Short Wave Radio [58]

By Peter Osman

The farthest from civilization I’ve ever kayaked is within the Kent group of islands in the middle of Bass Strait. A wonderful wild place and easy to get to, We traveled there on a fishing boat organized by Vince and spent most of the Christmas break 2003/04 paddling around the islands. You can understand it was really important to track the weather. So what options were feasible?

Some sources of weather information

The Bureau of Meteorology (BoM) marine forecast is available: by telephone on 1900 955 370; by Internet on: http://www.bom.gov.au/weather/global/; on VHF radio; or as a shortwave radio service described at: http://www.bom.gov.au/marine/marine_weather_radio.shtml.

Marine & Safety Tasmania have a site with a list of marine radio stations including Mersey Radio, a very popular site with local fisherman and a valuable source of on water information during the discussion following each forecast. http://www.mast.tas.gov.au/domino/mast/newweb.nsf/

Weatherzone is a source accessible by telephone or Internet but not radio. http://www.weatherzone.com.au/.

Modes of access

  • Satellite telephone – works anywhere but is expensive
  • Shortwave radio – works anywhere but is inappropriate for use at sea
  • CDMA telephone – works most places
  • VHF radio – very patchy coverage, but allows you to call boats within line of sight.
  • Internet cafes – comes with coffee!

In the Kent group of islands the average mobile phone has no chance of getting a signal. A CDMA phone can work, but you need to climb a hill and wander about to receive a signal. Of course a satellite phone will operate anywhere and is likely to be the most effective option, but it’s very costly. Shortwave radio is relatively cheap, typically $250, its reliable and you have many options for sources of weather information. There’s also a deal of fun to be had in operating such a radio well. From here on I’ll just focus on the shortwave receivers. Note they receive but don’t transmit. They are straightforward to use, certainly easier then the average TV remote control, but there are some points worth thinking about.

SW Theory and Terminology

The term frequency is used all the time with radios. It describes the rate at which the radio signal vibrates in cycles per second or Hertz (Hz). A related term is wavelength, which describes how far the wave can travel during one vibration cycle. As radio waves travel at the speed of light the frequency equals the speed of light divided by the wavelength. Radios can be tuned to respond to single frequencies, each carrying a signal from a radio station, one frequency per station.

If a radio is tuned to a frequency between 3 million cycles per second (frequency 3MHz – wavelength 100 meters) and 30 million cycles per second (frequency 30 MHz – wavelength 10 meters) it is operating as a high frequency (HF) radio, or if you are old fashioned a short wave (SW) wireless. Within this range the electromagnetic waves carrying the signal can travel around the world, even with quite low powered equipment. This is because the signals bounce backwards and forwards between the earth and layers of electrically charged air called the ionosphere, which float 50 to 100 km above the earth’s surface. Electromagnetic waves with frequencies greater than 30Mhz, the upper limit of the shortwave spectrum, include: VHF and UHF radio, television, microwaves and light. These tend to shoot straight through the ionosphere into space. Frequencies below 3Mhz the lower limit of the shortwave spectrum, tend to hug the ground and fade away fairly quickly. A useful reference is http://www.wordiq.com/definition/Shortwave

Using A Shortwave Radio To Receive Weather Forecasts

Two important and subtle differences between using a shortwave and a domestic radio are: the single sideband control (SSB) and the ability to pre-select stations using push button tuning.

SSB is essential to receive BoM forecasts and many cheaper radios don’t have it, so its important to check that the radio you buy comes with this facility. What SSB does is cut out redundant information from the signal at the transmitter and then feed it back in at the receiver. This means the transmitted signal can focus its energy in a narrow band of frequencies; the focused energy travels further and is less likely to be interfered with by signals on adjacent bands. Anyway when you have tuned in the station you will probably find the announcer has a voice sounding like Donald Duck or a demon possessed. To exorcise the demon find the upper sideband/ lower sideband switch and set it to upper side band (USB) then find the SSB tuning dial and adjust it until the radio announcer sounds normal. This is worth practicing before you need it.

Digital tuning greatly simplifies finding the stations you are interested in. But it’s essential for a subtler reason. It allows you to allocate frequencies to pre-selected buttons. This is important because during the broadcast a signal may start to fade as conditions deteriorate due to weather, sunspots or the time of day. But as the signal deteriorates on one frequency its probably getting better on another, so it’s handy to use the pre-select buttons, to switch quickly between frequencies and find one that’s working. This can bring back the signal without any apparent interruption to the broadcast.

At the end of this article is a form I use to record weather information. At the top of the form is a simplified table, which gives times and frequencies for the BoM broadcasts. This helps if the pre-select buttons are accidentally deprogrammed or the broadcast times forgotten. The schedule is for the BoM stations, call sign VMC, which serve the east coast of Australia. Full details for all regions of Australia are given at http://www.bom.gov.au/marine/voice_services.shtml. You can request a small “mini-guide to these services from the BoM, which takes up next to no room packed in with the set.

When using the BoM service be aware that they stick to Eastern, Western or Central standard times. They don’t use daylight saving times. If you work with daylight saving you may miss the broadcast by an hour. So check and practice before going on a trip.

Finally, early morning reports before setting out are well worth listening to, but I must confess to having been a bit of a wake up call to my mates. Using an earphone is not a bad idea!

Two Ways To Improve Performance

i) An External Aerial

The single most effective way to improve performance is to use an external wire aerial (antennae if you’re from America). Given two radios with different sensitivities you can almost guarantee that the unit with a decent external aerial will produce a stronger signal than the one without. The technical literature has much information on tuning aerials. For kayakers this is not relevant. Far too much wire is required for aerial tuning to be practical at the frequencies used by shortwave weather stations. A few metres of thin multi-strand copper wire held as near vertical as practical should make a significant difference. One end of the wire is connected to a plug for the external antennae socket in the radio, although you can often get away with using a crocodile clip to connect the wire to the telescopic aerial on the radio. The end not connected to the radio is tied with a length of insulating cord to a tree branch, pole or roof. Crocodile clips can be bought from any electronic hobby store (e.g. Dick Smith, Tandy or Jaycar).

Never use an external antennae in a lightning storm.

ii) Preset, Practice and Report Forms

Practice makes a huge difference to the quality of reception and reporting. Before any trip, it’s worth presetting the stations you will be using, listening to them and practicing to compensate for fading by switching between frequencies. You will notice a substantial difference between reception at dawn, midday, dusk or nighttime. It’s also worth becoming familiar with the SSB controls.

Preparation could include making a laminated card showing broadcast times and frequencies and a pad of weather report forms that can be easily filled in. An example is given at the end of this article. It’s worth developing a highly legible handwriting style and your own short hand for rapidly taking notes. These are typical of strategies used by radio operators in the 1940’s, before tape recorders and computers were used for report storage.

Always date the report. An undated or incorrectly dated report is a loaded gun It can be used by accident on the wrong day

What’s Important When Buying A Short Wave Radio For Kayaking

  • Ruggedness – unfortunately there are no truly rugged, portable, shortwave radios on the commercial market, certainly none that can be used on the water. I wrap mine in a towel, store it in a dry bag and keep it away from sand, when traveling.
  • Power consumption – A reasonable battery life for shortwave radios using alkaline batteries would be about 30 hours. This power consumption is more than for a regular radio because of the SSB facility and the digital controls. Batteries should be a standard size and readily available, preferably AA or D. During a three-week trip, Stuart Trueman manages with two sets of batteries for his Sangean AT 505. For much longer trips you might want to consider using a solar panel and rechargeable batteries.
  • A ‘Hold’ button or switch – This allows the controls to be inactivated so the radio isn’t accidentally reprogrammed or switched on while traveling. Just about every brand of radio used by kayakers has at some time been switched on accidentally when this facility wasn’t used and drained the batteries.
  • SSB capability – As mentioned before this is essential and is not available on a lot of commercial radios so it’s important to check that the unit you are buying has an SSB capability.
  • Push button tuning with preprogramming of stations – Again I believe this is essential to cope with fading during a broadcast. Quickly switching to another frequency can bring back the signal without interrupting the broadcast.
  • Adequate sensitivity and selectivity – Sensitivity measures the ability of a receiver to pick up weak signals and selectivity describes its ability to keep signals separate from each other so you don’t hear two or more stations at the same time talking over each other. Poor selectivity cannot be corrected by adding an un-tuned aerial. All but one of the radios mentioned below, have adequate sensitivity or selectivity.

Some Radios Suitable For Sea Kayaking

I won’t give a comprehensive review of shortwave radios – the magazine isn’t big enough. But I can recommend the Radio Netherlands web site http://www.rnw.nl/realradio/rx_current.html for a very professional survey of just about any radio you could ever be interested in. Another good web site is Ham Net http://www.eham.net/reviews/products/8, which gives reviews and user experience for each receiver. I wouldn’t bother with any of the commercial Internet based reviews.

It’s worth making a few points about four of the short wave radios commonly used by NSW kayakers. They are listed below and are all good units suitable for sea kayaking – just don’t operate them at sea – none of them are waterproof. I’ve also included a unit that is probably not much use for sea kayaking yet, but it’s tantalizing. The nominal prices shown are from the Radio Netherlands web site and don’t include tax, postage, packing and handling. Anyway you can do much better by shopping around.

Grundig Yacht Boy 400 – $267, http://www.rnw.nl/realradio/yb400.html

This unit is reputedly not quite as sensitive as the Sangean or Sony radios but should be adequate, particularly with an external aerial. It has very high quality sound reproduction.

Sangean ATS505 – $174, http://www.rnw.nl/realradio/ats505.html
Sangean ATS909 – $307, http://www.rnw.nl/realradio/ats909.html

Sangean – ATS505 and ATS909 These two units have very similar performance with the major difference being the availability of more memory for preselected stations in the AT909. Both are suitable for sea kayaking. The ATS505 is the model used by Andrew McAuley and Stuart Trueman. Peter Rattenbury uses an ATS909. Watch out for the tuning dial, which supplements the pushbutton tuning. It’s nice for general short wave listening, but could be a nuisance if it is accidentally knocked and detunes the receiver during a broadcast you really want to hear. However, this is a very minor issue.

Sony SW7600GR – $227 to $500, http://www.rnw.nl/realradio/icfsw7600gr.html

This is probably the best performing radio in its class, mainly due to a feature called synchronous detection, which means it has slightly better sensitivity and selectivity and less tendency for signals to fade than the units described above. But I’m prejudiced! Its also peculiar in that the price range is enormously variable. It could be worth searching the net or negotiating with the dealer if you want to buy this unit.

By the way all these radios will pick up medium wave and VHF as well as shortwave broadcasts from almost any country in the world. You don’t have to use them just for the weather!

ICOM – ICR10 at $800, http://www.icomamerica.com/products/receivers/r10/

Although its not suitable for sea kayaking, it’s worth mentioning the ICR10. This class of radio is used by various ‘three letter’ organizations around the world for short-range surveillance and testing applications. The next generation models have the potential to provide the ultimate hand held, robust, waterproof unit. It may be the way of the future but is not quite there yet. A good radio but probably not sensitive or selective enough for sea kayakers. I’ll be looking out for future models in this line of units from ICOM. A last vision for the distant future is Peter Rattenbury’s dream, an Australian ‘weather radio’ with the coastal radio transmit frequencies ‘hard wired’ in; as water-resistant as any electrical device we carry at the moment, and of a quality better than any SW radio you can buy. It would be the size of a cigarette pack and with a wire antenna rather than a telescoping whip, saving even more space and expense. These sorts of device exist in the states and if Peter has his way we may yet see one in Oz.

Quite a few people contributed to this article. Particular thanks to Peter Rattenbury, Stuart Trueman, Andrew McAuley, Terence Uren, Richard Birdsey, Stephan Meyn and Peter Treby. Also Vince for giving me a good reason to buy a short wave radio! Have fun!

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