Re: The Amazing All-Band Receiver

NOW, we have a receiver circuit topology; at least now we can see an antenna - although I think that a general purpose transistor should not be used for this kind of application on RF range. Anyway, if you consider as being reasonable to syntonize with any transmiter just by jiggling the antenna in random and experimental shapes (who knows, even your hand being part of the tuning circuit), it can actually pick up something audible, whatever it can be, but this is just for playing, experimenting, not something reliable.

If your radio could receive the entire radio spectrum simultaneously, I think you should not expect to hear several broadcasts at the same time. Instead I think it would sound like static. The mixture of carriers would cancel each other out. What is loud and getting worse is rf interference from light dimmers, cheap power adapters, etc.

The value of radio is to bring in one station at a time. A simple tuning method is an inductor-and-capacitor. It helps tremendously if you make the antenna sensitive to the band you prefer.

To pick up broadcasts higher than 1 MHz, your tuning circuit should be designed for high frequencies. Then you might pick up more of the shortwave band (1.7 to 30 MHz).

I have a radio that picks up several bands including shortwave. Activity has declined over the decades. I thought it was disappointingly sparse 20 years ago.

Can I use BC546 transistor?

We say it wont work...
You built it and it didn't work....

so what is the problem?

You just don't seem to comprehend what we are saying. A receiver that picks up all signals at once, no matter whether it is low frequency or high frequency, is of no use to anyone. All you hear is the envelope of a random selection of different frequencies, phases and amplitudes mixed together. It isn't a matter of gain or of the bandwidth of the devices, it is simply missing some necessary circuit functions to enable it to operate.

If it really is to receive audible EM waves (whistlers etc.), the detector at the input is a bad idea and should be replaced with a low-pass filter.

Brian.