700 Hz Filter Benefit

[W4JBB]

I'm not bashing the filter, but I'm pretty happy with my 2.7 kHz and 500
Hz filters (main and sub receiver). What would be the benefit of the 700
Hz filter?

BTW, if I had it to do over, I'd have gone with the 400 Hz filters as
that seems to be where I keep the width.

Thanks,
Joel - W4JBB
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[Don Wilhelm-4]

Joel (and all),

I got used to tuning the CW bands with a 700 Hz width when I used my K2,
and liked the ability to hear 'around my frequency'.  Certainly the K3
DSP can provide that width with a 1 kHz roofing filter (or even a 2.7
kHz), but when the bands get crowded with strong signals, and I still
want to tune around using a 700 Hz bandwidth, I found I needed a roofing
filter that was closer to my desired bandwidth.  So I got in on the
first batch of these filters.  Yes, I also have a 400 Hz filter in my K3.

When you 'home in' on a signal, the 500 Hz, 400 Hz, or even the 250 Hz
filters are an advantage, but if you are hunting for potential contacts,
I find the 700 Hz width to be ideal. YMMV.

Even my K2 had filters set for 400 Hz and 200 Hz that I could kick in
when necessary, but my normal filter width with the K2 was 700 Hz.  As I
said, I liked that and bought into the 700 Hz filters when they were
first offered.

73,
Don W3FPR

On 1/22/2014 5:06 PM, Joel Black wrote:
> I'm not bashing the filter, but I'm pretty happy with my 2.7 kHz and
> 500 Hz filters (main and sub receiver). What would be the benefit of
> the 700 Hz filter?
>
> BTW, if I had it to do over, I'd have gone with the 400 Hz filters as
> that seems to be where I keep the width.
>

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[k6dgw]

On 1/22/2014 2:06 PM, Joel Black wrote:
> I'm not bashing the filter, but I'm pretty happy with my 2.7 kHz and 500
> Hz filters (main and sub receiver). What would be the benefit of the 700
> Hz filter?

I have a 2.7 and 500 too and they seem to be all I need.  They're
roofing filters whose only job is to keep very strong signals adjacent
to the BW [set by the DSP] that you're listening to from activating the
HW AGC that protects the ADC.  If you have neighbors who run a lot of
power, or are physically close, the narrower filter would seem to be
valuable.  That said, I usually run CW at 200-250Hz DSP BW, RTTY takes a
minimum of 300Hz, and I can't understand SSB at anything much less than
1.8KHz.

That's a lot just to say, "I guess I don't know."  Maybe the passband is
smoother on the 700Hz filter?

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 2014 Cal QSO Party 4-5 Oct 2014
- www.cqp.org


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[Brian Hunt]

I don't have a 700 Hz filter (yet) but this is what I'm thinking. I've discovered that the K3 NR is more effective if the DSP bandwidth is set to 1 KHz or so. When I'm searching for or copying a weak CW signal I often get AGC pumping from a strong signal close by but outside the 1 KHz passband. The 700 Hz filter would solve this.

I currently have the 400 and 2700 Hz filters.

73,
Brian, K0DTJ
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[Ethan Miller K8GU]

Joel,

I think that this is one of those situations that if you need (want)
it, you know you need (want) it.  As you point out, a useful way to
determine the most effective roofing filters for your K3 is to see
where you keep the DSP set most of the time.  Like Don, W3FPR, writes,
I happen to find ~700 Hz to be a good bandwidth for scanning the band
(or a pileup).  I had been operating my K3 at 700 Hz DSP BW protected
by the 2.7-kHz roofing filter before I even knew about the special
filter!  I was planning to get the 1-kHz to help reduce AGC pumping
from signals farther away, but got the narrower one because I never
went above 700 Hz.  I also have the 400-Hz, which is really super for
running on a busy contest band.

I'm obviously very happy with my 700-Hz filter.  (No connection, just
a satisfied customer.)

73,

--Ethan, K8GU/3.


On Wed, Jan 22, 2014 at 5:06 PM, Joel Black <[hidden email]> wrote:

> I'm not bashing the filter, but I'm pretty happy with my 2.7 kHz and 500 Hz
> filters (main and sub receiver). What would be the benefit of the 700 Hz
> filter?
>
> BTW, if I had it to do over, I'd have gone with the 400 Hz filters as that
> seems to be where I keep the width.
>
> Thanks,
> Joel - W4JBB
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html

--
http://www.k8gu.com/
Repair.  Re-use.  Re-purpose.  Recycle.
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