VK4ZXI

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. say more?? 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

Variable-length phasing cables for tuning repeater duplexers: Part 1, Construction of the cable Introduction A variable-length phasing cable for use in determining duplexer cable lengths, using M/F SMA connectors to vary the length is proposed. It is a cheaper alternative to a set of phasing cables with a 10mm (5mm?) length increment. This post describes the concept and how it can be replicated. A simple idea, but some frustration in execution. The basic process of using the variable-length cables is outlined. The next post will cover the use of the variable length cables and include screenshots from instruments and photos. The problem: determining cable lengths for inter-connecting duplexer cavities Determining cable lengths for inter-connecting duplexer cavities is a perennial topic. Notionally, they are a quarter wavelength or odd multiple, allowing for coax velocity factor, but in practice that is a starting point. My understanding is that commercially, a set of incr