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K3 FSK power transients

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Dave Hachadorian

K3 FSK power transients

I'm getting my K3's set up for the CQWW DX RTTY, and notice
that there is a significant variation in power output
whenever the FSK goes from mark to space or space to mark.
One of these K3's is driving a high gain tetrode amp, and
the amp's screen current is jumping all over the place. The
power transient is only at the time of transition. The
steady-state power of the mark and space are equal.

I've complained about this before, but it seems to be even
worse now. I'm using FW rev 3.30.

This amplitude modulation has got to be producing some
illegal sidebands.

Dave Hachadorian, K6LL
Yuma, AZ

.

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Richard Ferch

Re: K3 FSK power transients

Hi Dave,

Have you tried AFSK instead? If so, do you see similar power transients?
Depending on what software is generating the tones and assuming the
audio level is set properly, it is possible that AFSK might produce a
cleaner signal than what you are seeing in FSK. Operationally, they are
the same, i.e. all the same features and operating techniques that you
use in FSK D can also be used in AFSK A (well, except maybe for using CW
paddles to transmit - that doesn't work in AFSK A).

Just another idle thought, but I wonder whether the TX Gain calibration
would make a difference?

When I try FSK I don't see any sign of similar transients, but my power
metering might not be able to respond quickly enough to see them if they
were there, so that doesn't necessarily mean a lot.

73,
Rich VE3KI

Dave Hachadorian K6LL wrote:

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Phil NA4M

Re: K3 FSK power transients

In reply to this post by Dave Hachadorian

Dave -

I experience the same issue and Elecraft indicated that the FSK mark/space
power fluctuations are caused by the transmit filter's passband ripple and
where the transmit signal falls within the filter's passband. I'm using the
standard 5 pole 2.7khz filter. They indicated the 8 pole filter should be
flatter.

73 Phil NA4M

Dave Hachadorian wrote:

>
> I'm getting my K3's set up for the CQWW DX RTTY, and notice
> that there is a significant variation in power output
> whenever the FSK goes from mark to space or space to mark.
> One of these K3's is driving a high gain tetrode amp, and
> the amp's screen current is jumping all over the place. The
> power transient is only at the time of transition. The
> steady-state power of the mark and space are equal.
>
> I've complained about this before, but it seems to be even
> worse now. I'm using FW rev 3.30.
>
> This amplitude modulation has got to be producing some
> illegal sidebands.
>
> Dave Hachadorian, K6LL
> Yuma, AZ
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> .
>
> ______________________________________________________________
> 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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>

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Jan Erik Holm

Re: K3 FSK power transients

In reply to this post by Dave Hachadorian

I just noticed some issues like that last weekend when
operating the SAC CW contest. All off a sudden when tuning
up on 10m a big bang occured in my linear amplifier. Now
nothing got hurt it just blew the fuses. This amp used
to be driven with 200W and I never ever had any issues
before. Of course it could be the amp and I haven´t measured
the K3 to confirm if there are any high power spikes
due to poor ALC regulation. I was tuning with fast dots
from the keyer.

Now I was thinking if the TXGain is set too high maybe
that could do something?

I guess I have to investigate but I simply haven´t had
the time.

Jim SM2EKM
--------------------------
Dave Hachadorian wrote:

> I'm getting my K3's set up for the CQWW DX RTTY, and notice
> that there is a significant variation in power output
> whenever the FSK goes from mark to space or space to mark.
> One of these K3's is driving a high gain tetrode amp, and
> the amp's screen current is jumping all over the place. The
> power transient is only at the time of transition. The
> steady-state power of the mark and space are equal.
>
> I've complained about this before, but it seems to be even
> worse now. I'm using FW rev 3.30.
>
> This amplitude modulation has got to be producing some
> illegal sidebands.
>
> Dave Hachadorian, K6LL
> Yuma, AZ
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> .
>
> ______________________________________________________________
> 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
>

Phil NA4M

Re: K3 FSK power transients

In reply to this post by Dave Hachadorian

Dave -

I experience the same issue and Elecraft indicated that the FSK mark/space power fluctuations are caused by the transmit filter's passband ripple and where the transmit signal falls within the filter's passband. I'm using the standard 5 pole 2.7khz filter. They indicated the 8 pole filter should be flatter.

73 Phil NA4M

Dave Hachadorian wrote

I'm getting my K3's set up for the CQWW DX RTTY, and notice
that there is a significant variation in power output
whenever the FSK goes from mark to space or space to mark.
One of these K3's is driving a high gain tetrode amp, and
the amp's screen current is jumping all over the place. The
power transient is only at the time of transition. The
steady-state power of the mark and space are equal.

I've complained about this before, but it seems to be even
worse now. I'm using FW rev 3.30.

This amplitude modulation has got to be producing some
illegal sidebands.

Dave Hachadorian, K6LL
Yuma, AZ

.

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w8fn

Re: K3 FSK power transients

>I experience the same issue and Elecraft indicated that the FSK mark/space
>power fluctuations are caused by the transmit filter's passband ripple and
>where the transmit signal falls within the filter's passband. I'm using the
>standard 5 pole 2.7khz filter. They indicated the 8 pole filter should be
>flatter.

I'm using a 2.8kHz 8-pole as the main transmit filter and at nominal
100W output I can see a perceptible "wobble" on the wattmeter as the
signal shifts between mark and space. It's hard to believe the
ripples in the filter would be so steep that a 170 Hz difference in
frequency of the two tones would make much difference. If you use the
standard 2125 Hz / 2295 Hz mark/space convention, this would make the
signal appear fairly close to the filter's transition band, assuming
there's no center frequency offset applied in the transmit path. This
amplitude mismatch will introduce an unintentional AM at the baud
rate, but it's probably not enough to appreciably broaden the
transmitted signal. I don't have access to a spectrum analyzer or I
would examine this further. Maybe someone with a well-instrumented
bench can have a look and report back.

73...
Randy, W8FN

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Joe Subich, W4TV-4

Re: K3 FSK power transients

> If you use the
> standard 2125 Hz / 2295 Hz mark/space convention, this would make the
> signal appear fairly close to the filter's transition band, assuming
> there's no center frequency offset applied in the transmit path.

The roofing filter IS offset to put the RTTY tones (Data | Pitch)
in the center of the filter. However, since the 5 pole filter
has +/- 1 dB of ripple in the passband and the ALC is applied in
DSP (not based on power output), it is possible to see 20 or 30
watts difference between the tones.

73,

... Joe, W4TV

> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of Randy Farmer
> Sent: Sunday, September 27, 2009 4:33 PM
> To: Phil NA4M; [hidden email]
> Subject: Re: [Elecraft] [K3] K3 FSK power transients
>
>
>
> >I experience the same issue and Elecraft indicated that the FSK
> >mark/space power fluctuations are caused by the transmit filter's
> >passband ripple and where the transmit signal falls within
> the filter's
> >passband. I'm using the standard 5 pole 2.7khz filter.
> They indicated
> >the 8 pole filter should be flatter.
>
> I'm using a 2.8kHz 8-pole as the main transmit filter and at nominal
> 100W output I can see a perceptible "wobble" on the wattmeter as the
> signal shifts between mark and space. It's hard to believe the
> ripples in the filter would be so steep that a 170 Hz difference in
> frequency of the two tones would make much difference. If you use the
> standard 2125 Hz / 2295 Hz mark/space convention, this would make the
> signal appear fairly close to the filter's transition band, assuming
> there's no center frequency offset applied in the transmit path. This
> amplitude mismatch will introduce an unintentional AM at the baud
> rate, but it's probably not enough to appreciably broaden the
> transmitted signal. I don't have access to a spectrum analyzer or I
> would examine this further. Maybe someone with a well-instrumented
> bench can have a look and report back.
>
> 73...
> Randy, W8FN
>
> ______________________________________________________________
> 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

w8fn

Re: K3 FSK power transients

The roofing filter IS offset to put the RTTY tones (Data | Pitch)
in the center of the filter.

Good to know. That's how I would have done it I were the designer.
I'm surprised I can see a difference between the two tones through
the flatter filter 8-pole filter. It's just enough to see on the 200W
scale of an old (pretty much uncalibrated) Daiwa CN-520.

73...
Randy, W8FN

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Joe Subich, W4TV-4

Re: K3 FSK power transients

> I'm surprised I can see a difference between the two tones
> through the flatter filter 8-pole filter. It's just enough
> to see on the 200W scale of an old (pretty much uncalibrated)
> Daiwa CN-520.

With the 8 pole filter I see 2 watts difference on the N8LP
LP-100 wattmeter. However, in AFSK A or DATA A modes for
PSK I see as much as 15 watts (0.7 dB) difference (maximum
to minimum) as the tone frequency varies from 200 Hz to 2800
Hz in DATA A (FC=1500 Hz) or 1000 Hz to 3500 Hz in AFSK
(FC=2210 Hz).

73,

... Joe, W4TV

> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of Randy Farmer
> Sent: Sunday, September 27, 2009 7:57 PM
> To: [hidden email]
> Subject: Re: [Elecraft] [K3] K3 FSK power transients
>
>
> The roofing filter IS offset to put the RTTY tones (Data |
> Pitch) in the center of the filter.
>
> Good to know. That's how I would have done it I were the designer.
> I'm surprised I can see a difference between the two tones through
> the flatter filter 8-pole filter. It's just enough to see on the 200W
> scale of an old (pretty much uncalibrated) Daiwa CN-520.
>
> 73...
> Randy, W8FN
>

Julian, G4ILO

Re: K3 FSK power transients

Joe Subich, W4TV-4 wrote

With the 8 pole filter I see 2 watts difference on the N8LP
LP-100 wattmeter. However, in AFSK A or DATA A modes for
PSK I see as much as 15 watts (0.7 dB) difference (maximum
to minimum) as the tone frequency varies from 200 Hz to 2800
Hz in DATA A (FC=1500 Hz) or 1000 Hz to 3500 Hz in AFSK
(FC=2210 Hz).

If the fall-off is only at the edges I wouldn't be unhappy with this. Last time I checked, a few months ago when the power control in data mode was finally made to work properly, I found that the power output was pretty well flat between about 400 to 2400Hz, once the audio level has been adjusted for 4 bars of ALC as instructed. Personally I wouldn't operate with a sound card program outside of that range, anyway.

If you are transmitting some sort of wide FSK mode then I suppose you will see differences because the ALC can only keep the power level average. I guess this is where having the option to set TX EQ in data mode could come in useful, though whether the adjustment currently permitted is fine enough to cancel out filter ripple is another matter. I wouldn't have thought any other radio would do any better, though. With many radios you have to keep the drive below the ALC threshold so you are completely at the mercy of the sound card frequency response and the TX filter ripple.

Julian, G4ILO. K2 #392 K3 #222 KX3 #110
* G4ILO's Shack - http://www.g4ilo.com
* KComm - http://www.g4ilo.com/kcomm.html
* KTune - http://www.g4ilo.com/ktune.html

Ken_ke2n

Re: K3 FSK power transients

yup. I am seeing this on FSK441 and Data A mode. I recently acquired a power meter that shows average and peak power and I am getting getting PEP = 1.8 times average on this data mode. Traced it to the K3 audio response on transmit. I am using the 8 pole SSB filter. It seems the 882 Hz and 1323 Hz tones are down from the other two tones (or the other tones are hot relative to these two, depending on your point of view). When I transmit a single tone (RRR or 73 report for example) the ALC brings things up to full output. When I transmit mixed characters then the ALC sets the output based on the highest tone and the average is down accordingly.

It is not the audio card. I looped the audio card output back to the input and the tones are all the same level.

73
Ken

Ken_ke2n

Re: K3 FSK power transients

2015-05-27_20_48_16-Time_domain_scope_no_radio.gif
2015-05-27_19_07_20-Time_domain_scope.gif

I hope this works.

I have shown, in two attached images, the tones being produced by WSJT FSK441 and then the monitor output of the K3. You can see a substantial drop off of the low frequency tones and some kind of additional modulation of the overall envelope (most noticeable with the higher frequency tone, but I think it affects all). Not sure if this is ALC action or something else.

Anyway, the K3 makes a bit of a mess out of some otherwise nice-looking tones.

Ken

73
Ken

Guy Olinger K2AV

Re: K3 FSK power transients

What roofing filter is being used for your transmit and have the offsets
been set correctly?

One issue I saw once was that the filters were mismatched with the filter
definitions entered and the guy was actually using an 8 pole 1.8 SSB for
transmit which was causing all kinds of problems in data mode.

73, Guy K2AV

On Thursday, May 28, 2015, Ken_ke2n via Elecraft <[hidden email]>
wrote:

> 2015-05-27_20_48_16-Time_domain_scope_no_radio.gif
> <
> http://elecraft.365791.n2.nabble.com/file/n7603596/2015-05-27_20_48_16-Time_domain_scope_no_radio.gif
> >
> 2015-05-27_19_07_20-Time_domain_scope.gif
> <
> http://elecraft.365791.n2.nabble.com/file/n7603596/2015-05-27_19_07_20-Time_domain_scope.gif
> >
>
> I hope this works.
>
> I have shown, in two attached images, the tones being produced by WSJT
> FSK441 and then the monitor output of the K3. You can see a substantial
> drop off of the low frequency tones and some kind of additional modulation
> of the overall envelope (most noticeable with the higher frequency tone,
> but
> I think it affects all). Not sure if this is ALC action or something else.
>
> Anyway, the K3 makes a bit of a mess out of some otherwise nice-looking
> tones.
>
> Ken
>
>
>
> -----
> 73
> Ken
>
> --
> View this message in context:
> http://elecraft.365791.n2.nabble.com/K3-FSK-power-transients-tp3712691p7603596.html
> Sent from the Elecraft mailing list archive at Nabble.com.
> ______________________________________________________________
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> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email] <javascript:;>
>

--
Sent via Gmail Mobile on my iPhone
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Joe Subich, W4TV-4

Re: K3 FSK power transients

In reply to this post by Ken_ke2n

Are you using DATA A or trying to force FSK-442 through the K3 in
USB with the TX_EQ enabled? Again, I see *NO* frequency effects
(crest factor < 0.1 dB at 30, 60 and 100 W) with my K3 when using
DATA A and the LINE In.

Also make sure your sound card does not have any "enhancements"
enabled.

73,

... Joe, W4TV

On 2015-05-28 9:53 PM, Ken_ke2n via Elecraft wrote:

> 2015-05-27_20_48_16-Time_domain_scope_no_radio.gif
> <http://elecraft.365791.n2.nabble.com/file/n7603596/2015-05-27_20_48_16-Time_domain_scope_no_radio.gif>
> 2015-05-27_19_07_20-Time_domain_scope.gif
> <http://elecraft.365791.n2.nabble.com/file/n7603596/2015-05-27_19_07_20-Time_domain_scope.gif>
>
> I hope this works.
>
> I have shown, in two attached images, the tones being produced by WSJT
> FSK441 and then the monitor output of the K3. You can see a substantial
> drop off of the low frequency tones and some kind of additional modulation
> of the overall envelope (most noticeable with the higher frequency tone, but
> I think it affects all). Not sure if this is ALC action or something else.
>
> Anyway, the K3 makes a bit of a mess out of some otherwise nice-looking
> tones.
>
> Ken
>
>
>
> -----
> 73
> Ken
>
> --
> View this message in context: http://elecraft.365791.n2.nabble.com/K3-FSK-power-transients-tp3712691p7603596.html
> Sent from the Elecraft mailing list archive at Nabble.com.
> ______________________________________________________________
> 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
> Message delivered to [hidden email]
>

Ken_ke2n

RE: K3 FSK power transients

Joe - I am using data mode with “DATA A” selected. (This mode uses the SSB filter and turns off equalization and compression. But of course the ALC is “on”).

What would be really helpful is if you would download a copy of Spectrum Lab and run the monitor output of your K3 through it while transmitting FSK441. Then we would both have a common point of comparison (eliminating the vagaries of power meter PEP algorithms).

http://www.qsl.net/dl4yhf/spectra1.html

The time domain scope is under the “components” tab. The default settings with the initial install will work fine, although you will have to select your input device (audio card) if it is not the system default. That is under the Options/Audio settings tab.

Regards

Ken

From: Joe Subich, W4TV-4 [via Elecraft] [mailto:[hidden email]]
Sent: Thursday, May 28, 2015 10:27 PM
To: Ken_ke2n
Subject: Re: K3 FSK power transients

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NAML

73
Ken

w4xp

Re: K3 FSK power transients

In reply to this post by Ken_ke2n

Wow, Those are UGLY effects, I wonder what's causing the "distortion" of the wave forms? DSP?

Very 73,
_______________________________________________
Chuck Watts W4XP; FM18ew 1.8 through 10368 MHz
Delmarva VHF and Microwave Society, K8GP
Grid Pirates Contest Group; http://k8gp.net
AO-27 Control Operator's Association, N4USI
http://www.ao27.org
Potomac Valley Radio Club (PVRC)
Ole Virginia Hams, W4OVH

On 5/28/2015 21:53, Ken_ke2n [via Elecraft] wrote:

2015-05-27_20_48_16-Time_domain_scope_no_radio.gif
2015-05-27_19_07_20-Time_domain_scope.gif

I hope this works.

I have shown, in two attached images, the tones being produced by WSJT FSK441 and then the monitor output of the K3. You can see a substantial drop off of the low frequency tones and some kind of additional modulation of the overall envelope (most noticeable with the higher frequency tone, but I think it affects all). Not sure if this is ALC action or something else.

Anyway, the K3 makes a bit of a mess out of some otherwise nice-looking tones.

Ken
73
Ken

If you reply to this email, your message will be added to the discussion below:
http://elecraft.365791.n2.nabble.com/K3-FSK-power-transients-tp3712691p7603596.html

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To receive all replies by email, subscribe to this discussion

Joe Subich, W4TV-4

Re: K3 FSK power transients

In reply to this post by Ken_ke2n

A quick reply since I'm on my way out ... I'll look more in depth
later.

I am concerned about the audio waveform generated by your WaveNode
device. I see peaks to 128 +/- and dips to 64 +/- with a significant
amount of asymmetry. The asymmetry would make me wonder if there is
not some clipping (bad transistor) in the LPA, KPA3 or in the WaveNode
device itself.

Perhaps the only way to know for sure would be to use a second receiver
and look at the *recovered* audio.

> Mine is using the more steep-sided 8 pole filter and has the new
> synthesizer board and the latest firmware updates.

I'm also using the 2.8 KHz filter, new synthesizer and most recent
production firmware for the KSYN3A. Note there was no change in DSP
code to support the KSYN3A so I would not expect the firmware to be
an issue.

> PEP/average (power) ratio is the (voltage) crest factor squared. It
> is hard to get the effective(average) value of the wave by eyeball.
> But you could take the min/max and divide by 2.

No - Crest factor is 10*log(Peak/Average) in terms of power and
20*log(Peak/Average) in terms of voltage. Since the modulation is
single sine waves (not a complex waveform) the average (RMS) is 0.7
x peak. The lowest voltage I see is 0.8V, the highest is slightly
less than 1.0 (call it 0.98). Using the average of 0.98 and 0.80
(there should be about as many of each tone) we get 20Log(.98/.89)
or 0.84 dB which is a reasonable match to the Peak to Average ratio
reported by the LP-100.

> I tried backing down the line level to where no ALC action was
> visible but there are still "dips".

Can't do that. With less than 4 bars of ALC the DSP code will try
to "follow level" and may make things worse depending on the time
constant.

73,

... Joe, W4TV

On 2015-05-29 10:04 AM, Ken wrote:

> Good job Joe.
>
> My understanding is that the monitor output of the K3 should be a
> fair representation of what another receiver would see - minus the
> effects of propagation and any external power amplifier. But it is
> just really something convenient to use (as evidenced by the
> quickness of your response).
>
>> From a subjective/eyeball view of the waveform - we can see your K3
>> is doing a better job than mine. I wonder what the differences
>> are?
> Mine is using the more steep-sided 8 pole filter and has the new
> synthesizer board and the latest firmware updates.
>
> PEP/average (power) ratio is the (voltage) crest factor squared. It
> is hard to get the effective(average) value of the wave by eyeball.
> But you could take the min/max and divide by 2. On your graph, the
> max is 1.0 and I see two points where it dips to about 0.75 (at 0.5
> ms and 11.5 ms). That gives a crest factor of 1.14 and a PEP/average
> power ratio of 1.3. In decibels that is 2.28 dB which is similar to
> what a filter passband ripple might be. Anyway, it's better that
> what I am seeing.
>
> Some other artifacts are visible on the 2 kHz segments. For example,
> at 2 ms there is a cycle that is shorter than the cycles on either
> side; at about 11.5 ms there is a cycle that is taller than the ones
> on either side. Some of this is probably in the actual signal as
> generated. Looking back at my "no-radio" graph I can see a small
> fluctuation in the level of a 2 kHz segment where there are 9 cycles
> in a row...
>
> In terms of RF sample, my power meter provides a scope function right
> off the RF detector. I have included two pictures of this. These are
> several overlaid scans snatched from a CQ message. The power readings
> of my wattmeter must come from squaring this voltage measurement. It
> has pretty high frequency response (0.1 ms features can easily be
> seen - this is a bit much if used for the power meter readings
> imho).
>
> One of the things I tried yesterday was some "pre-emphasis" using a
> software sound equalizer on my audio. The tone levels at the monitor
> output are closer in level, to each other, with the equalizer
> inserted. But there are still ups and downs in the envelope of
> monitored waveform. In terms of power, the graph with the
> equalization "on" shows fewer upward peaks in the power level (second
> file attached). I have not tried with the linear amplifier on yet,
> but it looks like the PEP/Average ratio has been reduced a bit with
> the equalizer on (from 1.8 to 1.6) so I guess I will keep it.
>
> The "dips" in power are present in both graphs. Perhaps that is
> inherent in the modulation? I don't know how to measure audio power
> at the input to the radio.... if the signal from the sound card does
> not have these dips, then the radio must be doing it somehow. I tried
> backing down the line level to where no ALC action was visible but
> there are still "dips".
>
> Later Ken
>
>
>
> -----Original Message----- From: Joe Subich, W4TV
> [mailto:[hidden email]] Sent: Friday, May 29, 2015 8:35 AM To:
> Ken_ke2n; [hidden email] Subject: Re: [Elecraft] K3 FSK
> power transients
>
>
> I don't know what a *monitor* output proves since it is *not* an RF
> sample. However, I have attached a Spectrum Lab Time Domain capture
> as requested. Notice the crest factor is well less than 1 dB.
>
> 73,
>
> ... Joe, W4TV
>
>
> On 2015-05-29 7:45 AM, Ken_ke2n via Elecraft wrote:
>> Joe - I am using data mode with "DATA A" selected. (This mode
>> uses the SSB filter and turns off equalization and compression. But
>> of course the ALC is "on").
>>
>>
>>
>> What would be really helpful is if you would download a copy of
>> Spectrum Lab and run the monitor output of your K3 through it while
>> transmitting FSK441. Then we would both have a common point of
>> comparison (eliminating the vagaries of power meter PEP
>> algorithms).
>>
>>
>>
>> http://www.qsl.net/dl4yhf/spectra1.html
>>
>>
>>
>> The time domain scope is under the "components" tab. The default
>> settings with the initial install will work fine, although you
>> will have to select your input device (audio card) if it is not the
>> system default. That is under the Options/Audio settings tab.
>>
>>
>>
>> Regards
>>
>> Ken
>>
>>
>>
>> From: Joe Subich, W4TV-4 [via Elecraft]
>> [mailto:[hidden email]] Sent: Thursday,
>> May 28, 2015 10:27 PM To: Ken_ke2n Subject: Re: K3 FSK power
>> transients
>>
>>
>>
>>
>> Are you using DATA A or trying to force FSK-442 through the K3 in
>> USB with the TX_EQ enabled? Again, I see *NO* frequency effects
>> (crest factor < 0.1 dB at 30, 60 and 100 W) with my K3 when using
>> DATA A and the LINE In.
>>
>> Also make sure your sound card does not have any "enhancements"
>> enabled.
>>
>> 73,
>>
>> ... Joe, W4TV
>>
>>
>> On 2015-05-28 9:53 PM, Ken_ke2n via Elecraft wrote:
>>
>>
>>> 2015-05-27_20_48_16-Time_domain_scope_no_radio.gif
>>>
>> <http://elecraft.365791.n2.nabble.com/file/n7603596/2015-05-27_20_48_1
>>
>>

6-Time
>> _domain_scope_no_radio.gif>
>>> 2015-05-27_19_07_20-Time_domain_scope.gif
>>>
>> <http://elecraft.365791.n2.nabble.com/file/n7603596/2015-05-27_19_07_2
>>
>>
0-Time

>> _domain_scope.gif>
>>>
>>> I hope this works.
>>>
>>> I have shown, in two attached images, the tones being produced
>>> by WSJT FSK441 and then the monitor output of the K3. You can
>>> see a substantial drop off of the low frequency tones and some
>>> kind of additional modulation
>>
>>> of the overall envelope (most noticeable with the higher
>>> frequency tone,
>> but
>>> I think it affects all). Not sure if this is ALC action or
>>> something else.
>>
>>>
>>> Anyway, the K3 makes a bit of a mess out of some otherwise
>>> nice-looking tones.
>>>
>>> Ken
>>>
>>>
>>>
>>> ----- 73 Ken
>>>
>>> -- View this message in context:
>> http://elecraft.365791.n2.nabble.com/K3-FSK-power-transients-tp3712691
>>
>>

p76035

>> 96.html
>>> Sent from the Elecraft mailing list archive at Nabble.com.
>>> ______________________________________________________________
>>> 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
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>>
>> ______________________________________________________________
>> Elecraft mailing list Home:
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>>
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>> email list: http://www.qsl.net/donate.html Message delivered to
>> [hidden email]
>>
>>
>>
>> _____
>>
>> If you reply to this email, your message will be added to the
>> discussion below:
>>
>> http://elecraft.365791.n2.nabble.com/K3-FSK-power-transients-tp3712691
>>
>>

p76035
>> 99.html
>>
>> To unsubscribe from K3 FSK power transients, click here
>> <http://elecraft.365791.n2.nabble.com/template/NamlServlet.jtp?macro=u
>>
>>
nsubsc
>> ribe_by_code&node=3712691&code=a2UybkBjcy5jb218MzcxMjY5MXwzMzYyNjM0NzE=>
>> .
>>
>> <http://elecraft.365791.n2.nabble.com/template/NamlServlet.jtp?macro=m
>>
>>
acro_v
>> iewer&id=instant_html%21nabble%3Aemail.naml&base=nabble.naml.namespace
>>
>>
s.Basi
>> cNamespace-nabble.view.web.template.NabbleNamespace-nabble.view.web.te
>>
>>
mplate
>> .NodeNamespace&breadcrumbs=notify_subscribers%21nabble%3Aemail.naml-in
>>
>>
stant_
>> emails%21nabble%3Aemail.naml-send_instant_email%21nabble%3Aemail.naml>
>>
>>
NAML

>>
>>
>>
>>
>>
>> ----- 73 Ken
>>
>> -- View this message in context:
>> http://elecraft.365791.n2.nabble.com/K3-FSK-power-transients-tp3712691
>>
>>

p7603604.html Sent from the Elecraft mailing list archive at

>> Nabble.com.
>> ______________________________________________________________
>> 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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Elecraft mailing list

Re: K3 FSK power transients

I was going by this definition:

http://en.wikipedia.org/wiki/Crest_factor

But I stand corrected on the average. I was computing an average of the crest, not the effective value of the wave. Since these are sine waves, the effective value is 0.707 of the crest. Of course, when the crest value is varying over the period under consideration, you might want to average the crests and then multiply by 0.707, which is kind of what I was doing.

That means the PAPR (peak to average power ratio) for a sine wave is, by definition, 3 dB. If you have more than one tone present at any moment the PAPR must be higher than 3 dB (see the URL above).

But that is not what our fancy power meters measure.

These power meters are supposed to measure Peak Envelope Power and average power. With complex waveforms like speech there is no analytical relationship between PEP and average. It depends on the user's voice and the amount of speech processing used. The peaks can easily be 10-20 times the average in an uncompressed voice signal.

For FSK441, the modulating wave is mostly pure tones (of a constant amplitude if all goes well) and some minimal "keying sidebands" due to the 441 baud modulation. So I was thinking there must be some way to calculate PEP/average.

The result of a pure tone, in SSB, is a steady carrier and the filtered envelope of that RF is the same as the average power - so RF PEP/average is 1.0. Mind you, the *instantaneous* value of the RF voltage wave will be 1.414 times the RMS value, but the usual definition of PEP says that a steady carrier has PEP equal to average power. And, when I send one of the steady tones, "73" for example, the Wave Node meter reads PEP equal to average (within some tolerance). What happens is that I see the average power reading rise to the PEP. The PEP reading stays the same. I imagine the K3 is riding herd on the peak and keeping it constant (even with no bars showing).

Time for lunch here ;-) But I will send a note to the Wave Node guy and see what he says about those peaks and dips.

Ken

-----Original Message-----
From: Joe Subich, W4TV [mailto:[hidden email]]
Sent: Friday, May 29, 2015 10:50 AM
To: Ken; [hidden email]
Subject: Re: [Elecraft] K3 FSK power transients

A quick reply since I'm on my way out ... I'll look more in depth later.

I am concerned about the audio waveform generated by your WaveNode device. I see peaks to 128 +/- and dips to 64 +/- with a significant amount of asymmetry. The asymmetry would make me wonder if there is not some clipping (bad transistor) in the LPA, KPA3 or in the WaveNode device itself.

Perhaps the only way to know for sure would be to use a second receiver and look at the *recovered* audio.

> Mine is using the more steep-sided 8 pole filter and has the new > synthesizer board and the latest firmware updates.

I'm also using the 2.8 KHz filter, new synthesizer and most recent production firmware for the KSYN3A. Note there was no change in DSP code to support the KSYN3A so I would not expect the firmware to be an issue.

> PEP/average (power) ratio is the (voltage) crest factor squared. It > is hard to get the effective(average) value of the wave by eyeball.
> But you could take the min/max and divide by 2.

No - Crest factor is 10*log(Peak/Average) in terms of power and
20*log(Peak/Average) in terms of voltage. Since the modulation is single sine waves (not a complex waveform) the average (RMS) is 0.7 x peak. The lowest voltage I see is 0.8V, the highest is slightly less than 1.0 (call it 0.98). Using the average of 0.98 and 0.80 (there should be about as many of each tone) we get 20Log(.98/.89) or 0.84 dB which is a reasonable match to the Peak to Average ratio reported by the LP-100.

> I tried backing down the line level to where no ALC action was visible
> but there are still "dips".

Can't do that. With less than 4 bars of ALC the DSP code will try to "follow level" and may make things worse depending on the time constant.

73,

... Joe, W4TV

On 2015-05-29 10:04 AM, Ken wrote:

> Good job Joe.
>
> My understanding is that the monitor output of the K3 should be a fair
> representation of what another receiver would see - minus the effects
> of propagation and any external power amplifier. But it is just really
> something convenient to use (as evidenced by the quickness of your
> response).
>
>> From a subjective/eyeball view of the waveform - we can see your K3
>> is doing a better job than mine. I wonder what the differences are?
> Mine is using the more steep-sided 8 pole filter and has the new
> synthesizer board and the latest firmware updates.
>
> PEP/average (power) ratio is the (voltage) crest factor squared. It
> is hard to get the effective(average) value of the wave by eyeball.
> But you could take the min/max and divide by 2. On your graph, the
> max is 1.0 and I see two points where it dips to about 0.75 (at 0.5 ms
> and 11.5 ms). That gives a crest factor of 1.14 and a PEP/average
> power ratio of 1.3. In decibels that is 2.28 dB which is similar to
> what a filter passband ripple might be. Anyway, it's better that what
> I am seeing.
>
> Some other artifacts are visible on the 2 kHz segments. For example,
> at 2 ms there is a cycle that is shorter than the cycles on either
> side; at about 11.5 ms there is a cycle that is taller than the ones
> on either side. Some of this is probably in the actual signal as
> generated. Looking back at my "no-radio" graph I can see a small
> fluctuation in the level of a 2 kHz segment where there are 9 cycles
> in a row...
>
> In terms of RF sample, my power meter provides a scope function right
> off the RF detector. I have included two pictures of this. These are
> several overlaid scans snatched from a CQ message. The power readings
> of my wattmeter must come from squaring this voltage measurement. It
> has pretty high frequency response (0.1 ms features can easily be seen
> - this is a bit much if used for the power meter readings imho).
>
> One of the things I tried yesterday was some "pre-emphasis" using a
> software sound equalizer on my audio. The tone levels at the monitor
> output are closer in level, to each other, with the equalizer
> inserted. But there are still ups and downs in the envelope of
> monitored waveform. In terms of power, the graph with the
> equalization "on" shows fewer upward peaks in the power level (second
> file attached). I have not tried with the linear amplifier on yet,
> but it looks like the PEP/Average ratio has been reduced a bit with
> the equalizer on (from 1.8 to 1.6) so I guess I will keep it.
>
> The "dips" in power are present in both graphs. Perhaps that is
> inherent in the modulation? I don't know how to measure audio power at
> the input to the radio.... if the signal from the sound card does not
> have these dips, then the radio must be doing it somehow. I tried
> backing down the line level to where no ALC action was visible but
> there are still "dips".
>
> Later Ken
>
>
>
> -----Original Message----- From: Joe Subich, W4TV
> [mailto:[hidden email]] Sent: Friday, May 29, 2015 8:35 AM To:
> Ken_ke2n; [hidden email] Subject: Re: [Elecraft] K3 FSK
> power transients
>
>
> I don't know what a *monitor* output proves since it is *not* an RF
> sample. However, I have attached a Spectrum Lab Time Domain capture
> as requested. Notice the crest factor is well less than 1 dB.
>
> 73,
>
> ... Joe, W4TV
>
>
> On 2015-05-29 7:45 AM, Ken_ke2n via Elecraft wrote:
>> Joe - I am using data mode with "DATA A" selected. (This mode uses
>> the SSB filter and turns off equalization and compression. But of
>> course the ALC is "on").
>>
>>
>>
>> What would be really helpful is if you would download a copy of
>> Spectrum Lab and run the monitor output of your K3 through it while
>> transmitting FSK441. Then we would both have a common point of
>> comparison (eliminating the vagaries of power meter PEP algorithms).
>>
>>
>>
>> http://www.qsl.net/dl4yhf/spectra1.html
>>
>>
>>
>> The time domain scope is under the "components" tab. The default
>> settings with the initial install will work fine, although you will
>> have to select your input device (audio card) if it is not the system
>> default. That is under the Options/Audio settings tab.
>>
>>
>>
>> Regards
>>
>> Ken
>>
>>
>>
>> From: Joe Subich, W4TV-4 [via Elecraft]
>> [mailto:[hidden email]] Sent: Thursday, May
>> 28, 2015 10:27 PM To: Ken_ke2n Subject: Re: K3 FSK power transients
>>
>>
>>
>>
>> Are you using DATA A or trying to force FSK-442 through the K3 in USB
>> with the TX_EQ enabled? Again, I see *NO* frequency effects (crest
>> factor < 0.1 dB at 30, 60 and 100 W) with my K3 when using DATA A and
>> the LINE In.
>>
>> Also make sure your sound card does not have any "enhancements"
>> enabled.
>>
>> 73,
>>
>> ... Joe, W4TV
>>
>>
>> On 2015-05-28 9:53 PM, Ken_ke2n via Elecraft wrote:
>>
>>
>>> 2015-05-27_20_48_16-Time_domain_scope_no_radio.gif
>>>
>> <http://elecraft.365791.n2.nabble.com/file/n7603596/2015-05-27_20_48_
>> 1
>>
>>

6-Time
>> _domain_scope_no_radio.gif>
>>> 2015-05-27_19_07_20-Time_domain_scope.gif
>>>
>> <http://elecraft.365791.n2.nabble.com/file/n7603596/2015-05-27_19_07_
>> 2
>>
>>
0-Time

>> _domain_scope.gif>
>>>
>>> I hope this works.
>>>
>>> I have shown, in two attached images, the tones being produced by
>>> WSJT FSK441 and then the monitor output of the K3. You can see a
>>> substantial drop off of the low frequency tones and some kind of
>>> additional modulation
>>
>>> of the overall envelope (most noticeable with the higher frequency
>>> tone,
>> but
>>> I think it affects all). Not sure if this is ALC action or something
>>> else.
>>
>>>
>>> Anyway, the K3 makes a bit of a mess out of some otherwise
>>> nice-looking tones.
>>>
>>> Ken
>>>
>>>
>>>
>>> ----- 73 Ken
>>>
>>> -- View this message in context:
>> http://elecraft.365791.n2.nabble.com/K3-FSK-power-transients-tp371269
>> 1
>>
>>

p76035

p76035
>> 99.html
>>
>> To unsubscribe from K3 FSK power transients, click here
>> <http://elecraft.365791.n2.nabble.com/template/NamlServlet.jtp?macro=
>> u
>>
>>
nsubsc
>> ribe_by_code&node=3712691&code=a2UybkBjcy5jb218MzcxMjY5MXwzMzYyNjM0Nz
>> E=>
>> .
>>
>> <http://elecraft.365791.n2.nabble.com/template/NamlServlet.jtp?macro=
>> m
>>
>>
acro_v
>> iewer&id=instant_html%21nabble%3Aemail.naml&base=nabble.naml.namespac
>> e
>>
>>
s.Basi
>> cNamespace-nabble.view.web.template.NabbleNamespace-nabble.view.web.t
>> e
>>
>>
mplate
>> .NodeNamespace&breadcrumbs=notify_subscribers%21nabble%3Aemail.naml-i
>> n
>>
>>
stant_
>> emails%21nabble%3Aemail.naml-send_instant_email%21nabble%3Aemail.naml
>> >
>>
>>
NAML

>>
>>
>>
>>
>>
>> ----- 73 Ken
>>
>> -- View this message in context:
>> http://elecraft.365791.n2.nabble.com/K3-FSK-power-transients-tp371269
>> 1
>>
>>

p7603604.html Sent from the Elecraft mailing list archive at

Don Wilhelm-4

Re: K3 FSK power transients

Ken,

It may be that you are over-analyzing it.

Simply increase the audio to produce 4 bars with the 5th bar
flickering. On the K3, that is the "NO ALC" point - the "less than 5
bars" area of the "ALC" meter is more or less like a VU meter, and is
done that way to allow you to properly adjust the audio level.
You must have adequate audio drive to allow the K3 power control to
operate correctly. Control the power output with the power knob, not
the audio.

The K3 is different in this respect from most (or all) the other
transceivers on the market. The sage advice of NO ALC offered for those
other transceivers does not work for the K3 (and K2 and KX3).

Yes, the K3 is 'riding herd' on the power output, and that is in PEP.

73,
Don W3FPR

On 5/29/2015 11:46 AM, Ken via Elecraft wrote:
> example, the Wave Node meter reads PEP equal to average (within some tolerance). What happens is that I see the average power reading rise to the PEP. The PEP reading stays the same. I imagine the K3 is riding herd on the peak and keeping it constant (even with no bars showing).
>
>

______________________________________________________________
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
Message delivered to [hidden email]

Elecraft mailing list

Re: K3 FSK power transients

Thanks Don - this is, in fact, how I run it: 4-5 bars. I control power with
the power control. I follow the directions ;-)

I was just surprised to see the ALC working even with no bars showing.

My problems is that my FSK441 has a lot of PEP. And apparently it is not
supposed to ...

73

Ken

-----Original Message-----
From: Don Wilhelm [mailto:[hidden email]]
Sent: Friday, May 29, 2015 12:09 PM
To: Ken; 'Joe Subich, W4TV'; [hidden email]
Subject: Re: [Elecraft] K3 FSK power transients

Ken,

It may be that you are over-analyzing it.

Simply increase the audio to produce 4 bars with the 5th bar flickering. On
the K3, that is the "NO ALC" point - the "less than 5 bars" area of the
"ALC" meter is more or less like a VU meter, and is done that way to allow
you to properly adjust the audio level.
You must have adequate audio drive to allow the K3 power control to operate
correctly. Control the power output with the power knob, not the audio.

The K3 is different in this respect from most (or all) the other
transceivers on the market. The sage advice of NO ALC offered for those
other transceivers does not work for the K3 (and K2 and KX3).

Yes, the K3 is 'riding herd' on the power output, and that is in PEP.

73,
Don W3FPR

On 5/29/2015 11:46 AM, Ken via Elecraft wrote:
> example, the Wave Node meter reads PEP equal to average (within some
tolerance). What happens is that I see the average power reading rise to
the PEP. The PEP reading stays the same. I imagine the K3 is riding herd on
the peak and keeping it constant (even with no bars showing).
>
>

______________________________________________________________
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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