OM4000 HF POWER AMPLIFIER
1
4
Tuning Table
shows proper tuning values for
50 Ohm termination
.
Band
Tune
Load
1.8
70
40
3.5
75
30
7
30
85
10
25
45
14
70
70
18
32
50
21
25
60
24
60
66
28
40
70
8. Set TUNE knob in such a way, that the TUNE-LED lights up maximum left.
9. Set LOAD in such a way, that the TUNE LED on the TUNE scale lights up under
the “
V
” sign. If it is possible to obtain the LOAD in 2 positions, set the position
that is more to the right.
10. Repeat tuning several times according to 8 and 9, power output should be abt. 600W
11. Increase the input power (to about 70 W) until an output power of approximately 4000W
will be reached.
12. Repeat steps 8 and 9
13. Set TUNE to maximum output power (RF POWER LED lights up maximum right)
After this procedure the amplifier is tuned correctly and ready to give 2500W output power in
all operation modes.
At optimal tuning and full output power a positive max. 80mA current goes through the second
grid. On 24 and 28 MHz bands optimal tuning can be achieved when one or two LEDs are lit
up to the right from the position “V”. If less output is desired you can simply decrease the load
of the transceiver.
CAUTION
Should the amplifier demonstrate any malfunctions during tuning or should it not behave
in accordance witch the description, interrupt the tuning procedure immediately and
check the amplifier! Be sure to have not done any mistakes in choosing bands or
TUNE/LOAD values! Be sure that VSWR is not higher than 2:1 and input power is LOW!
After excluding possible human mistakes you will be able to work for long time with this
amplifier!
