Woorabinda Lake - Stirling South Australia

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Radio Selection - by Ben Morris

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Thank goodness that the days of the 27/29 MHz and even 36/40 MHz sets are on the decline.  In Australia these were the old AM and FM sets which have different frequency bands in other countries though still use the same old technology.  They are all limited by the same inconveniently long aerials in both transmitter and receiver and their susceptibility to radio noise generated by electrical equipment such as motors etc.  Gone (almost) also is the reliance on a series of crystals (one each for the transmitter and receiver) to select a channel and the need to carry three or even more sets of crystals to a competition.

The 2.4 GHz sets introduced by the Spectrum range of radios and now made by many other manufacturers has revolutionised radio control and become the radio of choice for radio sailors.  The automatic way in which the radios select free frequency bans and avoid interference with other nearby users is just such a big bonus that one wonders how we managed before these were available.  Imagine the crystal nightmare in trying to run a world IOM event on the older technology!

So what are the advantages of using this new 2.4 GHz technology?

  • The resistance to interference from common electrical noise is a real plus.

  • The very convenient size of the aerials on both transmitter (~100mm) and receiver (~30mm)  This means no more dodging of the metre long transmitter aerials in the control area and no more stringing an aerial up the backstay of the yacht it can all be below decks.

  • The automatic channel selection where the transmitter does a quick scan of the available band and selects free ones to use.  Most sets in fact use two frequencies to add redundancy and reduce signal loss.

  • Simpler battery requirements.  For example transmitters often use 4 or 6 AA NiMH cells.  This allows for many hours of use - very important for radio sailors where a competition may run for 6hours of sailing or more.   Receivers can usually handle a much wider voltage range than older technologies say from ~4V to 8V or more allowing a much wider selection of battery types such as a two cell LiPo battery.

  • Very lightweight receivers (6g or so) are available for even the most weight conscious sailor.  There is even a water resistant receiver set

  • Built in fail safe which returns the controls to some predetermined point in the unlikely event of a loss of signal.

  • Except for the very simplest of sets ( which I do not recommend!), a microprocessor controlled programming process for the controls.

  • Comparable costs to older non computer radios.

  • Unlikely to poke out a fellow radio sailor's eye with the aerial

Nothing really good come without some baggage.  So what are some disadvantages of this system?

  • The initial set up or matching a transmitter to a receiver (often called binding) can be a nuisance but in reality only needs to be done once - well once every now and again perhaps.  It's not really very difficult more inconvenient.

  • With carbon fibre the common material for construction of most yachts there can be an issue with reception distance if receiver aerials are mounted too low in the hull.  Carbon fibre and water also tend to block the 2.4 GHz signals.  Ensuring the receivers are as high as possible in the hull or using aerials with an extension so that the active bit is above deck (in a small tube) can deal with this issue.

  • Interpreting the often strange instructions for programming the various functions of the transmitter can be a problem with some.  They are no more complicated than getting your Video recorder or set top box to work.  You can do this - can't you??  Anyway there will always be some smart, clever little nerd who can help.  I am going to make another page which outlines three or four of the most common program function you may wish to use so look back soon.

  • The sets are possible more sensitive to water or moisture damage than the older technologies but if you sail a yacht which leaks then you are always going to have trouble with electrics and electronics.  Fix the leaks! and use a waterproof cover over the transmitter in rainy weather.

  • Unlikely to be able to reach out with the aerial and retrieve a yacht whose radio you forgot to turn on to say nothing about recovering dropped hats etc.  Thanks to Colin from Lilydale Radio Control yacht Club for reminding me of this!

As you can see I am very much in favour of using the latest technology as revealed in the 2.4 GHz sets and can really see no reason for not starting out this way or upgrading soon.  In fact some clubs are prescribing that new members must have the 2.4GHz set up which seems a smart move to me.