Giga-tronics 2508A, Operation Manual

Page: 62 / 132

Chapter 2: Front Panel Operation
62 2500A Series Operation Manual, 34172 Revision C, March 2008
NOTE:
The Power Offset and Power Slope functions are no longer available.
8. Select the "Level" menu item in the CW menu and enter the desired output level using the keypad,
Step Up/Step Down buttons, or the rotary knob.
9. When entering a new level setting using the numeric keypad, use the dBm or dB Units buttons.
Units are assumed to be in dBV. Use the following formula to convert to Volts to dBV:
dBV = 20log
10
(V)
10. If the LED indicator that is above the RF ON button is not lit, press the RF ON button to enable the
signal at the RF output connector.
11. When the signal at the RF output connector is enabled, the LED indicator that is above the RF ON
button is blue.
2.4.3.3 Using the Ref Tune Feature
Ref Tune (Reference Tune) allows tuning the instrument's output frequency over a range of approxi-
mately 500 ppm using an analog tuning voltage of 0 to +10 volts applied to the Ref Tune input on the
rear panel. This is useful in applications where the instrument is be phase locked to another stable source
as shown in Figure 2-31.
Figure 2-31: Phase Locking the 2500A to a Second Source
The Reference Tune input is enabled from the System 3 menu. It is normal for the instrument to show the
unlock indication when the Ref Tune function is enabled.
The Ref Tune input is a high impedance input and has a 3 dB bandwidth of approximately 1 kHz which
is set by a pole consisting of 150
Ω
and 1 uF as shown in the Figure 2-32.
GT2500A
RF
Out
REF TUNE
RF Output
Approx.
4.5 V
Low Pass
Filter
Σ
Source