Title: Ferrite from flyback transformer for filament choke? Post by: n4joy on April 03, 2016, 10:35:52 AM Using an article from 73 magazine as I guide, I am constructing a homebrew 813 amplifier. I am winding my own filament choke and the author used a ferrite core from an old television flyback transformer for his (#12 wire, 12 turns bifilar). Well, I happen to have a burned out flyback transformer and am wondering what type of ferrite material is typically used in these transformers. I could purchase some type 43 on ePay but rather use what I have on hand if possible.
Thanks! Chris Title: Re: Ferrite from flyback transformer for filament choke? Post by: KD6VXI on April 03, 2016, 11:59:15 AM Got an mfj259 or vna or other such swr / network analyzer?
If so, you can measure the inductance across the freq range you are interested in directly. A single turn through or around the ferrite would let you see how 'reactive' the mix is at your freq(s) of interest. I had some rfi from a switcher led driver on upper hf. Pulled the ferrite out of it, was completely non reaction very above about 5 mhz. Added some 43 to the mix, no more EMI. --Shane KD6VXI Title: Re: Ferrite from flyback transformer for filament choke? Post by: KB5MD on April 03, 2016, 01:33:50 PM I built an 813 amp and used a flyback core. Just wind it with the same number of turns and wire size as given for a straight ferrite rod. Mine has been in service for quite a while with
no complaints. Title: Re: Ferrite from flyback transformer for filament choke? Post by: W7TFO on April 03, 2016, 03:30:56 PM I have a boatload of vintage flybacks, one or two free for postage ;)
Dennis Title: Re: Ferrite from flyback transformer for filament choke? Post by: Opcom on April 03, 2016, 10:32:17 PM I have a boatload of vintage flybacks, one or two free for postage ;) Dennis Do you happen to have any yokes for 45 to 70 degrees deflection? The tube necks are 1 7/16" +1/16" diameter (1.4375 to 1.5") 45-55 deg preferred. Not too critical on the inductances etc they sometimes have to be rewound for my uses when necessary. |