Signal Termination - Wavetek 145 Instruction Manual

The upper and lower limits are defined by the
maximum and minimum dial
@
settings multi-
plied by
@ .
VCG input will not drive the gen-
erator bey·ond the normal dial limits of a range.
@
FREQ/PERIOD MUL T Switch
Not
Shown
The outer knob selects one of ten frequency /period
multipliers for the dial
@
setting. Frequency,
then period, are noted at each setting.
VERNIER Control
A fine adjustment of the frequency dial
@
setting.
EXT DC OFFSET IN Connector (Rear Panel)
Applied voltage offsets the selected waveform
linearly. Offset is 1 V for each -1 V applied with
output connected into an open circuit. Maximum
input is ±7.5V. Offset is affected by the attenua-
tor®·
Not GCV OUT Connector (Rear Panel)
Shown
This connector gives a 0 to +2V signal propor-
tional to the frequency of the
g~nerator
within
any given range. The signal can be used as the
X drive for X-Y recorders.
3.2 OPERATION
Perform the initial checkout in Section 2 for.the feel of the
instrument. Any questions concerning individual controls
and connectors may be answered in paragraph 3.1.
3.2.1 Signal Termination
3.2.1.1 FUNCTION OUT Signal
Proper signal termination, or loading, of the generator con-
nectors is necessary for its specified operation. For example,
MODEL 145
OUTPUT
AMPLIFIER
3-4
EFFECTIVE
CIRCUIT
RESISTANCE
\~~.'\r-1
(SIGNAL
LOADI
I
LOAD RECEIVING .
INSTRUMENT
Figure 3·2. Signal Termination
the proper termination of the main output is shown in
figure 3-2." Placing the 50.Q terminator, or 50.Q resistance,
in parallel with a higher impedance matches the rr:ceiving
instrument input impedance to the generator output im-
pedance, thereby minimizing signal reflection or power loss
on the line due to phase angle mismatch.
3.2.1.2 TTL PULSE OUT Signals
The TTL and TTL PULSE OUT outputs can drive 50.Q and
higher impedance terminations.
3.2.1.3 ECL PULSE OUT Signals
The ECL and ECL PULSE. OUT outputs are driven by
MC10l24's. The signals must be properly terminated at
the point that they enter an external ECL circuit. Several
connection possibilities are shown in figure 3-3.
ECLORffi ,.....
ECL OR ECL
+
-2V
-5.2V
-2V
ECL
__,
-5.2Y
AND
NANO.
. AND
NANO
NOTE
All connecting cables are RG58
cables with BNC connectors.
Figure 3-3. ECL Terminations