Monday, 27 August 2018

Variable-length phasing cables for tuning repeater duplexers: Part 2, Using the cable

Variable-length phasing cables for tuning repeater duplexers: Part 2, Using the cable (draft)

Introduction

In Part 1, a variable-length phasing cable for use in determining duplexer cable lengths, using M/F SMA connectors to vary the length is discussed.

In Part 2, this post, I will cover the use of the variable-length phasing cable in more detail.

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The basic process

The basic process of using a variable-length phasing cable to tune a six cavity duplexer:

1/ Tune each cavity to frequency.

2/ Connect the three cavities with two same length adjustable phasing cables of approximately the right length

3/ Using a spectrum analyser and tracking generator or a vector network analyser (VNA), take out or insert SMA connectors in both cables until the desired response is achieved.

4/ Using a Tee connector between the ports of the instrument, measure the resonate frequency of one of the correct length variable cables as a quarter wave stub.

5/ Cut a length of cable a little longer than desired, attach one connector, connect to Tee and measure the resonate length. Cut the cable to that of the variable length cable.

6/ Attach the second connector and check that the resonate frequency is the same as the variable-length cable. Make a second phasing cable to the same length.

7/ Attach both new phasing cables to the duplexer and check the desired response is achieved.

8/ Repeat for the other side of the duplexer.


1/ Tune each cavity to frequency.

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2/ Connect the three cavities with two same length adjustable phasing cables of approximately the right length

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3/ Take out or insert SMA connectors in both cables until the desired response is achieved.

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4/ Measure the resonate frequency of one of the correct length variable cables as a quarter wave stub.

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5/ Cut a new cable of the same length. 

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6/ Complete cable and check length.

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7/ Attach both new phasing cables to the duplexer and check the desired response is achieved (repeat 2&3).

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8/ Repeat for the other side of the duplexer.

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Discussion

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Conclusion


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