RX 40m bandpass filter

40m bandpass filter simulation (RFSIM99)

8.2µH ------ 68pF ------ 68pF ---------- 16.4µH ---------- 68pF ----------- 68 pF -------------8.2µH
                               680 pF                                                              680pF
                                 gnd                                                                    gnd




A few pictures of the 40m band-pass filter finally adjusted today:

Coisl are made from T106-2 toroids (sampled offered by Micrometals, just asked them online !) and inductances (number of turns) were calculated using MiniRing Calculator (Freeware)

















So I got exactly 8.20 and 16.4 µH !!!!
Serial 68pF capacitors are NP0 type (tight tolerance, +/-1% max).
shunt capacitors (680pF) do not need to be that accurate, so I choose classical +/-10% type capacitors.
Components are mounted on a electronic board with 2.54mm pitch, 1-side printed. I had it for nothing in a few electronic bazar shop, HI !

The filter itself (with SMA connectors)


 





Nothing really new here. Just basic (but short) connections !








The results:















Don't be afraid by the -21.83dBm level : The input power is -20dBm, HI !!!!!!!!

As a summary

Insertion losses = 1.8dB, centered on 7.1 MHz
Ripple in 7.0-7.2MHz bandwidth = 0.3 dB max.
3 dB bandwidth: 600 KHz [from 6.85 up to 7.445 MHz]
6 dB bandwidth: 830 KHz [from 6.743 up to 7.573 MHz]
12 dB bandwidth: 1225 KHz [from 6.55 up to 7.775 MHz]
 Attenuation is higher than 40dB for frequencies
-         below 5 MHz
-         above 9 MHz

Next step : the 80m bandpass filter !!!
C U
Ronan, F8AFC