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## Re: LF: Loop (was Re: IGBT in 136 KHz TX?)

 To: [email protected] Re: LF: Loop (was Re: IGBT in 136 KHz TX?) John Andrews <[email protected]> Tue, 21 Jul 2009 20:41:40 -0400 <[email protected]> <[email protected]> [email protected] [email protected] Thunderbird 2.0.0.22 (Windows/20090605)
 ```Ha-Jo, ```That's one way to look at it, and a valid approach. But consider another example: Suppose you have a single-turn loop that has an (arbitrary) impedance of 0.1 +j10 ohms at a frequency of interest, and you desire to make it look like a 10-turn tuned loop. A 1:10 transformer will provide the same voltage step-up as a 10-turn loop, and will ideally step the impedance up by 10^2 = 100, giving you 10 +j1000 ohms. You would then have an option of series or parallel tuning the loop on either side of the transformer. The secondary side is much nicer for our use than the primary side. Parallel tuning would be a good choice into a hi-z input preamp. Series tuning would leave you with the 10 ohm resistance, which you could then step up to the characteristic impedance of your line, or leave at a lower value if BW were an issue. In the above case, I'd suggest a primary inductance on the transformer of 5X the magnitude of the loop impedance, but your 4X would probably do. Leakage reactance is pretty much inevitable, and will throw things off a bit. There's all sorts of ways to approach this, depending on your desire for tuning, etc. But I just wanted to point out that the much simpler single turn construction can work just as well as multi-turn. ```John, W1TAG [email protected] wrote: ``````Dear John, LF, I would like especially to comment on using a one winding loop combined with a step-up transformer: `````` ```
 Current Thread LF: Loop (was Re: IGBT in 136 KHz TX?), Warren Ziegler Re: LF: Loop (was Re: IGBT in 136 KHz TX?), w1tag LF: Re: Loop (was Re: IGBT in 136 KHz TX?), Dave Sergeant Re: LF: Loop (was Re: IGBT in 136 KHz TX?), mal hamilton LF: Warrens Kw's, Laurence BY3A-KL1X China LF: Eclipse, Mike Dennison Re: LF: Loop (was Re: IGBT in 136 KHz TX?), hajo . brandt . dj1zb Re: LF: Loop (was Re: IGBT in 136 KHz TX?), John Andrews <= Re: LF: Loop (was Re: IGBT in 136 KHz TX?), Alberto di Bene Re: LF: Loop (was Re: IGBT in 136 KHz TX?), James Moritz Re: LF: Loop (was Re: IGBT in 136 KHz TX?), Roelof Bakker Re: LF: Loop (was Re: IGBT in 136 KHz TX?), hajo . brandt . dj1zb Re: LF: Loop (was Re: IGBT in 136 KHz TX?), John Andrews