Topband: Modification to INRAD Roofing Filter

Dennis W0JX w0jx at
Sat Oct 20 14:53:41 EDT 2007

Those of you who have the INRAD Roofing Filter Kit in your 1000MP's might be interested in the following modification to improve the IMD numbers reported by W8JI:
  The mod was developed by Mike, W2AJI. It apparently reduces the gain a little in the roofing filter 2 stage amplifier. 
  I have not yet tried the modification but it looks simple, involving the change of only two resistors.
  I also believe, as does Mike, that the filter is actually a little wider than the specifications state. I have no trouble copying AM stations on my main rx. The filter kit I have is my second one due to a failure of the filter in my first kit purchased two years ago. The bandwidth of the first kit seemed a bit tighter than the one I presently have but it is still an
  improvement over the stock radio.
  73, Dennis W0JX/8
  Milan, OH

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