RX ANT Switching box, part 4 - High IP 40m Preamp with BPF

   There is my article about 40m preamplifier to new beverage box (click for all articles). It consists of BPF and notches for 160m and 80m, continue to switchable ATT (4dB) and switchable High IP preamp (click) with dual 2N5109 transistors. There is 3dB ATT and simple LC at the preamplifier output. Preamlifier is loaded with abt 7dB out of the band and with more than 25dB in band. Simple LC parts help to cut off unwanted signals at the preamp output. Look at measurement of that LC part.

Measurements:

	preamp
	OFF	ON
cut off 160m	87 dB	96 dB
cut off 80m	80 dB	92 dB
cut off 20m	80 dB	88 dB
preamp gain 40m *, **		13 dB

* include BPF + output ATT ( 4dB ) + LC output filter - supply +15V and 2 x 80mA
** IP3 could be different than in past article because it is not widely loaded with perfect impedance

Insert loss of BPF is abt 1.78 dB with "poor" NP0 capacitors - have to try it with better ones.

BPF + notch 160/80 + ATT ON/OFF + preamp + ATT + out LC

Preamp with BPF / Preamp with BPF + 4dB out ATT + out LC (measureed with 30dB ATT, add +30dB) 

Preamp OFF / Preamp ON

Measured with FSL-6

Simple LC filter at the preamp output