Path: news.eternal-september.org!eternal-september.org!feeder3.eternal-september.org!fu-berlin.de!uni-berlin.de!individual.net!not-for-mail From: liz@poppyrecords.invalid.invalid (Liz Tuddenham) Newsgroups: sci.electronics.design Subject: Re: Filter problem Date: Sat, 14 Jun 2025 09:31:55 +0100 Organization: Poppy Records Lines: 20 Message-ID: <1rdwv8h.p540xrbrx3xaN%liz@poppyrecords.invalid.invalid> References: <1rdt6jl.1pg084917xik3kN%liz@poppyrecords.invalid.invalid> <1rdtp22.b2622eqp8sdiN%liz@poppyrecords.invalid.invalid> <563n4k1r82tdbag8l2bunu6pcpj52pnti4@4ax.com> <1rdv57o.1xnoblu7eh74gN%liz@poppyrecords.invalid.invalid> <1rdvkeh.1a8nvgr1yl28xgN%liz@poppyrecords.invalid.invalid> <1rdvx80.1lwsxs0lmsq39N%liz@poppyrecords.invalid.invalid> X-Trace: individual.net 4Q+RI+JbgqmItmjw0VDAHwrtTKXuQ7b3zdZOBmhPNoe1xp4itA X-Orig-Path: liz Cancel-Lock: sha1:AGaBS+Z6/oVLBCfAoJOsQ+T3hC4= sha256:FhGGSX6f6+/ZE2UckmQ1qTGgdvnJ+MnQ8dYQIISYlGw= User-Agent: MacSOUP/2.4.6 Dave Platt wrote: > Is there any chance you can make enough room in your setup for > something of the following sort? > > https://www.pa0nhc.nl/IMDfilter/EN/Notch/Single/HelicalNotchfilters2mEN.htm That's exactly the sort of thing I had in mind. The author's dimensions of 4" diameter and 6" high might be a bit of a problem but I could try scaling it down and adding more turns to the helix. Perhaps a piece of 35mm copper pipe would make a good starting point. A length of thinner pipe would be easier to accommodate, so perhaps I could experiment with something intermediate between between a coaxial stub and a helical resonator. -- ~ Liz Tuddenham ~ (Remove the ".invalid"s and add ".co.uk" to reply) www.poppyrecords.co.uk