[OKDXA] RTTY Elmer?

[Calhoun, Charlie]

Thanks to everyone for the suggestions.  Here's a synopsis for the
archives.

1.  I need to utilize both edges of the pass band with IF shift.
2.  Use the attenuator when necessary.
3.  Use IF filters in the rig.  I have the 2.5KHz SSB filter installed
but the 500Hz CW filter would be better for this application.  The only
problem there is that I key the rig from the PC and the rig keys from
the key jack when in CW mode.  I always operate USB when running
digital.  My rig can kick in the CW filter in LSB/CW mode, so I can do
that and reverse the tones if needed.

I found some additional details on my rig and how the filters will help.
This explains almost exactly what I'm experiencing.

The IF bandwidth of the rig with the stock filters is wide enough that
the rig hears the signal you are centered on plus nearby signals that
you might or might not hear. You can use the DSP and the IF shift to
suppress those unwanted adjacent signals, and the DSP works superbly
well for that purpose.

However, those adjacent signals, even if you can't hear them (because
you've got your DSP on), can still affect the signal that you are
listening to. Since those adjacent signals are getting into the IF, they
affect the AGC control of your radio. If the adjacent signals are strong
enough, then the AGC will activate and will reduce the strength of the
signal passed to the audio circuitry (and the DSP). Thus, the signal you
want to listen to will be suppressed as well, sometimes to the point of
being inaudible. This action is called "AGC pumping." Since you can't
turn off the AGC on the FT-847, you're stuck.

By using supplemental filters designed to further restrict the IF
bandwidth, you will suppress the adjacent signals much more deeply than
the stock ceramic filters, and the AGC action will be substantially
reduced. Radios much more expensive than the FT-847 tend to have better
filters built in; it's really a case of paying for what you get.

Overall, I think I was pretty close to getting all I could get from the
rig.  My understanding of the methods to eliminate the front end
overload have been confirmed.  It's a good lesson on how the rigs and
IF/AF filters work.

I'm not a knob turner!  I want to be able to squeak out as much
performance as I can with what I've got.  Hopefully someone else can
benefit from this information too.

Thanks again everyone!  We'll see how I do in WPX RTTY.

73
Charlie, K5TTT