[Elecraft] OT; large ferrite toroid core?

[John Oppenheimer]

Hi Mike,

Initial permeability can be computed from your values:

Compute 4T permeability=1 (Lo) using core dimensions:
Lo = 0.0004606 * Log10(OD / ID) * Ht * Turns^2 (Ht in mm)
Lo = 0.0004606 * Log10(6 / 2.6) * 14.3 * 16 = 0.0383uH (Ht in mm)
Initial Permeability ui = 6.6 / 0.0383 = 172

Fair-Rite 61 material ui = 125, 52 material ui = 250. If characteristics
are close to 61 or 52 material, then could use it for an HF Choke Balun.

Complex permeability can be plotted out to 20 to 30 MHz range using a
single port VNA. Do you have a VNA? I can walk your through the process
if wanted.

John KN5L


On 10/21/21 1:24 PM, Mike Maloney wrote:
> We were gifted a somewhat large (6"OD, 2.6" ID, 9/16" thick) ferrite core of unknown mix and original use.   On face was marked 6.6uH w/4turns.   My thinking it might make a good common mode RF choke on the output of an inverter generator or on coax feedline.    Not familiar with properties of toroid cores of this size.   Any ideas?
> 73, Mike AC5P