Ref Set; How To Set A Reference To A Specific Amplitude (In Units Of Dem, V, My, /Lv, Emf V, Emf My, Or Emf /Lv) - HP 8642A Operation And Calibration Manual

Operation Model 8642A/B
Relative Amplitude (cont'd)
3-78
REF SET
Display
.....
f
0 0.0 0 0 0 0 0
m z
0.0]]
FREO AMPTO REL
The AMPTD REL annunciators indicate that the amplitude display is a relative
output. All subsequent amplitude settings will be entered and displayed in units of dB
relative to the absolute amplitude when the Relative Zero function was selected.
After setting the amplitude reference, the dBm key operates as a dB terminator (note
the dB printed above the dBm key). For example, after setting the output to read in
dB relative units, just key in 20 dB to output 20 dB relative to the absolute amplitude
when the Relative Zero function was selected.
How to Set a Reference to a Specific Amplitude
(In units of dBm, V, mY, uV, EMF V, EMF mY, or EMF uV.)
Setting a specific RF amplitude as the amplitude reference causes subsequent
amplitude settings to display the current output amplitude as dB relative to the
amplitude reference.
( AMPTD) REF SET «( SHIFT) (AMPTD
J )
followed by the value of the desired
reference amplitude (in dBm, V, mV, or uV).
REF SET Example 1
Configure the front panel to allow all amplitude setting values to be entered and
displayed as offset from a 1
V amplitude reference.
First select
(lNSm-PfiESET]
Lo
put the instrument in a known state, then:
ENTRY ENTRY DATA
LOCAL
(keys)
I
AMPTO )
~
REF SET OJ
[YJ
~
..
(program
APRSI VL
codes)
Display
f
0 0.0 0 0 0 0 0
m z
FREO AMPTD r:.EL
The AMPTD REL annunciators indicate the displayed amplitude is relative to a
reference amplitude. The displayed amplitude is -153.0 dB; the actual output
amplitude is the displayed amplitude plus the amplitude reference. To convert the
amplitude reference to dBm, first exit the relative mode, then select your reference
amplitude as the absolute output amplitude (lV in this case), then press the dBm key.
The equivalent value for 1 V is 13 dBm; therefore, -153 dB
+ (+
13 dBm) = -140 dBm.
I
I