This may have been stated in slightly different terms, but:
The circuit Q is the culprit. Lower Q results in dragging the resonant
frequency lower. Maybe get yourself some LN2 and immerse the parallel
tuned circuit and measure resonant frequency. Then progressively measeure
resonant frequency and temperature as the circuit warms. Of course, you
can take it the other way and increase the temperature while noting the
resonant frequency and temperature. You can also simulate this by adding /
subtracting loss - resistance - in series with each component.
Dave - W?LEV
On Fri, Mar 26, 2021 at 11:52 AM Simen Tobiassen <simen@...>
wrote:
Simulations show Currents do NOT cancel at the Parallel LC-resonance
frequency, contrary to what we learn is one of the main characteristics of
parallel resonance circuits. Why?
Testing various LC combinations, the two Currents always meet and cancel
at a frequency lower than the XL = XC frequency.
?
Micro-Cap 12 (Transient Analysis; Oscilloscope) shows LC-resonans
frequency / 1.034 ¡Ö frequency of current cancellation. Moving the input
frequency up and down from this point you can find the perfect frequency
where the two currents have the same amplitude = cancelling. Down in
frequency makes the current through the inductor stronger, up makes the
current through the capacitor stronger.
I mostly use RS = 10m Ohm in both the Capacitor and in the low induction
Coil. Same is true with RS = 0 Ohm.
LC wise they are perfect(ly fake ;) 0 parasitic L and C. Anyway, the
simulation makes no difference; Capacitance added to the inductor gives the
same result as if the C was in a separate capacitor; It just moves the
LC-resonance to a lower frequency. And the current-cancelling frequency
also thereby moves down.
This also correlate to the readings on my nanoVNA; two different
frequencies, and I do not understand how to combine them into an ¡°official¡±
Parallel LC-resonance circuit.
--
Simen Tobiassen
--
*Dave - W?LEV*
*Just Let Darwin Work*
