Hi all,

I use RFSim99 pretty often, and appreciate all it does. I've come
across a few "strangenesses" in the past, and just found a new one to
add to the list:

In the RF Calculator Resonance/Reactance tool, enter 10MHz and 50pF.
The resonating inductance is correctly shown as 5.066uH. Now change
the capacitance to 50nF; you'd expect the inductance to show as
5.066nH, but it shows instead as 5.061nH. Change the capacitance to
50uF and the inductance shows as 5.066pH as expected. This isn't a
big error, but it's a little puzzling that it's there at all. I
discovered it when calculating values for a very narrow LC filter near
10MHz; I'm not sure if the error is worse than this at some points or
not. This particular error seems to be only in the calculator, not in
the simulator.

Cheers,
Tom

On Wed, 8 Jun 2011 13:12:47 -0700 (PDT), K7ITM wrote:

Hi all,

I use RFSim99 pretty often, and appreciate all it does. I've come
across a few "strangenesses" in the past, and just found a new one to
add to the list:

In the RF Calculator Resonance/Reactance tool, enter 10MHz and 50pF.
The resonating inductance is correctly shown as 5.066uH. Now change
the capacitance to 50nF; you'd expect the inductance to show as
5.066nH, but it shows instead as 5.061nH. Change the capacitance to
50uF and the inductance shows as 5.066pH as expected. This isn't a
big error, but it's a little puzzling that it's there at all. I
discovered it when calculating values for a very narrow LC filter near
10MHz; I'm not sure if the error is worse than this at some points or
not. This particular error seems to be only in the calculator, not in
the simulator.

Cheers,
Tom

Artifacts of floating point arithmetic?