With 5 boontons and several missing filter cards plus the need for A weighting S/N measurements did a quick layout for the filter board that can be assembled as a 400 Hz filter, and A weighted filter or as an "audio" filter per the circuits in the Boonton manual.
They were done in expressPCB. They fit the miniboard footprint (and will need a portion cut off) so $51 will get three in about three to four days.
Enjoy.
PCB Schematic Assembly lists
They were done in expressPCB. They fit the miniboard footprint (and will need a portion cut off) so $51 will get three in about three to four days.
Enjoy.
PCB Schematic Assembly lists
I need to make some also. I'll repost the info here. There is an expresspcb file for the layout that uses the miniboard and an assembly list to make whichever version you want. Boonton had different layouts for each but I figured out how to make one layout work for all three.
The 400 Hz high pass filter does limit the distortion. The common mode stresses the input of the opamp. All Sallen key filters have this issue.
The parts may need updating, Its an old listing.
The 400 Hz high pass filter does limit the distortion. The common mode stresses the input of the opamp. All Sallen key filters have this issue.
The parts may need updating, Its an old listing.
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