10
High Power Measurements
Signal Level Characteristics
Use Figure 10-1 to examine the maximum p ower ratings and normal signal levels present
in the test set. The signal levels are approximate, with signal path loss increasing with
frequency. Note the follo wing characteristics:
Typically, the RF input is about 9 dBm and the loss to the selected test port is ab out 9 dB.
With the step attenuators set to zero dB, the loss from the RF input to the a1 or the a2
mixer, and the loss from Port 1 or Port 2 to the b1 or the b2 mixer, are approximately
equal at ab out 26 dB.
Since
eac
h
mixer
includes
a
20
MHz
preamplier to
oset its
conv
ersion loss,
measuremen
t
of
the User
Parameters
will sho
wthe
IF
lev
el
to
b
e
ab
out
22
dB
less
than
the
RF
input
or
the
signal
lev
el
at
the
test
p
ort.
F
or
sp
ecied
p
erformance,
the
maxim
um
IF
signal
lev
el
as
measured b
ythe
user
parameters
is
0
10
dBm.
Higher
signal
lev
els
cause
errors due
to
compression,
and
lo
w
er
signal
lev
els
pro
duce
greater uncertain
t
y
due
to
noise.
Caution
Comp
onen
ts
in
the
test
set
will
b
e
b
e
damaged at
certain
signal
lev
els.
T
o
a
v
oid
damage,
observ
ethe
follo
wing
op
erating
precautions:
Use the
POR
T
1
and
POR
T
2
atten
uators
(Stim
ulus
P
o
w
er
men
u)
to
protect
the
mixer
input
0
the
mixer
damage
lev
el
is
+20
dBm.
Install
appropriate
comp
onen
ts
in
the
rear
panel
extension
links
to
protect
the
test
set
F
orw
ard/Rev
erse
switc
h
0
the damage
level
is +20
dBm
applied
at any input or output. This means that if the device output is greater than
+20 dBm, the switch can b e damaged by +20 dBm present at either LOW
POWER OUT connector.
If the device output is greater than +43 dBm, use appropriate comp onents
to
protect
the
test
set
p
orts
(and
the
Forw
ard/Rev
erse
switc
h)
0
the
damage
lev
el is
+43
dBm
(20
w
atts)
applied
at
POR
T
1
or POR
T
2
for
the
HP 85110A, and +47 dBm (50 w
atts) for the HP
85110L.
High
P
o
w
er
Measurements
10-1
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