Yaesu FT DX 9000MP CONTEST - DATA MANAGEMENT OPERATION, Operation Manual

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Page 98 FT
DX
9000MP O
PERATION
M
ANUAL
SSB/AM M SSB/AM M
SSB/AM M SSB/AM M
SSB/AM M
ODE ODE
ODE ODE ODE
TTTTT
RANSMISSION RANSMISSION
RANSMISSION RANSMISSION RANSMISSION
(L(L(L(L(L
OOOOOWWWWW
- D - D
- D - D
- D
IST IST
IST IST
ISTOR OR
OR OR
ORTION TION
TION TION
TION
CLASS-A O CLASS-A O
CLASS-A O CLASS-A O
CLASS-A O
PERA PERA
PERA PERA
PERATION TION
TION TION
TION
)))))
L
OW
- D
ISTORTION
CLASS-A O
PERATION
Class-A operation of the FT
DX
9000MP transmitter is provided, yielding ultra-low distortion products during SSB opera-
tion. Power output during Class-A operation is 100 Watts.
1. To engage Class-A operation, press the [
CLASS-A
]
switch. The imbedded Red LED will light up, con-
firming that Class-A operation has been selected.
2. Engaging the “Class-A” mode actually places the
transceiver in a condition whereby the Bias level may
be adjusted, using the [
BIAS
] control, to set the trans-
ceiver for operation anywhere between Class A and
Class AB (which has lower heat dissipation but higher
distortion products).
Clockwise rotation of the [
BIAS
] control increases
the Bias, and fully clockwise rotation of the [ BIAS
]
control will place the transmitter in fully Class-A op-
eration. Counter-clockwise rotation of the [
BIAS
]
control will move the transmitter toward Class AB
operation.
A A
A A A
D D D D DVICE VICE VICE VICE VICE
During Class-A operation, ten Amps of Bias current will be flowing, regardless of the modulation level that leads
to actual power output. Therefore, if the ambient temperature in your operation loca-
tion is high, the transceiver temperature may rise as well, due to the high bias level
(which must be dissipated as heat). Depending on the temperature, you may wish to
reduce the swtting of the [
BIAS
] control, so as to reduce the amount of heat being
generated.
During Class A operation, we recommend that you monitor the heat sink temperature by pressing the [
TEMP
]
switch so as to engage the temperature monitoring mode of the [ TEMP/SWR
] meter. Usually, the temperature
will be well below the 80 °C “Red Zone,” because the fan speed will increase to control a rise in temperature. If
you are operating in a hot environment, though, and the increasing fan speed does not maintain the temperature
below 80 °C, try adjusting the Bias Level temporarily in the direction of Class AB operation; this will reduce the
amount of heat being dissipated in the heat sink.
The Bias Level is displayed on the [
VDD/BIAS
] meter when the [
BIAS
] switch is pushed. On the “Bias” scale,
“0%” represents Class AB operation, while “100%” represents Class A operation.
An innovative aspect of the “Class-A” mode is that the actual power output is always limited to 100 Watts. So
even though you might adjust the [
BIAS
] control in the direction of Class-AB operation, the power output will
not rise; this eliminates the need, for example, to re-tune your linear amplifier, if used.
[BIAS] knob [CLASS-A] switch
VDD TEMP SWR BIAS
[TEMP/SWR] meter [VDD/BIAS] meter [RF PWR] knob
[BIAS] switch
3. To exit from the CLASS-A mode, press the [
CLASS-
A
] switch once more. The Red LED imbedded in the
switch will go out, confirming that the CLASS-A mode
has been disengaged.