Scale Power Measurement
Pengcheng Jia
Nov 21, 2002
System Setup
LabView Program
Signal Source
Wiltron 68001
Power Meter
HP438A
Power Supply
Agilent 3631
TWTA
Power Supply
KEPCO
8 Channel Supply
for 32 MMICs
Coupl
er #1
Power Sensor A
Agilent 8485A
Power Sensor B
Agilent 8481B
Coupl
er #2
Gate
Bias
Spectrum Analyzer
HP8563
Drain
Bias
DUT
Attenuator
20dB / 100 Watt
Control Program
Calibration Procedure
Power Sensor A
SMA to N
Adapter
Coupler #1
Power Sensor B
(a)
Power Sensor A
Power Sensor B
SMA to N
Adapter
Attenuator
20dB / 100 Watt
Coupler #1
Coupler #2
Spectrum Analyzer
(b)
Power Meter & Power Sensor
•
Calibration of power meter (for 438A)
1. Press Zero
2. Connect power sensor to POWER REF port,
press Cal Adj, enter the Ref CF number on your
power sensor
3. Press Cal Factor, enter the CF number at your
frequency
Note: When calibrate with high power sensor
8481B, remove the 30 dB attenuator, then
connect to Power Ref port
Kepco RA55 Power Supply
KEPCO 8 Channel Power Supply
•Use PC’s program to
control 8 channel all
together
•Use Kepco’s
program to control
one channel at one
time
•Always set current
limit to protect your
system
Up to 15V, 12A each channel
TWT

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Wait for warm up
Gain is adjustable, very high gain(40-50
dB), Watch out your system’s limitation
Always connect with load at output port
before turn the RF output on
Let’s standby and cool down several
minutes before turn the power off
Tips for WinCal Key
WinCal License Key
We use a parallel port hub to connect the license
key with 3 computers and 1 printer. The key and
the printer is on the top port of the Hub. You can
switch it to different computers by pressing the
button at the lower part.
Always connect the printer and make sure the
printer is working fine. Otherwise the key
may not be seen by the computers.

Tip for 85108A
The 85108A test set has an option H11. This
option support 2 bands: 1-20GHz or 6-50GHz. It
can’t work continuously from 1 to 50Ghz. It
means if you measure from 1 to say 30 GHz. The
result will be very strange.
 Always load the configuration disk when you
change the band.
Press Disc->Load->more->Machine Dump->select
your band(NP for normal non-pulse
measurement)->Load file
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