Sunday, April 1, 2018

ELSIE and the RF input selector revisted

The question was asked about the frequency response of this circuit.
We have used ELSIE in the 40/80 design and it can be downloaded here:

download ELSIE

Click the second line on the page and this will take you to the download page. Scroll down to the blue button.

 I loaded the schematic into ELSIE. I just picked some component values for show and tell.
If you examine the circuit you should see the same hookup. Now for the frequency response.

What I want to show is that the circuit is being used to reject the lower frequencies and pass the higher frequencies. The circuit could be modified to be a low pass. With a superhet front end we could have a dual band receiver by selecting the high or low. This is the scheme The chief designer chose in the 40/80. He simply changes the preselector to change bands. It can also provide some RF gain control by tuning the signal to the slope of the curve.

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