Dave Pick wrote:

I put a pi network (LPF) in between and it worked.

Yes, that's the "impedance inversion" Markus DF6NM wrote
about on the topic of "Wilkinson Combiner" recently.

A Pi filter with all X = Zo behaves like a lumped circuit
version of a quarter wave transmission line.

For 50 ohms and 136.75 kHz that is:

  C1 = 23.3 nF across, L = 58.2 uH along, C2 = 23.3 nF across

Open load => L and C2 in series resonance => input looks shorted
Load = 50 ohms => input = 50 ohms
Shorted load => L and C1 in parallel resonance => input looks open

73
Johan SM6LKM



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