turntable/record player and unwanted reception of broadcast sw stations

[tiefbassuebertr]

here the appropriate terms and keywords to get the widest range of informations about "Google":
1) Radio Frequency Interference (RFI)
2) Radio Interference Damper (or Damping, RFD)
two examples:
RFI Information Page
AudiogoN Forums: Radio interference on my phono stage

[thermionic]

Andreas - have you put an oscilloscope at the output of the preamp to check that it's not oscillating? The only times I've seen RIAA preamps pick up radio has been when they're oscillating at 20+ mHz

Justin

[tiefbassuebertr]

Originally Posted by thermionic

Andreas - have you put an oscilloscope at the output of the preamp to check that it's not oscillating? The only times I've seen RIAA preamps pick up radio has been when they're oscillating at 20+ mHz Justin

sometimes this was the reason. But in some other cases only the faulty screening management causes this, and for this case I need an equivalent circuit to understand all the parasitic AM radio effects.

Please note, that I haven't this problem by a certainly RIAA head amp model, but I want to know the exactly relationships, if there are no hum and only short wafe (SW) radio stations to hear, especially when there are strong reflections of the ionosphere arround 6 MHz/AM