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rF hybrids System Manual
2.3 Testing
There are no adjustments necessary for the hybrids, but testing for correction operation is recommended.
A frequency selective voltmeter is recommended to verify proper operation of the hybrids. See list of
suggested suppliers below.
1. Check losses (between inputs and from each input to output) per the specification tables to see if
within expected range using a frequency selective voltmeter.
When measuring isolation between inputs, measure frequency F1 going into input 1 and verify that
the same frequency is at least 20 dB lower on input 2 with the output of the hybrid connected to a
50 Ω * load or to a line tuner with less than 10% reflected power. The higher the reflected power
is between the output and the line tuner then the worse (lower) the isolation will be between the
two inputs. When the line tuner is equal to 50 Ω * for the TX frequency then the isolation will be
at a maximum.
When measuring the level of one particular frequency, compare the level of that frequency at the
input versus the output and verify that the loss does not exceed the value in the specifications table.
2. The whole system should be connected when doing this test. If it is not connected to the coupling
capacitor (CCVT), use a power-line simulator on the line side of the Line Tuner .
High Impedance Frequency Selective Meter (30–535 kHz)
PowerComm Solutions PCA-4125
Signal Crafters Model 110
Spectrum Analyzer (Various Suppliers)
Table 2–2. Test Equipment.
*(or 75 Ω depending on hybrid setting)
