34 Chapter 2 
Front and Rear Panel Features
Rear-Panel Features
Demodulation (Option 106)” in the Options chapter for more information.
10  Frequency Extension Assembly controls the microwave front-end components in 
the Agilent E4404B, E4405B, E4407B, and E4408B. 
PRESEL TUNE OUTPUT provides a signal to control external preselected mixers if 
External Mixing (Option AYZ) is installed. 
11  Card Slot Identification Numbers. Refer to Table 2-2 and Table 2-3 for card slot 
versus option card compatibility information.
12  10 MHz REF IN accepts an external frequency source to provide the 10 MHz, 15 to 
+10 dBm as a timebase.
NOTE It is not necessary to connect the 10 MHz REF OUT to the 10 MHz REF IN on the 
rear panel of the analyzer. Doing so will result in a Frequency Reference Error 
message. 
13  10 MHz REF OUT provides a 10 MHz, 0 dBm minimum, timebase reference signal. 
14  Power On Selection selects an analyzer power preference. 
The 
PWR ALWAYS ON setting turns the analyzer on whenever external power 
is applied. This mode is useful if an external power switch is used to control a 
rack of several instruments. Nevertheless, if you set the analyzer to standby 
using the front panel 
Standby key (see Figure 2-1. on page  22, item 23) and the 
external power is removed and restored within 20 seconds, the analyzer will 
remain in standby. 
The 
PWR NORM setting assigns analyzer on/off control to the front-panel On 
and 
Standby keys (see Figure 2-1. on page  22, item 23). If the analyzer is on 
and the external power is removed and restored within 20 seconds, the analyzer 
will turn on. On the other hand, if the external power is removed and restored 
after 20 seconds, the analyzer will remain in standby regardless of the front 
panel switch settings.
Power Always On
Analyzer state before removing 
power
A lapse in power 
< 20 sec.
A lapse in power 
> 20 sec.
On On On
Standby Standby On
Power Norm
Analyzer state before removing 
power
A lapse in power 
< 20 sec.
A lapse in power 
> 20 sec.
On On Standby
Standby Standby Standby