high frequency intermittent noise
@jea48 I'm with you man. Check this out: https://www.select-fabricators.com/rf-emi-shielding/rf-emi-test-shielding/curtains/ I need to get more aluminum foil... |
almarg and or kosst_amojan, or others,Yes, Jim, I would think that a grounded copper screen would be effective against 700 - 800 MHz, since the openings in the mesh are far smaller than the wavelengths of those frequencies (which are about 17 and 15 inches respectively). Although as noted at the FCC link I provided earlier those frequencies can "penetrate buildings and walls easily," so keeping them from getting in via the window might not be all that helpful. Good suggestions, though, in your previous post. Best regards, -- Al |
This RF/EM signal must be picked up by the voice coil in the tweeter and it is likely a powerful megaHz signal and would be inaudible if it didnt cause problems for the amplifier(which tries to surpress distortion with negative feedback so as to match input) and the problem manifests itself in the audible range somehow due to signal saturation in the amp section making it a broadband signal. Try adding a choke across the speaker wires to short out the HF signal. http://audiosystemsgroup.com/RFI-Ham.pdf See Fig 4 for an example... |
I got my phone steaming videos last night and put it INSIDE my F5 right up against the left amp board.Nelson knows his stuff. If the amp is not properly stopped, it will be almost impossible to make this problem stop (if you will pardon the expression...). Sometimes the amplifier circuitry is OK, but RFI gets rectified right at the input. RF beads of the right value can help, if added right where the signal gets to the amp circuit. If the amp makes this sound with the inputs shorted, there really isn't much you can do about it but replace the amp or have it repaired. |
