Rel Off; How To Turn Off The Relative Mode; Comments - HP 8642A Operating Manual

Model 8642A/B Operation
Relative Amplitude (cont'd)
REL OFF
How to T u r n Off the Relative Mode
I AMPTD1 REL OFF ( f S F f i m fTFF^OTn
[ AMPTD I REF SET ( r s W T l (TREOTI )
Select a volts key with amplitude as the
absolute).
>
o r
fOTF~OTn, or
active
function (volts units are always
H P - I B
Codes
Keys
REF SET
REL ZERO
REL OFF
AMPTD
OFF ON
EMF
Codes
APRS
APRZ
APRF
AP
APRSOF, APRSON
EMON, EMOF
Keys
dBm
dB
V
mV
MV
dB^V
Codes
DM or DB
DB or DM
VL
MV
UV
DU
Comments Range of Amplitude Reference Settings
Allowable ranges for the amplitude reference settings:
+ 59.9 dBm to - 1 4 0 dBm
4.995V to 0.023 uV
9.99 EMF V to 0.046 EMF uV
Note that the maximum for the dBm setting is greater than that for the voltage
setting. If you want to set a higher voltage reference than 4.995V (9.99 EMF V),
convert the value to dBm and set the reference set value as high as +59.9 dBm (221V
or 442 EMF V).
Converting Amplitude Units
Refer to Amplitude Units Conversion on page 3-205 for information about changing
amplitude values from one unit to another.
When the dBm and dBuV Keys Function as dBuV Terminators
Both the dBm key ( rSHITBEMl ) and the dBuV key ( Q£T ~
function as dBuV
terminators when the amplitude is set in dBuV. All other relative amplitude settings
use only the dBm key as a dB terminator.
HP-IB. Either DB or DM
When in the relative amplitude mode, DM does not set dBm; DM and DB set dB
relative amplitudes. Therefore, amplitude relative must be turned off (APRF) to have
DM mean dBm.
EMF Conversions Are Automatic
Relative settings established in the n o n - E M F mode will be automatically converted to
EMF values when that mode is selected. Similarly, relative settings established in the
EMF mode will be converted to n o n - E M F values when the EMF mode is turned off.
Amplitude Settings Interact With Other Instrument Settings
Some settings are limited by the interaction of coupled functions (for example AM
depth and amplitude). Refer to the appropriate Detailed Operating Instruction for
setting limitations, and be aware that any restrictions are due to the absolute
amplitude, not the relative amplitude setting.
3-81