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questions about AM broadcast band images

Aug 24th 2015, 13:20

AB3FN

Joined: Jun 5th 2007, 14:11
Total Topics: 0
Total Posts: 0
I want to explore the spectrum below the AM broadcast band. The second IF in my late-model triple-conversion radio is 455 kHz, and I'm getting swamped with broadcast band images. E.g., an AM station broadcasting on x kHz has a powerful image at x-910 kHz. My radio is a modern one, but I live near a large metropolitan area with a lot of AM broadcasters.

Is this a common problem with modern radios? Any comments about specific brands / models? I've had marginal results with a home-brew filter - any suggestions about filters? Of course, I'm only interested in receiving, not transmitting.

Thanks in advance for your comments and suggestions.
Aug 24th 2015, 13:34

W1VT

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
Yes, I'd say this is a common problem with multiple conversion radios--adding the extra filters required to eliminate images from very strong stations is expensive.

One way around this is to use a simple direct conversion receiver--the only image is the opposite sideband. Software Defined Radio or SDR technologies can easily get rid of this image.

Another SDR approach that eliminates images is to directly sample the signal at RF.

Zack Lau W1VT
ARRL Senior Lab Engineer


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