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Difference in receivers

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Old 09-17-2003, 09:38 PM
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elevator_up
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Default Difference in receivers

I'm looking for another receiver for my JR tx, 7 channel rx or more. There are a few different manufacturers and sizes at the Horizon site. Is there any real difference between these receivers or are they all basically the same ? What the key difference, ie would a JR 7 channel receiver have better range than a Expert Electronics 7 channel receiver ?
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Old 09-18-2003, 12:01 AM
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Default RE: Difference in receivers

The difference is what's called shift.

A radio carrier wave is, of course, a sine wave. It's modulated either by amplituded or by frequency. Yours is FM.

Now, only one half of the sine wave is read. For JR, only the top half is used (positive shift). Futaba uses the bottom (negative shift).

Many companies sell RXs in both (such as HiTec). Just be sure of what you're getting before you buy.
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Old 09-18-2003, 11:11 AM
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Default RE: Difference in receivers

You can buy receivers for either positive or negative shift from most vendors. My personal preference in after market recievers is FMA--high quality and excellent performance. As to High or low shift, if you have a JR or Airtonics, it is most likely transmitting on high shift, if Futaba or Hitec, most probably on low shift.
If you read this yesterday, the later part was totally wrong. I had discriminators mixed up with high/low shift. I believe the difference in the shift is which direction from thecrystal frequency the frequency is shifted with a signal input. High shift means that the basic frequency is increased with signal while negative shift is when the basic frequency is decreased with input from the modulator. We really do not use FM but use what some call frequency shift keying where the RF output is either one frequency or another. True FM varies the freqency over a specified range where the varience is in proportion to the amplitude of the modulating signal. On frequency shift keying, you either tranmit at one frequency or the other, in our case a difference of less than 10 KHZ.
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