Frequency Measurement And Adjustment; Transmission Frequency Measurement; Connection Point Of Frequency Counter - Furuno FS-1575 Service Manual

5.4 Frequency Measurement and Adjustment

5.4.1 Transmission Frequency Measurement

• Preheat time:
• Frequency counter:
• Frequency deviation:
• Frequency adjustment: Select [MENU] -> 9.SERVICE -> 3.RT SETUP ->
• SSB output frequency = Set TX frequency + 1500 Hz (one-tone)
• DSC / NBDP output frequency = Set TX frequency + 85 Hz (Space Tone: 1785 Hz)
• CW output frequency = Set TX frequency

1. Connection point of frequency counter

1) Induce RF signal in the vicinity of the ATU terminal with a pickup coil, and then
input this RF signal in the frequency counter. For this purpose, fabricate a φ50 mm
pickup coil of 4 to 6 turns using suitable wire.
2) Connect a frequency counter to a RX antenna installed in the vicinity of R/T antenna.
However, since frequency pickup levels vary with frequency bands, there are cases
in which no frequency measurement can be made.
3) Connect a frequency counter to the FAX-5 antenna of WR1 (2). However, since
frequency pickup levels vary with frequency bands, there are cases in which no
frequency measurement can be made.
FS-2575C
CONFIDENTIAL (internal use only)
This confidential document is used only by FURUNO authorized persons.
It is strictly prohibited to reproduce the document in whole or in part without prior written permission of FURUNO.
Preheat for a period of 20 minutes or more.
Thoroughly preheat the counter.
Within ±10 Hz for SSB, DSC, NBDP, and CW
1. SETUP -> "REF OSC"
Frequency
counter
T/R ANT
FS-xx75T
COUPLER
Fig. 5.4.1 Frequency Measurement Circuit
5-26
5.4 Frequency Measurement and Adjustment
T/R ANT
Pickup coil
ANT
or
GND
ATU
R. ANT WR ANT
Frequency
counter