>Rich says:
>
>>mixing (discussions about) push-pull audio amplifiers with single-ended
>>RF amplifiers is hardly cricket.
>
>No, it's application of tube technology. A tube that will do push-pull AB2
>audio
>will do parallel or push pull AB2 RF. There's nothing magic in parallel v.
>push-pull when tuned tank circuits are used.
>
> >For the radio, grid-driven with grid current is an SWR shutdown
> >nightmare.
>
>?????? What has SWR got to do with it?
Modern radios shut down with even moderate swr. My TS-440S begins to
shut down at an SWR of less than 1.4:1.
>I presume you're assuming a change in
>load impedance on the driver. The argument so far assumes that the driver
>is a generic radio - that means it provides the same power into whatever
load. OK,
>that's not the practical case, but that your argument is that ALL grid driven
>amplifiers with grid current MUST, under all possible conditions, be bad
>on IMD.
Not quite. The 4CX600J and 4CX1500B will tolerate c. 0.3mA of grid
current in grid driven service. Philips reportedly makes some tubes that
will tolerate small amounts of grid current.
>Now you're trying to get specific. A driver with good regulation of the RF
>drive does not get a problem because of varying load - that was part of the
>original conditions I set, viz good RF drive regulation and good electrode
voltage
>regulation on the grid(s) of the tube(s).
>
>>G2DAF is not bad per se. It produces more distortion than the average
> >g-g amplifier.
>
>Can you prove mathematically (or otherwise) that is necessarily always the
>case with ALL tubes under ALL conditions?
>......
enough
cheers, Peter
- Rich..., 805.386.3734, www.vcnet.com/measures.
end
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