Southern Suburbs of Johannesburg Amateur Radio Club
439.125 Mhz -7.6Mhz Split 88.5 Tone
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Here you will find information on building an inexpensive 88.5 Hz CTCSS tone board that can be used in amateur radio transceivers and other transceivers .The completed unit is small enough to be fitted into older hand held transceivers and is stable providing you use the exact tolerance stated for the capacitors and resistors.The completed unit is suitable for use in mobile transceivers as well.If you need the tone board to be smaller then you can use a smaller variable resistor (R1) and smaller fixed resistors and you can scale down on the size of the veroboard and make cuts on the tracks with a sharp knife instead of using a drill bit.By changing the value of R2 you can lower or raise the tone board frequency range.Once you have finished building the tone board connect it to a 13.8 V supply and connect the tone output to a frequency counter then adjust R1 for 88.5 Hz

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