Here's some answers on the filter.... I got it boxed up and at work for good in the Kiwi.
* I needed this filter (and I need more of it) as there is a commercial AM transmitter not far from me on 1090 kHz. Artifacts of this daytime overload (it's off the air at night) are all over the Kiwi spectrum. I don't do any AM listening, so I'm not concerned about over attenuating things. I might cascade another to see if I can knock down the 1090 signal some more.
* The software I used was VNASaver, which is really a great way to control the VNA from the PC UI, rather than donking around with the little rockers on the screen. I'd really recommend this as it transforms the VNA into a very easy machine to use. Installation was easy, as was the calibration via the GUI.
* I'm not sure which all the core materials were. I know -37 and there was one more. I have a large junkbox and I just tried values which ended up measuring closely on my impedance bridge. I tweaked turns and core size until I got close (very ) to the design values in both L and C. I use an old (and great!) AADE LC bridge for this. I suppose the VNA would work great too.
UPDATE: I used type 43 and type 2 cores* Getting Chinesium standard extruded enclosures and precut Pride Of China (thanks Chris!) copperclad made housing this a simple affair (it's now in a box with BNC's at either end)
I wish a 1/4 wave coaxial stub cut for 1090 kHz wasn't so darned big!
PS:
https://toroids.info/ is really handy to get you close. You can also use this data + the empirical measurements to determine the core material. Great reference page !
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