[TenTec] Where do the filters go
Carl Moreschi
n4py at earthlink.net
Sat Aug 14 10:20:13 EDT 2004
Tommy,
The hiss you describe on the Orion can be easily eliminated. It is caused
by the AGC in the Orion trying to bring all signals no matter how weak to
the same volume level. The threshold control for AGC controls this. With
no signal being received, if you increase the AGC threshhold, you will find
a point where the hiss completely stops. This is the best place to put the
threshhold for that band. With my N4PY software, I put this control on the
front panel.
73,
Carl Moreschi N4PY
Franklinton, NC
----- Original Message -----
From: "Tommy" <aldermant at alltel.net>
To: <tentec at contesting.com>
Sent: Saturday, August 14, 2004 2:39 AM
Subject: Re: [TenTec] Where do the filters go
>
>
>
> >
> > > 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.
>
> Bill, I'm well aware of the 'problems' with the 500 and 250 Hz filters,
but
> why would a company release an unfinished product? We all know the reason
> for that. And yes, they can be used as 'simple bandpass' filters, but it's
> my understanding that was not the intent, and the purchasers received an
> unfinished product. Yes, 'we still have DSP filtering.....' and the loud
> hissy audio noise that accompanies it. My Omni 6 is so much quieter than
the
> Orion, its almost shameful. And we won't go into the fact that the Ten Tec
> amp's will not work with the Keying Loop. Heck, I haven't even seen that
on
> the 'we're working on it' agenda.
> >
> > >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.
>
> Well, with the Elcraft signal generator at 7.044 MHz, you sure can get
those
> filter 'close', that's for sure. But with the wideband noise generator and
> Spectragram, you can put the filters exactly centered on you offset
> (sidetone) frequency and determine their 6dB bandwidth, and observe when
> some of the roofing filters do not switch. Both are good, my first
> 'centering' try was by using my Omni 6 into a dummy load, as a signal
> generator and even that was pretty close. Just a users choice I guess.
> >
> > 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.
>
> Sorry, but I disagree with you here. It is not 'MY' QSK problem. It
would
> be my QSK problem if I was the only person to have purchased an Orion. The
> label '>40 wpm' is misleading. Look at the jitter of a CW character at 30
or
> 34 wpm....better yet, don't look as it's not what you would expect from a
> 'world class' radio. In my opinion, the Orion has the potential to be a
> world class radio........
>
> 73,
>
> Tom - W4BQF
> >
> > 73, Bill W4ZV
> >
>
>
> --------------------------------------------------------------------------
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