[Elecraft] NorCal40 -> K1 rx xtal filter evolution

For fun, I thought I'd make an archeological dig and take a look at how things changed from NorCal 40a to K1 since they're easy to study. Then I realized part of it is not so easy for me. The 40a uses a Cohn filter and I thought I'd run through analysis (not simulation) of it. Again, just fo

Re: [Elecraft] NorCal40 -> K1 rx xtal filter evolution

Hi Mike, I can probably scrounge up the original Lm and other specs for you. Varactor capacitance vs. voltage for the parts I used in the design is readily available on the web. Just search for the part datasheet. Varactor tuning of the filter is great for varying the bandwidth, but it is a co

Re: [Elecraft] NorCal40 -> K1 rx xtal filter evolution

Thanks, Wayne. If not too much trouble that would be great. Or even a run down of how you got the values. Maybe I'm just looking in the wrong place. And I guess the ripple doesn't matter too much for a cw-only qrp rig? It would be very interesting to read a technical "why we changed this"