Maximum field strength for receiver

[OgreVorbis]

There is no category that this fits in perfectly, but I think this is the best fit.

I am wondering how much RF power (field strength) does it take to blow out a generic handheld AM receiver? If I am about 200 ft away from a 1/4 wave MW antenna and it is producing 1kW, will I blow out my portable receiver? I know there is no clean cut answer to this, but I want to know if there is some math that can be done to give a better idea of the likelihood of blowing it out.
Has anyone personally tried this before?
I need to do this pretty soon, so I want to know if I need to open my receiver and cut the antenna.

 

[prcguy]

It all depends on the efficiency of your receiving antenna inside the AM receiver. If you had a 0dB gain antenna on the transmit end and a 0dB gain antenna on the receive end, you could have around 158 watts picked up by the receive antenna 200ft away. If the receive antenna gain is -20dB then you would pick up about 1.58 watts, a -30dB gain antenna would pick up about 158 miliwatts and so on.

200ft away at 1MHz is probably within the near field of the transmit antenna and things are very hard to calculate there as levels follow some strange rules. I think the receiver is probably ok at 200ft but if it were a 50kW station I might leave it in a metal box.

 

[OgreVorbis]

Thanks for the reply!
I did a field strength calculation online and got 3.7 V/m. Like you said, this is not so accurate for near field though.
The antenna in the radio is a ferrite rod about 5cm long.

That probably doesn't help much.

 

[cmdrwill]

about 1.58 watts, a -30dB gain antenna would pick up about 158 miliwatts

3.7 V/m

Both may be too much for the receiver's poor frontend.

prcguy says "I might leave it in a metal box." Not a bad idea.

 

[OgreVorbis]

prcguy says "I might leave it in a metal box." Not a bad idea.

Would I need to ground the metal box, or can it be left floating? I think it would be easier to open it up and desolder or cut the antenna. I think it should probably get enough signal to work with no antenna. Maybe I'll leave a little stub.

 

[jwt873]

The transmitter tower for Radio station WLS in Chicago is located in a residential area. It transmits at 50,000 Watts and there are houses as close as 800 feet away. No reports of fried radios.....