K3 power output on SSB

[Juha - oh6os]

Hello,

When I whistle to mic and tune my linear amplifier, I notice that last watts
going up very slowly. Without linear I tested and sometimes first 80 watts
out normally but from 80 to 100 watts it takes about 2-3 seconds.

When I am using my linear (Titan, has peak power meter by led) last one or
two leds don't light on ssb, on cw they do with the same driving power.

I tried TXG VCE, but not effect.

It is like ALC over react to voice peak.

Is that normal behavior?

73 de juha - oh6os K3 #2100
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[Joe Subich, W4TV-4]

> When I whistle to mic and tune my linear amplifier, I notice
> that last watts going up very slowly. Without linear I tested
> and sometimes first 80 watts out normally but from 80 to 100
> watts it takes about 2-3 seconds.

Sounds like a power calibration issue.  Double check the K3
wattmeter calibration, the amplifier gain calibrations and
TXG VCE.  

73,

   ... Joe, W4TV
 

> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of Juha Kasari
> Sent: Sunday, March 28, 2010 5:31 AM
> To: [hidden email]
> Subject: [Elecraft] K3 power output on SSB
>
>
> Hello,
>
> When I whistle to mic and tune my linear amplifier, I notice
> that last watts going up very slowly. Without linear I tested
> and sometimes first 80 watts out normally but from 80 to 100
> watts it takes about 2-3 seconds.
>
> When I am using my linear (Titan, has peak power meter by
> led) last one or two leds don't light on ssb, on cw they do
> with the same driving power.
>
> I tried TXG VCE, but not effect.
>
> It is like ALC over react to voice peak.
>
> Is that normal behavior?
>
> 73 de juha - oh6os K3 #2100
> ______________________________________________________________
> Elecraft mailing list
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[ab2tc]

Hi,

No, please, this is not a power calibration issue! A huge number of K3 users have complained about this propensity of the SSB power to aim "conservatively" for 50-80% of the requested peak power and then slowly, very slowly climbing up to the requested power. Once reaching 100% it stays there until you perform some kind of QSY operation other than just turning the wheel. It is not a huge irritant to me, but an irritant nonetheless. If I am in a big rush to have full power on SSB after a QSY, I switch mode to TX data FSK D, do a quick squirt of TX and I have instant full SSB peak power.

AB2TC - Knut

Joe Subich, W4TV-4 wrote

> When I whistle to mic and tune my linear amplifier, I notice
> that last watts going up very slowly. Without linear I tested
> and sometimes first 80 watts out normally but from 80 to 100
> watts it takes about 2-3 seconds.

Sounds like a power calibration issue.  Double check the K3
wattmeter calibration, the amplifier gain calibrations and
TXG VCE.  

73,

   ... Joe, W4TV
 
<snip>

[Brendan Minish]

An undershoot of ~ 20% for the first few seconds of transmission on a
new frequency might be an irritant but an overshoot or aggressive fast
acting ALC leads to spatter on peaks, this is very common issue on the
bands today
An undershoot of  ~20% on peaks (it's less on my K3) is negligible in
terms of the receiving end signal strength and a small price to pay for
a cleaner transmitted signal.

73
Brendan EI6IZ    


On Mon, 2010-03-29 at 14:59 -0800, ab2tc wrote:

> Hi,
>
> No, please, this is not a power calibration issue! A huge number of K3 users
> have complained about this propensity of the SSB power to aim
> "conservatively" for 50-80% of the requested peak power and then slowly,
> very slowly climbing up to the requested power. Once reaching 100% it stays
> there until you perform some kind of QSY operation other than just turning
> the wheel. It is not a huge irritant to me, but an irritant nonetheless. If
> I am in a big rush to have full power on SSB after a QSY, I switch mode to
> TX data FSK D, do a quick squirt of TX and I have instant full SSB peak
> power.
>
> AB2TC - Knut
>
>
> Joe Subich, W4TV-4 wrote:
> >
> >
> >
> >> When I whistle to mic and tune my linear amplifier, I notice
> >> that last watts going up very slowly. Without linear I tested
> >> and sometimes first 80 watts out normally but from 80 to 100
> >> watts it takes about 2-3 seconds.
> >
> > Sounds like a power calibration issue.  Double check the K3
> > wattmeter calibration, the amplifier gain calibrations and
> > TXG VCE.  
> >
> > 73,
> >
> >    ... Joe, W4TV
> >  
> > <snip>
> >
>

--
73
Brendan EI6IZ

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[W8JI]

> No, please, this is not a power calibration issue! A huge
> number of K3 users
> have complained about this propensity of the SSB power to
> aim
> "conservatively" for 50-80% of the requested peak power
> and then slowly,
> very slowly climbing up to the requested power. Once
> reaching 100% it stays

I'm having a weird SSB problem now. I just updated firmware
to  MCU 03.79, FPF 01.08, and DSP to 02.54

On 20M LSB it behaves pretty much OK, but now on USB it
barely makes any average power and has some weird peaks.
It's almost like it has severe gain expansion.

I reloaded the updates (but did not download fresh files)
and I have the same thing.

It was working OK with my older firmware. Anyone have any
ideas??


Tom

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[k6dgw]

Brendan Minish wrote:
> An undershoot of ~ 20% for the first few seconds of transmission on a
> new frequency might be an irritant but an overshoot or aggressive fast
> acting ALC leads to spatter on peaks, this is very common issue on the
> bands today
> An undershoot of  ~20% on peaks (it's less on my K3) is negligible in
> terms of the receiving end signal strength and a small price to pay for
> a cleaner transmitted signal.

Folks, maybe I am missing so much here, but 20% undershoot at 100W
"requested" is 20W.  The difference between 80W and 100W is 0.96910 dB,
assuming my HP48GX can still do logs after all these years.

I think Brendan has it right, a second or two of some power between 80
and 100W really is negligible.  On SSB [not often my mode], I step on
the switch under the desk and talk ... works every time ... as long as I
remember -- "Step, then talk."

Now, pretending that I actually know what I'm about to say ... I think
the power control in the K3 [and K2] is a big negative feedback loop
called ALC by some.  How would it know where to stabilize to a requested
power before power, any power, actually happened?

On a different subject, I'd pay money for a published decision tree for
firmware updates and whether or not I need to install them.  Often --
OK, always -- this occurs just before the contest.  Many affect things
that don't affect me, others can be another story.

73,

Fred K6DGW
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[W8JI]

> An undershoot of ~ 20% for the first few seconds of
> transmission on a
> new frequency might be an irritant but an overshoot or
> aggressive fast
> acting ALC leads to spatter on peaks, this is very common
> issue on the
> bands today
> An undershoot of  ~20% on peaks (it's less on my K3) is
> negligible in
> terms of the receiving end signal strength and a small
> price to pay for
> a cleaner transmitted signal.

I think overshoot on SSB is greatly overplayed in most
radios. There are some truly bad radios, but even in them
the overshoot is very short duration. It often won't even
show a regular peak reading meter. It is generally a few
milliseconds at most from a "cold" start with no ALC, and
then it is gone until the next nearly zero ALC drop. The
result from ALC on SSB is an occasional very short syllabic
tic. A couple milliseconds of spit or tic once every few
seconds is not a big deal breaker. The real annoying crud,
and bands like 20 are full of it, is caused by improper
loading of amplifiers, poorly designed amps, and overdriving
amps. It's the constant spitting and sputtering that wipes
out entire words that is damaging, and I don't see the real
damaging stuff changing much with work on ALC systems.

There are also the occasional phools who get inside radios
and crank the power limit controls up. I know this because I
repaired the FT1000MP's of a contester, set the power pots
back to 100 watts where the radio was about -35 dB PEP  on
3rd order, and six months later when I was doing a filter
mod to the same radios the power pots were back up to 140
watts where the radios have -20 dB PEP on IM3.

Someplace between the two is probably a good compromise, but
don't bank on 20 meters and other bands cleaning up if all
the ALC's in the world were fixed.

73 Tom

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[ab2tc]

Hello again,

Let's all agree that the undershoot problem is not huge. But it's much more than 20% and it lasts much longer than a couple of seconds. And I object to the notion that a properly working ALC, even a fairly fast one necessarily leads to severe distortion or splatter. I again hold the opinion that the real bad signals heard are due to to PAs being operated with no ALC feedback to the exciter feeding it and operators being clueless to this. A properly operating ALC system should be virtually impossible to talk into serious distortion.

AB2TC - Knut
 

W8JI wrote

> An undershoot of ~ 20% for the first few seconds of
> transmission on a
> new frequency might be an irritant but an overshoot or
> aggressive fast
> acting ALC leads to spatter on peaks, this is very common
> issue on the
> bands today
> An undershoot of  ~20% on peaks (it's less on my K3) is
> negligible in
> terms of the receiving end signal strength and a small
> price to pay for
> a cleaner transmitted signal.


I think overshoot on SSB is greatly overplayed in most
radios. There are some truly bad radios, but even in them
the overshoot is very short duration. It often won't even
<snip>

[Joe Subich, W4TV-4]

> No, please, this is not a power calibration issue!

Bull ... I have seen it and can recreate it at will.

If the wattmeter is not properly calibrated and the
transmit gains are off, the bower setting routines
do not act correctly.  With the transmitter properly
calibrated I see less than .5dB "undershoot" (more
than 95 W when commanded for 100W) when changing bands.

If I intentionally miscalibrate the wattmeter (as I
did by accident when building the unit) and then do
the transmit gain calibration with an  inaccurate
wattmeter, the radio will display a 2 to 3 dB undershoot
(50 to 60 watts) when first changing bands.  

73,

   ... Joe, W4TV
 

> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of ab2tc
> Sent: Monday, March 29, 2010 7:00 PM
> To: [hidden email]
> Subject: Re: [Elecraft] K3 power output on SSB
>
>
>
> Hi,
>
> No, please, this is not a power calibration issue! A huge
> number of K3 users have complained about this propensity of
> the SSB power to aim "conservatively" for 50-80% of the
> requested peak power and then slowly, very slowly climbing up
> to the requested power. Once reaching 100% it stays there
> until you perform some kind of QSY operation other than just
> turning the wheel. It is not a huge irritant to me, but an
> irritant nonetheless. If I am in a big rush to have full
> power on SSB after a QSY, I switch mode to TX data FSK D, do
> a quick squirt of TX and I have instant full SSB peak power.
>
> AB2TC - Knut
>
>
> Joe Subich, W4TV-4 wrote:
> >
> >
> >
> >> When I whistle to mic and tune my linear amplifier, I notice
> >> that last watts going up very slowly. Without linear I tested
> >> and sometimes first 80 watts out normally but from 80 to 100
> >> watts it takes about 2-3 seconds.
> >
> > Sounds like a power calibration issue.  Double check the K3
> > wattmeter calibration, the amplifier gain calibrations and
> > TXG VCE.  
> >
> > 73,
> >
> >    ... Joe, W4TV
> >  
> > <snip>
> >
>
> --
> View this message in context:
> http://n2.nabble.com/K3-power-output-on-SSB-tp4818879p4821485.html
> Sent from the Elecraft mailing list archive at Nabble.com.
> ______________________________________________________________
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[W8JI]

> leads to severe distortion or splatter. I again hold the
> opinion that the
> real bad signals heard are due to to PAs being operated
> with no ALC feedback
> to the exciter feeding it and operators being clueless to
> this.

Most amplifiers have very crummy ALC detection. All they do
is same RF level at the cathode of the tube, and that
doesn't indicate excessive drive or nonlinearity at all! In
most cases however people are just kidding themselves when
they connect ALC from an external amplifier. All the ALC
from the amp does is sample the same thing the radio's
directional coupler does, so the external ALC is redundant
to what the radio already has... except not as accurate or
stable from band to band.

In some later tube amps I used an ALC detector that samples
grid current (and in a few cases grid current and plate
current). This does work to limit excessive drive, but in
most radios the ALC has so much gain and group delay the
system will motorboat. The solution was to add a pot that
limits maximum ALC voltage, so it is a two-control system in
the amp. Still, it is better to do the ALC ahead of all the
signal path time delays, like the slower propagation through
filters.

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[P.B. Christensen]

> Most amplifiers have very crummy ALC detection. All they do
> is same RF level at the cathode of the tube, and that
> doesn't indicate excessive drive or nonlinearity at all!

The only ALC systems I've ever taken seriously are those that are designed
together between the transmitter and external amplifier as a system so that
the ALC "meet me point" is optimized.   But even among one common
manufacturer, that still does not guarantee good ALC performance.

Today, a commercial amplifier should be designed to be smart enough to know
when it's going into a fault condition from the exciter without requiring an
ALC "feedback" cable -- and some newer amps finally have this capability in
their feed-forward designs.

Paul, W9AC

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[W8JI]

I have an odd power and ALC problem.

When I load the latest firmware into my K3, it nearly quits
working on USB. The power output is very low with occasional
high peaks. LSB remains good.

If I offset the filter -800 Hz, USB starts working OK.

If I make no other changes and go back to the older
firmware, the problem goes away.

Any ideas anyone?

Tom

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[Don Wilhelm-4]

Tom,

I certainly don't know what is going on with your problem, but since no
one else has mentioned anything like that and teh current firmware has
been out for a while, I would guess that you have a corrupt firmware
download.  I would get a fresh copy from the Elecraft website and
re-load it.
No promises, but it certainly is worth a try.  If that does not fix it,
a note th K3support is in order.

73,
Don W3FPR

Tom W8JI wrote:

> I have an odd power and ALC problem.
>
> When I load the latest firmware into my K3, it nearly quits
> working on USB. The power output is very low with occasional
> high peaks. LSB remains good.
>
> If I offset the filter -800 Hz, USB starts working OK.
>
> If I make no other changes and go back to the older
> firmware, the problem goes away.
>
> Any ideas anyone?
>
> Tom
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> ------------------------------------------------------------------------
>
>
> No virus found in this incoming message.
> Checked by AVG - www.avg.com
> Version: 9.0.791 / Virus Database: 271.1.1/2777 - Release Date: 03/29/10 02:32:00
>
>  

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[W8JI]

Already deleted the firmware from my computer and
re-downloaded the firmware from the elecraft site fresh. No
help.

----- Original Message -----
From: "Don Wilhelm" <[hidden email]>
To: "Tom W8JI" <[hidden email]>
Cc: <[hidden email]>
Sent: Monday, March 29, 2010 10:43 PM
Subject: Re: [Elecraft] Odd power/ALC problem

> Tom,
>
> I certainly don't know what is going on with your problem,
> but since no one else has mentioned anything like that and
> teh current firmware has been out for a while, I would
> guess that you have a corrupt firmware download.  I would
> get a fresh copy from the Elecraft website and re-load it.
> No promises, but it certainly is worth a try.  If that
> does not fix it, a note th K3support is in order.
>
> 73,
> Don W3FPR
>
> Tom W8JI wrote:
>> I have an odd power and ALC problem.
>>
>> When I load the latest firmware into my K3, it nearly
>> quits working on USB. The power output is very low with
>> occasional high peaks. LSB remains good.
>>
>> If I offset the filter -800 Hz, USB starts working OK.
>>
>> If I make no other changes and go back to the older
>> firmware, the problem goes away.
>>
>> Any ideas anyone?
>>
>> Tom
>> ______________________________________________________________
>> 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
>> ------------------------------------------------------------------------
>>
>>
>> No virus found in this incoming message.
>> Checked by AVG - www.avg.com Version: 9.0.791 / Virus
>> Database: 271.1.1/2777 - Release Date: 03/29/10 02:32:00
>>
>>

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[Juha - oh6os]

Not so good behavior on the contest, where is alltime tuning.

juha - oh6os

ab2tc wrote

Hi,

No, please, this is not a power calibration issue! A huge number of K3 users have complained about this propensity of the SSB power to aim "conservatively" for 50-80% of the requested peak power and then slowly, very slowly climbing up to the requested power. Once reaching 100% it stays there until you perform some kind of QSY operation other than just turning the wheel. It is not a huge irritant to me, but an irritant nonetheless. If I am in a big rush to have full power on SSB after a QSY, I switch mode to TX data FSK D, do a quick squirt of TX and I have instant full SSB peak power.

AB2TC - Knut

Joe Subich, W4TV-4 wrote

> When I whistle to mic and tune my linear amplifier, I notice
> that last watts going up very slowly. Without linear I tested
> and sometimes first 80 watts out normally but from 80 to 100
> watts it takes about 2-3 seconds.

Sounds like a power calibration issue.  Double check the K3
wattmeter calibration, the amplifier gain calibrations and
TXG VCE.  

73,

   ... Joe, W4TV
 
<snip>

[Don Wilhelm-4]

Juha,

Tuning within any band will not reset the power output controls, however
changing bands does reset it.

As Joe has mentioned, do the power calibration, it will help.  The power
control mechanism does use the data obtained from the TX gain
calibration, so yes they are related.

73,
Don W3FPR

Juha - oh6os wrote:
> Not so good behavior on the contest, where is alltime tuning.
>
> juha - oh6os
>
>  
>
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[Don Wilhelm-5]

Tom,

Did you use K3 Utility in Advanced mode and check all the boxes and
click the box to load all checked items?  Any other method will not work
because the K3 is already loaded with the same level that you are trying
to re-load.

I believe the filter offset for LSB/USB is controlled in the DSP code,
so that must be force loaded to make any change.

73,
Don W3FPR

Tom W8JI wrote:

> Already deleted the firmware from my computer and re-downloaded the
> firmware from the elecraft site fresh. No help.
>
> ----- Original Message ----- From: "Don Wilhelm" <[hidden email]>
> To: "Tom W8JI" <[hidden email]>
> Cc: <[hidden email]>
> Sent: Monday, March 29, 2010 10:43 PM
> Subject: Re: [Elecraft] Odd power/ALC problem
>
>
>> Tom,
>>
>> I certainly don't know what is going on with your problem, but since
>> no one else has mentioned anything like that and teh current firmware
>> has been out for a while, I would guess that you have a corrupt
>> firmware download.  I would get a fresh copy from the Elecraft
>> website and re-load it.
>> No promises, but it certainly is worth a try.  If that does not fix
>> it, a note th K3support is in order.
>>
>> 73,
>> Don W3FPR
>>
>> Tom W8JI wrote:
>>> I have an odd power and ALC problem.
>>>
>>> When I load the latest firmware into my K3, it nearly quits working
>>> on USB. The power output is very low with occasional high peaks. LSB
>>> remains good.
>>>
>>> If I offset the filter -800 Hz, USB starts working OK.
>>>
>>> If I make no other changes and go back to the older firmware, the
>>> problem goes away.
>>>
>>> Any ideas anyone?
>>>
>>> Tom
>>> ______________________________________________________________
>>> 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
>>> ------------------------------------------------------------------------
>>>
>>>
>>>
>>> No virus found in this incoming message.
>>> Checked by AVG - www.avg.com Version: 9.0.791 / Virus Database:
>>> 271.1.1/2777 - Release Date: 03/29/10 02:32:00
>>>
>>>
> ------------------------------------------------------------------------
>
>
> No virus found in this incoming message.
> Checked by AVG - www.avg.com
> Version: 9.0.791 / Virus Database: 271.1.1/2777 - Release Date: 03/29/10 02:32:00
>
>  

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[ab2tc]

I will do the gain calibration again when I get home. I have done this several times in the past without improvement, but not terribly recently. Maybe there is a relatively recent firmware improvement in this area? Would it be possible to change the firmware to not reset the ALC when doing a band change without transmitting on the other band? I have a habit of using the A/B button to take a quick peek on 10m, then coming back if there is nothing there.

AB2TC - Knut

Joe Subich, W4TV-4 wrote

> No, please, this is not a power calibration issue!

Bull ... I have seen it and can recreate it at will.

If the wattmeter is not properly calibrated and the
transmit gains are off, the bower setting routines
do not act correctly.  With the transmitter properly
calibrated I see less than .5dB "undershoot" (more
than 95 W when commanded for 100W) when changing bands.

<snip>

[W8JI]

I unloaded the firmware by going back to an earlier version.

After seeing it worked "OK" on USB, I deleted the new files
from the K3 utility, reloaded them in a new folder, and
installed from that folder. The problem repeats. The problem
seems to go away if I offset the SSB TX filter by -800 Hz.



----- Original Message -----
From: "Don Wilhelm" <[hidden email]>
To: "Tom W8JI" <[hidden email]>
Cc: <[hidden email]>
Sent: Tuesday, March 30, 2010 8:45 AM
Subject: Re: [Elecraft] Odd power/ALC problem

> Tom,
>
> Did you use K3 Utility in Advanced mode and check all the
> boxes and click the box to load all checked items?  Any
> other method will not work because the K3 is already
> loaded with the same level that you are trying to re-load.
>
> I believe the filter offset for LSB/USB is controlled in
> the DSP code, so that must be force loaded to make any
> change.
>
> 73,
> Don W3FPR
>
> Tom W8JI wrote:
>> Already deleted the firmware from my computer and
>> re-downloaded the firmware from the elecraft site fresh.
>> No help.
>>
>> ----- Original Message ----- From: "Don Wilhelm"
>> <[hidden email]>
>> To: "Tom W8JI" <[hidden email]>
>> Cc: <[hidden email]>
>> Sent: Monday, March 29, 2010 10:43 PM
>> Subject: Re: [Elecraft] Odd power/ALC problem
>>
>>
>>> Tom,
>>>
>>> I certainly don't know what is going on with your
>>> problem, but since no one else has mentioned anything
>>> like that and teh current firmware has been out for a
>>> while, I would guess that you have a corrupt firmware
>>> download.  I would get a fresh copy from the Elecraft
>>> website and re-load it.
>>> No promises, but it certainly is worth a try.  If that
>>> does not fix it, a note th K3support is in order.
>>>
>>> 73,
>>> Don W3FPR
>>>
>>> Tom W8JI wrote:
>>>> I have an odd power and ALC problem.
>>>>
>>>> When I load the latest firmware into my K3, it nearly
>>>> quits working on USB. The power output is very low with
>>>> occasional high peaks. LSB remains good.
>>>>
>>>> If I offset the filter -800 Hz, USB starts working OK.
>>>>
>>>> If I make no other changes and go back to the older
>>>> firmware, the problem goes away.
>>>>
>>>> Any ideas anyone?
>>>>
>>>> Tom
>>>> ______________________________________________________________
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>>>>
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>>>>
>>>>
>>>>
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>>>> Database: 271.1.1/2777 - Release Date: 03/29/10
>>>> 02:32:00
>>>>
>>>>
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>>
>>
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[Don Wilhelm-4]

Knut,

That is not possible.  If it were done, there would be a large variation
in output power from band to band - the gain of the transmit chain is
not constant from band to band.

73,
Don W3FPR


ab2tc wrote:

> I will do the gain calibration again when I get home. I have done this
> several times in the past without improvement, but not terribly recently.
> Maybe there is a relatively recent firmware improvement in this area? Would
> it be possible to change the firmware to not reset the ALC when doing a band
> change without transmitting on the other band? I have a habit of using the
> A/B button to take a quick peek on 10m, then coming back if there is nothing
> there.
>
> AB2TC - Knut
>
>
> Joe Subich, W4TV-4 wrote:
>  
>>    
>>> No, please, this is not a power calibration issue!
>>>      
>> Bull ... I have seen it and can recreate it at will.
>>
>> If the wattmeter is not properly calibrated and the
>> transmit gains are off, the bower setting routines
>> do not act correctly.  With the transmitter properly
>> calibrated I see less than .5dB "undershoot" (more
>> than 95 W when commanded for 100W) when changing bands.
>>
>> <snip>
>>
>>
>>    
>
>  
> ------------------------------------------------------------------------
>
>
> No virus found in this incoming message.
> Checked by AVG - www.avg.com
> Version: 9.0.791 / Virus Database: 271.1.1/2779 - Release Date: 03/30/10 02:32:00
>
>  

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