The AM Forum

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

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

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. 

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.