Specifications

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5. OPERATION
SET-UP
Connect all the cables as previously described in the manual, then double-check.
When you are satisfied that everything is correct and the STBY/TX switch is on
STBY, switch the amplifier on. The WAIT light should be on. After approximately 3
minutes the WAIT light should go out and the READY light should come on,
indicating that the valve has warmed up and is ready for operation. Now put the
STBY switch to TX, which puts it into the operate mode. With no RF drive applied,
key the amplifier and check that the Plate meter shows a standing current of about
80 – 100 mA. The green TX LED will be on when the amplifier is keyed.
TUNE-UP
Now set your driver to about 30W output, in either CW or FM mode, and using the
two dials tune for maximum output on your power meter. This should indicate about
300W output. The amplifier will give about 800W RMS when 80W of drive is now
applied with very slight adjustments being necessary.
In the tune mode with 600W O/P, the plate meter should rise to about half scale.
CAUTION. Maximum grid current should NEVER exceed 300mA.
The amplifier is now ready for operation.
OPERATION
The mode of operation, SSB or CW, can now be selected and operate as normal.
When the amplifier is in the STBY position the RF goes straight through from the
transceiver to the antenna, and when it is in the TX position the amplifier comes into
operation.
To key the amplifier, an earth on transmit is required from the transceiver (relay) to
the PTT socket on the back of the amplifier. When the transceiver and amplifier are
keyed, the green TX LED indicator on the front panel is lit.
During operation, keep a careful eye on the Grid meter making sure it does not
exceed 300mA.
PROTECTION and RESET
There are two kinds of reset fitted to this model of 70cm Discovery, hard and soft.
Soft reset: If the yellow GRID LED comes on - this is for faults such as over-drive,
over-grid current and over-plate current. To reset, simply de-key the PTT.
Hard reset: If the red ANODE LED comes on - this is for major problems e.g.
Internal valve flash-over. To reset, switch the OFF/ON switch to OFF and ON again.