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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.
High Impedance Frequency Selective Meter (30–535 kHz)
1. Check losses (between inputs and from each input to output) per Table 2–1, or the specification
tables, to see if close to expected values exist, using a bridging frequency selective voltmeter
connected to the front test points.
a) 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.
b) 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 Table 2–1 or 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 .
*(or 75 Ω depending on hybrid setting)
Page 2–4
Table 2–2. Test Equipment.
PowerComm Solutions PCA-4125
Signal Crafters Model 110
Spectrum Analyzer (Various Suppliers)
April 2023
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