ad: Amateur-1

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

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

ad: L-HROutlet
ad: l-rl
ad: Left-3
ad: abrind-2
ad: Left-2
ad: Subscribe
ad: L-MFJ
  1. AC0OB

    AC0OB Platinum Subscriber Platinum Subscriber QRZ Page

    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."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.


    AC0OB - A Place where Thermionic Emitters Rule!

    Besides, when you're a Ham, you experiment with and improve boat anchors - that's what you do.:)
    Last edited by a moderator: Apr 12, 2016
    N6YW likes this.
  2. AC0OB

    AC0OB Platinum Subscriber Platinum Subscriber QRZ Page

    N6YW likes this.

Share This Page