Level Check; Tx Board: 05P0856 - Furuno FS-1575 Service Manual

6.11 Level Check

RF output power measurement is made with power data set to default value, SSB to
4.2 MHz and internal tone to 1500 Hz. Variations in output power among models result
from IF GAIN (MIC gain) adjustment and ALC adjustment in the overall Tx adjustment.
In other words, the variations result from the overall gain of the transmission circuit.

1. TX board: 05P0856

：
CR3 RF CHK
FS-2575:
0.45VDC at rated output, 1.11VDC when
terminated through a 50-ohm resistor
FS-5075:
0.23VDC at rated output, 0.97VDC when
terminated through a 50-ohm resistor
J5: TX OUT rated output
FS-2575: 2.3Vp-p (when terminated
through a 50-ohm resistor)
FS-5075: 2.0Vp-p (when terminated
through a 50-ohm resistor)
J1, J2, and J3 output are outputted from VCTCXO. If no signal is outputted to all, the
VCTCXO circuit has a trouble.
In case of no 18-MHz RX output frequency to J1,
an error message saying "RX PLL UNLOCK" will be outputted.
In case of no 36-MHz output frequency from WR1 to J2 and from WR2 to J3,
an error message saying "WR1, 2 PLL UNLOCK" will be outputted.
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.
R208: IF Gain ADJ. VR
With MIC input set to "−46dBm,"
adjust the VR so that the gain will
come to 1/4 of the rated output.
J3: 36MHz WR2
180mVp-p (when
terminated through a
50-ohm resistor)
6-74
6.11 Level Check
CR1 ： IF CHK
0.96VDC at rated
output
J1: 18MHz RX
200mVp-p (when
terminated through a
50-ohm resistor)
J2: 36MHz WR1
180mVp-p (when
terminated through a
50-ohm resistor)