How can I accurately measure conduction angle of an RF amplifier?

Discussion in 'Amplitude Modulation - AM Fans' started by WB2CAU, Apr 8, 2016.

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  1. AC0OB

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    You can measure the conduction angle with an oscilliscope but you will need some very specialized very low capacitance and HV probes, with one channel sampling the input voltage (at the tuned input or swamping resistor) and another channel sampling the grid voltage at the grid.

    The input circuit should show a complete sine wave whereas the grid should show a a partial sine ellipse.

    Frederick Terman has stated in his various texts that so-called class C operation occurs not at 90 degrees conduction angle but at conduction angles between 120 to 140 degrees.

    https://searchworks.stanford.edu/q="Frederick+Emmons+Terman+Collection.+"&qt=searchq="Frederick+Emmons+Terman+Collection.+"&qt=search

    Cutoff (grid negative voltage) bias is adjusted until the grid voltage shows a 120 to 140 degree ellipse.

    And as KH2G has stated, this occurs at approx. 3X cut-off bias.

    Phil

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    Last edited by a moderator: Apr 12, 2016
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  2. AC0OB

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