> >Add another winding to a choke and it magically becomes a transformer! >
Unfortunately that doesn't work for RF current measurement. The objective for a choke is to create a high series impedance, but the objective for an RF current transformer is exactly the opposite: to avoid disturbing the situation that is being measured, the impedance inserted into the main line must be as low as possible. To achieve a low impedance in the main line, an RF current transformer requires *ONE* pass of the primary winding (feedline) through the core and typically about 10 turns on the secondary. The secondary must also be terminated in a low load resistance, typically about 50 ohms. With a 1:10 turns ratio the series impedance inserted into the main line is then about 0.5 ohms. That is why a common-mode choke and a common-mode current transformer are two completely different creatures. Don't confuse them. 73 from Ian GM3SEK >-----Original Message----- >From: Elecraft [mailto:[email protected]] On Behalf Of >Josh Fiden >Sent: 09 August 2016 22:16 >To: [email protected] >Subject: Re: [Elecraft] Common mode chokes > >Add another winding to a choke and it magically becomes a transformer! > >73, >Josh W6XU > >On 8/9/2016 1:56 PM, MaverickNH wrote: >> Just wondering - short of +/- RF Burns and Audible Noice, can one readily >> detect/measure Common Mode Current on a coax antenna feedline? >> >> >> >> -- >> View this message in context: >http://elecraft.365791.n2.nabble.com/Common-mode-chokes- >tp7621305p7621430.html >> Sent from the Elecraft mailing list archive at Nabble.com. >> ______________________________________________________________ >> 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] >> > >______________________________________________________________ >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] ______________________________________________________________ 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]
