TB 9-6625-2185-24
(3) Connect multimeter to VRF center connector on rear panel of power meter and
pin 1 of interconnect cable.
(4) Record bridge resistance value (2 decimal place resolution) as indicated on
multimeter as R (approximately 200 :).
(5) Disconnect multimeter and set to read dc V.
(6) Reconnect thermistor mount to interconnect cable and press power meter power
to ON. Allow power meter to stabilize.
NOTE
Ensure that multimeter input leads are isolated from chassis
ground in following steps.
(8) Set power meter RANGE switch to COARSE ZERO and adjust front panel
COARSE ZERO control for a zero meter indication.
(9) Fine zero power meter on most sensitive range, then set power meter RANGE
switch to 1 mW. If multimeter indicates less than 400 mV, record this value to the nearest
microvolt as V0. If value is greater than 400 mV, rezero power meter.
(10) Connect thermistor mount to PWR REF and record multimeter indication
as V1.
(11) Disconnect multimeter (-) input lead from the VRF connector and reconnect to
power meter chassis ground. Record multimeter indication as VCOMP.
(12) Calculate PWR REF output power using the following formula:
2 VCOMP (V1 - V0 ) + V02 - V12
PO =
4 R (CALIBRATION FACTOR)
Where:
PO = Power output in watts
VCOMP = Value recorded in (11) above
V1 = Value recorded in (10) above
V0 = Value recorded in (9) above
R = Value recorded in (4) above
CALIBRATION FACTOR = Test report value for thermistor mount at 50 MHz (or other test
frequencies being measured).
NOTE
The technique of (7) through (12) for measuring power will be
used throughout this procedure and will be referred to as
precision power measurement technique.
NOTE
Retain value of R recorded in (4) above for use in precision
power measurement technique.
6
