Operating instructions

ACCEPTANCE TESTING
5-20 46882-311D
Test equipment
Description Minimum specification Example
RF signal
generator
5.5 MHz to 1 GHz Deviation 0 to 75 kHz
Modulation rate 10 Hz to 15 kHz.
IFR 2041
Modulation meter RF I/P 5.5 MHz to 1 GHz FM Measurement
accuracy ±0.5% of reading ±1 least significant
changing digit at 1 kHz mod rate for deviation
>5 kHz.
IFR 2305
Power splitter 6 dB 50 Ω 5.5 MHz to 1 GHz. WEINSCHEL
1870A
DVM 1 % accuracy 1 kHz Solatron 7150+
Splitter
Signal generator
C2592
RF INPUT
ANTENNA
INPUT
RF OUTPUT
Modulation meter
UUT
Fig. 5-15 Modulation meter FM
(1) Refer to Results table 5-30 on page 5-41. Connect the equipment as shown in Fig. 5-15,
connecting the incoming signal to the antenna input socket of the UUT.
(2) Set the Modulation meter to monitor FM in a 50 Hz to 15 kHz bandwidth, noise averaging
on.
(3) Set the UUT to [Tx TEST], RF IN/OUT [SELECT] antenna BNC input socket. From the
power up default, the instrument should already be set to demodulate FM with an IF filter of
30 kHz and AF filter of 0.3 to 3.4 kHz selected. Check that this is the case and select if
necessary.
(4) On the UUT, set [Tx Freq] 5.5 MHz. Set the RF signal generator to provide a signal of
5.5 MHz with 20 kHz deviation at 1 kHz modulation rate. Set the RF level to 6 dBm. (If a
2041 is being used then it should be set to normal noise mode.)
(5) Check that the deviation level indicated on the UUT is within
±
5%
±
resolution of the
deviation indicated on the external Modulation meter.
(6) Repeat steps 4 and 5 for RF carrier frequencies of 500 MHz and 1000 MHz.
(7) Manually tune the UUT to 300 MHz and set the RF signal generator to provide 300 MHz
with 20 kHz deviation.
(8) Select the 50 kHz low-pass filter by pressing [return], [Mod Meter], [AF Filter],
[50kHz LP], and check the UUT still indicates 20 kHz deviation. (Functional check only.)