[TenTec] Audio filters

[Mike Hyder]

Hi Ken, et al

The Ten-Tec audio filter for the Argosy is the same as that from Embedded
Research.  The only problem I had with either of those filters was because
the Argosy had two circuit configurations which differed as follows:

1.  In my Argosy the AGC sampling point was after the audio filter.  In this
case the filter would reduce or remove audio signals outside its passband
and would keep them from pumping up the AGC.

2.  In my Argosy II the AGC sampling point was before the audio filter.  In
this case the filter would still reduce or remove audio signals outside its
passband but would not keep them from pumping up the AGC.