User`s guide

2-10 Agilent E6432A Microwave Synthesizer User’s Guide

Hardware Front Panel Connectors

The input impedance for this input connector is factory set at 2 kilohms.

Damage levels for this input are greater than or equal to +15 Vp, or less

than or equal to –15 Vp.

For complete specifications, refer to “Specifications and

Characteristics” on page 6-1.

TIP When using a signal generator to drive the AM input, the output

impedance of the signal generator must be taken into account. If the

signal generator has an output impedance of 50 ohms and it is set to

output a –0.5 Vp to +0.5 Vp signal into a 50-ohm load, the actual signal

level at the AM input will be a –1 Vp to +1 Vp. This occurs because the

AM input on the synthesizer has a 2 kilohm input impedance; a –1 Vp

to +1 Vp signal at the AM input will generate 100% AM modulation.

One solution to remedy this impedance mismatch is to place a BNC tee

connector on the AM input with a 50-ohm load connected to one port of

the BNC tee connector. The input signal from the signal generator

would be connected to the other port so that the output impedance of

the signal generator sees approximately a 50-ohm input impedance as a

load. If the signal generator is set to output a –1 Vp to +1 Vp signal, the

actual signal level at the AM input should be a –1 Vp to +1 Vp, +/– the

accuracy of the signal generator itself.

Another way to assure that the output level of the signal generator is

set to the expected level, is to measure the signal generator output with

an oscilloscope or multimeter. When measuring the output level of the

signal generator with these devices, it should be noted that many

models have switchable inputs that may allow 50 ohm, 1 megohm, or

some other value to be selected as the input impedance. If the incorrect

input impedance is selected, you could also generate an incorrect signal

level.