• Effective immediately we will be deleting, without notice, any negative threads or posts that deal with the use of encryption and streaming of scanner audio.

    We've noticed a huge increase in rants and negative posts that revolve around agencies going to encryption due to the broadcasting of scanner audio on the internet. It's now worn out and continues to be the same recycled rants. These rants hijack the threads and derail the conversation. They no longer have a place anywhere on this forum other than in the designated threads in the Rants forum in the Tavern.

    If you violate these guidelines your post will be deleted without notice and an infraction will be issued. We are not against discussion of this issue. You just need to do it in the right place. For example:

869.400MHz filter

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Dec 13, 2016
Hi everybody. I am making a long range transciever based on RFM12BP, but i get serious problems, because the RFM outputs a lot of unacceptable noise on whole range from 100MHz up to 1GHz. Would somebody help me to design a bandpass filter for 869.4MHz center freq. BW is about 40kHz? The output power is about 500mW. I attach a measurement of the spectrum that outputs the RFM.


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