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Thanks to everyone's input - I was able to get things sorted out. I actually tried both methods (Back to Back Method - thanks to Gary and the resistor method - thanks to Roger and found reasonable agreement.

I also compared it with the insertion loss calculated using the Fair-rite 43 permeability values which can be found in Owen Duffy's Blog 43 Ferrite for a 3 turn primary. Interestingly, the computed value is smack in between the resistor method -0.44 dB at 3.5 MHz and the Back-to-Back Method at -.75 dB. The calculated value using the Duffy calculator and the permeability values which ignores flux leakage and conductor losses provides a result of -0.61 dB at 3.5 MHz. This leads me to think that the back to back approach might be more conservative.

The comparison plot from both methods is attached.

Ariel NY4G

?On 3/18/21, 4:57 PM, "[email protected] on behalf of Gary W9TD" <[email protected] on behalf of w9td@...> wrote:

Ariel,
That would be satisfactory but your test fixture looks like ground is connected between inpuy and output anyway so connect to that grounds
Gary
W9TD