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switches. Switch bounce is literally mechanical bounce that results from
the pressing of the switch. High speed electronic circuits will see this
bouncing and will respond as though the switch was depressed many
times very quickly. Typical switch bounce is in the 10 to 20 millisecond
range (that's 10 to 20 thousandths of a second!).
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22. Install R11, 10K ohm resistor (brown-black-orange).
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23. Install R1, 10K ohm resistor (brown-black-orange).
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24. Install C1, .01uF disc capacitor (marked .01 or 103 or 10nf).
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25. Install C5, .01uF disc capacitor (marked .01 or 103 or 10nF).
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26. Install C17, another .01uF disc capacitor (marked .01 or 103 or
10nF).
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27. Install C8, .1uF ceramic disc capacitor (marked .1 or 104).
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28. Install a 16 pin IC socket at location U3. Take care to do it
correctly! Like before, check that all 16 pins are correctly inserted into
the PC board before soldering. Double check for solder bridges when
finished soldering. This is where the microcontroller chip (the IC with the
sticker on top, or marked XC705K1P) is to be inserted. Insert U3 into the
socket, being careful of bent-under pins.
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29. Install jumper JMP1.
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30. Install R9, 4.7K ohm resistor (yellow-violet-red). This is a current limit
resistor that limits the amount of current to transistors Q1 and Q2, which
in turn key the radio output.
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31. Install Q9, 2N3904 NPN transistor. Observe the correct orientation of
the flat side. This transistor is part of the PTT key detect circuit if you use
a radio mike.
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32. Install R10, 4.7K ohm resistor (yellow-violet-red).
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33. Install Q6, 2N3904 NPN transistor, observing the orientation of the
part. Q6 is part of the LED display driving circuit.
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34. Install R5, 1K ohm resistor (brown-black-red).
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35. Install Q4, another 2N3904 transistor. Make sure that the flat side is
facing R5.
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36. Install R4, 1K ohm resistor (brown-black-red).
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37. Install Q5, yet another 2N3904 transistor. Still watching the position
of the flat side, aren't you?
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38. Install R8, 1K ohm resistor (brown-black-red).
CB-1 • 10
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