I was told that one of the killers of superconductivity is magnetic fields. I guess they 'fixed' that.
Tom Holmes, N8ZM -----Original Message----- From: time-nuts <[email protected]> On Behalf Of Mike Feher Sent: Tuesday, January 26, 2021 1:07 PM To: 'Discussion of precise time and frequency measurement' <[email protected]> Subject: Re: [time-nuts] "Q for dummies" I recall back in the late 60’s visiting some friends at BNL. One of them took me through the cryogenic lab. In one they had an LC running at near 0 and it could be heard in a receiver. We know for L, Q in its simplest form is Xl/R. At superconductor temperatures R approaches 0 and therefore Q approaches infinity. Consequently the circuit oscillated by itself. I was amazed. Slightly different, but in the same lab they showed me an electromagnet in a superconductor cooled environment. I noticed it was wound with uninsulated wire. I inquired about that and was told that contact resistance is so much higher than the superconductor resistance, and they could get more turns without insulation. Regards – Mike Mike B. Feher, N4FS 89 Arnold Blvd. Howell NJ 07731 848-245-9115 -----Original Message----- From: time-nuts <[email protected]> On Behalf Of Dana Whitlow Sent: Tuesday, January 26, 2021 9:36 AM To: Discussion of precise time and frequency measurement <[email protected]> Subject: Re: [time-nuts] "Q for dummies" If anybody can even approach doing justice to the Q concept, including why it matters, in just two sentences, that person will have definitely earned the "Qulitzer prize" in technical journalism. Here's my entry: "A circuit's Q is closely related to its internal energy losses compared to external energy exchanges. A high Q can mean better efficiency, better conformance with expected performance (especially in filter applications), longer ringdown times (wineglass compared to milk glass) and (unfortunately) higher price." Dana _______________________________________________ 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.
