10
The PTT input is a female RCA connector (red). This line controls the transmit / receive switching system.
This jack must be connected to transceiver or exciter relay contacts which are open on RECEIVE and closed
on TRANSMIT. In the standard version (DX-1d fitted with a l2V antenna relay), the PTT input presents an
open circuit voltage of + l2V with respect to the chassis, with an impedance of about 70 ohm. Therefore, a
current of typically 0.17 A must be switched by the transceiver or exciter.
In the QSK version, the voltage at the PTT input is typically 28V loaded (up to 35V unloaded), with an
impedance of about 240 ohm. A current of about 0.12 A has to be switched in this case.
ALC CONTROL
This is a user-accessible control for setting the negative voltage at the ALC output. Further details are given
in section 10.2
6
FRONT
PANEL
The following controls and indicators are present on the front panel:
6.1
Controls
BAND SWITCH
A nine position switch selects the desired frequency range. The operating bands are indicated in metres.
PLATE TUNE
Tunes the amplifier operating frequency. A chart of approximate starting settings is given in Table-1
LOAD TUNE
Tunes the amplifier output loading. A chart of approximate starting settings is given in Table-1
ON/OFF
Switches the AC power on and off. On initial switch on, the standby mode is enabled. Note also the
appropriate switch down sequence, given in Section 11.
OPR/STBY
Enables the amplifier once it has warmed up. In STANDBY mode, the screen voltage is removed and any RF
power applied to the input, is bypassed to the output. If this switch is changed to OPERATE before the
READY light comes on, the FAULT light will turn on. This is not a fault, but it is better to leave the switch in
STBY position until the amplifier is ready to operate.
6.2 Displays
Output Power
- Scale up to 1 kW, non linear.
Reflected Power
- Scale up to 150W, non linear.
Plate Voltage
- Scale up to 3kV
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 35 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 40 mA, the protective current
limiting will cut in.
Plate Current
- Scale up to 1.5A.
ON Air
- single LED, green. When pressing PTT, this LED turns on (while in OPERATE)
