Instruction Manual

Power requirement is +24 VDC at approximately 20 mA per amplifier, and any
supp1y with better than -60 dBm noise (less than 1 mV ripple) can be used
without adding noise to the output of the amplifier. The amplifier printed
circuit card module may be inserted in or withdrawn from the card holder, with
power applied, without harm to the amplifier.
Each amplifier possesses an individual input and output ground and these
must be wired in accordance with the grounding instructions.
All amplifiers should be allowed to warm-up for approximately 15 minutes
prior to any critical measurements, although the performance is instantaneous
with slightly increased distortion for the first few minutes.
WARNING: The following details should be carefully checked when utilizing the
amplifier otherwise the amplifier may be damaged:
l. Do not accidentally short the DC Signal Output + to ground.
2. Do not terminate the power supply +24 VDC backwards.
3. When applying continuous signals through the amplifier, load the amplifier
output with from 600 ohms to infinity.
4. Do not allow an unrestrained oscillation to continue. Typical causes of
oscillation are due to improper wiring and grounding practices such as:
Capacitive coupling between high and low signal levels in very close
proximity (eg. bundled cables) where excessive loop gain from a single or
series of amplifiers exists; grounding of input and output signal negatives
through common wire to ground plane: etc.
5. Power should not be applied when inserting the amplifier into an
unrestrained connector, as misalignment may cause contact shorting.
GAIN
The overall gain of the amplifier is determined solely by the value of one
resistor, Rf (in feedback circuit). This resistor is intended to be utilized
externally (on the circuit card connector: terminals K and L) thereby allowing
all circuit cards to be interchangeable, irrespective of the gain desired in
any given amplifier plug-in locatíon. Resistance values for normally employed
gains are:
35 dB (34.7) = 5.6 kohm, low noíse
40 dB (40.0) = 10.7 kohm, low noise
45 dB (44.6) = 20 kohm, low noise
50 dB (49.6) = 42.2 kohm, low noise Gain, dB = 20 log((Rf||100 K)/100)
Any desired gain between the above indicated values may be obtained (using
the above gain equation) by an appropriate change in Rf, the feedback resistor.
The resistor should be loww noise, metal film, for optimum amplifier noise
considerations.
FREQUENCY RESPONSE
The high end response of the Mode1 101 Audio Amplifier may be tailored in
the same manner as the gain - and with the same ease and faci1ity. High