2
ISOMET
1.
GENERAL
The RFA2x1 is a combined Analog Driver and Power Amplifier is a fixed frequency RF power source
specifically designed to operate with Isomet acousto-optic devices such as the M1208, M1346 and
M1396. The driver accepts two independent modulating signals and provides a double-sideband
amplitude modulated RF output to the acousto-optic modulator. A summary of the driver specification
is shown in the following table:
Model
Center Frequency
Output Power
RFA241
40MHz
> 70.0 Watt
RFA
4
41
40MHz
> 90.0 Watt
RFA251
50MHz
> 60.0 Watt
RFA261
60MHz
> 60.0 Watt
RFA281
80MHz
> 50.0 Watt
Figure 2 is a functional block diagram of the driver. The center frequency of the driver is determined
by the free-running quartz-crystal oscillator. This frequency and stability are accurate to within
±
25ppm. The oscillator is not temperature stabilized.
A high-frequency, diode ring modulator is used to amplitude-modulate the RF carrier. The single turn
potentiometer provides gain control for adjusting the peak RF power level when the modulation input
is at maximum.
A solid-state RF switch provides a high-speed gate function. A TTL equivalent high level will gate the
RF ON. The MMIC r-f pre-amplifier stage isolates the low-level modulation and control circuitry from
the power amplifier stage.
The rise and fall times for the amplifier from either the modulation or the Gate input is near identical.
Please refer to Table 1
The analog input level must not exceed 15 volts
The digital inputs must not exceed 7 volts
This amplifier is designed to operate at full rated power into a 50
Ω
load with 100% duty cycle.
