HOW TO USE OUR UAF DEVELOPEMENT BOARD

Changing the filter frequency is done by connecting a capacitor to Cf1 (TB2) and a matching capacitor to Cf2 (TB4).  These two capacitors set the "range" of the filter while a dual 50K pot is connected to Rf1 (TB1) and Rf2 (TB3).  This pot, in conjunction with the two "range" capacitors, will set the frequency over the range of 50CPS to 20KCS. 

For one frequency only, the pot may be replaced with two fixed resistors.

The filter Q is set by the resistance connected from the "Q" terminal on TB5 to ground.  This may be a pot, or, more likely, a fixed resistor.  The lower the resistance of the Q resistor the higher the Q.  For example, a 1K resistor will give a high Q while a 47K resistor will give a much lower Q.  

An interesting use for the UAF is to have it configured as a high Q bandpass filter.  This is done by using a low value Q resistor (1K or less) and using resistors to set the filter frequency (example 1KC).  The signal output from the generator is fed into the filter and the output of the filter is fed to the DUT. 

This is a simple way of lowering the THD.  In tests using an older BK Precision 4017A, we managed to reduce the THD by as much as 33DB, a significant improvement.