11
6.2 Displays
All the DX-3 indicators are concentrated in a single, solid state, “moving LEDs” display (
See drawing
). The
following values are displayed (top to bottom):
Output Power
- Scale up to 4 kW, non linear. Yellow LED’s with red indicating power over 3kW.
Reflected Power
- Scale up to 500W, non linear. The colour is green, yellow and red, indicating
progressively higher reflected power and possibly problems with your antenna.
Ig2
- Zero-centred display. The left (green) side has a full scale of about 25 mA of negative screen current.
The right (red) side has a full scale of about 50 mA of positive screen current. Above this value, the red LEDs
will flash, warning you to increase the loading, or reduce the drive. At about 60 mA, the protective current
limiting will cut in.
Plate Voltage
- Scale up to 3.5 kV, green.
Plate Current
- Scale up to 2.4 A. Yellow, with a green zone indicating the standing current bias (when EBS
is disabled only.
NOTE
: the factory adjustment could be slightly different from the green zone indication).
The area above 2.4 A is red. It indicates excessive plate current, due to high drive level and improper tuning
(especially plate tuning –
see “Tuning” chapter, 10.1
)
ON Air
- single LED, green. When pressing PTT, this LED turns on (while in OPERATE)
READY
- single LED, yellow. Turns on at the end of warm-up period, when the mains power to DX-3 is
switched on. It turns off for about 2 minutes if the plate current protection is triggered. In this case, the
FAULT light also turns on.
FAULT
- single LED, red. Turns on in 3 situations:
•
when the over-temperature protection is triggered, the FAULT turns on until the tube cools to a safe
level. During this time, the operation of the amplifier is disabled, the screen voltage is off and any RF
power applied to the input is bypassed directly to the output.
•
when the over-current protection is triggered, FAULT turns on for 2 minutes, while READY turns off
•
at DX-3 power up, if the OPR/STBY switch on the front panel is left in OPR position. The FAULT
light will go off when the DX-3 is ready for operation, after warm-up.
SWR
- single LED, red. A three second cut-off will happen if your antenna has a SWR worse than 2:1
(typical 2.6:1) at the operating frequency. During the cut-off, the RF from the input is directly by-passed to
the output.
OVER-DRIVE
- single LED, yellow. Flashes when the input drive is exceeding the linear operation level. If
even more drive is applied, the overdrive protection will cut off the operation (bypass) for about 2 seconds.
NOTE
: the input drive at which the indicator turns on depends on a certain extent on the tuning.
Figure 1.
Front Panel Display
RF OUTPUT POWER (kW)
REFLECTED POWER (W)
PLATE VOLTAGE (kV)
PLATE CURRENT (A)
Ig2
OVER
DRIVE
ON AIR
READY
SWR
FAULT
