>
>>? Hej! You made a three letter mistake Rich when you, in your answer to the
>guy
>said " Up to about 200kHz, it is possible to construct a grid-driven
>neutralized, triode amplifier, providing you use a triode with a Mu of 5
>maximum." It should have been "NOT neutralized ", of course. Yes, in them
>good old days hams used TPTG ( tuned plate - tuned grid ) triode
>oscillators even at high powers. Some of those tubes used are listed in the
>book I mentioned.
? ... which of course meant that no driver was required, However, for
designers who wanted to construct a grid-driven triode linear-amplifier,
the low-Mu triode is the only game in town.
>
>With some well shielded multigrid tubes , however, there is usually no
>neutralizing required grid driven on the lower short wave bands.
? Not a good bet for "tetrodes with handles" type of amplifiers. 8171
tend to have a mind of their own without neutralization. Another
advantage of neutralization is that it results in virtually Perfect
input-SWR on all HF frequencies.
>But you
>have to reduce external feed back paths and use good shielding.
Good shielding is not as effective as good neutralization.
> More of this
>in the RCA TT-5 Technical Manual on transmitting tubes.
>
>Grid driven neutralized triode linears where often used in the fifties, even
>commercially. JOHNSSON made a such a linear with 300W out using 811A's.
? "linear" -- You gotta be kidding. Grid-driven high-Mu triodes are
never linear because it takes a metric-ton of grid-current to cause
normal anode current to flow due to the high-Mu. . However, with
cathode-driven, the built-in RF negative-feedback corrects for the
non-linearity brought about by the flow of substantial grid-current. .
- later, Hans
- Rich..., 805.386.3734, www.vcnet.com/measures.
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