fredag 20 mars 2015


Minima Input-filter


This is the 15 MHz filter RF OUT - C13


This is the 30 MHz filter RF OUT - C8


This is the notch L7, CT3, L9, CT2, L11, CT1


This is the 30 MHz filter RF OUT - C8 and notch.


This is the 30 MHz filter RF OUT - C8 and notch and K1.


First comment  L1, L5 is 0,68uH and L2, L3, L4 is 0,82uH. Notch L7, L9, L11 is 3,3uH I check in filter-program Elsie before I order inductor and the effect was small.

I think the vna-plot says more than a lot of data or word. The notch is not so selective so it effect the 21MHz band, perhaps it is possible to compensate with preamplifier. Locking at the plot it can be possible to change IF to 16 MHz -1,65 to 14MHz and + 2,68 MHz to 18 MHz band. Chang lo-filter to 10 to 12 MHz cut off.

I think it is better to have tow small relays in sted of one, the K1 on this solution I work with (pp2kr pcb). I think this is the reason way there is les attenuations in the last plot. K1 serves out and in of the filters.

  Here is the result a finished board.




Next step is to load original sw and start playing with it the receiver. I will be back in May stay tuned.