K3: Choosing which filters to buy

[DOUGLAS ZWIEBEL]

Shane:

With respect to a CW filter...

If you are a "casual" cw op (or plan to be), then I would not get any
"cw" filter.  The 2.7kc roofing filter is already narrower than 99% of
everything else available out there (for a roofing filter).

As for the final BW, use the DSP and you can crank it down to 50hz
(really, really narrow!).  It works really well too.

I am an AVID cw op and I use the 500hz filter (5 pole) because 99% of
my operating is DX Contesting.  Outside of contest, I think that you
would be hard pressed to find a situation (outside of Europe on 40m or
low band DX pileups) where you would "need" a narrow CW roofing
filter.

If you simply "must have" a cw filter, I would suggest either the 500
or 400.  You already know which one I use.

de Doug KR2Q
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[drewko]

Just wondering... Can the CW Text Decoder be made to read (or try to
read) your manual key while in Test mode?

73,
Drew
AF2Z

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[Darwin, Keith]

I think Doug has hit the nail on the head.  For casual CW, just use the
DSP.  If it isn't good enough, you can always add the 500 Hz roofing
filter later.

For more serious CW operating, I'm thinking the next filter to get is
the 1 KHz filter to give better tuning-across-the-band performance.  My
3rd choice would then be the ultra narrow (250?) filter.

- Keith N1AS -
- K3 711 -

-----Original Message-----
If you are a "casual" cw op (or plan to be), then I would not get any
"cw" filter.  The 2.7kc roofing filter is already narrower than 99% of
everything else available out there (for a roofing filter).
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[Darwin, Keith]

I tried and it did not work.  Was told the solution was to hook the
manual key to a K2 feeding a dummy load, then receive the signal on the
K3 and send away!

I tried that and it worked fine.  It could copy both my straight key and
bug fists.  I did not try cootie sending because I'm so bad I can't even
tell what I sent :-)

- Keith N1AS -
- K3 711 -

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of
[hidden email]
Sent: Wednesday, June 25, 2008 3:30 PM
To: [hidden email]
Subject: [Elecraft] K3 CW Text Decode

Just wondering... Can the CW Text Decoder be made to read (or try to
read) your manual key while in Test mode?

73,
Drew
AF2Z

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[Ed Muns, W0YK]

> I think Doug has hit the nail on the head.  For casual CW,
> just use the DSP.  If it isn't good enough, you can always
> add the 500 Hz roofing filter later.

The take-away advice was to not add any additional filters until:

1.  You know what bandwidth(s) you will use a lot in each mode of interest,
AND
2.  You know that you have large signals near your operating frequency that
interfere with the DSP filtering.

Most of us seldom have condition 2, so the DSP filtering is completely
satisfactory with the 2.7 or 2.8 kHz roofing filter.  Unless one is very
sure about both points above, it makes much more sense to use the K3 for a
while until you have definitive answers before selecting protective roofing
filters.

> For more serious CW operating, I'm thinking the next filter
> to get is the 1 KHz filter to give better
> tuning-across-the-band performance.  My 3rd choice would then
> be the ultra narrow (250?) filter.

As has been stated many times on this reflector, the 250 Hz 8-pole filter is
actually 370 Hz at the -6 dB points.  Review the filter plots on the
Elecraft web site.  If you already have a 400 (actually 435 Hz) or a 500
(about 520 Hz, I think), then the "250 Hz filter" is superfluous.  If you
need a narrow roofing filter for crowded 160 meter band conditions, then the
200 Hz 5-pole is an excellent complement to the 400 or 500 Hz roofer.

The only cases I see for the 250 Hz filter are:

A.  If you do NOT have a 400 or 500 Hz filter and want a slightly tighter
CW/RTTY filter, then 370 Hz (called "250 Hz") is great.
B.  If you are primarily interested in RTTY contesting with very crowded
band conditions, then the 370 is the tightest roofing filter now available
for the K3 that doesn't roll off the outside passband of a 170 Hz shift
tone-pair.  Even so, I often use 200 Hz DSP and tolerate the roll off in
exchange for attenuation of more of the pile-up.  When the variable crystal
filters come out, the 200-500 Hz (or whatever it turns out to be in that
range) will be another excellent alternative.

73,
Ed - W0YK

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