On 12/20/2021 6:21 PM, Pete Smith N4ZR wrote:
Others can speak more authoritatively about this, but I thought those clamp-on cores, where they go right on the existing run of coax, offered too little inductance to be of much use below VHF. Experts?
That's right, sort of. But it misses the principle of how ferrite chokes work. It's NOT the inductance, it's the resonance formed by the parallel resonant circuit of series inductance and resistance coupled from the core with stray (parasitic) capacitance of the winding. Choking action is provided by the resistance associated with that parallel resonance. The most useful chokes are those with a broad, low Q resonance. THAT'S what is so special about the #31 mix, which combines the resonance of the winding with a dimensional resonance within the core. OTs among us will remember stagger-tuned IFs. Same principle.
k9yc.com/RFI-Ham.pdf includes a tutorial discussion of this, so I won't repeat it here.
73, Jim K9YC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
