[K3] Perfect for Field Day S&P ... Limited Production 700 Hz 8-Pole Filters

[Gary W. Hvizdak]

Unless you have a panadapter, you'll never work weak stations, if you can't
hear them because they're outside your passband!  (This is the beauty of 700
Hz!)  In fact, many seasoned Elecraft K3 owners feel that using the radio's
400 Hz default (NORM) CW passband setting, is kind of like "viewing the
world thru a drinking straw while riding a bicycle".  That is, it would be
fairly easy to skip right past a weak calling station, without ever
realizing it was there.

But even more importantly, prolonged scanning with a 400 Hz passband can be
tedious and fatiguing.  This is why, band conditions permitting, savvy
operators prefer a 700 Hz passband:

o   "for general CW tuning" -- W3FPR
o   "for scanning the band (or a pileup)." -- K8GU
o   "for combing through the pileups with VFO [B]" -- NI0C
o   "to cruise the CW bands from a wider perspective" -- N1LQ

--- - - - ---

The next batch is due to arrive May 16th.  Demand for these custom filters
can fluctuate dramatically, so it's impossible to say precisely when this
next manufacturing lot might sell out.  (Our best guess is:  "April 1st,
give or take a few weeks".)  A subsequent production run can be expected
about 15 weeks thereafter.

If you have a sub-receiver or you are considering getting one, then FYI the
center frequency offset of individual manufacturing lots, can vary by up to
plus or minus 100 Hz.  In contrast, the variation across any given lot is
typically only plus or minus 5 Hz; yielding superbly matched pairs for
diversity reception!

--- - - - ---

Visit http://www.unpcbs.com to place an order, and for full details
including:

o   Retail price.
o   The filter's passband response plot.
o   User comments.
o   Special terms of sale.
o   Bandwidth and availability FAQs.
o   App notes.
o   An animated slideshow illustrating all five INRAD CW bandwidths.

73,
Gary  KI4GGX
(webmaster)


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[Wes (N7WS)]

This seems like an increasingly commercial trend cluttering up this list, with
dubious claims to boot.

I guess that I'm not a "savvy operator" since I use the discredited 400 Hz
filter and manage to get by.

Apparently, 700 Hz is a magical bandwidth, just as 43 feet is a magical length
for a vertical antenna.

Who knew?

Wes  N7WS


On 3/1/2014 12:27 AM, Gary W. Hvizdak wrote:

> Unless you have a panadapter, you'll never work weak stations, if you can't
> hear them because they're outside your passband!  (This is the beauty of 700
> Hz!)  In fact, many seasoned Elecraft K3 owners feel that using the radio's
> 400 Hz default (NORM) CW passband setting, is kind of like "viewing the
> world thru a drinking straw while riding a bicycle".  That is, it would be
> fairly easy to skip right past a weak calling station, without ever
> realizing it was there.
>
> But even more importantly, prolonged scanning with a 400 Hz passband can be
> tedious and fatiguing.  This is why, band conditions permitting, savvy
> operators prefer a 700 Hz passband:
>
> o   "for general CW tuning" -- W3FPR
> o   "for scanning the band (or a pileup)." -- K8GU
> o   "for combing through the pileups with VFO [B]" -- NI0C
> o   "to cruise the CW bands from a wider perspective" -- N1LQ

[commercial snipped to spare the reader]

73,
Gary  KI4GGX
(webmaster)


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[Phil Wheeler-2]

Agree re commercial messages of dubious merit. I
have a 400 and a 1000. Gee, that averages to 700
so I must be really clever :-)

Phil w7ox

On 3/1/14, 11:20 AM, Wes (N7WS) wrote:

> This seems like an increasingly commercial trend
> cluttering up this list, with dubious claims to
> boot.
>
> I guess that I'm not a "savvy operator" since I
> use the discredited 400 Hz filter and manage to
> get by.
>
> Apparently, 700 Hz is a magical bandwidth, just
> as 43 feet is a magical length for a vertical
> antenna.
>
> Who knew?
>
> Wes  N7WS
>
>
> On 3/1/2014 12:27 AM, Gary W. Hvizdak wrote:
>> Unless you have a panadapter, you'll never work
>> weak stations, if you can't
>> hear them because they're outside your
>> passband!  (This is the beauty of 700
>> Hz!)  In fact, many seasoned Elecraft K3 owners
>> feel that using the radio's
>> 400 Hz default (NORM) CW passband setting, is
>> kind of like "viewing the
>> world thru a drinking straw while riding a
>> bicycle".  That is, it would be
>> fairly easy to skip right past a weak calling
>> station, without ever
>> realizing it was there.
>>
>> But even more importantly, prolonged scanning
>> with a 400 Hz passband can be
>> tedious and fatiguing.  This is why, band
>> conditions permitting, savvy
>> operators prefer a 700 Hz passband:
>>
>> o   "for general CW tuning" -- W3FPR
>> o   "for scanning the band (or a pileup)." -- K8GU
>> o   "for combing through the pileups with VFO
>> [B]" -- NI0C
>> o   "to cruise the CW bands from a wider
>> perspective" -- N1LQ
> [commercial snipped to spare the reader]
>
> 73,
> Gary  KI4GGX
> (webmaster)
>
>
> ______________________________________________________________
>
> Elecraft mailing list
> Home:
> http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
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> http://www.qsl.net/donate.html
>

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[N5GE]

The advertisements for that particular brand of 700Hz filter are
passed through my junk filter or I wouldn't have seen it.

I'm surprised you didn't delete the entire advertisement.  I guess
I'm going have to add the phrase "limited production" to my filters.

In the K3, as it comes from the factory you already have a 700Hz
filter with the standard 2.7 or 2.8 filter.  Just use the width
control to set either of them to 700Hz.  It may not have the same
slop as the 700Hz filter in question, but when you are listening wide
on the sub RX in the K3 the difference between 700hz and 1Khzis not
that much.

I use a 1K filter to listen to to the pileup and a 200Hz filter to
listen to the DX.

Amateure Radio Operator N5GE


On Sat, 01 Mar 2014 12:20:03 -0700, you wrote:

>This seems like an increasingly commercial trend cluttering up this list, with
>dubious claims to boot.
>
>I guess that I'm not a "savvy operator" since I use the discredited 400 Hz
>filter and manage to get by.
>
>Apparently, 700 Hz is a magical bandwidth, just as 43 feet is a magical length
>for a vertical antenna.
>
>Who knew?
>
>Wes  N7WS
>
>
>On 3/1/2014 12:27 AM, Gary W. Hvizdak wrote:
>> Unless you have a panadapter, you'll never work weak stations, if you can't
>> hear them because they're outside your passband!  (This is the beauty of 700
>> Hz!)  In fact, many seasoned Elecraft K3 owners feel that using the radio's
>> 400 Hz default (NORM) CW passband setting, is kind of like "viewing the
>> world thru a drinking straw while riding a bicycle".  That is, it would be
>> fairly easy to skip right past a weak calling station, without ever
>> realizing it was there.
>>
>> But even more importantly, prolonged scanning with a 400 Hz passband can be
>> tedious and fatiguing.  This is why, band conditions permitting, savvy
>> operators prefer a 700 Hz passband:
>>
>> o   "for general CW tuning" -- W3FPR
>> o   "for scanning the band (or a pileup)." -- K8GU
>> o   "for combing through the pileups with VFO [B]" -- NI0C
>> o   "to cruise the CW bands from a wider perspective" -- N1LQ
>[commercial snipped to spare the reader]
>
>73,
>Gary  KI4GGX
>(webmaster)
>
>
>______________________________________________________________
>Elecraft mailing list
>Home: http://mailman.qth.net/mailman/listinfo/elecraft
>Help: http://mailman.qth.net/mmfaq.htm
>Post: mailto:[hidden email]
>
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[Don Wilhelm-4]

Eric has permitted such announcements, but limits them to one a month.
You will see offers to build a K2 that come in that same category.

Personal comment -- I particularly like the 700 Hz CW filter in my K3.  
I got used to tuning the bands using a 700 Hz filter width in my K2, and
opted for the 700 Hz roofing filter when it was offered. Yes, I find it
nice for 'scouring the pileup' before switching to the narrower 400 Hz
filter when listening to a pileup.  YMMV, but it is an available option.

73,
Don W3FPR

On 3/1/2014 6:32 PM, Amateur Radio Operator N5GE wrote:

> The advertisements for that particular brand of 700Hz filter are
> passed through my junk filter or I wouldn't have seen it.
>
> I'm surprised you didn't delete the entire advertisement.  I guess
> I'm going have to add the phrase "limited production" to my filters.
>
> In the K3, as it comes from the factory you already have a 700Hz
> filter with the standard 2.7 or 2.8 filter.  Just use the width
> control to set either of them to 700Hz.  It may not have the same
> slop as the 700Hz filter in question, but when you are listening wide
> on the sub RX in the K3 the difference between 700hz and 1Khzis not
> that much.
>
>

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[k6dgw]

If you can, help me out here Don ...

These are roofing filters.  From my perspective, which is likely wrong,
their job is to restrict the bandwidth presented to the 2nd mixer [and
downstream ADC].  They are of most value when you have very strong [i.e.
geographically close] signals adjacent to the desired signal [That would
be WX6V for me :-)].  The ultimate BW is set by the DSP of course, but a
really strong adjacent signal can begin to activate the HW AGC in the K3
which affects the signal inside your DSP BW, or I think that's true.
So, it follows to me that, if you are plagued by KW neighbors, narrower
roofing filters can reduce that problem.  This could be true on FD or
any other closely spaced HF operations ... IF you have two stations on
the same band/mode.

If you are not so plagued, I can't figure out why it really matters.  I
have the filter that came with the K3 and I bought one [2.7 and .5, I
don't remember which was which], I've had no difficulties.  Jim [WX6V]
and Jack KF6T [equally close] became non-problems when I got my K3 ...
even more so now that Jim has a K3 and phase-noise has disappeared. :-)

I've got to be missing something here, and sadly, it wouldn't be even
close to the first time.

73,

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


On 3/1/2014 4:03 PM, Don Wilhelm wrote:
> Eric has permitted such announcements, but limits them to one a month.
> You will see offers to build a K2 that come in that same category.
>
> Personal comment -- I particularly like the 700 Hz CW filter in my K3. I
> got used to tuning the bands using a 700 Hz filter width in my K2, and
> opted for the 700 Hz roofing filter when it was offered. Yes, I find it
> nice for 'scouring the pileup' before switching to the narrower 400 Hz
> filter when listening to a pileup.  YMMV, but it is an available option.


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[Jack Brindle-2]

As usual, Fred has things pretty much right. Here in Silicon Valley narrow roofing filters are needed to keep the local massive signals out of the receiver. With the 500 Hz 5-pole filter I can operate within a few hundred hertz of the big guys with very little problems. In fact it is pretty cool in Sweepstakes to be running with local 1500 watt stations up and down just a few hundred hundred hertz, not affecting my receiver at all. The DSP will be set to about 200 Hz in this situation. Without the local high-power stations, I like to widen out the bandwidth as much as possible so I can hear stations calling me that are away from my frequency, just like we used to do it in the days of the SB303, KWM2, etc.

Now on voice it is a different matter. 500 Hz doesn’t cut it. I use an 1800Hz filter there, and set the DSP for 500 Hz low cut and something around 1500-1800 Hz high cut. Sometimes it helps to drop the low cut a bit for someone with a deep voice, or raise the high cut for an YL. And again, under light conditions, I’ll widen up the filter to make use to the 2.7KHz roofing filter.

The roofing filters just keep big signals lout, allowing the DSP to do the really great job Lyle designed it to do.

Jack B, W6FB

On Mar 1, 2014, at 4:59 PM, Fred Jensen <[hidden email]> wrote:

> If you can, help me out here Don ...
>
> These are roofing filters.  From my perspective, which is likely wrong, their job is to restrict the bandwidth presented to the 2nd mixer [and downstream ADC].  They are of most value when you have very strong [i.e. geographically close] signals adjacent to the desired signal [That would be WX6V for me :-)].  The ultimate BW is set by the DSP of course, but a really strong adjacent signal can begin to activate the HW AGC in the K3 which affects the signal inside your DSP BW, or I think that's true. So, it follows to me that, if you are plagued by KW neighbors, narrower roofing filters can reduce that problem.  This could be true on FD or any other closely spaced HF operations ... IF you have two stations on the same band/mode.
>
> If you are not so plagued, I can't figure out why it really matters.  I have the filter that came with the K3 and I bought one [2.7 and .5, I don't remember which was which], I've had no difficulties.  Jim [WX6V] and Jack KF6T [equally close] became non-problems when I got my K3 ... even more so now that Jim has a K3 and phase-noise has disappeared. :-)
>
> I've got to be missing something here, and sadly, it wouldn't be even close to the first time.
>
> 73,
>
> Fred K6DGW
> - Northern California Contest Club
> - CU in the 2014 Cal QSO Party 4-5 Oct 2014
> - www.cqp.org
>
>
> On 3/1/2014 4:03 PM, Don Wilhelm wrote:
>> Eric has permitted such announcements, but limits them to one a month.
>> You will see offers to build a K2 that come in that same category.
>>
>> Personal comment -- I particularly like the 700 Hz CW filter in my K3. I
>> got used to tuning the bands using a 700 Hz filter width in my K2, and
>> opted for the 700 Hz roofing filter when it was offered. Yes, I find it
>> nice for 'scouring the pileup' before switching to the narrower 400 Hz
>> filter when listening to a pileup.  YMMV, but it is an available option.
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> Post: mailto:[hidden email]
>
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[Joe Subich, W4TV-4]

Fred,

In general you are correct.  However, there is one other effect that
the narrow roofing filters are not going to resolve - garbage from
your neighbors in the form of key clicks, transmitted phase noise and
IMD.  I see it every time my neighbor (.66 mi) comes on a band with
his Icom POS ... phase noise an clicks +/- 20 KHz.  The K3 handles his
fundamental just fine as little as 500 Hz away but the phase noise and
clicks make any band almost unusable.

73,

    ... Joe, W4TV


On 3/1/2014 7:59 PM, Fred Jensen wrote:

> If you can, help me out here Don ...
>
> These are roofing filters.  From my perspective, which is likely wrong,
> their job is to restrict the bandwidth presented to the 2nd mixer [and
> downstream ADC].  They are of most value when you have very strong [i.e.
> geographically close] signals adjacent to the desired signal [That would
> be WX6V for me :-)].  The ultimate BW is set by the DSP of course, but a
> really strong adjacent signal can begin to activate the HW AGC in the K3
> which affects the signal inside your DSP BW, or I think that's true. So,
> it follows to me that, if you are plagued by KW neighbors, narrower
> roofing filters can reduce that problem.  This could be true on FD or
> any other closely spaced HF operations ... IF you have two stations on
> the same band/mode.
>
> If you are not so plagued, I can't figure out why it really matters.  I
> have the filter that came with the K3 and I bought one [2.7 and .5, I
> don't remember which was which], I've had no difficulties.  Jim [WX6V]
> and Jack KF6T [equally close] became non-problems when I got my K3 ...
> even more so now that Jim has a K3 and phase-noise has disappeared. :-)
>
> I've got to be missing something here, and sadly, it wouldn't be even
> close to the first time.
>
> 73,
>
> Fred K6DGW
> - Northern California Contest Club
> - CU in the 2014 Cal QSO Party 4-5 Oct 2014
> - www.cqp.org
>
>
> On 3/1/2014 4:03 PM, Don Wilhelm wrote:
>> Eric has permitted such announcements, but limits them to one a month.
>> You will see offers to build a K2 that come in that same category.
>>
>> Personal comment -- I particularly like the 700 Hz CW filter in my K3. I
>> got used to tuning the bands using a 700 Hz filter width in my K2, and
>> opted for the 700 Hz roofing filter when it was offered. Yes, I find it
>> nice for 'scouring the pileup' before switching to the narrower 400 Hz
>> filter when listening to a pileup.  YMMV, but it is an available option.
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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[Wes (N7WS)]

That's why on more than one occasion I've said that to evaluate a transceiver's
receiver performance, instead of a couple of HP8663 signal generators, two other
like transceiver transmitters should be used as the signal sources for the
measurements, until that is, our transceivers have the spectral purity of '8663s.:-)

  On 3/1/2014 7:17 PM, Joe Subich, W4TV wrote:

>
> Fred,
>
> In general you are correct.  However, there is one other effect that
> the narrow roofing filters are not going to resolve - garbage from
> your neighbors in the form of key clicks, transmitted phase noise and
> IMD.  I see it every time my neighbor (.66 mi) comes on a band with
> his Icom POS ... phase noise an clicks +/- 20 KHz.  The K3 handles his
> fundamental just fine as little as 500 Hz away but the phase noise and
> clicks make any band almost unusable.
>
> 73,
>
>    ... Joe, W4TV
>
>
> On 3/1/2014 7:59 PM, Fred Jensen wrote:
>> If you can, help me out here Don ...
>>
>> These are roofing filters.  From my perspective, which is likely wrong,
>> their job is to restrict the bandwidth presented to the 2nd mixer [and
>> downstream ADC].  They are of most value when you have very strong [i.e.
>> geographically close] signals adjacent to the desired signal [That would
>> be WX6V for me :-)].  The ultimate BW is set by the DSP of course, but a
>> really strong adjacent signal can begin to activate the HW AGC in the K3
>> which affects the signal inside your DSP BW, or I think that's true. So,
>> it follows to me that, if you are plagued by KW neighbors, narrower
>> roofing filters can reduce that problem.  This could be true on FD or
>> any other closely spaced HF operations ... IF you have two stations on
>> the same band/mode.
>>
>> If you are not so plagued, I can't figure out why it really matters.  I
>> have the filter that came with the K3 and I bought one [2.7 and .5, I
>> don't remember which was which], I've had no difficulties.  Jim [WX6V]
>> and Jack KF6T [equally close] became non-problems when I got my K3 ...
>> even more so now that Jim has a K3 and phase-noise has disappeared. :-)
>>
>> I've got to be missing something here, and sadly, it wouldn't be even
>> close to the first time.
>>

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[Don Wilhelm-4]

Fred,

Everything you say is true, the DSP does set the final filter width, but
the hardware AGC can cause pumping in the presence of nearby strong signals.
Since my normal desired CW tuning width is in the vicinity of 700 Hz, I
bought and installed one of the 700 Hz filters.  YMMV some say that a
1000 kHz roofer is fine, and others say that the 2.7 kHz filter works
just fine too, but I am satisfied with the 700 Hz width - that is a
personal preference, I am not here to convince others about my choices,
but only to give information that will allow others to make intelligent
choices that suit their needs and desires.

73,
Don W3FPR

On 3/1/2014 7:59 PM, Fred Jensen wrote:

> If you can, help me out here Don ...
>
> These are roofing filters.  From my perspective, which is likely
> wrong, their job is to restrict the bandwidth presented to the 2nd
> mixer [and downstream ADC].  They are of most value when you have very
> strong [i.e. geographically close] signals adjacent to the desired
> signal [That would be WX6V for me :-)].  The ultimate BW is set by the
> DSP of course, but a really strong adjacent signal can begin to
> activate the HW AGC in the K3 which affects the signal inside your DSP
> BW, or I think that's true. So, it follows to me that, if you are
> plagued by KW neighbors, narrower roofing filters can reduce that
> problem.  This could be true on FD or any other closely spaced HF
> operations ... IF you have two stations on the same band/mode.
>
> If you are not so plagued, I can't figure out why it really matters.  
> I have the filter that came with the K3 and I bought one [2.7 and .5,
> I don't remember which was which], I've had no difficulties.  Jim
> [WX6V] and Jack KF6T [equally close] became non-problems when I got my
> K3 ... even more so now that Jim has a K3 and phase-noise has
> disappeared. :-)
>

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[Bill Frantz]

I have the 2.1 KHz (for SSB) and the 250Hz (for CW and digital)
filters. I used the frequencies marked on the filters for the K3
setup, so everything is quite standard. I notice as I am
narrowing the bandwidth in both CW and SSB, when the K3 switches
to a narrower filter, there is a noticeable step down in the
noise level that doesn't occur when just narrowing the DSP
bandwidth one notch. This reduction in noise is one of the big
advantages in having the filters, and I don't think it involves
AGC pumping, even though I live in Silicon Valley with a large
number of other hams.

Cheers - Bill, AE6JV
-------------------------------------------------------------------------
Bill Frantz        | Re: Hardware Management Modes: | Periwinkle
[phone]      | If there's a mode, there's a   | 16345
Englewood Ave
www.pwpconsult.com | failure mode. - Jerry Leichter | Los Gatos,
CA 95032

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[Matt Zilmer-3]

Hi Bill,

In the K3 Utility -> Configuration tab -> Configure Crystal Filters,
you will see that each filter has a Gain setting.  You can change the
gain on a per-filter basis to maintain approximately the same overall
gain.  Generally the smaller bandwidth filters require a few more dB
gain than wider ones.

An example:
13 KHz:  0 dB
6 KHz: 0 dB
2.8 KHz: 1 dB
1.8 KHz: 2 dB
0.25 KHz: 4 dB

These settings work well in my K3.  Yours may be somewhat different
though.  Don't forget to balance filter gains for the subreceiver if
you have one.

73,
matt W6NIA

On Sun,  2 Mar 2014 11:37:58 -0800, you wrote:

>I have the 2.1 KHz (for SSB) and the 250Hz (for CW and digital)
>filters. I used the frequencies marked on the filters for the K3
>setup, so everything is quite standard. I notice as I am
>narrowing the bandwidth in both CW and SSB, when the K3 switches
>to a narrower filter, there is a noticeable step down in the
>noise level that doesn't occur when just narrowing the DSP
>bandwidth one notch. This reduction in noise is one of the big
>advantages in having the filters, and I don't think it involves
>AGC pumping, even though I live in Silicon Valley with a large
>number of other hams.
>
>Cheers - Bill, AE6JV
>-------------------------------------------------------------------------
>Bill Frantz        | Re: Hardware Management Modes: | Periwinkle
>[phone]      | If there's a mode, there's a   | 16345
>Englewood Ave
>www.pwpconsult.com | failure mode. - Jerry Leichter | Los Gatos,
>CA 95032
>
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Matt Zilmer, W6NIA
--
"Give me six hours to chop down a tree and I will
spend the first four sharpening the axe." -A. Lincoln
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[Bill Frantz]

I am using:

13 KHz: 0 dB
2.7 KHz: 0 dB
2.1 KHz: 0 dB
250 Hz: 6 dB

When the 2.1 and 250 filters switch in, the signal level in the
earphones doesn't seem to change, but the noise level does
indicating an improvement in S/N. Perhaps they are sharpening
the cutoff of the DSP filter removing some of the off-frequency noise?

Cheers - Bill, AE6JV

On 3/2/14 at 11:51 AM, [hidden email] (Matt Zilmer) wrote:

>In the K3 Utility -> Configuration tab -> Configure Crystal Filters,
>you will see that each filter has a Gain setting.  You can change the
>gain on a per-filter basis to maintain approximately the same overall
>gain.  Generally the smaller bandwidth filters require a few more dB
>gain than wider ones.
>
>An example:
>13 KHz:  0 dB
>6 KHz: 0 dB
>2.8 KHz: 1 dB
>1.8 KHz: 2 dB
>0.25 KHz: 4 dB
>
>These settings work well in my K3.

>On Sun,  2 Mar 2014 11:37:58 -0800, you wrote:
>
>>I have the 2.1 KHz (for SSB) and the 250Hz (for CW and
>>digital) filters. ... I notice as I am narrowing the bandwidth
>>in both CW and SSB, when the K3 switches to a narrower filter,
>>there is a noticeable step down in the noise level that
>>doesn't occur when just narrowing the DSP bandwidth one notch.
-----------------------------------------------------------------------
Bill Frantz        | "The only thing we have to   | Periwinkle
[phone]      | fear is fear itself." - FDR  | 16345
Englewood Ave
www.pwpconsult.com | Inaugural address, 3/4/1933  | Los Gatos,
CA 95032

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[Ethan Miller K8GU]

Like Don, I have the 700-Hz filter and would never have heard of it
without Gary's announcements on the list.  Considering some the other
dubious stuff that gets posted on the list, I'm happy to hear about
things that are actually of interest to me.  It's not magical, but
when I found myself opening up the DSP bandwidth beyond 400 Hz to
600-800 Hz a lot of the time while working/listening to pileups,
quickly tuning a band, or operating casually, I thought it a good idea
to invest in one.  It's been worthwhile for me...

Personally, I would think it is of limited utility at Field Day versus
the 400 or 250/200...trashy rigs (and AKTR operators) notwithstanding.

73,

--Ethan, K8GU/3.

K3/100 #6714
K2/100 #7372
TS-930S #5010245


On Sun, Mar 2, 2014 at 3:05 AM, Don Wilhelm <[hidden email]> wrote:

> Fred,
>
> Everything you say is true, the DSP does set the final filter width, but the
> hardware AGC can cause pumping in the presence of nearby strong signals.
> Since my normal desired CW tuning width is in the vicinity of 700 Hz, I
> bought and installed one of the 700 Hz filters.  YMMV some say that a 1000
> kHz roofer is fine, and others say that the 2.7 kHz filter works just fine
> too, but I am satisfied with the 700 Hz width - that is a personal
> preference, I am not here to convince others about my choices, but only to
> give information that will allow others to make intelligent choices that
> suit their needs and desires.
>
> 73,
> Don W3FPR
>
> On 3/1/2014 7:59 PM, Fred Jensen wrote:
>>
>> If you can, help me out here Don ...
>>
>> These are roofing filters.  From my perspective, which is likely wrong,
>> their job is to restrict the bandwidth presented to the 2nd mixer [and
>> downstream ADC].  They are of most value when you have very strong [i.e.
>> geographically close] signals adjacent to the desired signal [That would be
>> WX6V for me :-)].  The ultimate BW is set by the DSP of course, but a really
>> strong adjacent signal can begin to activate the HW AGC in the K3 which
>> affects the signal inside your DSP BW, or I think that's true. So, it
>> follows to me that, if you are plagued by KW neighbors, narrower roofing
>> filters can reduce that problem.  This could be true on FD or any other
>> closely spaced HF operations ... IF you have two stations on the same
>> band/mode.
>>
>> If you are not so plagued, I can't figure out why it really matters.  I
>> have the filter that came with the K3 and I bought one [2.7 and .5, I don't
>> remember which was which], I've had no difficulties.  Jim [WX6V] and Jack
>> KF6T [equally close] became non-problems when I got my K3 ... even more so
>> now that Jim has a K3 and phase-noise has disappeared. :-)
>>
>
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--
http://www.k8gu.com/
Repair.  Re-use.  Re-purpose.  Recycle.
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[Phil Wheeler-2]

My filters are 6, 2.8, 2.1.1.0 and 0.4.  1.0 and
0.4 average to 0.7 so I think I have it covered ;-)

73, Phil w7ox

On 3/2/14, 11:05 PM, Bill Frantz wrote:

> I am using:
>
> 13 KHz: 0 dB
> 2.7 KHz: 0 dB
> 2.1 KHz: 0 dB
> 250 Hz: 6 dB
>
> When the 2.1 and 250 filters switch in, the
> signal level in the earphones doesn't seem to
> change, but the noise level does indicating an
> improvement in S/N. Perhaps they are sharpening
> the cutoff of the DSP filter removing some of
> the off-frequency noise?
>
> Cheers - Bill, AE6JV
>
> On 3/2/14 at 11:51 AM, [hidden email]
> (Matt Zilmer) wrote:
>
>> In the K3 Utility -> Configuration tab ->
>> Configure Crystal Filters,
>> you will see that each filter has a Gain
>> setting.  You can change the
>> gain on a per-filter basis to maintain
>> approximately the same overall
>> gain.  Generally the smaller bandwidth filters
>> require a few more dB
>> gain than wider ones.
>>
>> An example:
>> 13 KHz:  0 dB
>> 6 KHz: 0 dB
>> 2.8 KHz: 1 dB
>> 1.8 KHz: 2 dB
>> 0.25 KHz: 4 dB
>>
>> These settings work well in my K3.
>
>> On Sun,  2 Mar 2014 11:37:58 -0800, you wrote:
>>
>>> I have the 2.1 KHz (for SSB) and the 250Hz
>>> (for CW and digital) filters. ... I notice as
>>> I am narrowing the bandwidth in both CW and
>>> SSB, when the K3 switches to a narrower
>>> filter, there is a noticeable step down in the
>>> noise level that doesn't occur when just
>>> narrowing the DSP bandwidth one notch.
> -----------------------------------------------------------------------
>
> Bill Frantz        | "The only thing we have
> to   | Periwinkle
> [phone]      | fear is fear itself." -
> FDR  | 16345 Englewood Ave
> www.pwpconsult.com | Inaugural address,
> 3/4/1933  | Los Gatos, CA 95032
>
> ______________________________________________________________
>
> Elecraft mailing list
> Home:
> http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list:
> http://www.qsl.net/donate.html
>

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