[TenTec] Where do the filters go

[Bill Tippett]

 > N1EU wrote:
 >  >I tend to agree with W4BQF on the 2.4Khz 10-pole Inrad
 > as being unnecessary.  However, the 1.8Khz filter
 > could be helpful if the rig is used for ssb
 > contesting.
 >

 >          In my opinion, if you are a CW ONLY op, the only
 > optional filter you would ever need is the Inrad 762.
 > If you are also an SSB op, I would definitely add the
 > 1800 filter (either the TT 218 or Inrad 761).  I used
 > the TT 218 last October in the CQ WW SSB and would not
 > be without it.  If you are a casual operator...no serious
 > contesting, no heavy-duty low-band DX-ing, etc, you don't
 > really need ANY optional roofing filters.
 >
 >                                          73,  Bill  W4ZV

 >W4BQF wrote:
Well, being a CW only op, I have to disagree with this just a little. My
Orion does not have the 1.8kc filter, so today when I received my 600hz
filter, I moved the 1kc filter into the empty 1.8kc position, put the 600hz
fliter into the 1kc position, and kept my 500hz and 250hz installed.
(Running v1.369 so I can switch the filters correctly and also so the Orion
does not crash while I'm using my Titan 3 in the Keying loop)

Tom, as IMD reduction devices, the 500 and 250 filters are worthless.  Sure
you can use them for simple bandpass filtering, but they are FAR worse than the
1800/1000/600 for reducing IMD products, which is the true purpose of roofing
filters.  Remember that we still have DSP filtering with filters every 10 Hz
from 100 to 6000 Hz following the roofing filter.

 >I then used my Elecraft wide band noise generator and watched, using
Spetragram, as I switched the filters. One thing that showed me was how far
off I had my 500hz and 250hz filters adjusted. With the Orion, Spectrgram is
an invaluable tool when used with a  wide band noise generator. You can SEE
exactly what's really happening with the filters, and when you adjust BW and
PBT....it's amazing how much your ear lies to you!! hihi.

You don't need Spectrogram to properly center the 500 and 250 filters.  A
simple signal generator plus Orion's internal 6 dB attenuator will do it
nicely.  However, to really understand the capability of Orion, Spectrogram
really does add some new insights...such as the one I recently had regarding
using PBT to shift the 600 Hz roofing filter +/- 300 Hz.  This is truly
powerful and a capability that NO other radio has including the IC-7800/756,
FT-1000, and Omni families.  Using this properly, it should be possible
to even further improve the 600 Hz filter's IMD rejection capability for
extremely close interfering signals.

I hope you get your QSK problems solved in Omni and Orion.  It may be that
Ten-Tec is simply recognizing that >40 WPM QSK is an extremely small segment
of the total market.  I operate a lot of CW contests and never go much over
36 WPM.  In fact, speeds much over 36 WPM are counter-productive in terms
of maximizing overall rate.  It always amazes me to hear an operator like
W0UA calling CQ at 40+ WPM, getting no answers and then continuing to call
CQ at speeds that 95% of average hams cannot copy.

                                                 73,  Bill  W4ZV