User's Manual

EX7100 Technical Manual - Module Descriptions
©1999 Exicom Technologies (1996) Ltd 7-49 Issue 3 - May 2001
Refer to Figure 7.26 and the steps outlined below:
Figure 7.26: VHF Duplex Filter Adjustment Locations
1. Connect a 50Ω termination to the antenna port.
2. Connect the analyser input to the high frequency port.
3. Feed the tracking generator output into the low frequency port of the Duplexer. Set
the analyser to the maximum output level available.
4. Adjust the three low pass adjustment screws to maximise the notch on the high
operating frequency of the Duplexer.
5. Adjust the three high pass adjustment screws to maximise the notch on the low
operating frequency of the Duplexer.
6. Repeat the two steps above until the notches are centred and maximised on the two
notch frequencies. The notches should provide greater than 85dB isolation (typically
90dB). On many analysers, it is not possible to measure the full isolation, as there is
not sufficient dynamic range available.
7. Check that the insertion loss from the low frequency port to the antenna port is less
than 1.5dB (0.8dB typical).
8. Check that the insertion loss from the high frequency port to the antenna port is less
than 1.5dB (0.8dB typical).
9. Check that the return loss into the high and low frequency ports is better than 16dB.
High Pass Adjustment Screws
Low Pass Adjustment Screws
High Freq Port
Low Freq Port
High Freq Port
matching capacitors
Low Freq Port
matching inductors
Antenna Port