Re: BPF 80m


KI7MWA
 

This discussion has been very informative, but has failed (as I see it) to respond to the original question, which is, what are the potential sources of insertion loss for the QRP-Labs standard bandpass filter kit.

What are the potential sources of loss, and how would one identify them?  

One potential source mentioned is the T37-2 toroid.  How would you (anyone) go about testing this?

Are there other potenital sources of loss?  (Other than poor construction technique.)  And how would one go about testing them.

I have built a number of these bandpass filters, and, with the exception of the 80 meter filters, the insertion losses have all been below 2dB.  I have been unable to achieve a loss of less than 5dB on either of the two 80 meter filters I have built.

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