Hi J_Player and thanks for your advice.
Yes i understand that this is probably a noise from my house.
About test with a spark i used to do sparks with my frequency generator, so this way i can pick up signals on the rigth frequency. Indeed i had done test with diferent turns from my rx coil and when i move frequency i got good spark at 40 Khz for the first coil and then the second try with lees turns on the coil gave me a good spark at 71 Khz. So i m not shure if this way of testing coils is correct, but in my case this seems to work.
This days i had not to much time to go out the city to give a try to my pdk that can by tune using capacitor, to 40 and 71 Khz.
Regards
Nelson
Quote:
Originally Posted by J_Player
Hi nelson,
Take a look at the coils which can detect RF in your PDk.
If you are familiar with RF reception from a loop, you will see that the direction your PDK points is a null point.
The signals which you can receive come from the sides of the coil, not the front.
But since you are using a super sensitive detector circuit which is nearly unstable, in theory you could detect a move from null to nearly null.
But I doubt this is what is happening in your case.
My guess is you are more likely detecting noise which probably comes from man-made sources and propagates in the ground and through walls at VLF frequencies.
This kind of noise tends to follow strongly in paths which telluric currents favor, or follow underground conductors more easily such as pipes and cables.
Is it possible there are any metal pipes or cables under your house, or to the sides of where the coil is pointed?
One way to test is to put a portable oscilloscope on the loop or early stages of the receiver, and examine the signal you receive when you point the PDK at the corner of the house.
Then connect the oscilloscope to a pair of ground probes placed in the ground where you are standing, separated by 2 meters.
I am guessing you will find some kind of signal in the ground that is similar to what you receive in the receiver.
If you cannot put ground probes then you can connect a simple loop with 30 turns to your oscilloscope set to low uV scale.
When you will move the loop around the air you will find a lot of noise in your house.
I believe you will find enough noise even if you turn off all the power to your house, because neighboring houses will send noise which you can detect in your house.
But you shouldn't be testing the PDK inside your house anyway, because houses are full of electronic noises which will propagate through the air and through the ground.
The people who claim success to tune a PDK say you need to be far away from any house or power... I believe 100 meters is good enough.
Only simple power testing or spark tests are done near buildings that have electrical power.
-- Just an idea,
Best wishes,
J_P
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