Frequency Adjustment - Furuno FS-1575 Service Manual

5.4.2 Frequency Adjustment

The reference oscillator circuit is incorporated in the TX board. The PLL reference
frequency is 36 MHz.
This is taken as the reference frequency for the PLL circuit of TX, RX, WR1, and WR2.
To make frequency adjustment, select [MENU] -> 9.SERVICE -> 3.RT SETUP ->
1. SETUP -> "REF OSC."
Procedure)
1. Terminate the [J3: 36MHz WR2] on the TX board with a 50 ohm dummy load, and
then connect a frequency counter to each end of the dummy load.
2. Make measurement of 36 MHz frequency deviation.
3. Adjust "REF OSC" in [MENU] -> 9.SERVICE -> 3.RT SETUP -> 1.SETUP to set
the frequency deviation to "within ±10 Hz," and then press the [ENTER] knob.
CONFIDENTIAL (internal use only)
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It is strictly prohibited to reproduce the document in whole or in part without prior written permission of FURUNO.
5.4 Frequency Measurement and Adjustment
[J3: WR2]
5-29
TX Board
50-ohm Dummy
Frequency Counter