Agilent Technologies E4438C External 1 input, External 2 input, Into a 50 Ω load are as follows

General Characteristics

External 1 input	This BNC input connector accepts a ±1 Vpeak signal for
	AM, FM, pulse, burst, and phase modulation. For all
	these modulations, ±1 Vpeak produces the indicated
	deviation or depth. When ac-coupled inputs are selected
	for AM, FM, or phase modulation and the peak input
	voltage differs from 1 Vpeak by more than 3%, the hi/lo
	annunciator light on the display. The input impedance is
	50 ohms and the damage levels are 5 Vrms and 10 Vpeak.
	If you configure your signal generator with Option 1EM,
	this input is relocated to a female BNC connector on the
	rear panel.
External 2 input	This BNC input connector accepts a ±1 Vpeak signal for
	AM, FM, phase modulation, and pulse modulation. With
	AM, FM, or phase modulation, ±1 Vpeak produces the
	indicated deviation or depth. With pulse modulation,
	+1 V is on and 0 V is off. When ac-coupled inputs are
	selected for AM, FM, or phase modulation, and the peak
	voltage differs from 1 Vpeak by more than 3%, the hi/lo
	annunciator light on the display. The input impedance is
	50 ohms and the damage levels are 5 Vrms and 10 Vpeak.
	If you configure your signal generator with Option 1EM,
	this input is relocated to a female BNC connector on the
	rear panel.
GPIB	Allows communication with compatible devices.
	[rear panel]
I input	Accepts an I input either for I/Q modulation or for
	wideband AM. Nominal input impedance 50 or 600 ohms.
	Damage levels are 1 Vrms and 10 Vpeak. [BNC, front panel]
I out and Q out1	The I out and Q out connectors output the analog
	components of I/Q modulation from the internal
	baseband generator. The nominal output impedance of
	these connectors are 50 Ω, DC-coupled. The damage
	levels are > +3.5 V and < –3.5 V. The output signal levels
	into a 50 Ω load are as follows:
	• (O.5 Vpeak,), corresponds to one unit length of
	the I/Q vector.
	• (0.7 Vpeak ), for peaks for p/4 DQPSK.
	• (1.6 Vp-p) maximum [Options 601, 602, 001, 002 only].
	These female BNC connectors are provided on signal
	generators with Option 601 or 602. On signal generators
	with Option 1EM, these inputs are relocated to rear
	panel SMB connectors.

1. Parentheses denote typical performance.

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