16
9 POWERING UP
Before switching the power on, check all the necessary connections: Earth, Antenna, Transceiver, PTT, ALC.
Make sure the 2 switches on the front panel are in the positions: OFF, STBY.
Switch now the mains power ON (The power switch to ON position). The "soft start" system will take about 5
seconds to fully turn the power on. SWR light will turn on briefly, then off. Wait for the DX-3 to warm up, until
the READY light turns on.
This takes about 2 - 3 minutes. This warm up time is a minimum. Some extra time is recommended.
WARNING !
WHEN YOU SWITCH THE POWER ON, YOU MUST HEAR AIR FLOW NOISE.
IF THERE IS NO AIR FLOW NOISE, SWITCH THE POWER OFF IMMEDIATELY
AND CONTACT YOUR SUPPLIER
.
10 OPERATION
10.1 TUNNING PROCEDURE
10.1.1 General
For each band and operating frequency, the transceiver settings must match the position of the BAND switch on
the front panel of the DX-3, while the PLATE and LOAD knobs must be adjusted for optimum operation which
gives – in conjunction with the input drive level, the maximum output power that can be obtained for that input
power. When the tuning is correct, this will also result in a minimum plate current, minimum plate dissipation
and good linearity.
10.1.2 Preliminary
tuning
•
Turn the BAND switch to the same band setting as the transceiver.
•
Put LOAD and PLATE knobs in the initial positions given in Table 1.
•
DX-3 must be powered ON and "Ready", with the OPR/STBY switch in OPR position.
•
Start with the transmitter at minimum power, in a "carrier" mode e.g. RTTY of CW - key down.
•
Key the transceiver ON and gradually apply power to the DX-3. When 0.5 to l W of drive is reached, the
EBS is activated and the plate current jumps from zero to about 0.75 A
•
Increase the drive until there is some output power indicated. If the current plate Ip reaches about 1.5 A
and there is still no output indication, turn PTT off and check the connections, the band and the initial
settings.
•
As soon as there is any power indication, tune PLATE for maximum output (and minimum plate
current).
•
Apply more drive and adjust PLATE again for maximum output. Keep PTT ON for short time only
(about 10 seconds). Go gradually, in several steps. When about 1500W output is reached, adjust LOAD
for maximum output. If there is no red Ig2 indication, it is likely that LOAD needs to be turned
clockwise, towards higher numbers on the dial.
•
Apply more drive and adjust both knobs again. When screen current appears (red Ig2 indication),
increase loading by turning anti-clockwise the loading knob. (LOAD towards lower numbers on dial)
until Ig2 drops almost to zero. Then adjust PLATE for maximum output power and maximum Ig2.
At
this point, Ig2 is the most sensitive indicator of resonance on the working frequency.
If Ig2 goes too
high (e.g. starts blinking), increase the loading again, then tune PLATE.
