Falco Systems WMA-200 User Manual - page 2
more information on how to connect the
amplifier for the lowest possible noise
level, please read the ‘Noise’ section later
in this manual.
The WMA-200 high voltage amplifier is
designed to be fully stable and free of
spurious signals with any capacitive load.
The amplification is a precise 20.0x (fixed,
defined by 0.1% precision resistors). The
amplifier has an output range of –175V to
+175V, a large signal bandwidth of
100kHz @ -3dB, and a slew rate of
80V/µs. The short-circuit protection with a
fast current limit of ±275mA make this
amplifier suitable for both
normal daily
laboratory use and for implementing
automated measurement systems.
Recommendations:
- Never apply more than +15V (or less
than -15V) to the amplifier input to prevent
damage.
- Do not connect separate signal sources
to both the BNC and differential inputs
simultaneously, as the signal sources are
be connected together inside the amplifier.
- A short voltage spike may appear at the
output, when the amplifier is turned on or
off. Pay attention not to damage sensitive
circuitry or equipment already connected.
- The amplifier cannot be damaged by a
short-circuit
condition
or
capacitive
loading, but two situations should be
avoided:
● Connecting a charged capacitor to
the input or output.
● Connecting a highly inductive load to
the output (such as a coil).
- Do not connect anything to the output
that can act as an antenna.
- This product should only be cleaned with
a soft, slightly moist cloth. Unplug the
WMA-200 amplifier from the mains power
before cleaning.
Safety
- This product is able to produce over
175V at more than 275mA at its output,
which is a very high level (risk of electric
shock). Safety measures should be taken
accordingly. This is indicated by the sign
above the output connector of the
amplifier.
- This product is a Class I appliance which
requires
a
mains
connection
with
protective earth.
- Always position the WMA-200 amplifier
such that the on/off power switch is easily
accessible.
- The airflow to and from the WMA-200
amplifier should not be blocked or
impeded, at the front, sides and the back.
- The internal circuitry of the amplifier
operates at high voltage. Only qualified
personnel from Falco Systems should
service this amplifier.
- Only replace fuses with the correct type:
● 230V version of the WMA-200: 250V
800mA 5x20mm slow blow.
● 115V version of the WMA-200: 250V
1.6A 5x20mm slow blow.
- The Falco Systems WMA-200 amplifier is
only suitable for indoor use in a class II
environment (domestic, light industrial).
- Non-sinusoidal mains power generators
cannot be used to power this product.
Detailed properties of the WMA-
200 high voltage amplifier
Inputs
Two inputs are available on the WMA-200
front panel: a standard BNC input for easy
interfacing to existing setups, and a
differential connector (TE Connectivity
T01-0560-S03) to reject interference. Such
interference is almost always present on
the incoming cable, picked up from the
environment external to the amplifier. A
mating cable connector for the differential
input (TE Connectivity T01-0550-S03) is
supplied with the amplifier.
The input impedance of both inputs of the
WMA-200 high voltage amplifier is defined
by a 1kΩ resistor to ground, in parallel with
100pF to prevent electrostatic discharge
(ESD) input damage. These resistors add
some noise to the output voltage unless a
low-impedance source (e.g. the output of a
preamplifier) is connected to the input. The
noise will be slightly higher when the
amplifier input is left open.
The 1kΩ resistors will form a voltage
divider with the output resistance of the
signal source which is used to drive the
WMA-200. If this impedance is very low,
no change in gain will be observable, but if
this source has e.g. a (commonly
encountered) 50Ω output resistance, the
apparent gain will change from 20x to a
lower but very well-defined 19.05x due to
this voltage divider effect.