Duane, N9DG, wrote, in part:
> It is also conceivable that these "gentle" qualities
> of the TT filters may be more desirable in the role of
> roofing filters than a sharper filter which may have
> more ripple and/or ringing.
> Since the Orions's true and final RX selectivity is
> achieved in the DSP-IF the important roofing filter
> qualities and requirements are somewhat different than
> they are for an analog only RX design.
Have just rcvd a note from an Orion owner who has opened
the rig up and had a look at the "standard" filters therein.
He reports that the 9 mHz roofing filters -- 15 kHz, 6 kHz, 2.4 kHz,
and 1.0 kHz -- are only 4 poles each! Nice gentle ones, not the 6 and
8 pole filters used in the 9 MHz slots in the Omni's. However,
the optional 1.8kHz, 500 and 250 Hz filters are the 8 pole and
6 pole (250Hz, CW) filters as stock for the Omni's. So the Orion
"standard" roofing filters are of "special" design specifically
for that purpose.
Why were we not told this? Another design "secret" we had
to mine out for ourselves; or just such an obvious engineering
decision that to Doug Smith and others did not merit special
mention? Or, maybe my source error'd, and they are larger
than four pole filters. Anyone else look, check and verify.
I am especially interested to know if the very wide 15 kHz
filter is even more than 2 poles.
You can tell daytime propagation is poor, and I am getting
anxious to rcv my own Orion!!
73, Jim KH7M