Measuring Transmitter Power
The meter should be connected to the transmitter according to the
“FORWARD SIGNAL” label on the meter (see the illustration on the opposite
page). Depending on the gender of the type “N” connector on the transmit-
ter it may be necessary to use the double male type “N” adapter. The meter
should be terminated with the 50Ωload included in the kit.
Turn the PM-2458 on by pressing the ON-OFF button. Select the frequency
band of interest by pressing the MODE button until the frequency list is
shown. Use the SELECT button to scroll through, and select the appropriate
band. A small arrow should be displayed beside the band (2.4, 5.3, or 5.8).
Press the FWD button to read the forward power. A small right-pointing ar-
row will appear in the upper right side of the display. This is the amplitude
of the signal (in dBm or mW, depending on the unit selected in the MODE
menu) in the forward direction.
The meter is designed to detect signals between 0 and 20dBm in the for-
ward direction, and –20 to 17dBm in the reflected. Damage can occur to the
meter if the forward power into the meter (without the attenuator) exceeds
36dBm.
Most broadband radio transmitters deliver less than 100mW (20dBm). The
2W 10dB attenuator can be used for sources that are between 20 and
30dBm in amplitude. Remember to apply the appropriate offset in the
MODE setting (+10 if the attenuator included in the kit is used). If the out-
put of the transmitter exceeds 33dBm (2W), an attenuator of the appropri-
ate power rating and insertion loss should be used to lower the signal to a
level below 20dBm. Using the MODE button an offset can be configured for
attenuators up to 30dB. If an attenuator is not used, the offset should be set
to “+00”.
While the forward power is displayed constantly on the top line of the dis-
play, the bottom line alternates between the VSWR and the frequency band
and offset settings.
NOTE: A good way to verify proper operation of the 50Ωtermination
(included in the kit) is to make sure that the a VSWR of 1.2:1 is displayed
when the meter is connected according to the diagram on the opposite
page. If the VSWR is not 1.2:1 the termination should be replaced.
PM-2458
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