My friend Gaye (www.backdoorsurvival.com) and her hubby are proud new ham radio owners, having picked up a pair of Baofeng UV-5R 136-174/400-480 MHz Dual-Band DTMF CTCSS DCS FM Ham Two Way Radio at under $30 each, along with a programming cable (USB Programming Cable for Baofeng UV-5R UV-3R+ Two way Radio With Driver CD) for less than $7-bucks. Dandy season gift, huh?
Which means, they’re about to pick up ham radio licenses and become part of a US population of hams which presently numbers (as of a year ago) in the area of 710,000.
I think a couple of things have driven them to ham radio. The most recent being that they live in the San Juan Islands of Washington State. And, up there, they were recently part of the 20,000 people, or so, who were impacted by a major Internet failure when fiber optic cable serving the islands’ population was severed due (apparently) to a small undersea earth slide and accompanying small quake.
That little adventure left them without communications which became very spotted. Ever check the cost of roaming from the US to Canada? That IF you could get a connection.
A good bit of the San Juan island group is covered by radio services, such as the Mt. Constitution tower site which puts antennas up at 2300 – feet, or so. In addition to things like public safety (fire and police agencies) such towers (around most of the US) provide television coverage, cell phone antenna space, and more.
What was interesting during the Internet issues, was that the two-way services kept on working, since the AC power to the island didn’t fail. And, even if it had, there is plenty of back-up and emergency power at the typical such mountain-top site.
And it’s on tall towers that this that ham radio clubs often put their “repeaters.”
The operation of a repeater is pretty simple: A person transmits on one frequency (called the repeater input frequency) which is “heard” by a receiver on a high location (like Mt. Constitution). The “repeater” then rebroadcasts this on what’s call the “repeater output” which is a different frequency, often times 600 kilohertz above, or below the input frequency.
This difference between the input frequency is also commonly called the “off-set” of the repeater.
Only one more little addition: Sub audible tones.
Pretend, for a moment, that you didn’t want random interference to “key” (begin transmitting) of your repeater on a mountain somewhere. How would you prevent it?
One simple way is to encode a low-frequency audio tone – something that would almost never happen with interference. All you need to do is inject a low frequency tone, say 103.5 Hz, into the audio of the handheld unit and tell the repeater (using a very selective audio filter) not to transmit until this tone is heard.
This technology has been around for a long time and is called a CTCSS tone and most ham radio repeaters (as well as public services) use them. It stands for Continuous Tone-Coded Squelch System.
A few other useful things to know about tone encoding systems: It’s a variant (quite audible) of this tone-encoding system that is used by the National Weather Service to trigger NOAA Weather Radio Alerts. You can read move about the alert system (as well as discover the tone frequency they use is 1060 Hz) and get a list of receiver manufacturers over at the NOAA website here.
Gaye and I spent a fair bit of time figuring out which ham radios they wanted as “beginner rigs” and the Baofengs are very good. For under $30-bucks, are you kidding?
But Gaye’s a stickler for detail, so this led her to learning about the UV-5R reviews over at eHam.net, which is a favorite watering hole for hams to post reviews and thoughts on equipment, both new and old school.
As long as you’re over at eHam, check out their review of the Nagoya-771 antenna here.
Here’s how the antenna discussion game up: Gaye and Shelly are both in Seattle and the Eastside often.; And, since Mt. Constitution is about 80 miles (liner of sight) from Mt. Constitution, the odds of making a reliable connection at that distance is fairly low with the “stock” antenna with the Baofeng.
However, the odds improve after seven bucks per radio spent on the Nagoya NA-771 dual band 144/430Mhz U/V SMA-F antenna for Baofeng UV-5R radios.
That ought to get them coverage from most of Anacortes up into the Islands from the ferry terminal in Anacortes. But will they be able to connect into Seattle? Or, into Bellevue?
This is where budding hams, like our friends up north learn about the differences between antenna height above sea level and HAAT, or antenna “height above average terrain.”
So Can They Communicate?
Pardon the crude drawing here, but here’s how the question (can they communicate?) will be solved:
We know that the Mt. Constitution ham repeater is at 2,300 feet elevation (*above mean sea level) and so we click over to the one of the convenient online calculators to keep us from having to find a calculator to work out the formulas by hand. Their output frequency (the one to listen to) is 146.740 MHz. Tone is 103.5.
A good one is located over here. And we can see that if the mountain is 2300 feet to the antenna (or thereabouts) and the handheld radio is at 100 feet up, then it should work.
But there are a couple of variables here that are still flapping around in the breeze.
The first is that we don’t know how strong the signal from a 5-watt handheld will be from Seattle up to the mountain. Radio waves, you know, propagate at the “inverse square law.” This simply means that at twice the distance, there’s only a quarter of the power. Do that several times because of the distance involved in getting 5-watts to “talk” 90 miles and a LOT of whether this works will depend on how a) sensitive the Mt. Constitution receiver is – and where its squelch threshold is set and b) how high the handheld radio is above average terrain.
If you look at a map, there’s a lot of high ground between Seattle and Mt. Constitution. And while height above sea level is useful, it’s only applicable when you’re using boats and open water. In this case we have a good chunk of Whidbey Island in our way.
By the way, this map is something I snipped out of Streets and Trips 2013 with GPS which is now under $40 at Amazon. You talk about a great stocking stuffer?
We always fly our old Beechcrate with my traveling computer (with Streets and Trips) and the USB-GPS antenna) as a “just in case” tool. No, it doesn’t given airport data, but if I can just find an airport, I can land by just looking at it.