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Figure 3-27. Example Mixer ID to RF Isolation Measurement

RF Feedthrough

The procedure and equipment configuration necessary for this measurement are very similar to those above, with the addition of an external source to drive the mixer’s LC port as we measure the mixer’s RF feedthrough. RF feedthrough measurements do not use the frequency offset mode.

1. Select the CW Lo frequency and source power from the front panel of the external source.

CW frequency = 300 MHz

Power = 10 dBm

2.Initialize the analyzer by pressing B.

3.To select the analyzer’s frequency range and source power, press:

This signal stimulates the mixer’s RF port.

4. To select a ratio measurement, press:

Note Isolation is dependent on Lo power level and frequency. To ensure good test results, you should choose these parameters as close to actual operating conditions as possible.

5.Make the connections as shown in Figure 3-28.

Making Mixer Measurements 3-36

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HP 8753E manual RF Feedthrough, Example Mixer ID to RF Isolation Measurement