Re: Minimally modified QCX-17 has been heard on 80, 60, 40, 30, 20, 17, 15, 12, 10m this UTC day !

Guido PE1NNZ

With C1, C5, C8 removed and with T1 configured for 40m RX is working well for all bands, but the lower bands (80m, 160m) are a bit deaf. So initially wind T1 for 80m would do probably better.
With a LPF installed, higher band harmonics on RX are not really an issue in practice in my experience; but a LPF is recommended to prevent FM broadcast mixing products.
For LPF switching, I like KD1JVs minimalistic approach by using a few series DPDT slider switches to select the appropriate LPF. Another interesting way to switch LPFs is to use 1N4007 for swiching [1], were you can use the rectified RF + 12V at C30 to bias the diodes either forward or in reverse.


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