Figure 4. Signal Generator AN/URM-70, tube location.
selector through its three positions. A different indicator
This provides space for tools and for movement of the
lamp will light for each position.
unit under test.
The signal generator should be
positioned close enough to permit use of the test cables
b. External Audio Modulator Connection. It is not
supplied. In all cases, the support used for the signal
necessary to use an external audio oscillator unless a
generator must be free from vibration, which could
modulation frequency other than 1,000 cycles per
cause microphonics and noise during operation. The
second (cps), 1,600 cps, or 20 kc is desired. If an
location for the instrument should be free from external
external audio oscillator is to be used, the input
electrical interference.
terminals marked EXT. MOD. must be connected to
the output of the external audio oscillator. The lower
b. Locate the signal generator so that its rf
terminal (GND) is grounded and is to be connected to
radiation during tests will not interfere with other
the ground terminal of the audio generator. Connection
equipment.
by means of twisted leads or a shielded cable is preferr :
d, especially if the local electrical interference J great or
14. Connections
if long lengths of wire are necessary. Any hum or noise
After the signal generator is installed in the operating
picked up from these input leads will be reproduced at
position, connections can be made for testing.
the signal generator output.
a. Power Connection. Determine the local power
c. Rf Output Connections. The adapters and
source voltage and frequency. The signal generator
requires an input voltage source of 115 volts 10
connectors listed in paragraph 9 are used to provide
various output connections.
They include Radio
percent, 50 to 60 cycles. Connect the power cord to this
Frequency Cable Assembly CG-718/U, two adapters
source. Place the POWER switch in the STANDBY or1
with alligator clips (one is terminated in 51-ohm shunt,
ON position to energize the signal generator power
and the other is unterminated), and three different cable
transformer. Lighting of the 50-100, 100-200, or the
adapters (Adapter Connector
200-400 indicator lamp will indicate that the signal
generator is energized. Rotate the FREQ. RANGEMC
9
