Yes the audio filter was an option in the Triton and Argosy. In the Omni
and Delta 580, it was standard. The Delta 580 has one knob for
selectivity. If you select the narrow position, it kicks in an audio
filter and if you happend to have the cw filter installed, it kicks that
in at the same time. Adding the xtal filter makes little difference since
they are both ahead of the agc.
With the Omni-C in it's most narrow position, you have the following
filters engaged at the same time. 8 pole 2.4khz, 500hz or 250hz 6 pole
crystal filter and finally 150hz audio filter which is in the agc loop.
Pretty impressive indeed.
On the Corsair, the removed the audio filter from the agc loop but added
an extra stage of tuneable IF resulting in more IF noise and little if any
improvement in bandwidth. From then on, audio filtering was after the agc
and pretty useless.
>
> About all the Ten-Tec rigs had the audio CW filter as an OPTION. If you
> need one to add to a rig now, you are probably going to be out of luck -
> except the one for the Argosy is available as a kit from Embedded Research.
> Probably it could be adapted to the other rigs.
>
> I don't know about the newer rigs (Omni-V and VI) but in the older ones, the
> AGC is derived from audio. In most of them the sampling point for the AGC
> was AFTER the audio filter. That means that if a signal was out of the
> audio passband, it would not pump up the AGC.
>
Steve Ellington N4LQ
N4LQ@IGLOU.COM
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