On 18 mayo, 23:39, Cecil Moore wrote:
On May 18, 4:05*pm, Cecil Moore wrote:

Give me some time and I will compose an example based on EZNEC results
for a lumped inductor vs a helical inductor of equal inductance. The
results are nowhere near the same.

The example is a 4 MHz series circuit with a 100v source, a 72uH
inductance, and a 2570 ohm resistor.

Using a 72uH lumped inductance, the current is the same all around the
circuit and is 0.032 amps at -24 degrees, i.e. the source current is
24 degrees out of phase with the source voltage.

Using a 72uH helical inductance, the source current is 0.039 amps at
-0.02 degrees, i.e. in phase with the source voltage. The load current
is 0.039 amps at -42.4 degrees. The phase shift through the helical
inductor is more than 40 degrees.

As you probably know, the phase angles of superposed waves have a
drastic effect on the resulting impedance.
--
73, Cecil, w5dxp.com

Hello Cecil,

Can you describe the complete setup, or post a simple drawing
(including ground path, source and load and position of current and
voltmeters). I think that I can model it by using a lumped inductor
with 2 capacitors (in fact a section of an LC delay line). What is the
total wire length (just curious to know)?

72 uH, seems large for a matching inductor in a PA (at say 4 MHz, just
22 pF to resonate).


Wim
PA3DJS
www.tetech.nl