User's Manual

Exhibit 6 Page 24 from 35
5.4. Tuning of the Power Amplifier
The OM2000+ power amplifier is operated in class AB. Thus it’s possible to obtain a maximum output
power at excellent linearity. For this purpose the amplifier has to be tuned carefully.
CAUTION
The operation of a mistuned PA will cause malfunctions, the increase of grid current and problems
with TVI/BCI.
CAUTION
If the input power is higher than 10W and the power amplifier is NOT correctly tuned, the safety
devices will switch it to STBY. After switching the amplifier to STBY, you need to switch it back to
the OPER mode by pressing RESET button shortly.
A tuning table is delivered with the power amplifier. For coarse tuning select a band with BAND switch
and choose the setting of “TUNE” and “LOAD” capacitors according to the table.
Band (MHz)
Tune
Load
Input PWR (W)
Output PWR (W)
1.845
70
45
75
1500
3.630
69
51
72
1500
7.050
50
90
71
1500
10.125
72
28
72
1500
14.175
69
40
70
1500
18.150
81
48
69
1500
21.230
47
67
65
1500
24.940
61
64
59
1500
28.450
33
76
52
1500
50.200
22
90
64
1500
NOTE
Delivered tuning table was made for 50 Ohm loading of PA (dummy load). Each amplifier should have
different values depending on used frequency and used type of antenna. Make your own table valid
for your real conditions.
There are two ways how to do fine tuning. The first method uses a gradual increase in the input power
when tuning the PA (as most operators accustomed). In every case we recommend adjust the display
for both of methods so it shows two parameters important for fine tuning - TUNE and Is graph (> l <).