll see that the two are inversely proportional. So the lower the frequency the higher the bandwidth. The HF bands are the lowest frequencies that amateur radio operators can use, the lowest being 1.8 MHz, which falls around 160 meters for the wavelength.

Why is any of this important? The wavelength is what you need to build effective antennas. Dipole antennas are good and ideal dipoles are one-half the wavelength. So an ideal dipole for 1.8 MHz would be 80 meters long (or just over 262 feet if you refuse to use metric). An antenna that large, even a quarter-length antenna is more or less impossible to have when you live in a condo.

Apartment and condo dwellers have come up with really interesting and unique antenna designs to operate on HF bands without the ability to set up large antennas. One of my favorites is making a dipole antenna using two metal Slinky toys. To have an antenna made from a Slinky would be cool. Click here for more information.

Another one that I like that's been recommended before is the TAK-tenna. I really like the design of the TAK-tenna and the fact that it would be outdoors. Also looks like it'd stand up to the environment here a bit better than others.

In the radio club I belong to, one of the members suggesting using the railing on the lanai as an antenna. Connect a tuner to it and tune it to whatever band and see how it works.

I think I'm going to have to use some creative variant on the dipole given the grounding limitations here. Any other antenna ideas? Again, I've been an operator for almost 10 years and am just now getting in to HF.