Bird Technologies 21-87A-11-xx-T Series-Manual - Manual (Page 16)

TX RX Systems Inc. Manual 7-9100-5 10/17/11 Page 10
For a Power Out (P
O
) of 45 watts and a Power
Input (P
I
) of 105 watts:
Loss (dB) = 10 Log
10
(45/105)
Loss (dB) = -3.7
For a P
O
of 55 watts and P
I
of 95 watts:
Loss (dB) = 10 Log
10
(55/95)
Loss (dB) = -2.4
So the calculated loss for this channel can run from
-2.4 to -3.7dB and be acceptable considering the
measurement error factor. The actual error could
be much greater if a 250 watt element was used;
the measured values could vary by as much as +/-
12.5 watts. So using a wattmeter element with the
smallest possible rating is important for accuracy.
Use of between series adapters or UHF type con-
nectors for making connections to the wattmeters,
device under test or loads, could make this error
even worse due to the additional impedance mis-
match that these connectors can cause.
Transmitter Combiner Test Data Sheet
Combiner Model Number:
Serial / Job Number:
Date: Technician:
Wattmeter #1 Serial Number:
Wattmeter #2 Serial Number:
Channel
Number
Power Input
(Pi) in Watts Power Output
(Po) in Watts
Power Ratio
Po / Pi
Calculated
Loss (dB)
Factory Measured
Loss (dB)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Table 3: Test Data Sheet.