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Channel spacing

The following information has been received from the manufacturers on what channel spacing is required,

FutabaAll current sets will operate at 10 KHz, however, they do only supply xtals at 20KHz Channel spacings, starting at (tba) So these can operate on either the new 35, or 36 MHz bands.

JR. All current sets will operate at 10 KHz, as will some older sets, but for safety, it would be wise to operate non- current sets on a 20 KHz channel spacing. So these can operate on either the new 35, or 36 MHz bands.

Hitec All sets must be on a 20 KHz channel spacing, so only the 36MHz band can be used. However, Hitec sets have not been imported on 35 nor 72 MHz, and in limited numbers on 36MHz. Synthesized modules (and synthesized receivers) on 36 MHz only, will be brought in for those with Prism 7X, Eclipse and Optic 6 transmitters.

The following can carry out re-tuning work, as well as any other service work that may be required.

Trevor Bringhans Ltd, Auckland. Tel 09 262-3758. Note that they have offered to retune sets "at cost"
Airsail, Auckland. Tel 09 579-6052.
Amsel Communications, Havelock Nth. Tel 06 877 0466 (David Appleton)
Mark Halliday, Christchurch. Tel 03 384-4547
And some model shops do have local technicians that can carry out retuning, Check with them.

Do not use imported 35 MHz crystals in older sets. The set may work, but may also be off-frequency, or have too wide a bandwidth, thus causing severe problems to other users. The 35 to 35.5 MHz band is for 10 kHz channel spacing only. Current production systems manufactured by Futaba and JR only, at this stage. Hitec equipment must operate at a 20 kHz channel spacing, i.e. 36 MHz. If you want to put an older set into this band, then it is imperative that you:

1. Use only the correct manufacture’s xtals

2. Ensure the set is properly tuned by a service agent., and is considered suitable, by measurement, to operate at a 10KHz channel spacing.

You will also want to be careful with older sets in any event, and the test written by the British Model Flying Assn. some years ago is an easy and effective way of doing this:

The check is quick and easy to do. Flyer A switches on transmitter (with aerial down), then switches on his receiver and stands about 4 metres from his model. Flyer B, on an adjacent channel, switches on transmitter (aerial up) and stands alongside flyer A. No interference should be noted on A’s model and it should be under the full control of A’s transmitter. The test is then repeated using B’s model and with his transmitter aerial down and A’s extended..

Any interference noted indicates possible tuning or crystal problems and must be investigated further. The test may save your model, as it will give early warning of problems beginning in your radio equipment, usually well before they become bad enough to cause control problems in the air.

If there is any doubt, or the above tests show any sign of interference, take the peg either side of the one you are operating on, for an extra safety margin.