Topband: W8JI Crossfire Phasing

David Cole g3rcq at
Sun Feb 14 13:17:00 PST 2010

Hi all I am in need of some advice please - firstly has anyone built a 4 square using Tom's crossfire method - does it work and was it worth the effort over a conventional phasing method?

My next question is regarding the circuit on page( ON4UN 4th Edition) 11-48 fig 11-58 in which Tom describes his system. I presume that the impedance's shown at the elements are the driven impendance's calculated in the usual way - can this be confirmed? I am not sure if this is correct as although I have not calculated the driven impedance's  because I do not have the source data - it seems odd that Tom resonates the solitary elements to 25 j0 and obtains the same impedance when driven - this is only for the 2 centre elements.

 - my next questions is how can I calculate the impedance at the end of the 90 degree line from the driven impedance.

In other words how does Tom get from  6.6 +j3 to 313 -j143 - these are the figures shown for the back element, and are before and after the 90degree line from the centre of the 4square to the individual elements.

Likewise how do I calculate the Zarray value of 20.6 -j13.4 

Thanks in advance - hope its not to mind blowing a question - regards  Dave G3RCQ

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