Be careful, shielding can lower the Q impressively due to parasitic capacitance. Winding more than about a third of the length results in flux lines not coupling to the outboard turns. Ferrite antennas are fascinating.
https://en.tdk-electronics.tdk.com/download/2176996/8d0ef9c30ea64c62edc15b3a2888f6d9/ferrites-impeder-cores-pp.pdf Ferrite impeder cores may work better than solid cores, if the material works at frequency. I've seen a magnetic version of the "Skin effect" in ferrites, and increasing the perimeter seems to work better than a solid rod. -----Original Message----- From: time-nuts <[email protected]> On Behalf Of jimlux Sent: Wednesday, December 5, 2018 3:18 PM To: Discussion of precise time and frequency measurement <[email protected]> Subject: Re: [time-nuts] simple phase finder On 12/5/18 7:30 AM, Poul-Henning Kamp wrote: > -------- > In message <[email protected]>, jimlux > writes: > >> If anyone has a suggestion for an off the shelf active antenna that's >> orderable and receivable by Friday, I'd love to hear it. There's 3 >> or 4 of them I've seen (Clifford labs, DX Engineering has one, I'm >> sure MFJ has one) > > There is one experiment I have thought about, but not tried: Wind a > big loop, run it directly into a sound card with microphone input. > That's true.. many turns would give you more voltage. Hmm, I've got a 3 foot long, 6" diameter tesla coil secondary with about 800 turns on it. Aluminum foil over it for an electrostatic shield would be easy. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
