The High-Frequency (HF) Project

My only real experience with emergency radio communications involves 2-meter/VHF and 800Mhz/UHF. Both rely on existing infrastructure to operate well. Either local 2-meter repeaters or the 800Mhz municipal trunking system. In addition to my portable HT, I have a couple of old 2m mobiles that I use for temporary base stations. While fairly easy to operate, their distance is limited to "around town." This is convenient for local emergencies, but there are scenarios where one needs to reach out much further. While I can only count on one hand the number of times I've seen our infrastructure become unavailable during an emergency I don't want to be left without any options should it happen again.

Thinking of the Audience

One of the challenges of trying to bring different groups of readers together (amateur radio, hardware hackers, and social media types) is choosing which group is the primary audience for a piece. In this particular case, the initial audience that I imagined was Me. Mainly because I'm writing this down as I do it-- or shortly after an experiment/phase is completed. Later on I'll try to extrapolate on sections to make it approachable from all of the groups. What I'm trying to do, a majority of amateur radio operators have already done, so they're going to be chuckling to themselves as I make blunders, so I'll instead try to focus on beginning radio operators and try to translate it to people with stronger Internet backgrounds. With that settled, on to...

What is High-Frequency?

Hopefully you're familiar with the concept of the radio spectrum. Radios usually work only on small slices of the radio spectrum and don't cover the entire spectrum (although exceptions do exist.) Plus not every frequency is ideal for every type of transmission mode (e.g. voice vs. data.) When describing what frequency you're on, people typically use the frequency (e.g. 440 MHz or 2.4GHz) but when discussing a chunk of the spectrum they instead use the wavelength (e.g. 70cm or 13cm.) These are known as bands and each band had a band-plan or an agreement on how chunks of the spectrum will be used.

With me so far? So we have frequencies, and we have bands, now we'll look at groups of bands, or "ranges." Radios that work in the 2m band are also referred to as Very High Frequency (VHF) radios. While your 2.4GHz wi-fi WLAN is working in the upper side of the Ultra High Frequency (UHF) range. While the topic of discussion is plain-old High Frequency (HF) which includes the largest number of bands (9) but covers a small bit of spectrum: 3.5 to 29.7 MHz. Each band has subtle differences in propagation (e.g some work long distances during the daytime, others are long-distance day or night, except when there's high sunspot activity) and each has it's own peculiar temperament and modes of operation.

Finding Liberation in Constraints

So you want to get some HF experience, where do you start? I often suffer from "option-paralysis" where the number of alternatives exceeds my ability to weigh all of the options. There are a lot of bands to choose from in HF. So first, I'll limit what I'm trying to accomplish down from something vague like "I want HF capability/experience" to something more measurable like: "I want to connect to a WinLink node via HF." This will sufficiently demonstrate to myself that it can be done, and I can stick with digital modes and not really have to coordinate with anyone else so I can work at my own pace.

So, now that I've set a goal for myself, how do I get there? Again there are so many options. Fortunately I have a few more constraints imposed. Firstly, HF transceivers aren't cheap. Used ones still run three to five hundred dollars. I currently have an old Kenwood TS-520 that I picked up at an estate sale a few years ago, but never had the courage to fire it up. That limits the bands that I can easily operate on.

The next big design decision is the antenna. This will be transmitting, so I have to be more conscious about where I put the antenna and how much power I put through it. I'm really not keen on setting up a permanent shack in the house, and I like the idea of being mobile/portable(ish-- they don't call the TS-520 a boat-anchor for nothing.) So I started looking into using mobile antennas because they're relatively inexpensive (say about $20 to $40 for a whip antenna) and I don't have hundreds of feet to install a wire dipole outside. After a few nights of hemming and hawing on things, I ordered a few antennas from eBay and a mount that allows you to hook up two antennas to create a bit of a dipole configuration.

While those are in the mail, I'm planning my feed-line for my first night on HF. I'm not sure if I'm going to end up at my stated goal, but I am going to learn a thing or two along the way.

What is WinLink?

But first, a sidebar on WinLink. There are a couple of active projects that integrate amateur radio and the Internet. There is:

• APRS-- which is a twitter-like service over packet radio with a strong geo-location focus.
• Echolink-- which links geographically- and band- diverse transceivers using VOIP technology.
• WinLink 2000-- a network of computer/transceiver nodes intended to route email over the Internet or radio.

So simply put, WinLink a way to send and receive email (including attachments) in situations when you don't have reliable internet access. It's very popular with ships at sea and in emergency communications situations. So you can see the appeal that it has for me.

The Antennas Arrive

Today one of the packages arrive. It contains two 17-meter mobile whip antennas, a single 40-meter whip antenna and a nice bracket that creates a keen little dipole out of two matched mobile whip antennas. The very astute reader will begin chuckling as they realize my big mistake. So I have enough parts to start building a portable 17-meter dipole. Unfortunately my radio doesn't operate on 17-meters. Funny story: in 1979 the powers that be set aside portions of the 17-meter band for amateur radio use, before then, there were no frequencies allocated for hams. Another interesting fact about 17-meters is that is supposed to stay free of contest related traffic. When I was shopping I took that into account when making my antenna purchasing decision-- well that and it was the only band that had 2 identical and affordable antennas available. My Kenwood TS-520 was produced in the mid to late 70s. So no 17-meter on my current rig. I'll just set those whips aside for a moment and take a look at the 40-meter and the 10-meter that should be arriving any day now.

The Other Components

In order to really get on the air I need the following:

• Transceiver-- check
• Antenna-- check, mostly
• Feed lines-- I need to get the signal to/from the antenna and the transceiver.

Choosing the proper feed line is yet another balancing act of competing requirements. The trick is to match the right cable to the frequencies that you want to operate on for a cost that you can afford. Another major factor is the length of cable that you need. I'm guessing that I'll need perhaps 50' at the most for these tests. That's enough to run out a window to the back yard, or around the corner if I'm completely outside, or from my office up into the attic through a hole I drilled in the closet many years ago.

Since I'm operating at low, HF frequencies (yeah, that sounds contradictory to me too,) running about 50' or less I can get away with the cheaper RG-58 cable. I can get a 50' rg-58 assembly with ends for $18.99 at my local radio shack. A www.universal-radio.com, the local toy store here in Columbus, 50' will cost me $12, but I'll have to put on the ends myself. For $24.95 I can get 50' of RG-8X with ends-- which is a little better cable.

So a little shopping trip is in order...