HP HP 8753E, User Manual, Page: 403 / 699

Receiver and Source Requirements.
Refer to Chapter 7, “Specifications and Measurement
Uncertainties.
IF Input: R always; and port 1 or port 2 for a ratio measurement.
Display Annotations. The analyzer shows the annotation of s when the frequency offset mode
is on. The annotation of? indicates that the source frequency is approximately 10 MHz away
from the sum of the IF and frequencies that you requested. This is most likely caused by
the frequency being outside the 1 to + 5 MHz accuracy requirement.
Error Message.
If you connect your test device before you switch on the frequency offset
function, the error message PHASE LOCK CAL appears on the screen. This is normal, and
. . . . . . . . . . . . . . . . . . . . ..A
Spurious Signal Frequencies. Unwanted mixing products (or spurious signals)
at specific frequencies can cause measurement inaccuracy, because of the characteristics of
a sampler. These specific frequencies can be calculated. You can reduce unwanted mixing
products going to the sampler by inserting a low pass filter at your test device’s IF output.
6-122 Application and Operation Concepts