Posted by
Guy, K2AV on
Feb 17, 2010; 11:32pm
URL: http://elecraft.85.s1.nabble.com/My-Five-Filters-tp4586377p4589166.html
My lineup for both RX in my K3 is
13, 2.7, 1.8, 400, 250
6, 2.7, 1.8, 400, 250
I didn't purchase the "250" 8 pole specifically as my roofer over
200/150/100/50 DSP bandwidths. I have the "400" 8-pole identified as 450 in
the K3 and the "250" identified as 350. I use WIDTH 350 as my "tighter" run
bandwidth.
I will use DSP width of 450 when I can, to hear callers well off frequency
(surprising how many there are), but will narrow to 400 then 350 when I get
"crowders" up or down. I find myself using 350 more and more often as people
are crowding in closer than +/- 500. With the 8 pole "250" and the DSP at
350, the steepest of skirts nearly coincide at +/- 250, allowing a small
adjustment in SHIFT to make a large adjustment in "down the skirt", to put a
crowder well down without losing so much up and down hearing space.
I think that there are a lot of people who are fairly tone deaf (as in
couldn't carry a tune in a bucket, etc) who are just never going to hear
zero beat, and packet spots that are off that keep bringing calls off
frequency. So we are going to continue to have off frequency callers. The
real 200 of the "200" is just too narrow for running and the "400" is
sometimes too broad for running.
For really narrow work, the DSP has always seemed to be enough under the
"250".
I find DSP of 1000 under the SSB 1.8 more than adequate for casual CW tuning
around. I tighten down to 450 if I call someone.
So my lineup for both RX is
13, 2.7, 1.8, 400, 250
6, 2.7, 1.8, 400, 250
Anything from 2.7 to 250 might be used for diversity.
For SSB contesting I can barely manage using the 1.8, but can't stand it for
casual, and use the 2.7 instead. I am in awe of someone who can get voice
intelligibility out of 1.5. I can't. Simple enough to try 1.5, just
reducing using WIDTH.
13 for FM in one, and 6.0 for broadcast listening in the other (BC and HF
bands).
73, Guy.
On Wed, Feb 17, 2010 at 4:07 PM, Joe Subich, W4TV <
[hidden email]> wrote:
>
>
> > Ditto. W4TV (?) measured the 250 (actually 370 Hz) versus
> > the 200 and the latter had more rejection at ALL frequencies,
> > even though it's only a 5-pole.
>
> Actually, I compared both of my 200 Hz filters (measured) to
> the curves for the 250 Hz filter on the Elecraft web page:
>
http://www.elecraft.com/K3/K3_8_pole_plots.htm specifically
>
http://www.elecraft.com/K3/filter_plots/250.gif.
>
> The stated conclusion is correct ... my filters were 190 and
> 200 Hz at -6dB and 440 Hz wide at - 30dB vs. 360/525 Hz for
> the INRAD/Elecraft 250 Hz filter. Note, according to Wayne
> only the first 30 dB or so of rejection is significant as that
> is enough to protect the AGC and mixers and after 30 dB the
> DSP is the dominant bandwidth determining factor.
>
> As recommended by others, I would use 400 Hz for general CW
> and RTTY with the 200 Hz for critical CW only (200 Hz is
> too narrow for 170 Hz shift RTTY which, in theory, needs
> around 300 Hz to properly pass the keying sidebands).
>
> My own rigs have 13 KHz, 2.8 KHz, open, 500 Hz and 200 Hz
> filters. I'm waiting on Elecraft to allow use of the 13 KHz
> filter for AM and ESSB transmit (there is no reason to not
> allow it) and will eventually add the 1.5 KHz "narrow SSB"
> filter. If I were to do it again, I would have saved the
> money on the 2,8 KHz filters and gotten the 400 Hz filters
> instead. The savings in sticking with two stock 2.7 KHz
> filters (even with matching for the sub receiver) would
> have paid for the 13 KHz Hz and 200 Hz filters.
>
> 73,
>
> ... Joe, W4TV
>
>
>
>
>
>
> > -----Original Message-----
> > From:
[hidden email]
> > [mailto:
[hidden email]] On Behalf Of Bill W4ZV
> > Sent: Wednesday, February 17, 2010 10:23 AM
> > To:
[hidden email]
> > Subject: Re: [Elecraft] My Five Filters
> >
> >
> >
> >
> > Craig D. Smith wrote:
> > >
> > > But I would recommend the 200 Hz 5 pole rather than the 250
> > Hz 8 pole.
> > >
> >
> > Ditto. W4TV (?) measured the 250 (actually 370 Hz) versus
> > the 200 and the latter had more rejection at ALL frequencies,
> > even though it's only a 5-pole. I only use my 200 ~1% of the
> > time (500 Hz 8-pole the other 99%) but there are times when
> > it's nice to have (such as large simplex pileups).
> >
> > Someone previously commented on the 1000 Hz (actually ~1100
> > Hz) for CW. I had one but found it too wide to be of much
> > use. If there are NOT a lot of strong signals around, the
> > stock 2.7k will work about as well. If there ARE a lot of
> > strong signals around, the 1000 allows too many of them to
> > desense the rig. This is especially true if you use a low
> > pitch as I do (3-400 Hz).
> > In that case the bandpass is shifted upwards from 200 Hz such
> > that signals as much as 1000 Hz above zero beat will desense
> > the K3 (e.g. a 200-1300 Hz bandpass for a 300 Hz pitch).
> >
> > 73, Bill
> >
> > --
> > View this message in context:
> >
http://n2.nabble.com/My-Five-Filters-tp4586377p4586571.html> > Sent from the Elecraft mailing list archive at Nabble.com.
> > ______________________________________________________________
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