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. There is a slight delay while the soft-start operates,
then the POWER and WAIT lights should be on. After approximately 2 minutes the
WAIT light should go out, 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
400W output. The amplifier will give about 1000W 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.
GRID PROTECTION
There is grid protection fitted to this model of 2m Discovery. If the grid current
exceeds the recommended maximum level the yellow LED will come on and the PTT
will be disabled. As the maximum level is approached the LED will flicker and an
audible clicking will be heard.
Investigate the reason for the high grid current and rectify it. Possible causes are that
there is a fault on the aerial or that the amplifier has been overdriven.