dr pepper
Advanced Member level 1
I've thrown togther a double conversion am receiver for lf to hf frequencies, the front end and 1st osc is a Ne602 mixer/Vfo.
It works but if I turn up the volume on weak signals I get mechnical type feedback noises, I traced this back to the 1st local osc (ne602) coil, using my sig gen as the local osc removes the issue altogether.
I realise that older receivers using a coil tended to have them in a can made from tin, some ally, the former isnt antimagnetic and the latter is, maybe the tin shielded just enough.
To get around this I'm going to put the whole mixer/osc front end in a shielding can, if this was a minimal mass produced item what would be the work around, stick the coil in a can, use a different design coil one more like a transformer with a closed magnetic path, or some other method.
It works but if I turn up the volume on weak signals I get mechnical type feedback noises, I traced this back to the 1st local osc (ne602) coil, using my sig gen as the local osc removes the issue altogether.
I realise that older receivers using a coil tended to have them in a can made from tin, some ally, the former isnt antimagnetic and the latter is, maybe the tin shielded just enough.
To get around this I'm going to put the whole mixer/osc front end in a shielding can, if this was a minimal mass produced item what would be the work around, stick the coil in a can, use a different design coil one more like a transformer with a closed magnetic path, or some other method.