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Hi, i want to buy some ferrite GDT, i chose EPCOS B64290-L40-X830 Ferit toroid R58 AL5400nH N30
but i can have it for 11,4€ ONE, which is somewhere around 15$
for example, i could have TN20/10-3E25 Toroidal ferrite core TN, material 3E25, 5340nH for just 1,7€, but i must take 10 (which looks like only choice)
is epcos really more expensive than ferroxcube?
This is from 2 different part resellers. How much cost some good GDT in US?
Personally i would never buy such a expensive core, as for replacment i am using cores from toroidical EMI line filters, it's not the best way but these works just great for me. But of course if u wanna quality core especially designed for HF its good thing to invest in this component.
Registered Member #51
Joined: Thu Feb 09 2006, 04:17AM
Location:
Posts: 263
$15 is crazy for one core. An American company called electronics goldmine sells nice cores for about $0.25 each. See if electronics goldmine will ship to you. Also try amadon. Farnel might also sell cores that you could use. If all else fails, you can take apart a computer power supply and use the small E cores for your GDT.
Registered Member #162
Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140
Almost all ac line common mode filters (the type with identical windings for each phase) are of MnZn ferrite so perfect for a GDT up to 100's of kHz. Typical Al would be several uH per turn-squared.
It doesn't matter which particular MnZn ferrite you use. With very few exceptions any large ferrite toroid that you find will be MnZn.
NiZn ferrite has MUCH lower permeability than MnZn, at least 10x less but they are useful to the highest sstc frequencies practical.
So just get any ferrite toroids that are of a suitable size and wind your gdt.
As above, put a capacitor in parallel or series and measure the resonant frequency to determine actual inductance if you wish. Knowing the core size, number of turns and inductance you can look for a similar core to determine the ferrite type. You will probably not find an exact match as MnZn ferrite permeability varies significantly with flux density and temperature, just use a near approximation +/- 50%
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overpriced gdt?
