Furuno FS-1570, Service Manual

Page: 205 / 322

7.1 Output power
7-3
7.1.2 Output power measurement
(1) Transceiver output
To measure the output power from the transceiver unit, FS-1570T and FS-2570T,
connect the 50-ohm power meter and dummy load to “T/R ANT” connector as shown in
Fig. 7.1.1.
Fig.7.1.1 T/R output power measurement
(2) Antenna power
Antenna power is calculated by using the following formula with readouts of Vc and Ic
on the control unit FS-2570C.
Po = Vc x Ic x
η
Ic = Po/(Vc x
η
)
where,
η
is efficiency on the factory test data.
For example, when the output power of 4 MHz signal is adjusted to 150 W, Po = 150,
η
= 40 %, Vc = 23.5 V and Ic = 150/(23.5 x 40) = 15.9. Thus, Ic is set to 15.9 A.
Fig.7.1.2 Measurement of antenna power