Control
Function
Panel receptacle (un-
Provides a receptacle for stor-
marked) (standard ac
ing the power plug when
type).
disconnected.
EXT. MOD. binding
Provide for connection of ex-
posts.
ternal audio oscillator with
a frequency range between
250 and 70,000 cps. MODU-
LATION switch must be
in EXT. position to use
these binding posts.
R. F. OUTPUT con-
The rf output test signal is
nector.
available at this point.
Fuses F1 and F2-----------------------
1.5-ampere fuses for the ac
input line.
Note. The two remaining front-panel fuses are spares.
Section II. OPERATION UNDER USUAL CONDITIONS
18. Starting Procedures
the terminated test adapter is used.
The
a. Starting
.
Connect the ac line cord to the
terminated test adapter has an internal 51-ohm
required power source. Place the POWER switch in the
resistor across its terminals.
ON position. Rotate the FREQ. RANGEMC selector
(2) When injecting the test signal into a circuit
through its three positions. An indicator lamp (green for
having an input impedance between 45 and 55
position 1, amber for position 2, blue for position 3)
ohms, the rf output cable, adapter fittings,
should light for each position. If any lamp fails to light,
and/or the unterminated test adapter is all that is
replace it with a spare lamp which is mounted inside the
required for the hookup.
instrument. If all three indicators fail to light, check for
blown fuses (F1 and F2) on the front panel. If the signal
(3) If the signal gnerator is connected to a circuit
e
generator starting indications are normal, allow a 5-
of less than 45 ohms, a resistor must be added
minute to 1/2-hour warmup period before beginning any
in series with the output lead to match
tests. Following the warmup period, the instrument is
impedances. To determine the value of the
ready for use.
series resistor required, subtract the input
Note
impedance of the unit under test from 50 ohms.
If an abnormal result is obtained
This results in a resistance value in ohms for the
during the starting procedure, refer to
series resistor required.
the equipment performance check list
(4) If the signal generator is connected to a circuit
having impedance between 55 and 1,000 ohms,
a resistor should be connected in shunt to bring
b. Standby Operatio.n If at any time it is
the input -impedance of the unit under test down
necessary to turn the signal generator off for short
to 50 ohms. To determine the value of the
periods during any test sequence, throw the POWER
shunt resistor, multiply the impedance of the
switch to the STANDBY position. This will disconnect
unit under test by .02. Subtract 1 and divide this
the plate voltage rectifier. The filament circuit of the
answer into. the impedance of the unit under
signal generator will remain energized, maintaining the
test. The. results in the value of the shunt
proper operating temperature.
resistor required.
c. Output Impedanc. The output impedance of
e
the signal generator is 50 ohms. The internal voltage
Warning
standing wave ratio is less than 1.5.
The use of open leads and alligator
clips in the 50- to 400-mc range
(1) When working the signal generator into a high
impedance circuit of' 1,000 ohms and higher,
13
