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3.7 FREQUENCY STABILITY (FCC Rule Part 2.1055)
3.7.1 Method of Measurement
The FS-2570 stored in the chamber, is connected with measuring equipment as in Fig. 3.7.1.
Fig. 3.7.1 Test set-up for Frequency Stability Measurements
With the power switch off, the FS-2570 is left in the chamber until thermal equilibrium is
achieved. Power is then applied and, after 15 minutes of warm-up, the reference oscillator
frequency is measured. Measurements are made within the temperature range -30°C to +
50°C at 10°C interval, by applying 85 % (20.4 V), 100% (24 V),and 115% (27.6V) of the
rated DC power supply voltage.
Frequency stability measurements are also performed in cold start conditions (no warm-up
period). For the purpose of these measurements, change in the reference oscillator
frequency is plotted in the function of the lapse of time up to 60 minutes. The FS-2570 is
tested at -30°C, -20°C, 0°C and + 30°C.
3.7.2 Test Result
The results are shown in Fig. 3.7.2 to 3.7.4, and Fig. 3.7.5 to 3.7.8, respectively.
DC Power Supply
Model GP035-50R
S/N: 13086029
Takasago
Frequency Counter
Model TR5824
S/N: 41930036
Takeda Riken
2nd LO
72.0 MHz
CHAMBER
EUT
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