>
>At 08:55 AM 10/15/00 -0400, Tom Rauch wrote:
>>
>>> Remember in the last few days we have been told equipment has to be
>>> designed for the cheap and the ignorant
>>
>>Actually that is true. It doesn't mean everyone doesn't know how to
>>tune a PA or is cheap, but the fact is many people don't. You'd be
>>amazed at the calls!
>
>I don't think that this is anything to get angry about -- manufacturers of
>"normal" products weigh cost and quality considerations every day, and
>there is nothing inherently less honorable about being a Hyundai than a
>Lexus.
>
>As for the question of proper operation, we're all prone to think we know
>what we're doing and ignore the manual. Trouble is, there aren't that many
>tetrode linears around, and the tune-up routine is so different from a GG
>triode that many of us would rely on our triode experience and risk burning
>up the tube.
With a tetrode, one tunes/loads for a specified screen current when the
tank is resonant. Heavier loading =s less screen current. In practice,
this proceedure is close enough to simply tuning for max. relative output
-- as with a g-g triode. // Burning up a tetrode's screen from
mistuning is unlikely because screen supply power transformers usually
have fast-acting fuses in the primary.
> It's not hard to understand why a manufacturer would weigh
>that tendency (and the resulting support headaches) in the decision whether
>to go with a tetrode or a triode.
>
The decision to go with one or the other is largely determined by how
much gain is needed. Triodes provide x 10 - 20 gain. Tetrodes are good
for up to x 200 gain. (8281)
later, Pete
- Rich..., 805.386.3734, www.vcnet.com/measures.
end
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