Ramsey Electronics AR2 Manual de instrucciones descargar pdf (Pagina 17)

ABM1 • 17

 U2 is already installed.

 Install C17, 100nF ceramic disk capacitor (marked 104).

 Install R6, 560 ohm resistor (green-blue-brown). This is our 3

and last

lay-down resistor.

SQUELCH CIRCUIT

 Install C19, 1uF electrolytic capacitor. Electrolytic caps have a polarity

and must be installed correctly in order to work . . . and in some cases in

order not to blow up when power is applied! You’ll note that the legs of the

part are different lengths and there is a stripe or band down one side of

the capacitor that corresponds to the shorter of the two leads. This is the

negative side of the cap. The silkscreen and Parts Layout Diagram will

show where the positive lead is to be placed by a “+” sign on the board.

Orient the part with the longer lead in the “+” hole and solder the part in.

The legs of this part may need to be straightened so that the bottom of the

capacitor body will sit flat on the PCB. If this part doesn’t sit flat on the

PCB the case will not fit together properly.

 Install R9, 10k ohm resistor (brown-black-orange). R9 and all the rest of

the resistors are stand-up resistors. A stand-up resistor has one end of

the resistor body resting on the circuit board with its lead through the pad.

It is important that this end of the resistor actually rests on the board. The

other end is up in the air with the lead bent over going though the other

pad. It is important to make this bent lead as short as possible. Refer to

the Parts Layout Diagram; it has a circle on the pad the resistor body is to

rest on. Proper orientation of stand-up resistors may be important for RF

or for physical spacing reasons.

 Install R8, 330k ohm resistor (orange-orange-yellow).

 U3 is already installed

 Install C18, 100nF ceramic disk capacitor (marked 104).

 Install C16, 1nF ceramic disk capacitor (marked 102).

 Install R10, 1M ohm resistor (brown-black-green).

 Install Q1, a BS170 (marked BS170) FET in a TO-92 package. The part

has a flat side with the number on it and you’ll see the outline showing

where to place this flat side on the PC board silkscreen. Bend the center

lead out to fit in the holes and push the part down close to the circuit

board without forcing. Solder the transistor.

 Install R7, 1k ohm resistor (brown-black-red).

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Ramsey Electronics AR2 Manual de instrucciones Pagina 17