vaka85
Advanced Member level 4
Hi,
I'm on this problem from few weeks, it seems to be very easy, as there are a lot of DIY project on this stuff, but it's not so easy for me
I'd like to transmit a sine wave. It's obtained by a square wave generated by a quartz oscillator, filtered, amplified a little (but it's not so important) and then sent to a ferrite loopstick antenna:
**broken link removed**
with an inductance/capacitance meter I've measured impedance (22 uH), and the capacitance of a variable capacitor taken from an old am radio (from 10 to 130 pF), and I've set them to resonate at 4 MHz.
Then I connected the L C in parallel, and with a spectrum analyzer (in parallel with LC) I checked if the LC filter works. It doesn't!
The spectrum is exactly the same if I put the LC or if I remove it!
Also if I vary the value of the capacitor, nothing changes.
So, some questions:
1. What I'm doing wrong?
2. What's the best configuration of LC? in series or in parallel? Because I've tried also in series, it works a little better, but not so much..
3. I'm doing it right connecting the spectrum analyzer in parallel with LC?
4. Is possibile that the parasitic components in L and C are so high that the formula
F = 1/2*pi*sqrt(LC)
is wrong? Because I'm using low cost instrument to measure L and C...
Any other suggestion is also welcome
Thank you
I'm on this problem from few weeks, it seems to be very easy, as there are a lot of DIY project on this stuff, but it's not so easy for me
I'd like to transmit a sine wave. It's obtained by a square wave generated by a quartz oscillator, filtered, amplified a little (but it's not so important) and then sent to a ferrite loopstick antenna:
**broken link removed**
with an inductance/capacitance meter I've measured impedance (22 uH), and the capacitance of a variable capacitor taken from an old am radio (from 10 to 130 pF), and I've set them to resonate at 4 MHz.
Then I connected the L C in parallel, and with a spectrum analyzer (in parallel with LC) I checked if the LC filter works. It doesn't!
The spectrum is exactly the same if I put the LC or if I remove it!
Also if I vary the value of the capacitor, nothing changes.
So, some questions:
1. What I'm doing wrong?
2. What's the best configuration of LC? in series or in parallel? Because I've tried also in series, it works a little better, but not so much..
3. I'm doing it right connecting the spectrum analyzer in parallel with LC?
4. Is possibile that the parasitic components in L and C are so high that the formula
F = 1/2*pi*sqrt(LC)
is wrong? Because I'm using low cost instrument to measure L and C...
Any other suggestion is also welcome
Thank you