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  WHAT RADIO - ADVANCED ARTICLE

 

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 WHAT RADIO SHOULD I BUY?

SUMMARY - INTRO ARTICLE

Two and Multi-channel; Traps for young players ; Computor radios ; Crystals; Certification; Frequencies; Buying Second Hand.

ADVANCED ARTICLE

AM & FM; PPM; PCM; ZPCM; Mode 1 & 2; Mixing different brands; Flying Wings; Considering the expense; Features and Functions explained.

THE RADIO(S) YOU NEED will depend on the planes that you intend to fly - initially and into the future, so try to figure this out first.

To some extent you get what you pay for - but you need to know what features you want to get value for money for your needs.

If you intend to start with a two channel glider, do not underestimate the excellent value of a simple two channel radio.

For powered models (except the el-cheapo's) you will need a multi channel radio.

Before you buy, remember that shops can sometimes do a "package" if you pick up a lot of gear (plane, accessories etc) in the one visit - so forward plan to take advantage of that if available. See also Servos Article re swapping servos.

LET'S GET STARTED

I am leaving the "cheapie" 27mhz radios out of this article because these are constantly changing, at time of writing, are not well regarded for safe flying, and use a frequency which it legitimately used by other communication applications and so may be subject to interference.

Note that apart from radios on the 40mhz band, it is generally not possible to import radios directly from overseas to Australia because of the frequencies used here.

TWO CHANNEL RADIOS

Two channel radios (on the 29mhz band in Australia) are generally good value for 2 channel gliders. You get transmitter, receiver, crystal, 2 standard sized servos, battery holder for receiver and switch harness to go into the plane, all for about A$120. (That's less than just one receiver for a multi channel radio.)

Most 2 channel sets sold in Australia do what is asked of them - if it doesn't - see your hobby shop and if they can't help then speak the supplier. (If they can't help - tell others!!).

These will run the Rudder and Elevator on a polyhedral (multi-bend) or dihedral (single bend) winged model or the Elevator and Ailerons on a model with ailerons. The ailerons will be run by a single servo pushing one up and one down - or by two servos connected by a "Y" lead to one channel.

It is also possible to use a 2 channel radio on a flying wing, but they have limitations. For details, see the WHAT RADIO - ADVANCED ARTICLE or the REVIEW OF THE ZAGI FLYING WING.

Most (if not all) 2 channel radios sold in Australia have Elevator on the left stick - and Steering on the right. This is called Mode 1. Many US 2 channel radios have both on the one stick (Mode 2).

Two channel transmitters and receivers are generally powered by dry cells, such as Duracells or Energizers or their generic equivalents.

A TRAP FOR YOUNG PLAYERS

A mistake I made was to buy one of the early model Sanwa radios which had the plug polarity reversed and plugs which were incompatible with other gear. The radio worked well - but I ended up burning out more servos than the radio cost me - which was pretty silly on my part - but a trap you may wish to avoid. I understand later Sanwa radios have the same plugs as Hitec and JR - but check before you buy.

Yes, it IS possible to easily swap the polarity on the plugs BUT expensive if you forget when moving a servo from one plane to another.

THE DISADVANTAGES OF 2 CHANNEL RADIOS

Firstly, they are a bit more prone to interference (though some fliers have no problems).

Secondly, to fly anything other than an unpowered 2 channel glider, you will need 3 or more channels.

THREE CHANNEL RADIOS

These are common in the US, but rare in Australia.

MULTI-CHANNEL RADIOS

In Australia, these are generally FM, 36 mhz and the range of goodies depends on the price. Most are good quality - so what you need to look for are features. These are covered in the Advanced Article on this topic

Non-computer radios are usually (but not always) cheaper, but less flexible, and will generally only cope with one model.

Computer radios can have a range of functions and mixers, and those with multi-model memories can be programmed for different planes. Even of they have fewer channels than the non-computer radio, they will usually take you further into your modelling.

Most multi-channel radios come with a heat-shrink wrapped pack of rechargeable ni-cad cells for each of the transmitter and receiver, and, in Australia, a 240 volt "overnight" charger is usually included.

CRYSTALS - there are a number of channels on each of the 29, 36 and 40mhz frequencies. Only one flier can be up at a time on any channel. If your channel is taken, you will have to wait - or to change to an alternative channel - if you have the transmitter and receiver crystals to do so. If you have multiple crystals, also have multiple frequency keys with your name and frequency on it.

  • Although the transmitter and receiver crystals are labelled with the same frequency, the crystals are actually slight different - and so Transmitter (also labelled Tx) and Receiver (Rx) crystals must go into their respective units.
  • You can't simply put a 29mhz crystal into a 36mhz unit - or vice versa.
  • You can't use a 2 channel receiver with a multi-channel transmitter or vice versa

RADIO CERTIFICATION

Clubs will require your transmitter to be checked periodically by an approved technician, to certify that it is operating only within the frequency range for its particular channel. This costs about A$30, or less if there is someone at the club who can do it for you.

If you are running additional frequencies, it will need to be certified for these also.

FREQUENCY CONTROL

In Australia, the most common form of frequency clearance is the placing of a "key" (a rectangular coloured piece of plastic) on the frequency control board in the slot corresponding to the transmitting frequency.

YOU MUST NEVER TURN ON YOUR RADIO WITHOUT FIRST HAVING FREQUENCY CLEARANCE. YOU MAY BE LIABLE FOR ANY DAMAGE CAUSED BY YOU "SHOOTING DOWN" SOMEONE ELSE'S PLANE!!!

CONSTANTLY SWAPPING GEAR FROM PLANE TO PLANE

This sounds like a money saver but it is not because sooner or later the delicate wires are likely to be damaged.

Have set of gear in each plane and avoid swapping them until the plane has been "retired".

BUYING SECOND HAND

In my opinion,

(a) don't buy any radio gear that isn't near new or that needs repair - and

(b) know its suitability for your purposes.

In addition, be aware of what accessories are coming with the radio (working servos etc) because, without them, it may not be a bargain.

(Missing 4 servos at A$25-$30 each = $100-$120. Missing 1 receiver = $130. Missing charger ..... no warrantee..... is it still a bargain?)

 Radios have come down in price, and if the cheaper price does not compensate for the gear that does not come with it (receiver, charger, servos, batteries, switch harness) or it doesn't have the features you require, then you have not bought a bargain, as well as carrying the risk of it not working.

 

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