neazoi
Advanced Member level 6
Hi, in my receiver, **broken link removed** I have noticed that sometimes, besides the useful tuned signals, I hear some stations that shouldn't exist in the passband. This happens only sometimes and it is independent from the tuning of the circuit. No matter if I tune it in different frequency, the same background station plays at very low volume though.
Initially I thought it would be intermodulation distortion by strong signals by the low dynamic range untuned RF preamplifier, so I replaced this stage with a high dynamic range untuned amplifier, dual gate mosfet running at 30mA. However, I could detect the same signals again, so I suppose it is not because of the dynamic range of the RF preamplifier.
Have you got any idea what could cause the problem? It is not annoying, as it is at very low level at the background when it happens, but I would like to know if I can fix this.
Initially I thought it would be intermodulation distortion by strong signals by the low dynamic range untuned RF preamplifier, so I replaced this stage with a high dynamic range untuned amplifier, dual gate mosfet running at 30mA. However, I could detect the same signals again, so I suppose it is not because of the dynamic range of the RF preamplifier.
Have you got any idea what could cause the problem? It is not annoying, as it is at very low level at the background when it happens, but I would like to know if I can fix this.