[Amps] Grid vs cathode driven

[Will Matney]

Peter,

Why would one want to go through all the trouble with sweep tubes on that when 
10 of them can be ran grid driven? The Galaxy amateur amp was a good example
of this. I have built them using as high as 10 in G-G in parallel. No neutralization
was necessary, and they ran just fine. I've used as high as 4 grid driven, they did
ok too. I'd try this first before do that arrangement.

Best,

Will

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On 8/4/06 at 10:13 AM Peter Chadwick wrote:

>Hsu said:
>>I think we can use similar design in RF amplifier, add a wide band HV RF
>transformer to change the push-pull output to single end output, so we can
>use same Pi network as same as single end 811A GG amplifier,even we can
>useing RF transformer reduce the output impedance, so we can use
>inexpensive low volt air capacitor(reciving caps).simple input net work,
>withou screen and grid PS, cheap out put Pi network,it seems very perfect
>amplifier!<
>I would be very dubious about the practicality of making the transformer.
>You're looking for a wideband transformer from about 13k ohm or so down to
>whatever, and that means a lot of primary inductance, and thus capacity
>(because of the number of turns) You also need a lot of ferrite to avoid
>saturation. With a low impedance arrangement ( say a lot of sweep tubes)
>it becoems more practial because the impedance is lower.
>73
>Peter G3RZP
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