Tom Rauch wrote:
>Ian wrote:
>
>> It isn't quite a simple bridge neutralization network, because the
>> anode-cathode capacitance is not a single capacitor. It's actually a
>> T- network composed of anode-grid capacitance and grid-cathode
>> capacitance in series, shunted by the grid lead inductance to
>> ground... and that's before you add in the other parasitic
>> inductances.
>
>At HF, with most tubes I've seen, the tube behaves like a simple
>capacitor exists between the anode and cathode WHEN the grid is
>properly grounded.
>
>Grid inductance can be ignored, and the cathode-to-grid and anode-
>to-grid capacitances effectively parallel the input and output.
>
OK, having reached the end of the working day and now put in some
numbers for typical reactances, I see your point. The T-network
involving the grid inductance is a minor effect compared with the simple
anode-cathode capacitance.
73 from Ian G3SEK Editor, 'The VHF/UHF DX Book'
'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.com/g3sek
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