K3 Filter Option Questions (revisited yet again)

[Phil Hystad]

One of the things that I have not yet decided is the filters to get for my K3 order.  I am firm on getting the 400 Hz 8-pole filter (80 percent or so CW ops).  But, I like to scan the band looking for signals with a wider filter, say around 1 to 1.2 KHz.  Do I need to get the 1 K filter.  If I remember right, I can set DSP filtering to about 1 KHz which may be good enough or is there an advantage to the 1 KHz filter.

Also, is there a good reason to swap out the 5-pole 2.7 kHz filter for the 2.8 KHz 8-pole?  I presume this gives the filter sharper skirts so you can cut off those close stations a bit better but I am curious as to how much better.

Since the dollar cost differences in decisions regarding filters is not that great I would prefer answers that ignore the cost issue.

So far, I am planning on getting the following filters with a ? on the 1 KHz 8-pole and 2.8 KHz 8-pole:

400 KHz 8-pole
1 KHz 8-pole  ??
2.8 KHz 8-pole swap for 2.7 KHz 5-pole ??
6.0 KHz 8-pole

73,
phil, K7PEH
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[Dunc Carter - W5DC]

Currently I have the 8 pole 2.8 KHz filter and the 250 Hertz cw filter.  
One of my friends, W5XZ, who is considering buying a K3 asked me about
filter choices and especially whether a narrow cw filter.  My reply was
the "It depends".  Do you want to work near strong local signals without
blocking?  I f so, then you need a narrow crystal filter for cw.  I
chose the 250 Hz filter and I'm happy that I did as I can work very
close, like within 200 Hz to strong locals like K0RF and, in Chuck's
case, even blank his key ( Yaesu?) clicks at the same time.  I'm
debating about getting the 400 Hz cw filter or the 500 Hz version from
Inrad.  Some of my operation is on relatively empty bands like 17 meters
right now and I use the SCAN feature on cw; 250 Hertz or less seems too
narrow for this most of the time unless the scan rate is really slow
using the 1 Hz frequency increment but 400 to 500 Hz is a wide as I ever
use for that.  For my purposes, I see no need for a 1 KHz cw filter but
I think this depends, to a considerable degree, on the strength of other
in-band signals and how close your ham neighbors are.  I don't work much
ssb and so far, my neighborhood big signals all use the opposite
polarization but this my change.

Dunc, W5DC

Phil Hystad wrote:

> One of the things that I have not yet decided is the filters to get for my K3 order.  I am firm on getting the 400 Hz 8-pole filter (80 percent or so CW ops).  But, I like to scan the band looking for signals with a wider filter, say around 1 to 1.2 KHz.  Do I need to get the 1 K filter.  If I remember right, I can set DSP filtering to about 1 KHz which may be good enough or is there an advantage to the 1 KHz filter.
>
> Also, is there a good reason to swap out the 5-pole 2.7 kHz filter for the 2.8 KHz 8-pole?  I presume this gives the filter sharper skirts so you can cut off those close stations a bit better but I am curious as to how much better.
>
> Since the dollar cost differences in decisions regarding filters is not that great I would prefer answers that ignore the cost issue.
>
> So far, I am planning on getting the following filters with a ? on the 1 KHz 8-pole and 2.8 KHz 8-pole:
>
> 400 KHz 8-pole
> 1 KHz 8-pole  ??
> 2.8 KHz 8-pole swap for 2.7 KHz 5-pole ??
> 6.0 KHz 8-pole
>
> 73,
> phil, K7PEH
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>
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>  

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[Dick Dievendorff]

Phil:

I'm also primarily a CW operator. I chose the 1 KHz filter for "normal" wide
CW contest use when I want to be aware of stations around my run frequency.
I chose a 1.8 KHz filter for SSB contesting based on recommendations from
friends whose opinions I respect. The 1.8 kHz filter is also helpful for
wide CW.

I also have the 400 Hz and 250 Hz eight pole filters.  I don't think the 400
and 250 are enough different to recommend that configuration.  If you're an
RTTY enthusiast, the 250 Hz filter may be just what you need.  Upon
reflection, I perhaps should have gotten the 200 Hz 5-pole instead of the
250 Hz 8-pole. I ordered this on the first announcement at Visalia, and went
with my best guesses.

I chose the 2.8 kHz filters for steep skirts and also to avoid matching
issues with the sub receiver's filter.  I'm not sure they were necessary,
but it's all subjective. I didn't want to be in mid-contest and wish then
that I'd spent a relatively few dollars more for better skirt selectivity.

One reason to choose the 2.8 8-pole over the 2.7 five-pole is if you plan on
using a sub receiver. You should either match the 2.7 kHz five-pole filters
or get two 2.8 kHz filters. I chose the latter.

I don't require ESSB, AM transmit, or FM, and my main RF board is full with
250, 400, 1000, 1800, and 2800 eight-pole filters. I have fewer filters on
my sub receiver.

Also review Eric's detailed Roofing Filters essay at
http://www.elecraft.com/K3/Roofing_Filters.htm

Nice to have the choices, but there are a lot of them!

73 de Dick, K6KR


-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Phil Hystad
Sent: Wednesday, December 23, 2009 11:41 AM
To: Elecraft Reflector
Subject: [Elecraft] K3 Filter Option Questions (revisited yet again)

One of the things that I have not yet decided is the filters to get for my
K3 order.  I am firm on getting the 400 Hz 8-pole filter (80 percent or so
CW ops).  But, I like to scan the band looking for signals with a wider
filter, say around 1 to 1.2 KHz.  Do I need to get the 1 K filter.  If I
remember right, I can set DSP filtering to about 1 KHz which may be good
enough or is there an advantage to the 1 KHz filter.

Also, is there a good reason to swap out the 5-pole 2.7 kHz filter for the
2.8 KHz 8-pole?  I presume this gives the filter sharper skirts so you can
cut off those close stations a bit better but I am curious as to how much
better.

Since the dollar cost differences in decisions regarding filters is not that
great I would prefer answers that ignore the cost issue.

So far, I am planning on getting the following filters with a ? on the 1 KHz
8-pole and 2.8 KHz 8-pole:

400 KHz 8-pole
1 KHz 8-pole  ??
2.8 KHz 8-pole swap for 2.7 KHz 5-pole ??
6.0 KHz 8-pole

73,
phil, K7PEH
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[Joe Subich, W4TV-4]

Phil,

I chose to replace the 2.7 KHz filters with the 2.8 KHz 8-pole
filters when I ordered my K3s and would not do so again.  If I
were ordering a K3/KRX3 today, I would choose:

13 KHz    FM and AM/SWL RX (waiting on Elecraft to lift the block
          on using the FM filter for AM transmit).
2.7 KHz   Match frequencies for main/sub RX
open      reserve for 1.5 (INRAD) or 1.8 (Elecraft) KHz (narrow
          SSB and band scanning)
400 Hz  
200 Hz

The subreceiver would have only the 2.7 and 400 Hz filters

The savings with matched 2.7 KHz and the 400 Hz filters vs.
2.8 KHz and matched 500 Hz filters more than pays for one
of the 8-pole filters (or would pay to fill the "open"
slot).

73,

   ... Joe, W4TV
   

> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of Phil Hystad
> Sent: Wednesday, December 23, 2009 2:41 PM
> To: Elecraft Reflector
> Subject: [Elecraft] K3 Filter Option Questions (revisited yet again)
>
>
> One of the things that I have not yet decided is the filters
> to get for my K3 order.  I am firm on getting the 400 Hz
> 8-pole filter (80 percent or so CW ops).  But, I like to scan
> the band looking for signals with a wider filter, say around
> 1 to 1.2 KHz.  Do I need to get the 1 K filter.  If I
> remember right, I can set DSP filtering to about 1 KHz which
> may be good enough or is there an advantage to the 1 KHz filter.
>
> Also, is there a good reason to swap out the 5-pole 2.7 kHz
> filter for the 2.8 KHz 8-pole?  I presume this gives the
> filter sharper skirts so you can cut off those close stations
> a bit better but I am curious as to how much better.
>
> Since the dollar cost differences in decisions regarding
> filters is not that great I would prefer answers that ignore
> the cost issue.
>
> So far, I am planning on getting the following filters with a
> ? on the 1 KHz 8-pole and 2.8 KHz 8-pole:
>
> 400 KHz 8-pole
> 1 KHz 8-pole  ??
> 2.8 KHz 8-pole swap for 2.7 KHz 5-pole ??
> 6.0 KHz 8-pole
>
> 73,
> phil, K7PEH

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