Vector Network Analyzer and Spectrum Analyzer

[giantkiller]

These are great little yet powerful devices.
Nanovna.comhttps://www.amazon.com/dp/B08132DJLS?psc=1&ref=ppx_yo2ov_dt_b_product_detailstinysa.orghttps://www.temu.com/goods_snapshot.html?goods_id=601099514383300&title=Details&_x_sessn_id=itn36cnt2n&refer_page_name=goods&refer_page_id=10032_1704828852592_hr9ir2smyd&refer_page_sn=10032

[3D Magnetics]

Its great to have access to these cheap but useful tools .
They are clunky and non intuitive at first .
It is astonishing just how accurate they are once understood ,calibrated and connected properly .
They come with cheap sma leads and connectors and are not always terminated well .
The patch cables  often look like leaky coax with inadequate shielding.
I found that bnc adapters fitted to all ports  made things less troublesome.
eevblog forum has many pages of info on them .

I just want a bigger screen or a hdmi output someday

Thanks for posting this

[giantkiller]

Yeah. Any coalesced, separate physical materials becomes a grievous signal leakage point. The industry uses special materials, torque, impedance and grounding techniques to diminish the coupling gap or conductor distance. I think my PHD is leaking.

[giantkiller]

Hello,
I need a reality check.  I am following this video.
https://www.youtube.com/watch?v=hqhV50852jA starting @ 4:00.
I use https://www.calctool.org/electronics/rlc-circuit for the calculations.
I have measured the RLC devices and set RLC with the settings in the pic but I do not get any results at the frequency of a sine wave 10p-p. 
In fact I can not get any response at all until I am up above 900khz.  I switch in other inductors and no results at calculated frequency.  Any ideas?

[Itsu]

Hi Giant,

at series resonance (in that circuit around 19kHz) the impedance will approach 0 Ohm.

Your Function Generator working at 50 Ohm impedance will probably not be able to supply enough (or any) power to that circuit.

I had to crank up my FG to 20Vpp and set the scope to 500mV / div. to get similar traces and behavior as he has.

Scope the input coming from the FG and look how much signal you have there.

You probably need to find another way to inject enough signal into this circuit if your FG cannot deliver it (20Vpp).

Just my 2 cents,   Itsu

[gyula]

Hi GK,

I agree with Itsu.
If we use this calculator, https://www.redcrab-software.com/en/calculator/electrics/resistors-capacitors-inductors-series it reveals some more data, see attachment.

I used 3.54 V RMS in the calculator instead of the 10 V_p-p to get the real current of 70.8 mA, this is set entirely by the 50 Ohm internal resistance of your generator
at the series LC resonance of 19.59 kHz.  (50 Ohm = 3.54V / 0.0708A)

The Q factor is very very small, 0.0738 (3.69 Ohm / 50 Ohm) hence the voltage across either L or C can only be 10V_p-p x 0.0738 = 0.738V_p-p (0.261 V RMS) at resonance.
Because the bandwidth of this LC circuit is very wide, around 265 kHz due to the very low circuit Q, it is quasi impossible to find resonant voltage peaks across either L or C.

In the video you refer to the L inductance is 220 uH (i.e. nearly 8 times higher) and his resonant frequency is around 32 kHz, so the inductive and the capacitive voltages across L and C can be higher
as seen on his scope.

Back to your circuit, if you enter 20 V into the calculator I refer to above, (remembering it is a peak to peak value) the voltages across the 30 uH and the 2.2 uF would be 1.48 V_p-p and this is
very close to that of the values Itsu measured.

PS  if you use a MOSFET driver IC like say TC4420 it has a 2.5 Ohm output impedance only instead of the 50 Ohm, so the driving current to the series LC circuit can be much higher (but should be within the specs of
the TC4420 max output current rating of course).

Gyula