J3E Rx Total Gain; Measurement Of Tx Output Power - Furuno FS-1503 Service Manual

4. J3E RX Total Gain

1. Make a connection as shown in figure 5-3.
2. Set the FS-1503 as below.
⋅ RF GAIN: Maximum
⋅ RX Freq.: 4.0 MHz, MODE: J3E, AGC: on
⋅ AF GAIN: Maximum
3. Applying 4.0 MHz + 1.0 kHz signal from the SSG, adjust the SSG output level so
that the AF output level is 1W.
The output should be –5 to + 1dBµV.
(Rated output; 2Vrms for 4-ohm speaker; 2.83Vrms for 8-ohm speaker)
5. J3E TX Output Power
Refer to 4.4 Power Data Setting in chapter 4 for power adjustment.
1. Make a connection as below.
50 Ω Pwr meter
oscilloscope
2. Set the measuring instrument as below.
AF Oscillators: one for 1000 Hz and another for 1600 Hz, output level of +6 dBm
Attenuator: 46dB or microphone input of –46 dBm
3. While pressing the PTT switch down, read the power meter. (Output power meas-
urement with two tone signal) Double the reading for peak-to-peak power(Px).
References)
1) J2B(EIB): Power is measured by applying 0dB, 600 ohm.
2) NBDP
3) DSC
ANT
50 Ω
50 Ω
(
Coax.)
13.6 V
Figure 5-4 Measurement of TX output power
: Measured in FEC-C mode.
: Measured by transmitting DOT signal.
MIC
(H)
3
(C)
FS-1503 4
(GND)
1
(PTT)
2
PTT SW
5-10
AF OSC
Ω
600
Ω
200
+6 dBm
Ω
200
ATT
Ω
600
Ω
– 46 dBm
600 Ω
200
+ 6 dBm
AF OSC