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K3: killing RX key clicks

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K1LI

K3: killing RX key clicks

Stewart,

I'm starting a new thread on this subject because your post reminded me to
write in on the subject.

Since a "key click" is an impulse of signal to the RX, perhaps they could be
reduced by a "noise blanker" type of function. That will make it even more
impossible to know that you're close to an offending station! Now, if we
could just cancel the offending station's signal all together, there will be
no more QRM!

--
73 -- Brian -- K1LI

On Tue, Dec 1, 2009 at 4:41 AM, GW0ETF <[hidden email]> wrote:

>
> Ref key clicks..... adjust the onboard system which emits anti-phase sound
> to cancel the engine noise and so make them silent to other vessels nearby.
>
> So I wonder if it might be feasible to develop a system on the K3 to use
> the 2nd rx to listen to the offending signal and the software produce an
> anti-phase 'key click' in the main receiving bandwidth to cancel the
> clicks...?
>
> 73,
>
> Stewart Rolfe, GW0ETF (GW6W in cqww..)
>
>
>

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Guy, K2AV

Re: K3: killing RX key clicks

Already done.

Using roofing and DSP width that are closely matched, a clicky signal
that is down very steep skirts will be converted into pulses. The
roofing and DSP skirts need to **combine to be as steep as possible**.

Set the NB to off for IF, and use DSP settings 2-7 or 3-7. I've had
3-7 suppress S9+10 key clicks to S3 (ABS noise level) in some
instances, and able to use slow AGC as if the offending signal were
not there. 2-7 makes the CW sound somewhat mushy, 3-7 makes CW
signals sound real mushy, but fully readable. I routinely use NB set
to DSP 2-7, no IF, just for this purpose.

I use the 250 Hz (really 310 or 320) 8 pole narrow CW filter defined
to the radio as 350 Hz and 350 DSP to live with ghastly clicks from a
signal up 400 Hz while running.

73, Guy.

On Tue, Dec 1, 2009 at 8:25 AM, Brian Machesney <[hidden email]> wrote:

> Stewart,
>
> I'm starting a new thread on this subject because your post reminded me to
> write in on the subject.
>
> Since a "key click" is an impulse of signal to the RX, perhaps they could be
> reduced by a "noise blanker" type of function. That will make it even more
> impossible to know that you're close to an offending station! Now, if we
> could just cancel the offending station's signal all together, there will be
> no more QRM!
>
> --
> 73 -- Brian -- K1LI
>
> On Tue, Dec 1, 2009 at 4:41 AM, GW0ETF <[hidden email]> wrote:
>
>>
>> Ref key clicks..... adjust the onboard system which emits anti-phase sound
>> to cancel the engine noise and so make them silent to other vessels nearby.
>>
>> So I wonder if it might be feasible to develop a system on the K3 to use
>> the 2nd rx to listen to the offending signal and the software produce an
>> anti-phase 'key click' in the main receiving bandwidth to cancel the
>> clicks...?
>>
>> 73,
>>
>> Stewart Rolfe, GW0ETF (GW6W in cqww..)
>>
>>
>>
> ______________________________________________________________
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AC7AC

Re: K3: killing RX key clicks

In reply to this post by K1LI

CONTENTS DELETED

The author has deleted this message.

P.B. Christensen

Re: K3: killing RX key clicks

All good suggestions, Ron -- including turning off the NB if not mentioned
previously. Engaging the NB function oftentimes produces
internally-generated clicks.

Paul, W9AC

----- Original Message -----
From: "Ron D'Eau Claire" <[hidden email]>
To: "'Elecraft Reflector'" <[hidden email]>
Sent: Tuesday, December 01, 2009 12:51 PM
Subject: Re: [Elecraft] K3: killing RX key clicks

> Key clicks can be generated by several different mechanisms within the
> receiver itself. Paradoxically, it's easier to produce false clicks with a
> high performance receiver than it is with a lesser receiver.
>
> These have nothing to do with the transmitted signal.
>
> The first line of "defense" is to turn off the Preamp and turn on the
> Attenuator to reduce the overall strength of the signals. Next is to set
> the
> AGC to "Slow" to ensure a strong signal isn't within the roofing filter
> bandpass and triggering the AGC while the variable DSP filter is set
> narrow
> so the beat note isn't heard. In some cases using the RF gain to control
> the
> level helps a great deal. Another approach is to use a narrower roofing
> filter or to shift your bandpass so the edge of the roofing filter is very
> close to the desired signal on the side toward the interfering station and
> as far from the interfering station as possible. Shifting the bandpass may
> require you open up your DSP bandwidth to continue to hear the desired
> signal or shifting the DSP filter position within the roofing filter
> bandpass.
>
> And, remember, "clicks" are an essential component of a CW signal. They
> are
> the sidebands created by modulating (keying) the signal. Very careful
> shaping of the keying envelope, such as used in the K2 and K3, can
> minimize
> clicks while maintaining an easily readable signal, but the only way to
> completely eliminate clicks is to not key the signal at all. With a really
> high-performance you can snuggle up very close to a signal, as many here
> have noted. When you do that, you're much more likely to hear the
> essential
> clicks required for good keying.
>
> Ron AC7AC
>
>

--------------------------------------------------------------------------------

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David Gilbert

Re: K3: killing RX key clicks

In reply to this post by Guy, K2AV

Great information. Too bad it isn't possible to make K3 DSP changes via
macros. I wouldn't want to use those settings all the time in a
contest, but it would be nice to quickly jump to them with the push of a
K3 button or N1MM function key when needed.

73,
Dave AB7E

Guy Olinger K2AV wrote:

> Already done.
>
> Using roofing and DSP width that are closely matched, a clicky signal
> that is down very steep skirts will be converted into pulses. The
> roofing and DSP skirts need to **combine to be as steep as possible**.
>
> Set the NB to off for IF, and use DSP settings 2-7 or 3-7. I've had
> 3-7 suppress S9+10 key clicks to S3 (ABS noise level) in some
> instances, and able to use slow AGC as if the offending signal were
> not there. 2-7 makes the CW sound somewhat mushy, 3-7 makes CW
> signals sound real mushy, but fully readable. I routinely use NB set
> to DSP 2-7, no IF, just for this purpose.
>
> I use the 250 Hz (really 310 or 320) 8 pole narrow CW filter defined
> to the radio as 350 Hz and 350 DSP to live with ghastly clicks from a
> signal up 400 Hz while running.
>
> 73, Guy.
>
> On Tue, Dec 1, 2009 at 8:25 AM, Brian Machesney <[hidden email]> wrote:
>
>> Stewart,
>>
>> I'm starting a new thread on this subject because your post reminded me to
>> write in on the subject.
>>
>> Since a "key click" is an impulse of signal to the RX, perhaps they could be
>> reduced by a "noise blanker" type of function. That will make it even more
>> impossible to know that you're close to an offending station! Now, if we
>> could just cancel the offending station's signal all together, there will be
>> no more QRM!
>>
>> --
>> 73 -- Brian -- K1LI
>>
>>

David Gilbert

Re: K3: killing RX key clicks

In reply to this post by AC7AC

I'll accept all of that, but it still doesn't change the fact that there
are some rigs out there that generate bad key clicks for no reason other
than the fact that their users either don't realize it or don't care
enough to fix them.

When I first received my Icom 756Pro (now my backup rig) several years
ago I discovered that the default rise/fall times (adjustable in one of
the menus) was set to 2 msec (!). That's unconscionable, but I'll bet
the majority of Icom users never bothered to check it. Many of the
Yaesu rigs generate horrible key clicks unless their users have
performed a simple hardware modification on them (see the info at W8JI.com).

I operated about 36 hours in the contest this last weekend and made over
a thousand contacts using the 8-pole 250Hz roofing filter. Many times
I'd be running a frequency within 200 Hz of a S9+30db station without
even knowing he was there. Other times I'd hear key clicks (loud enough
to cover the dits in callsigns I was trying to copy) from stations I
couldn't even find while tuning with the subreceiver! One large M/M
operation had great sounding signals on all bands except 15m, where the
key clicks were objectionable two KHz away even when their signal was
S5-S7. At least in that case they have promised to find the problem and
fix it.

Actually, there is a third reason why some stations have bad key
clicks. They admit they do it on purpose in a contest because it gives
them more elbow room.

In my experience with the K3 in several major contests since I bought it
last January, the very great majority of bad signals I've heard on the
air have been due to the TX on the other end, not the RX on my end.

73,
Dave AB7E

Ron D'Eau Claire wrote:

> Key clicks can be generated by several different mechanisms within the
> receiver itself. Paradoxically, it's easier to produce false clicks with a
> high performance receiver than it is with a lesser receiver.
>
> These have nothing to do with the transmitted signal.
>
> The first line of "defense" is to turn off the Preamp and turn on the
> Attenuator to reduce the overall strength of the signals. Next is to set the
> AGC to "Slow" to ensure a strong signal isn't within the roofing filter
> bandpass and triggering the AGC while the variable DSP filter is set narrow
> so the beat note isn't heard. In some cases using the RF gain to control the
> level helps a great deal. Another approach is to use a narrower roofing
> filter or to shift your bandpass so the edge of the roofing filter is very
> close to the desired signal on the side toward the interfering station and
> as far from the interfering station as possible. Shifting the bandpass may
> require you open up your DSP bandwidth to continue to hear the desired
> signal or shifting the DSP filter position within the roofing filter
> bandpass.
>
> And, remember, "clicks" are an essential component of a CW signal. They are
> the sidebands created by modulating (keying) the signal. Very careful
> shaping of the keying envelope, such as used in the K2 and K3, can minimize
> clicks while maintaining an easily readable signal, but the only way to
> completely eliminate clicks is to not key the signal at all. With a really
> high-performance you can snuggle up very close to a signal, as many here
> have noted. When you do that, you're much more likely to hear the essential
> clicks required for good keying.
>
> Ron AC7AC
>
>
> ------------------------------------------------------------------------
>
> ______________________________________________________________
> 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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> Please help support this email list: http://www.qsl.net/donate.html

Jim Brown-10

Re: K3: killing RX key clicks

On Tue, 01 Dec 2009 11:29:24 -0700, David Gilbert wrote:

>In my experience with the K3 in several major contests since I bought it
>last January, the very great majority of bad signals I've heard on the
>air have been due to the TX on the other end, not the RX on my end.

Strongly agree.

And I strongly DISAGREE with Ron's statement that clicks are an essential
part of CW. Clicks are a function of a FAST RISE TIME and DISTORTION, not
keying speed. There's a KH6 contester who moved from K4 with a monster
signal, monster clicks, monster SSB splatter, and monster attitude to go
with it. I've told him about his clicks and splatter several times, but
the clicks, splatter, and attitude are still there.

73,

Jim K9YC

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Merv Schweigert

Re: K3: killing RX key clicks

>
>
> And I strongly DISAGREE with Ron's statement that clicks are an essential
> part of CW. Clicks are a function of a FAST RISE TIME and DISTORTION, not
> keying speed. There's a KH6 contester who moved from K4 with a monster
> signal, monster clicks, monster SSB splatter, and monster attitude to go
> with it. I've told him about his clicks and splatter several times, but
> the clicks, splatter, and attitude are still there.
>
> 73,
>
> Jim K9YC
>

Not sure if you checked his signal in the last couple contests? If so
you are criticizing a K3
for having monster Klix and SSB splatter. He has ran a K3 now for some
time.
He is 40 to 50 over nine here on 160 meters and I can get within less
than 1/2KC
and copy the weakest DX signals, so have to say K3 to K3 I dont have
any problems
with him.
I do have problems with a couple other KH6 stations on that same island,
they have
klix and splatter that covers several KC of the band and they are only
20 over 9.
Understand the radio is only as good as the operator setting it up, but
that goes for
both ends of the QSO.
Merv KH7C

>
> ______________________________________________________________
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>

Steve Ellington

Re: K3: killing RX key clicks

In reply to this post by David Gilbert

While on 160m a few nights ago I heard loud key clicks and tracked it down
to a ham just 1 mile away who was chasing a DX station. When he transmitted,
my K3 was rendered totally deft from any signal within 10 Khz of him! My
200hz roofing filter, ATTN, preamp off and RFG down had no effect. I guess
even the K3 has it's limits.
Steve
N4LQ
[hidden email]
----- Original Message -----
From: "David Gilbert" <[hidden email]>
To: "Ron D'Eau Claire" <[hidden email]>
Cc: "'Elecraft Reflector'" <[hidden email]>
Sent: Tuesday, December 01, 2009 1:29 PM
Subject: Re: [Elecraft] K3: killing RX key clicks

>
> I'll accept all of that, but it still doesn't change the fact that there
> are some rigs out there that generate bad key clicks for no reason other
> than the fact that their users either don't realize it or don't care
> enough to fix them.
>
> When I first received my Icom 756Pro (now my backup rig) several years
> ago I discovered that the default rise/fall times (adjustable in one of
> the menus) was set to 2 msec (!). That's unconscionable, but I'll bet
> the majority of Icom users never bothered to check it. Many of the
> Yaesu rigs generate horrible key clicks unless their users have
> performed a simple hardware modification on them (see the info at
> W8JI.com).
>
> I operated about 36 hours in the contest this last weekend and made over
> a thousand contacts using the 8-pole 250Hz roofing filter. Many times
> I'd be running a frequency within 200 Hz of a S9+30db station without
> even knowing he was there. Other times I'd hear key clicks (loud enough
> to cover the dits in callsigns I was trying to copy) from stations I
> couldn't even find while tuning with the subreceiver! One large M/M
> operation had great sounding signals on all bands except 15m, where the
> key clicks were objectionable two KHz away even when their signal was
> S5-S7. At least in that case they have promised to find the problem and
> fix it.
>
> Actually, there is a third reason why some stations have bad key
> clicks. They admit they do it on purpose in a contest because it gives
> them more elbow room.
>
> In my experience with the K3 in several major contests since I bought it
> last January, the very great majority of bad signals I've heard on the
> air have been due to the TX on the other end, not the RX on my end.
>
> 73,
> Dave AB7E
>
>
>
> Ron D'Eau Claire wrote:
>> Key clicks can be generated by several different mechanisms within the
>> receiver itself. Paradoxically, it's easier to produce false clicks with
>> a
>> high performance receiver than it is with a lesser receiver.
>>
>> These have nothing to do with the transmitted signal.
>>
>> The first line of "defense" is to turn off the Preamp and turn on the
>> Attenuator to reduce the overall strength of the signals. Next is to set
>> the
>> AGC to "Slow" to ensure a strong signal isn't within the roofing filter
>> bandpass and triggering the AGC while the variable DSP filter is set
>> narrow
>> so the beat note isn't heard. In some cases using the RF gain to control
>> the
>> level helps a great deal. Another approach is to use a narrower roofing
>> filter or to shift your bandpass so the edge of the roofing filter is
>> very
>> close to the desired signal on the side toward the interfering station
>> and
>> as far from the interfering station as possible. Shifting the bandpass
>> may
>> require you open up your DSP bandwidth to continue to hear the desired
>> signal or shifting the DSP filter position within the roofing filter
>> bandpass.
>>
>> And, remember, "clicks" are an essential component of a CW signal. They
>> are
>> the sidebands created by modulating (keying) the signal. Very careful
>> shaping of the keying envelope, such as used in the K2 and K3, can
>> minimize
>> clicks while maintaining an easily readable signal, but the only way to
>> completely eliminate clicks is to not key the signal at all. With a
>> really
>> high-performance you can snuggle up very close to a signal, as many here
>> have noted. When you do that, you're much more likely to hear the
>> essential
>> clicks required for good keying.
>>
>> Ron AC7AC
>>
>>
>> ------------------------------------------------------------------------
>>
>> ______________________________________________________________
>> 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
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
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>
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> Please help support this email list: http://www.qsl.net/donate.html

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P.B. Christensen

Re: K3: killing RX key clicks

In reply to this post by David Gilbert

> When I first received my Icom 756Pro (now my backup rig) several years
> ago I discovered that the default rise/fall times (adjustable in one of
> the menus) was set to 2 msec (!). That's unconscionable...

It's unconscionable with some rigs, but not all. Take a look at the K3's
keying envelope on a scope since the ca. 3.00 firmware release earlier this
year. Compare it against the QST Product Reviews. I currently measure the
rise time of about 2.5 msec and the K3 occupies minimal RF spectrum. Even
at very fast CW speeds, it's the slope of the rise and fall that primarily
determines occupied bandwidth. As keying speed increases, there's a point
where the keying rate becomes a dominant factor but that's largely due to
the fact that as the keying rate increases so must the envelope slope.

The clicks heard with many transmitters occurs because the slope is
discontinuous. Using a Blackman-Harris or raised-cosine window function
minimizes occupied bandwidth but that function is also dependent on envelope
distortion created by a transmitter's ALC circuitry. So, it's possible to
set two completely different brands of transmitters to 2 msec and the
bandwidth results can be radically different.

Paul W9AC

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Guy, K2AV

Re: K3: killing RX key clicks

In reply to this post by P.B. Christensen

Not once in my experience has the K3 NB made clicks worse (that's N*B*
I'm talking about, not N*R*). I gave a formula in an earlier post in
this thread. I invite anyone to actually try it and see. NR does not
seem to do anything for or against clicks.

73, Guy.

On Tue, Dec 1, 2009 at 12:57 PM, Paul Christensen <[hidden email]> wrote:

> All good suggestions, Ron -- including turning off the NB if not mentioned
> previously. Engaging the NB function oftentimes produces
> internally-generated clicks.
>
> Paul, W9AC
>
> ----- Original Message -----
> From: "Ron D'Eau Claire" <[hidden email]>
> To: "'Elecraft Reflector'" <[hidden email]>
> Sent: Tuesday, December 01, 2009 12:51 PM
> Subject: Re: [Elecraft] K3: killing RX key clicks
>
>
>> Key clicks can be generated by several different mechanisms within the
>> receiver itself. Paradoxically, it's easier to produce false clicks with a
>> high performance receiver than it is with a lesser receiver.
>>
>> These have nothing to do with the transmitted signal.
>>
>> The first line of "defense" is to turn off the Preamp and turn on the
>> Attenuator to reduce the overall strength of the signals. Next is to set
>> the
>> AGC to "Slow" to ensure a strong signal isn't within the roofing filter
>> bandpass and triggering the AGC while the variable DSP filter is set
>> narrow
>> so the beat note isn't heard. In some cases using the RF gain to control
>> the
>> level helps a great deal. Another approach is to use a narrower roofing
>> filter or to shift your bandpass so the edge of the roofing filter is very
>> close to the desired signal on the side toward the interfering station and
>> as far from the interfering station as possible. Shifting the bandpass may
>> require you open up your DSP bandwidth to continue to hear the desired
>> signal or shifting the DSP filter position within the roofing filter
>> bandpass.
>>
>> And, remember, "clicks" are an essential component of a CW signal. They
>> are
>> the sidebands created by modulating (keying) the signal. Very careful
>> shaping of the keying envelope, such as used in the K2 and K3, can
>> minimize
>> clicks while maintaining an easily readable signal, but the only way to
>> completely eliminate clicks is to not key the signal at all. With a really
>> high-performance you can snuggle up very close to a signal, as many here
>> have noted. When you do that, you're much more likely to hear the
>> essential
>> clicks required for good keying.
>>
>> Ron AC7AC
>>
>>
>
>
> --------------------------------------------------------------------------------
>
>
>> ______________________________________________________________
>> 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
>
> ______________________________________________________________
> 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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> Please help support this email list: http://www.qsl.net/donate.html
>

Jim Brown-10

Re: K3: killing RX key clicks

In reply to this post by Merv Schweigert

On Tue, 01 Dec 2009 08:55:55 -1000, Merv Schweigert wrote:

>Not sure if you checked his signal in the last couple contests? If so
>you are criticizing a K3 for having monster Klix and SSB splatter.

The exciter is not the ONLY click or trash generator in a station. ANY
non-linear device can produce splatter and clicks. An overdriven power
amp can create clicks and splatter. The most common way that happens is
depending on ALC to reduce the drive to hit the desired TX power. A
poorly tuned power amp will also produce clicks and splatter.

A VERY well known contester and K3 user lives about 15 miles from me.
His clicks and splatter make life miserable for several of his neighbors
including K6RB, K6XX, and me. He's otherwise a nice guy and a member of
our club, but he's long been in denial about the trash on his signal. It
IS better since he converted to K3s a couple of years ago, but his
splatter was 10 kHz wide during SS. Another guy, a casual operator and
sometimes contester, runs a high priced ICOM rig into a high priced
auto-tune power amp. He's also a click generator.

73,

Jim K9YC

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Joe Subich, W4TV-4

Re: K3: killing RX key clicks

In reply to this post by Jim Brown-10

> Clicks are a function of a FAST RISE TIME and DISTORTION, not
> keying speed.

Not quite ... keyclicks are often a second derivative effect.
They occur when the rate of change of the rate of change is
high - specifically at the "corners" of the waveform (a abrupt
change in the slope coupled with high power levels).

At one time W8JI had some scope and spectrum samples of CW
waveforms with "slow" rise/fall rates but very bad clicks.
In every case the ramp was fine but there was an abrupt change
when the ramp reached the steady state (on) condition or at
instant of transition from the steady state (on) condition to
the start of the decay phase.

These effects can be most readily observed in rigs with high
IF gain as they are quite similar to clicks generated in the
old class C amplifiers as the drive level passed from AB into
"hard" C.

73,

... Joe, W4TV

> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of Jim Brown
> Sent: Tuesday, December 01, 2009 1:42 PM
> To: Elecraft List
> Subject: Re: [Elecraft] K3: killing RX key clicks
>
>
> On Tue, 01 Dec 2009 11:29:24 -0700, David Gilbert wrote:
>
> >In my experience with the K3 in several major contests since
> I bought
> >it
> >last January, the very great majority of bad signals I've
> heard on the
> >air have been due to the TX on the other end, not the RX on my end.
>
> Strongly agree.
>
> And I strongly DISAGREE with Ron's statement that clicks are
> an essential
> part of CW. Clicks are a function of a FAST RISE TIME and
> DISTORTION, not
> keying speed. There's a KH6 contester who moved from K4 with
> a monster
> signal, monster clicks, monster SSB splatter, and monster
> attitude to go
> with it. I've told him about his clicks and splatter several
> times, but
> the clicks, splatter, and attitude are still there.
>
> 73,
>
> Jim K9YC
>
>
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AC7AC

Re: K3: killing RX key clicks

In reply to this post by Jim Brown-10

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AC7AC

Re: K3: killing RX key clicks

In reply to this post by Jim Brown-10

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gm3sek

Re: K3: killing RX key clicks

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

Joe Subich, W4TV wrote:

>
>
>> Clicks are a function of a FAST RISE TIME and DISTORTION, not
>> keying speed.
>
>Not quite ... keyclicks are often a second derivative effect.
>They occur when the rate of change of the rate of change is
>high - specifically at the "corners" of the waveform (a abrupt
>change in the slope coupled with high power levels).
>
>At one time W8JI had some scope and spectrum samples of CW
>waveforms with "slow" rise/fall rates but very bad clicks.
>In every case the ramp was fine but there was an abrupt change
>when the ramp reached the steady state (on) condition or at
>instant of transition from the steady state (on) condition to
>the start of the decay phase.
>

Correct - both the overall rise/fall time and absence of sharp corners
are important. W9CF shows that an optimum wave shape has a gradual
start, accelerating to a more rapid rise/fall through the middle part,
and then slowing to a more gradual finish.

The 'RC rise/decay' wave shape that was in the handbooks for many years
is actually a *bad* shape because it has a very sharp corner on key-up.

Another factor that can cause nasty key-clicks from a K3 is the default
TX delay of 8ms. This may not be enough time for some amplifiers to
change over, causing clicks due to hot-switching. This time can be
increased using CONFIG / TX DLY.

--

73 from Ian GM3SEK
http://www.ifwtech.co.uk/g3sek
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P.B. Christensen

Re: K3: killing RX key clicks

In reply to this post by AC7AC

>I suspect that over-driving an external amplifier is a major cause of
> excessive clicks on the bands today. Many Hams think that CW doesn't
> require
> the final amplifier be linear and drive their rigs into saturation. But a
> "linear" amplifier needs to be linear for CW just as with any amplitude
> modulation (SSB, AM, CW, etc.)

Key clicks also occur when bias is suddenly applied to an amp where the
transceiver is already producing an RF envelope. I recently experienced
this when I purchased the SPE 1K-FA solid-state amp. The amp is advertised
as being "Full QSK" compatible. However, it uses general purpose frame
relays at the RF input and output. As such, the firmware is programmed to
apply bias at a very long 15 msec after the amp's relay line is pulled low
by the transceiver. The problem isn't terribly bad with a transceiver like
the K3 as its RF envelope can be delayed in the K3 menu. However, rigs like
the Icom 7700 and 7800 produce RF at ~ 9 msec. after key closure and there's
no menu to adjust it. On the scope, WYSIWYG.

In the K3's default setting of 8 msec., my SPE amp was hot switching as a
result of bias being applied at 15 msec when the K3 was already producing
its RF envelope at exactly 12 msec after key closure. And so, the RF
envelope was being truncated by 3 msec in full QSK mode. SPE chose that
bias time to give the general-purpose frame relays an opportunity to settle
without contact bounce. Sure, the amp's relays were not being hot-switched,
but the effect of key clicks is the same when the sudden onset of bias
causes the FET output transistors to instantly conduct, producing a sharp
vertical rise time of the RF envelope.

I then delayed the K3 to 16 msec and the hot-switch problem disappeared.
But in doing so, the keyed elements were also being shortened, albeit
without RF hot-switching. That fix requires use of pulse-stretching key
compensation using an external keyer. Next, I tried using the K3's TX INH
handshake with the SPE amp. More dit shortening problems. Was the problem
with the K3 or the SPE amp. I honestly don't know and don't care. I only
care that there's a viable solution is available. Really, the only way to
cleanly fix these problems is at the source of the timing issue.

The solution: I ended up modifying a beat-up Ameritron QSK-5, keeping the
logic interface between the QSK-5 and the SPE amp100% optically-isolated.

http://72.52.250.47/images/QSK-5-Interface.pdf

Now, instead of the amp's firmware setting the bias activation time, the
QSK-5 tells the SPE amp when to apply bias. QSK is pretty awesome with this
set-up and even the first leading 'dit' switches cleanly with no keyed
element shortening. Long-term, the fix calls for using a Gigavac GH-1
vacuum relay at the amp's output and an Aromat RSD-12V RF reed relay at the
amp's input. SPE has sent me the revised firmware that reduces bias time to
8 msec, but that requires an EEPROM programmer and a spare chip that I need
to order. But with either solution, bias key clicks won't be a problem.

Paul, W9AC

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Jim Brown-10

Re: K3: killing RX key clicks

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

On Tue, 1 Dec 2009 16:52:00 -0500, Joe Subich, W4TV wrote:

>Not quite ... keyclicks are often a second derivative effect.
>They occur when the rate of change of the rate of change is
>high - specifically at the "corners" of the waveform (a abrupt
>change in the slope coupled with high power levels).

No disagreement from me on this -- you're simply looking at it in
greater detail than my simpllification.

73,

Jim K9YC

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P.B. Christensen

Re: K3: killing RX key clicks

In reply to this post by gm3sek

> The 'RC rise/decay' wave shape that was in the handbooks for many years
> is actually a *bad* shape because it has a very sharp corner on key-up.

Ian, *bad* may be a bit too harsh. The League's optimized envelope was
described during a time when only simple R/C values were used to develop a
keyed envelope. I'm not sure how one would have produced an economical
Blackman-Harris or raised cosine function until say...the early to mid '90s.
How would you have done it? Probably the only solution at the time was to
set leading and trailing edges produced by the R/C network so soft that
they're painful to copy.

Myself, I actually prefer the R/C keying as shown in those issues of the
ARRL Handbook for reasons that Ron cited. What I like is a slightly fast
leading edge, but an exponential trail of the falling edge. Irrational?
Yes, I'll admit it. My favorite rig to listen during a CW rag-chew is
either the Drake T-4XC or TR-7. Both produce nearly identical keyed
envelopes. And, yes, neither are optimized for minimal bandwidth. However,
with just a bit of help on the leading edge, keying bandwidth can be kept
reasonably narrow.

Paul, W9AC

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Jan Erik Holm

Re: K3: killing RX key clicks

In reply to this post by P.B. Christensen

Paul Christensen wrote:

>> When I first received my Icom 756Pro (now my backup rig) several years
>> ago I discovered that the default rise/fall times (adjustable in one of
>> the menus) was set to 2 msec (!). That's unconscionable...
>
> It's unconscionable with some rigs, but not all. Take a look at the K3's
> keying envelope on a scope since the ca. 3.00 firmware release earlier this
> year. Compare it against the QST Product Reviews. I currently measure the
> rise time of about 2.5 msec and the K3 occupies minimal RF spectrum. Even
> at very fast CW speeds, it's the slope of the rise and fall that primarily
> determines occupied bandwidth. As keying speed increases, there's a point
> where the keying rate becomes a dominant factor but that's largely due to
> the fact that as the keying rate increases so must the envelope slope.
>
> The clicks heard with many transmitters occurs because the slope is
> discontinuous. Using a Blackman-Harris or raised-cosine window function
> minimizes occupied bandwidth but that function is also dependent on envelope
> distortion created by a transmitter's ALC circuitry. So, it's possible to
> set two completely different brands of transmitters to 2 msec and the
> bandwidth results can be radically different.
>
> Paul W9AC
>

Are you sure about 2.5 ms? As far as I remember I measured my K3
to about 5 ms and Elecraft also stated 5 ms. This was over a year
ago however, if 2.5 is correct they have changed it or my memmory
is corrupted.

/ SM2EKM

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