Eagle 2000 – 2kW FM Broadcasting Amplifier
User’s manual – Page 17 of 66
Analog board
RV1
Reflected Power reading adjustment
RV2
Direct Power reading
adjustment
RV3
Max Output Power
adjustment
5.4 Analog
board
This board manages all the equipment protections via the output power loop control and the reflected power loop control. On the
board there are two trimmers to adjust the direct (
RV2
) and reflected (
RV1
) powers shown on the display (e.g. in the working page,
Ö
9.2), and a third trimmer (
RV3
) for the adjustment of the maximum output power level (see the following paragraph for information
on how to locate and adjust these trimmers). If there is the need to reduce the amplifier gain, to maintain an high efficiency, this
board regulates the output power gain loop adjusting, first of all, the MOSFET Drain-Source voltage (the voltage can be regulated
from 48 down to 30V). If this isn’t sufficient, then the BIAS voltage is be also reduced (please see the bottom note).
As soon as the equipment is powered, the fans will start turning at the minimum speed. Then, the control board will change
their speed according to the heatsink temperature (i.e. the environmental one).
5.4.a
Adjustment of the maximum output Power level
With the equipment working, increase the level of the input R.F. driving
power until the output one reaches 2400W (measured with a hi-precision
power meter). Now with
RV3
adjust the output power level until the
measurement instrument reading is 2000W.
,
Do not exceed 30W as maximum driving input power!
5.4.b
Adjustment of direct and reflected power levels readings
With the equipment in normal operation (ON mode), and the display
showing the working page (
Ö
9.1), check with an hi-precision R.F. power-
meter that the output power is 2000W, then adjust
RV2
until the display
shows the same direct power reading. Check the reflected power level
with an hi-precision directional power meter, then adjust the reflected
power level reading accordingly using
RV1
.
5.4.c Analog
board
connections
[50]
Exciter enabling/disabling command output
– this signal (relay contacts) is sent to a connector (if present) located on the
rear panel.
52
51
50
55
56
57
58
59
60
53
54
61
