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Operating Instructions
15
Measuring
Power in dBm
Operation of the forward and reflected dBm modes is
identical to the forward and reflected CW power modes,
except that the resulting reading is converted to dB above 1
milliwatt before it is displayed. It should be noted that in
doing this conversion, the range set on the slide switches is
assumed to be watts rather than kilowatts or milliwatts. If it
is not, 30.0 must be added to all dBm readings when the
range is in kilowatts, or subtracted from all readings when it
is in milliwatts. An error message is displayed if CW power
is more than 24 dB below, or peak power is more than 6 dB
above the nominal element range. Refer to Table 4.
Table 4
Watts/dBm
Equivalents
Measuring
Return Loss
The measurement of return loss is the same as that of SWR
except that the result is displayed in dB. In other words a
reading of 21.65 indicates that reflected power is 21.6 dB
down from forward power.
Figure 11
CW Power in
dBm
Power dBm Power dBm
1 milliwatt 0 4 watts 36
10 milliwatts 10 10 watts 40
100 milliwatts 20 20 watts 43
1 watt 30 40 watts 46
2 watts 33 100 watts 50
Figure 12
Return Loss,
Insertion
Loss, or
Attenuation