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FT200-2 RF Toroid RF Choke
In article ,
Barett wrote: I have found some FT140-43's. Do you know if I stacked 3 Ferrite FT140-43's rings and wound 6 winding of RG58cu through, what would the maximum impedance Ohms could I expect @ 3.5MHz? I did something like that a few years ago, to build a common-mode choke for our ARES/RACES ham shack's HF feedline. I used off-the-shelf (surplus-store) ferrite tubes - very probably a 43 mix or something close to it, based on the simple inductance measurements I did with an MFJ analyzer. They're roughly 1 inch long, and large enough to allow three through-the-center passes of RG-8X coax. I glued somewhere around six of them, end-to-end, to create a long tube, and then ran the RG-8X through... creating a long three-turn choke. Added N connectors to the ends of the coax and stuffed the whole thing into a chunk of PVC tube with end-caps. The results were gratifying. When I tried a common-mode measurement - along the braid, from one end connector to the other - the impedance at 3.5 MHz was too high for the MFJ meter to read it... it simply said " 1500". A normal (differential-mode) measurement through the coax, looking into a 50-ohm dummy load, reads 50 ohms (1:1 SWR) as closely as matters not (i.e. within the accuracy of the MFJ meter). -- Dave Platt AE6EO Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
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