>
>Rich-
>
>The specs say approx 30pf input
>
>rough figuring.....
>2 tubes 60pf
The max. grid C is 16pF per 4cx300A
>misc wire and socket TT about 100pf
stray C on the grid is a few pF.
>Xc@50Mc about 30k ohms.
>
Xc of 32 pF at 50MHz is 138 ohms.
>The specs also say the tube wants about 2.5W
>drive. 2 x tube about 5W.
>
For Class C, not for Class AB1.
>If I have 10W and I want 60V and half the power
>is going into my tubes and half into my resistor it looks
>like a 1:6 turns ratio and an 1800ohm resistor will get me
>the right swing from my 10W and look like 50ohm to the
>exciter.
>
>So, why do I need tuned input?
>
You need 60v pk to drive the grids. 10w-rms / 50-ohms is 32v pk. A
bifilar toroidial tranformer would increase the potential to about 60v
peak. The terminating R would be 200 ohms.
- later, Bob.
>
>
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>
- Rich..., 805.386.3734, www.vcnet.com/measures.
--
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