12
ON Air
- single LED, green. When pressing PTT, this LED turns on (while in OPERATE and READY).
READY
- single LED, yellow. Turns on at the end of warm-up period, when the mains power to DX-3SP 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. It turns OFF while in an SWR Fault condition or over-temperature Fault.
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. The READY light is also off.
•
when the over-current protection is triggered, FAULT turns on for 2 minutes, while READY turns off.
•
at DX-3SP 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-3SP 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 2.6:1 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 for about 2 seconds.
NOTE
: the input drive for the indicator to turn on depends on a certain extent on the tuning of the amplifier.
6 REAR PANEL
The following connectors and controls are present on the rear panel
6.1 Power / Earth connections
A wing-nut Earth connection is provided at the rear of DX-3SP. A good Earth link must be provided here.
Connect this first, before making any other connection to the amplifier. Two fuse holders are fitted along with
40A, normal acting fuses.
6.2 RF connections
RF INPUT
The RF input is an SO-239 female connector. A 50 ohm coaxial cable line of good quality terminated with a
PL-259 coaxial connector is required to connect the transceiver or exciter output to the input connector of
your DX-3SP amplifier.
RF OUTPUT
The RF output is also a female SO-239 connector. The use of a high quality RG-8A/U, RG-213 or similar 50
ohm coaxial cable line terminated with a ‘VHF’ type PL-259 connector is essential. Similarly, a VSWR of
2.6: 1 or better is mandatory. Remember too, that the EMTRON DX-3SP amplifier can deliver 4000 W
continuously and up to 5000 W PEP in the SSB mode. Not all antennas can handle such power.
6.3 Transceiver control
PTT
The PTT input is a female RCA connector. 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.
The PTT input presents an open circuit voltage of + 6V with respect to the chassis. A current of 6 mA must
be switched by the transceiver or exciter.
