[TenTec] Additional Thoughts on New Orion

[Bill Tippett <btippett@alum.mit.edu>]

WA4OEJ wrote:

>I really have to wonder why they selected 6 kHz for the second filter

        For AM users who want to reject adjacent channel IMD.

>and 2.4 kHz for the third filter.

        For SSB users who want to reject the same.

>I find it difficult to copy a SSB signal with a bandwidth of less than 
2.0 kHz.

        Try setting PBT to +150 to +200.  That allows me to copy
reasonably well down to ~1600 Hz BW (contest conditions).

>In the Orion auto filter selection position, my 2.4 filter doesn't kick 
in until the bandwidth is around 1.9kHz.  That's just too narrow for me.

        It actually activates at ~2000 Hz.  This brings up another
point.  If you use the optional 1800 Hz filter, "Auto" only activates
it at ~1400 Hz which is definitely too low.  The only time I really
use my 1800 is in contests, and I simply "lock" the 1800 in at all
times.  The 1800's actual 6 dB bandwidth is closer to 1900 Hz, and
it works fine for the 1600-2000 Hz range IF you set PBT as mentioned
above.

>Other than the obvious reason of having compatibility with their other 
rigs, why wouldn't they have selected something like 7 or 8 kHz for the 
second filter and then something like 3.5 kHz  for the third filter?

        Again Ten-Tec's logic was probably to choose roofing filters
that would allow normal AM and SSB bandwidths.

>Second question, in the auto mode, how is the change over filter 
selected.  In other words, if I put a 2.8 kHz filter in place of the 2.4 
kHz, at what bandwidth would it be enabled?

        In auto mode, the filters are switched when DSP BW is
set to approximately 75% of the roofing filter's nominal
bandwidth.  The transition points are as follows:

Filter  Switches @
6000            4500
2400            2000
1800            1400
1000            750
500             380
250             190

You could move or substitute filters in different
positions but they would still switch at the above
fixed setpoints in Auto mode.

CAUTION #1:

Orion transmits through these filters also, and I
believe 2400 Hz is used in CW and 6000 Hz is used
in SSB.  You should probably NOT put anything but
standard filters in these two slots.  Possibly
slightly wider filters such as the 2800 would be
OK in the 2400 slot but I would NOT recommend
narrower filtes in these two slots.  There is not
a problem for the other positions.  For example,
I have my 1000 in the 1800 slot now and the Inrad
#352 600 Hz in the 1000 slot.  This works fine in
Auto with the 1000 switching in at 1400 Hz and the
600 switching in at 750 Hz.

CAUTION #2:

Standard 500 Hz and 250 Hz Ten-Tec or Inrad filters
will NOT work in the 1000 Hz and higher slots.  The
reason is that the 500/250 slots assume an IF of
9.00075 and the 1000+ slots assume an IF of 9.0015.
Therefore, the 500/250 filters will NOT center properly
if inserted into the 1000 or higher slots.

        Hope I didn't totally confuse you!

                                        73,  Bill  W4ZV

P.S.  It is of course always possible to override
any of the Auto settings by simply fixing the filter
of your choice in Menu > Filter.

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