On 11/24/2022 2:35 PM, Steve Thompson wrote:
For sure the stub (looking like a short to even harmonics) works best
when combined with some series inductance to work against. Hopefully the
load cap is already a low impedance to harmonics so the short circuit of
stub won't do so much when added across it - but it shouldn't do any
harm either, and appeals to my laziness compared with having to
manufacture a nice choke like you did.
Take a look at the fundamental concepts in these two links, which
address the placement of stubs for harmonic suppression at HF. The first
doc ran in National Contest Journal about five years ago, correcting
some less than ideal work published a year earlier, the second is the
slide deck for a talk I did at Visalia around the same time. My work got
pretty thoroughly peer reviewed.
http://k9yc.com/LocatingStubs.pdf
http://k9yc.com/StubPlacement.pdf
Some of the same techniques are used with cavity filter networks.
73, Jim K9YC
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