Ramsey Electronics URC1 Instruction Manual download pdf (Page 15)

WSR-1A• 15

 64. Install R7, a 1K ohm resistor (brown-black-red).

 65. Install R8, a 68K ohm resistor (blue-gray-orange).

 66. Install R16, a 22K ohm resistor (red-red-orange).

 67. Install C28, a .1uF ceramic capacitor (marked .1, 104, or 100n).

 68. Install C33, a .1uF ceramic capacitor (marked .1, 104, or 100n)

 69. Install R24, a 1K ohm resistor (brown-black-red).

 70. Install TP4 with a 1/2” piece of scrap

component lead.

 71. Install C34, another .1uF ceramic

capacitor (marked .1, 104, or 100n).

 72. Install C35, yet another .1uF ceramic capacitor (you know!).

 73. Install C38, even another .1uF ceramic capacitor.

 74. Install C45, a 22pF ceramic capacitor (marked 22).

 75. Install C44, another 22pF ceramic capacitor (marked 22).

 76. Install Y2, the 10.240MHz crystal, (marked 10.240!). This crystal is the

reference frequency by which the PLL operates. All of the frequencies

produced by the PLL are referenced to this crystal’s operating frequency, so

the oscillations generated by the PLL are as accurate as the crystal is.

 77. Install C53, a 22pF ceramic capacitor (marked 22).

 78. Install FL2, a 450kHz ceramic filter. This filter isn’t even close in

appearance to the previous ceramic filter. This filter comes in a little black

plastic box with three leads, and only fits in its holes neatly in one direction.

 78A. It is necessary to install a 100

pF capacitor on the bottom of the

board, under FL2. See the drawing

at right for correct placement of the

capacitor.

 79. Install the 16 pin IC socket

where U3 is to go. Check step 56 for

more details. When done installing

the socket, install U3, The

MC145170 digitally controlled phase

locked loop. Observe the correct

orientation of the part’s notched

end. Make sure its the same as the parts layout diagram!

1/2"

PCB

Small loop f

test probes.

100

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Ramsey Electronics URC1 Instruction Manual Page 15