In SSB you will have a good output power if the green LED lights up a bit. The current of screen
grid is measured and shown in a Bar graph indicator. The amplifier has to be tuned in such a
way that the current is between - 20 mA to +50 mA. At currents beyond these values the
operating point will be shifted and IM-products will be rapidly increased. If a value of + 70mA is
exceeded, the safety devices will switch the amplifier to STBY mode.
Tuning instruction :
Please note :
Before starting tuning you have to check if the right antenna or a 50 Ohms
load resistance is connected at the antenna output !
Switching on the amplifier:
put the switch at the multimeter to HV position
put the OPR/STBY switch to STBY position
press the „ON“ button
The amplifier is prepared for operation with the following steps:
the toroidal transformers are switched step by step.
the blower of tube is switched on.
the multimeter bargraph measures the high voltage; the normal value is 3.4 kV
the WAIT LED lights up
After switching on you have to check the functioning of the blower. Air must be blown out of the
ventilating apertures above the tube. ( If there is any failure you have to press the „OFF”-button
immediately !)
Heating the tube takes about 150 seconds. After this time the WAIT LED goes out and the amplifier is
ready for operation.
Tuning the amplifier to an output of 3000 W
1. Switch BAND, TUNE and LOAD to the position according to the table:
The tuning table available to you is made by using a dummy load! Each amplifier will have other
values depending on used frequency and antenna! Make your own list for your own antennas! Use
tuning position (see later)!
2. Reduce the power output of your transceiver to the 0.
3. Switch OPR/STBY to „OPR“ position (OPR LED lights up)
4. Choose TUNE position of multimeter.
5. Switch the PA to CW and increase driver power to 10W (OUTPUT power will be PA abt.
500W)
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