Yaesu FT-2000 Operating Manual page 41

VDD
The drain voltage of the final FETs is measured and
displayed here.
In the FT-2000 (100 W version), the measurement
range is 0 ~ 18 V, and the proper voltage is around
13.8 V. On TX, if around 13.8 V is displayed, the
transceiver is operating normally.
In the FT-2000D (200 W version), the measurement
range is 0 ~ 60 V, and the proper voltage is around 50
V. On TX, if around 50 V is displayed, the transceiver
is operating normally.
BIAS
While operating with the Class-A on the FT-2000D
(200 W version), and the bias is changed via the Menu
item "141 tGEN BIAS" from Class-A to Class-AB,
this indication can be used to observe the current set-
ting. The indication is 0 ~ 100 % and "0 %" means
Class-AB, while "100 %" means Class-A.
Even if the Bias is varied, the RF output will not
change (up to the 75 Watts of maximum power under
Class-A), and you can change the bias safely even when
you are using a linear amplifier.
In the FT-2000 (100 W version), this indicator al-
ways shows "0 %."
DMU-2000 D M
T
EMPERATURE
G M
RAPHIC
U
/ SWR I
D
ETER ISPLAYS
TEMP
This indicates the temperature (measured) of the fi-
nal amplifier FETs' heat sink.
The measured temperature range of this meter is 0 ~
100 °C, and above 80 °C is the "Red Zone" tempera-
ture range to be avoided, so as to ensure a safe oper-
ating temperature range. When the temperature rises
above 80 °C, the fan speed will increase by a factor
of four, providing a significant increase in air flow.
The heat sink temperature may rise appreciably dur-
ing Class-A operation on the FT-2000D (200 W ver-
sion), especially if the ambient temperature is warm,
and we recommend that you monitor the temperature
during Class-A transmission, adjusting the Bias con-
trol downward (more toward Class-AB) if excessive
heating is observed. A lower bias level will cause less
heat to be dissipated, thus reducing the heat sink tem-
perature.
SWR
This displays the SWR characteristic of the amateur
band that you are currently using, with points along
the graph indicating the frequencies that have been
measured.
NDICATION
Page 39