HP 8756A How To Use

AUTO LOCK
The instructions so far have detailed
operation using MANUAL LOCK . This section
contains a description of AUTO LOCK, its
advantages and disadvantages, and ins truc-
tions on ho w to use it.
The HP 53445 can phase lock the source
using either MANUAL LOCK, as already
deser ibed, or AUTO LOCK. In both modes, the
d esire d lock frequency is entered on the HP
53445, and lock can occur with no manual
tuning. AUTO LOCK requires an HP-IB
connection from the HP 53445 to the HP 8350B,
and cannot be used in an automatic system
when an external computer is used as a
controller.
The HP 8756A scalar network analyzer is
also capable of HP-IB communication with the
HP 8350B over a dedicated bus called the 8756
System Interface. This connection allows
several powerful advantages :
1. HP 8756A CRT will display sweep
frequency information and sweeper
marker frequencies .
2 . HP 8756A INSTRUMENT PRESET will
preset both the HP 8756A and the HP
83508.
3. Save/Recall function on either the
analyzer or the s w eeper wi ll save or
recall the measurement configura-
tion of both instruments.
4 . The alternate sweep function of the
8756A / 8350B will be enabled .
The HP 8350B has only one HP-IB
connector . It can go ei ther to the HP 5344A
HP - IB connector , or to the 8756 System
Interface , but not to both . If the 8756
System Interface is used , then the sweeper
cannot be controlled by the HP 53445 and
therefore AU TO LOCK cannot be used (see
figure 1). If the HP 5344A HP - IB is
connected , the AUTO LOCK function can be
used , but the advantages of the 8756 System
Interface must be sacrificed (se e figure 6) .
HP 8756A
Sc.Ilar Network Analyzer
HP 8350B
Sweep Oscillator
HP · IB
o 0
HP 53445 Microwave
Source Synchronizer
SYS CONT Switch
to " 1 ". ADDRESS
Switche5 set to
Sweeper Address
Figure 6. HP-IB connection for A UTa LOCK.
10
AUTO LOCK should only be used when the
convenience of locking automatically is
more important than the convenience added by
the 8756 System Interrace.
USI NG A UTO LOCK
In all modes , using the system in AUT O
LOCK is very similar to using it in MANUAL
LOCK. However , the 8756 System Interface
cannot be used. AUTO LOCK requires an SP-IB
connection from the HP 53445 t o the sweeper
(see figure 6) . Note that the 8756 System
Interface is not used. The DIP switch o n the
back panel of the HP 5344A must be set
properly to run in the AUTO LOCK mode. The
top sw itch must be set to the SYS CONT
position. This will be indicated on the
front by a "CONT" annunciator on the HP
5344A . The bottom five switches must be set
to the HP-IB address of the HP 8350B . ( This
address is factory set to 19, but can be
checked and reset by preSSing [SH I FT ], [ LC L]
on the HP 8350B . ) The bottom switch is the
least significant bit. See the HP 53445
Operating and Service Manual for details.
CW , CF / C>. F, STRT/ STOP, m odes i n AUTO LOCK
The instructions for operation in AUTO
LOCK are essentially the same as those for
MANUAL LOCK in all fo u r HP 53445 modes .
However, in AUTO LOCK, the HP 5344S can set up
the m ode and the frequency of the HP 8350B
over H P-IB , so it is not necessary to do this
ma n ually . You will need to turn the cw
filter ( if any) off, and make sure the SWEEP
TRIGGER mode is set to inte r nal (INT) on the
HP 8350B . In CW, be sure that the HP 8350B
s w eep ti me is set to at least 100 ms. In the
final step, the [AUTO LOCK] key should be
activated instead of the [MANUAL LOCK] key.
The s w eeper's frequency will be set
automatically over HP-IB , a nd the 8350B mod e
will be set to regular CWo For single
frequency measurements (CW mode on the HP
53445), the 8350B mode must be set to swept
CW o Do this by preSSing [SHIFT ] [ CW ].
LK/R mode in AUTO LOCK
When using LK /R mode in AUTO LOCK, the HP
5344S sets the sweeper to STRT/ STOP mode and
sets the start frequency to the lock
frequency entered on the HP 5344A. However
it does not set the stop frequency. This
must be entered manually on the sweeper .
Also, do not forget to disable the CW
filter , set the sweeper ' s sweep time to at
least 100 ms , and set the sweep trigger to
external (EXT) .
QUESTIONS/ ANSWERS REGARD I NG CONNECTORS
Q:
A:
I don I t have the programming connector
cable. Can I use the system without
it?
This connector ( HP Part No . 8120-3545)
is used to trigger the sweep in LK /R

HP 8756A Specifications

General

Brand	HP
Model	8756A
Category	Measuring Instruments
Language	English