> You, Rich, and Eimac like pi networks.
No, I "like" ANY network that provides a low impedance from
cathode to ground for harmonics of the drive frequency at the
cathode of the tube. It doesn't matter what that network is, as long
as it bypasses the cathode for harmonics of the plate current
waveform and isolates harmonics generated in the tube from the
exciter.
Creative Electronics,
> RF Power Products, ETO-Alpha. myself, and others like
> parallel or T networks.
That doesn't make it a good choice! Just look at IMD in reviews of
amplifiers (and transmitters), and you will see how little attention
people pay to building clean systems.
While parallel networks are often just as good, T networks are
really a very poor choice. They are a system begging for less-than-
obtainable IMD or efficiency.
You have two basic flavors of T networks, and while one type is a
low-pass and will reduce harmonics appearing back at the exciter
none of them do a good job of ensuring that cathode doesn't pump
around with harmonic energy.
If you have to use three components and a DP switch, you might
as well do it the most reliable way no matter what you "like". You
never know what cable length and exciter someone will use.
73, Tom W8JI
W8JI@contesting.com
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