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K3 Filter question - SSB

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Bruce Meier-2

K3 Filter question - SSB

As I operate much more CW than SSB I need some advice and opinions from the
SSB contesters before adding additional filters for my K3s. Currently I
only have the stock 2.7Khz filters in both K3s (main and sub rx) for SSB. I
have 400hz and 250hz for CW. If I wanted to add an additional roofing
filter for SSB contesting, would I add a 1.8Khz or would I add the 2.1Khz.

73,
Bruce - N1LN

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Jeff Cochrane - VK4XA

Re: K3 Filter question - SSB

CONTENTS DELETED

The author has deleted this message.

Bill W4ZV

Re: K3 Filter question - SSB

In reply to this post by Bruce Meier-2

Bruce this is from a similar question on the Yahoo Groups K3 list:

-- In Elecraft_K3@yahoogroups.com, Hector Padron <ad4c2006@...> wrote:
>
> The 1.8 roofer today with so much band noise and fool ops close to your
> freq disrespecting the spectrum, its a must.This 8 poles filter together
> with the DSP makes brick rx easy to work dx or contesting.The trick to
> recover the lost audio quality when using it is to move counterclockwise
> the shift control down to 1.2 and inteligibility is back.

This is very misleading and I must strongly disagree. I preface this by saying
I made ~2500 QSOs on 10m single band in the CQ WW (high-claimed USA SOSB/10
score) and was never able to effectively use the 1.8k filter even though I tried
in vain several times.

Here's what a 1.8k will and will not do:

1. It *WILL* keep your AGC from pumping if there's another strong station
within the 1.8 kHz passband. However, do you really think you could copy a weak
signal while a S9+30 interfering signal is inside your 1.8k bandwidth? I don't
think so. With any typical SSB filter bandwidth, AGC pumping is not a practical
issue (it IS a big deal for CW however).

2. It *WILL *NOT* keep splatter from adjacent signals out of your passband. If
an interfering signal is 5 kHz wide and partially falls within your passband, NO
filter can remove it. Splatter is a real signal which NO filter (XTAL or DSP)
can remove.

3. It *WILL* require very careful tuning for intelligibility. With callers
that are off frequency by only 100 Hz, you'll miss off-frequency callers the
first time which will slow your run rate. I had one caller even 500 Hz below my
run frequency and I'm certain I would never have heard him if I was using the
1.8k.

The most effective use of a 1.8k is probably for copying an extremely weak DX
signal in white noise (not strong splatter or QRM). By tuning VERY carefully,
you may slightly reduce the noise floor by reducing the noise bandwidth
(potential reduction of 1.8k BW versus 2.1k BW is 10*[log (1.8/2.1)] = -0.67
dB). I really doubt many of us can detect a 0.67 dB improvement in
signal/noise.

The 1.8k is mainly a DXing tool...not a contesting tool. It cannot magically
overcome the basic laws of physics.

73, Bill W4ZV

Bill W4ZV

Re: K3 Filter question - SSB

Bill W4ZV wrote

3. It *WILL* require very careful tuning for intelligibility. With callers
that are off frequency by only 100 Hz, you'll miss off-frequency callers the
first time which will slow your run rate. I had one caller even 500 Hz below my
run frequency and I'm certain I would never have heard him if I was using the
1.8k.

Just to qualify what I mean by high run rates:

-------------- Q S O R a t e S u m m a r y ---------------------
Hour 160 80 40 20 15 10 Rate Total Pct
--------------------------------------------------------------------
1200 0 0 0 0 0 173 173 226 9.1
1300 0 0 0 0 0 186 186 412 16.6
1400 0 0 0 0 0 200 200 612 24.6
1500 0 0 0 0 0 163 163 775 31.2
1600 0 0 0 0 0 112 112 887 35.7

1200 0 0 0 0 0 128 128 1481 59.6
1300 0 0 0 0 0 155 155 1636 65.8
1400 0 0 0 0 0 144 144 1780 71.6
1500 0 0 0 0 0 163 163 1943 78.2
1600 0 0 0 0 0 128 128 2071 83.3
1700 0 0 0 0 0 138 138 2209 88.9

The best 60 minute rate was 217/hour from 1349 to 1448
The best 30 minute rate was 228/hour from 1358 to 1427
The best 10 minute rate was 246/hour from 1418 to 1427

The best 1 minute rates were:
6 QSOs/minute 7 times.
5 QSOs/minute 32 times.
4 QSOs/minute 122 times.
3 QSOs/minute 238 times.
2 QSOs/minute 328 times.
1 QSOs/minute 425 times.

The 1.8k is a nice tool when working a weak DX station who is running the pileup. It is very poor if you're the one who is running and attempting to work callers at high rates (i.e. getting the call correctly the first time without repeats). I'll be selling my 1.8k in favor of a 2.1k after my recent experience.

73, Bill

w0mu

Re: K3 Filter question - SSB

In reply to this post by Bruce Meier-2

The 1.8 is where I would go. Inrad also sells a 1.5 which a number of
people swear by for really nasty SSB contests.

Mike W0MU

J6M CQ WW DX CW Contest 2011
J6/W0MU November 21 - December 1 2011
W0MU-1 CC Cluster w0mu.net

On 11/10/2011 4:29 AM, Bruce Meier wrote:

> As I operate much more CW than SSB I need some advice and opinions from the
> SSB contesters before adding additional filters for my K3s. Currently I
> only have the stock 2.7Khz filters in both K3s (main and sub rx) for SSB. I
> have 400hz and 250hz for CW. If I wanted to add an additional roofing
> filter for SSB contesting, would I add a 1.8Khz or would I add the 2.1Khz.
>
> 73,
> Bruce - N1LN
>
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Joe Subich, W4TV-4

Re: K3 Filter question - SSB

I would not go any tighter than 1.8 KHz. I have a pair of the 1.5 KHz
filters that I would swap for 1.8s.

73,

... Joe, W4TV

On 11/10/2011 10:11 AM, W0MU Mike Fatchett wrote:

> The 1.8 is where I would go. Inrad also sells a 1.5 which a number of
> people swear by for really nasty SSB contests.
>
> Mike W0MU
>
> J6M CQ WW DX CW Contest 2011
> J6/W0MU November 21 - December 1 2011
> W0MU-1 CC Cluster w0mu.net
>
>
> On 11/10/2011 4:29 AM, Bruce Meier wrote:
>> As I operate much more CW than SSB I need some advice and opinions from the
>> SSB contesters before adding additional filters for my K3s. Currently I
>> only have the stock 2.7Khz filters in both K3s (main and sub rx) for SSB. I
>> have 400hz and 250hz for CW. If I wanted to add an additional roofing
>> filter for SSB contesting, would I add a 1.8Khz or would I add the 2.1Khz.
>>
>> 73,
>> Bruce - N1LN
>>

Barry N1EU

Re: K3 Filter question - SSB

In reply to this post by Bill W4ZV

Bill W4ZV wrote

1. It *WILL* keep your AGC from pumping if there's another strong station
within the 1.8 kHz passband. However, do you really think you could copy a weak
signal while a S9+30 interfering signal is inside your 1.8k bandwidth? I don't
think so. With any typical SSB filter bandwidth, AGC pumping is not a practical
issue (it IS a big deal for CW however).

Bill, I'm confused by that first sentence. How can a signal within the passband NOT pump the AGC?

Normally when AGC pumping is discussed, it's a negative reference to an adjacent signal that's outside of the passband.

Barry N1EU

David Gilbert

Re: K3 Filter question - SSB

In reply to this post by Joe Subich, W4TV-4

I also have a pair of the 1.5 KHz filters, and while I find them to be
desirable under certain DXing situations, I rarely use them in a
contest. In a contest you need quick intelligibility and filters as
narrow as 1.5 KHz don't necessarily give you that. I have a pretty good
ear, but lots of human voices have enough energy in different parts of
the audio spectrum that I find it sometimes necessary to either shift to
a wider filter or change the shift on the 1.5 KHz filter (I typically
use 1.1 KHz for the center with that filter) in order to copy the other
guy's callsign or exchange. Plus, as W4ZV pointed out, there is so much
atrocious splatter from crummy rigs or ignorantly adjusted rigs during a
major contest that it is truly rare to find such a narrow filter
actually being helpful. I also would trade my 1.5 KHz filters for a
pair of 1.8 KHz filters in a heartbeat.

73,
Dave AB7E

On 11/10/2011 8:27 AM, Joe Subich, W4TV wrote:

> I would not go any tighter than 1.8 KHz. I have a pair of the 1.5 KHz
> filters that I would swap for 1.8s.
>
> 73,
>
> ... Joe, W4TV
>
>
> On 11/10/2011 10:11 AM, W0MU Mike Fatchett wrote:
>> The 1.8 is where I would go. Inrad also sells a 1.5 which a number of
>> people swear by for really nasty SSB contests.
>>
>> Mike W0MU
>>
>> J6M CQ WW DX CW Contest 2011
>> J6/W0MU November 21 - December 1 2011
>> W0MU-1 CC Cluster w0mu.net
>>
>>
>> On 11/10/2011 4:29 AM, Bruce Meier wrote:
>>> As I operate much more CW than SSB I need some advice and opinions from the
>>> SSB contesters before adding additional filters for my K3s. Currently I
>>> only have the stock 2.7Khz filters in both K3s (main and sub rx) for SSB. I
>>> have 400hz and 250hz for CW. If I wanted to add an additional roofing
>>> filter for SSB contesting, would I add a 1.8Khz or would I add the 2.1Khz.
>>>
>>> 73,
>>> Bruce - N1LN
>>>
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Jim Brown-10

Re: K3 Filter question - SSB

On 11/10/2011 8:34 AM, David Gilbert wrote:
> there is so much
> atrocious splatter from crummy rigs or ignorantly adjusted rigs during a
> major contest

YES, YES, YES.

> that it is truly rare to find such a narrow filter
> actually being helpful. I also would trade my 1.5 KHz filters for a
> pair of 1.8 KHz filters in a heartbeat.

I strongly agree. I have 1.8 kHz filters in my K3s, and find that I
rarely use them during a contest for the reasons that W4ZV has
articulated. Paraphrasing from another world, "it's the TRASH, stupid!"

73, Jim K9YC
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Bill W4ZV

Re: K3 Filter question - SSB

In reply to this post by Barry N1EU

Barry N1EU wrote

Bill W4ZV wrote

1. It *WILL* keep your AGC from pumping if there's another strong station
within the 1.8 kHz passband. However, do you really think you could copy a weak
signal while a S9+30 interfering signal is inside your 1.8k bandwidth? I don't
think so. With any typical SSB filter bandwidth, AGC pumping is not a practical
issue (it IS a big deal for CW however).

Bill, I'm confused by that first sentence. How can a signal within the passband NOT pump the AGC?

Normally when AGC pumping is discussed, it's a negative reference to an adjacent signal that's outside of the passband.

Barry N1EU

You're correct Barry. I meant to say just outside your passband. However, given that most SSB signals generate 3rd garbage (spurs, phase noise, etc) in the area of -35 dBc, an S9+30 signal just outside your 1.8k passband will easily obliterate a weak signal inside the passband.

I found my ears to be the best tool for copying weak signals in the presence of strong adjacent splatter. For whatever reason they heard better using the stock 5-pole 2.7k set to a DSP BW of 2.0-2.1k than the 8-pole 1.8k set to actuate at DSP = 1.9k. I tried many times to use the 1.8k but simply just found the 2.7k worked better for me. Of course that's just my experience which wouldn't necessarily apply to everyone.

73, Bill

David Gilbert

Re: K3 Filter question - SSB

I've had exactly the same experience. If the offending QRM is outside
the passband of the filter, the narrower filter setting helps. However,
If the offending QRM is heavily inside the passband (i.e., splatter), it
seems that the additional intelligibility gain by capturing more of the
desired station's audio bandwidth can often more than offset the
additional interference you get from using a wider bandwidth. A lot
depends upon the desired station's voice characteristics, but I've
played with this quite a bit and the results can be surprising.

Splatter is the enemy of us all, except of course for the idiots who do
it intentionally to give themselves "elbow room". One of these days I'm
going to start posting spectral screenshots of significant offenders on
my web site.

73,
Dave AB7E

On 11/10/2011 12:21 PM, Bill W4ZV wrote:

>
>
> I found my ears to be the best tool for copying weak signals in the presence
> of strong adjacent splatter. For whatever reason they heard better using
> the stock 5-pole 2.7k set to a DSP BW of 2.0-2.1k than the 8-pole 1.8k set
> to actuate at DSP = 1.9k. I tried many times to use the 1.8k but simply
> just found the 2.7k worked better for me. Of course that's just my
> experience which wouldn't necessarily apply to everyone.
>
> 73, Bill
>
>

Barry N1EU

Re: K3 Filter question - SSB

In reply to this post by Bill W4ZV

Bill W4ZV wrote

However, given that most SSB signals generate 3rd garbage (spurs, phase noise, etc) in the area of -35 dBc, an S9+30 signal just outside your 1.8k passband will easily obliterate a weak signal inside the passband.

I agree. Although I routinely use 1.8Khz roofing filters in ssb contests, I doubt they help at all and are probably a waste of money.

What does help to copy a weaker signal in the presence of splatter is to turn AGC off.

Barry N1EU

riese-k3djc

Re: K3 Filter question - SSB

In reply to this post by Bruce Meier-2

happens outside of contests as well
I can get alongside of a SSB signal
and if it is clean have no problem
but the guys that feel increasing there bandwidth for a better/pleasant
sounding
signal creep me out,,, the K3 is the first rcv I can say this about
if the signal next door is clean regardless of strength it causes no
problems
looking forward to the KX3

Bob K3DJC

On Thu, 10 Nov 2011 10:58:46 -0800 Jim Brown <[hidden email]>
writes:

> On 11/10/2011 8:34 AM, David Gilbert wrote:
> > there is so much
> > atrocious splatter from crummy rigs or ignorantly adjusted rigs
> during a
> > major contest
>
> YES, YES, YES.
>
> > that it is truly rare to find such a narrow filter
> > actually being helpful. I also would trade my 1.5 KHz filters
> for a
> > pair of 1.8 KHz filters in a heartbeat.
>
> I strongly agree. I have 1.8 kHz filters in my K3s, and find that I
>
> rarely use them during a contest for the reasons that W4ZV has
> articulated. Paraphrasing from another world, "it's the TRASH,
> stupid!"
>
> 73, Jim K9YC
> ______________________________________________________________
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>

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alorona

Re: K3 Filter question - SSB

In reply to this post by Bill W4ZV

I'm glad this came up because it is an aspect of filtering that seldom is
addressed.

Many folks seem to think that you can arbitrarily close down the bandwidth of a
receiver to eliminate QRM and improve intelligibility.

1.8 kHz is deemed better than 2.1 kHz, and 1.5 kHz is deemed better than both.

But at some point intelligibility itself suffers because you start to eliminate
the signal you're trying to copy in the first place.

I for one suffer from a type of listener's fatigue when forced to copy SSB
signals in anything less than about 2.2 kHz or so.

Others folks suffer from hearing loss and need to hear as much of the voice
frequencies as possible. 1.8 kHz just doesn't work for many of these folks.

If you're okay with such narrow bandwidths, more power to you, but you can't
make blanket statements about them being equally effective for everybody.

As Bill, Dave, and Barry alluded to, the ear-brain filter is the most effective
of all, and it would do us all good to exercise it more often. The more you use
it, the better you get at it.

>> Bill W4ZV wrote:
>> 3. It *WILL* require very careful tuning for intelligibility.
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John Oppenheimer

Re: K3 Filter question - SSB

In reply to this post by riese-k3djc

Interesting to me is position today that 2.1 kHz is narrow. For many
decades, a 2.1 kHz filter was normal, and sometimes only SSB filter.

Heathkit SB-101 etc 350 - 2450 (center 1400)
Collins KWM-2A etc 400 - 2500 (center 1450)

Sometime during the 90s, or so, the standard seemed to move to 2.4 kHz
and up. What happened?

Because of my early experiences with a SB-101, I decided that the Heath
SSB BW settings were for me. Therefore I have a 2.1 kHz roofing filter
installed and set the BW to 350 - 2450 and stored into NORM1.

Which leads into a K3 issue. I believe that it would be a service to all
of us users if the K3 manual had a set of optimal center frequencies for
some of the pseudo standard settings optimized by those before us at
Heathkit, Collins, and others.

And it would be nice if the NORM button was programmable. I understand
that there are the NORM1 and NORM2 settings, but for me, simple NORM is
a wasted SSB button as I never use a 100 - 2900 Hz BW.

And it would be nice if there was a default SSB center for each of the
filters in Filter configuration. Tapping XFIL would not only move to the
next filter, but also set to it's optimal SSB filter center frequency.

John, KN5L
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Dunc Carter - W5DC

Re: K3 Filter question - SSB

On 11/10/2011 3:33 PM, John Oppenheimer wrote:

>> I use a 1200 Hz center frequency with my 1800 Hz roofing filter. It gives roughly the same passband as my ancient FT-101E with a cascaded pair of Yaesu filters, one in the normal receive line and the second in the speech clipper.
>
> Dunc, W5DC
> Which leads into a K3 issue. I believe that it would be a service to all
> of us users if the K3 manual had a set of optimal center frequencies for
> some of the pseudo standard settings optimized by those before us at
> Heathkit, Collins, and others.
>
> And it would be nice if the NORM button was programmable. I understand
> that there are the NORM1 and NORM2 settings, but for me, simple NORM is
> a wasted SSB button as I never use a 100 - 2900 Hz BW.
>
> And it would be nice if there was a default SSB center for each of the
> filters in Filter configuration. Tapping XFIL would not only move to the
> next filter, but also set to it's optimal SSB filter center frequency.
>
> John, KN5L
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gm3sek

Re: K3 Filter question - SSB

In reply to this post by alorona

Al Lorona wrote:

>
>1.8 kHz is deemed better than 2.1 kHz, and 1.5 kHz is deemed better
>than both.
>
>But at some point intelligibility itself suffers because you start to
>eliminate the signal you're trying to copy in the first place.
>
>I for one suffer from a type of listener's fatigue when forced to copy
>SSB signals in anything less than about 2.2 kHz or so.
>
>Others folks suffer from hearing loss and need to hear as much of
>the voice frequencies as possible. 1.8 kHz just doesn't work for many
>of these folks.
>

Here's some more individual data.

Although my hearing cuts off sharply at about 2.5kHz, I love the 1.8kHz
crystal filter for heavy QRM. That Inrad filter was originally purchased
for the 'narrow SSB' slot of my old FT-1000MP, and I'm so glad that I
kept it for the K3.

The 1.8kHz filter also works very well for my wife and other guest
operators who don't have hearing loss. In our typical contest QRM
conditions (running W/VE with the whole of Continental Europe right
behind us) the narrower filter helps to eliminate the high-pitched
splatter which we find the most tiring.

Unlike a 1.8kHz DSP filter with a 2.5kHz roofing filter, the 1.8kHz
crystal filter also avoids artefacts caused by pumping of the hardware
AGC loop by strong signals in the gaps between the wider and the
narrower passband.

The 1.8kHz filter does require careful initial setting of the center
frequency to obtain the best possible intelligibility; but those
settings will then require very little further adjustment. In other
words, they make a very effective working compromise to maximize the QSO
rate.

The 1.8kHz crystal filter is switched in at a DSP setting of 1.9kHz to
avoid excessive narrowing of the passband. I would certainly agree that
1.5kHz is too narrow, because almost every voice would then require its
own critical tuning.

>If you're okay with such narrow bandwidths, more power to you, but you
>can't make blanket statements about them being equally effective for
>everybody.
>
But neither can anyone else make blanket statements about them being
INeffective.

The fairest that anyone can say is, "If you don't like the 1.8kHz DSP
setting, then don't even think about buying the crystal filter. But if
you do like 1.8kHz DSP, you might like the crystal filter a lot."

--

73 from Ian GM3SEK
http://www.ifwtech.co.uk/g3sek
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gm3sek

Re: K3 Filter question - SSB

In reply to this post by Jim Brown-10

Jim Brown wrote:

>On 11/10/2011 8:34 AM, David Gilbert wrote:
>> there is so much
>> atrocious splatter from crummy rigs or ignorantly adjusted rigs during a
>> major contest
>
>YES, YES, YES.
>
>> that it is truly rare to find such a narrow filter
>> actually being helpful. I also would trade my 1.5 KHz filters for a
>> pair of 1.8 KHz filters in a heartbeat.
>
>I strongly agree. I have 1.8 kHz filters in my K3s, and find that I
>rarely use them during a contest for the reasons that W4ZV has
>articulated. Paraphrasing from another world, "it's the TRASH, stupid!"

Forgive me, Jim, but claiming that it's only about one single thing will
always lead to bad advice. One-line slogans don't even work in politics,
and even less so in engineering.

Whatever the problem, it's ALWAYS about finding the optimum working
balance between several different aspects.

In this particular case we are trying maximize the QSO rate by finding
the best possible balance between intelligibility, minimum use of front
panel controls, longer-term operator fatigue and probably several other
factors that will be of genuine importance to some people, at least some
of the time.

--

73 from Ian GM3SEK
http://www.ifwtech.co.uk/g3sek
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Eric Swartz - WA6HHQ

Re: K3 Filter question - SSB

Administrator

Folks - We are now hitting the single subject posting limit. Please wrap
this thread up ASAP.

73, Eric
list moderator

---
www.elecraft.com

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Barry N1EU

Re: K3 Filter question - SSB

In reply to this post by gm3sek

Ian White GM3SEK wrote

Unlike a 1.8kHz DSP filter with a 2.5kHz roofing filter, the 1.8kHz
crystal filter also avoids artefacts caused by pumping of the hardware
AGC loop by strong signals in the gaps between the wider and the
narrower passband.

The suggestion is that a 1.8Khz roofing filter will avoid HAGC pumping if the shoulder of an s9+25dB signal is present in the 350hz gap (2500-1800/2) that would have been spanned by the 2.5Khz filter. This is true but I'd suggest that if the s9+25dB shoulder is within 350hz, there's going to be plenty of that adjacent signal spilling over into your dsp passband that's going to pump your dsp AGC. So at best you will get slight improvement with the narrower filter but I wonder if it would ever make a difference in copy ability. A narrow filter just isn't buying you that much in ssb.

Barry N1EU