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Chapter 1 9
Signal Generator Overview
Front Panel
12. EXT 2 INPUT
This female BNC input connector (E8257C and E8267C only) accepts a ±1V
p
signal for AM, FM, and ΦM.
With AM, FM, or ΦM, ±1V
p
produces the indicated deviation or depth. When ac-coupled inputs are
selected for AM, FM, or ΦM and the peak input voltage differs from 1V
p
by more than 3%, the HI/LO
annunciators light on the display. The input impedance is selectable as either 50Ω or 600Ω and damage
levels are 5 V
rms
and 10 V
p
. On signal generators with Option 1EM, this input is relocated to the rear panel.
13. LF OUTPUT
This female BNC output connector (E8257C and E8267C only) outputs modulation signals generated by the
low frequency (LF) source function generator. This output is capable of driving 3V
p
(nominal) into a 50Ω
load. On signal generators with Option 1EM, this output is relocated to the rear panel.
14. Mod On/Off
This hardkey (E8257C and E8267C only) enables or disables all active modulation formats (AM, FM, ΦM,
Pulse, or I/Q) applied to the output carrier signal available through the RF Output connector. This hardkey
does not set up or activate an AM, FM, ΦM, Pulse, or I/Q format; each modulation format must still be set
up and activated (for example,
AM > AM On) or nothing is applied to the output carrier signal when the Mod
On/Off
hardkey is enabled. The MOD ON/OFF annunciator, which is always present on the display, indicates
whether active modulation formats have been enabled or disabled with the
Mod On/Off hardkey.
15. ALC INPUT
This female BNC input connector is used for negative external detector leveling. This connector accepts an
input of −0.2 mV to −0.5V. The nominal input impedance is 120 kΩ and the damage level is ±15V. On signal
generators with Option 1EM, this input is relocated to the rear panel.
16. RF On/Off
Pressing this hardkey toggles the operating state of the RF signal present at the RF OUTPUT connector.
Although you can set up and enable various frequency, power, and modulation states, the RF and microwave
output signal is not present at the RF OUTPUT until
RF On/Off is set to On. An annunciator is always visible
in the display to indicate whether the RF is turned on or off.
17. Numeric Keypad
The numeric keypad consists of the 0 through 9 hardkeys, a decimal point hardkey, and a backspace hardkey
( ). The backspace hardkey enables you to backspace or alternate between a positive and a negative
value. When specifying a negative numeric value, the negative sign must be entered prior to entering the
numeric value.