Wilkinson combiner coil induction measurement question

[Chris Wilson]

If I plug my desired frequency (137.55kHz yes, kHz, I am inputting 0.13755MHz) into this on line calculator I get a figure for the two coils of 81.82uH each

http://leleivre.com/rf_wilkinson.html

I have two coils prepped with a few excess turns, and can measure with a calibrated Philips LCR meter at 1kHz, or I can try and measure them with an AIM4170 antenna analyzer at 137khz. Is it important to measure and trim them at 137khz or not please? Can I assume the on line calculator is assuming measurement at the operating frequency?

[Andy Watson]

Try the Skin depth calculator at 1kHz and 137kHz. I think it might have a significant effect on the Q of your coils - i.e. I think you should test at 137kHz.

[T3sl4co1l]

If they're air core, use this:
http://hamwaves.com/antennas/inductance.html

The network Q is quite low, so the Q of the components will have only a small effect (i.e., Q > 10 gives < 10% losses, roughly speaking).

BTW, why use a Wilkinson divider instead of a wideband transformer splitter?  No need for tuned components, just one winding (well, and a few taps and such) and a lump of ferrite.

Tim

[Chris Wilson]

Thanks for that Andy, I will use the AIM4170 to verify the impedance then, as the calculator cited above gives different turns to the one I used.

[Chris Wilson]

OK, understood, thanks for that. The reasons i am using a combiner are two fold. Someone with similar amps to combine has buikt it and it apparently works well, and I am not qualified to design a good output transformer. plus I don't know where to source a suitably efficient core to handle the combined power as the FT-240-78 material one used in each amp seems as big as I can get in that material (designed for the frequency) and it already runs slightly warm. Specifics on what to try welcome