Friends,
There are plenty of claims that it is wise to use tuned input circuits
on Grounded Grid amps and that the reasons are reduced IMD, better
efficiency and better matching to modern day exciters. It is easy for us
to see the matching benefit. There doesn't appear to be any published
data to demonstrate the differences of IMD and efficiency in a real amp,
or several real amps between using tuned input and not using a tuned input.
Have any of you documented this kind of test before? Have you published
the data? Would you care to? If you have, would you share it? I have
searched the web but have found no published comparison between running
with and without a tuned input circuit on a Grounded Grid amp. I don't
have the equipment to run this kind of test but it certainly looks like
it would be worth while doing. We could argue theory all day long (and
we have!) but a practical demonstration would be worth a thousand arguments.
Obviously it would be more meaningful if tests were done on more than
one amp but even one good demonstration could prove the point. I would
suggest using the same drive power, not overdriving the amp in any case,
showing the output power difference and the IMD difference between the
same amp with and without the tuned input circuit.
Anyone care to comment, run the tests or offer their data?
Thanks and 73,
Tony W4ZT
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