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[ELECRAFT] KPA500 NEW OWNER QUESTIONS.......

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john@kk9a.com

[ELECRAFT] KPA500 NEW OWNER QUESTIONS.......

I have not used ALC with any amplifier since transceivers switched to
transistor finals. From what I have read on this list, using ALC
improperly can cause distortion. Just be very careful with your drive
level. I believe that the KPA500 can handle 100 watts in bypass, 200
watts may be pushing it. The KPA500 is a very nice amp and it is easy to
use with any transceiver.

GL,
John KK9A

JIM LAGESON N0UR wrote
_Thu Feb 28 13:07:27 EST 2019_

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

I have never owned an amp before and recently put together a KPA500. All
seems to be working well, but I have a few questions. I am using with a
IC-7300.

How important is the ALC cable? I notice it is not included in the Basic
Cabling Diagram in the manual but is discussed later in the manual.

If I were accidently to run 100 watts into the KPA500 will the PWRIN HI
Hard Fault/STBY protect itself before any damage is done. Would ALC
protect
me from that?

Is it standard procedure to keep the KPA500 in line when turned off and
not
in use? I see you may run up to 200 through the KPA500 in STBY.

Is there any concerns or settings on radio when running full break in on
CW?

Thanks
Jim-N0UR
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Jim Brown-10

Re: [ELECRAFT] KPA500 NEW OWNER QUESTIONS.......

On 2/28/2019 11:04 AM, [hidden email] wrote:
> I have not used ALC with any amplifier since transceivers switched to
> transistor finals. From what I have read on this list, using ALC
> improperly can cause distortion.

That's correct. And it's not limited to solid state amplifiers. The
owner's manual for my Ten Tec Titan 425 amp, designed around 1979 and
using a pair of 3CX800A7s, provides an ALC input, but advises against
using ALC to set power.

73, Jim K9YC

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Bob McGraw - K4TAX

Re: [ELECRAFT] KPA500 NEW OWNER QUESTIONS.......

In reply to this post by john@kk9a.com

Yes, improperly or incorrectly using ALC with any amp or any
transceiver, for that matter, can and usually does produce distortion
and splatter.   Just look at some of the signals on the bands and
observe the ALC overshoot which exists with many radios. And it is
made worse by the addition of an amplifier in line. It isn't pretty!.
Yet it has little impact on the on frequency signal as heard and thus
the "great signal" complements follow. But look at the other factors
where you will find "NOT so great signal".   These points should be
addressed as well.

73

Bob, K4TAX

On 2/28/2019 1:04 PM, [hidden email] wrote:

> I have not used ALC with any amplifier since transceivers switched to
> transistor finals. From what I have read on this list, using ALC
> improperly can cause distortion. Just be very careful with your drive
> level. I believe that the KPA500 can handle 100 watts in bypass, 200
> watts may be pushing it. The KPA500 is a very nice amp and it is easy
> to use with any transceiver.
>
> GL,
> John KK9A
>
>
> JIM LAGESON N0UR wrote
> _Thu Feb 28 13:07:27 EST 2019_
>
>
> -------------------------
>
> I have never owned an amp before and recently put together a KPA500. All
> seems to be working well, but I have a few questions. I am using with a
> IC-7300.
>
> How important is the ALC cable? I notice it is not included in the Basic
> Cabling Diagram in the manual but is discussed later in the manual.
>
> If I were accidently to run 100 watts into the KPA500 will the PWRIN HI
> Hard Fault/STBY protect itself before any damage is done. Would ALC
> protect
> me from that?
>
> Is it standard procedure to keep the KPA500 in line when turned off
> and not
> in use? I see you may run up to 200 through the KPA500 in STBY.
>
> Is there any concerns or settings on radio when running full break in
> on CW?
>
> Thanks
> Jim-N0UR
> ______________________________________________________________
> 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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Barry Simpson-2

Re: [ELECRAFT] KPA500 NEW OWNER QUESTIONS.......

I have had my KPA500 for around 5 years. I frequently feed through 200w from my TS990S.

I have also accidentally abused it many times by putting 100w or more into it or using the wrong antenna or some such operator error.

It has always just faulted appropriately and come back up smiling.

It is a tough little cookie !

Barry VK2BJ

Sent from my iPad

> On 1 Mar 2019, at 06:12, Bob McGraw K4TAX <[hidden email]> wrote:
>
> Yes, improperly or incorrectly using ALC with any amp or any transceiver, for that matter, can and usually does produce distortion and splatter. Just look at some of the signals on the bands and observe the ALC overshoot which exists with many radios. And it is made worse by the addition of an amplifier in line. It isn't pretty!. Yet it has little impact on the on frequency signal as heard and thus the "great signal" complements follow. But look at the other factors where you will find "NOT so great signal". These points should be addressed as well.
>
> 73
>
> Bob, K4TAX
>
>
>> On 2/28/2019 1:04 PM, [hidden email] wrote:
>> I have not used ALC with any amplifier since transceivers switched to transistor finals. From what I have read on this list, using ALC improperly can cause distortion. Just be very careful with your drive level. I believe that the KPA500 can handle 100 watts in bypass, 200 watts may be pushing it. The KPA500 is a very nice amp and it is easy to use with any transceiver.
>>
>> GL,
>> John KK9A
>>
>>
>> JIM LAGESON N0UR wrote
>> _Thu Feb 28 13:07:27 EST 2019_
>>
>>
>> -------------------------
>>
>> I have never owned an amp before and recently put together a KPA500. All
>> seems to be working well, but I have a few questions. I am using with a
>> IC-7300.
>>
>> How important is the ALC cable? I notice it is not included in the Basic
>> Cabling Diagram in the manual but is discussed later in the manual.
>>
>> If I were accidently to run 100 watts into the KPA500 will the PWRIN HI
>> Hard Fault/STBY protect itself before any damage is done. Would ALC protect
>> me from that?
>>
>> Is it standard procedure to keep the KPA500 in line when turned off and not
>> in use? I see you may run up to 200 through the KPA500 in STBY.
>>
>> Is there any concerns or settings on radio when running full break in on CW?
>>
>> Thanks
>> Jim-N0UR
>> ______________________________________________________________
>> 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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k4vd

Re: [ELECRAFT] KPA500 NEW OWNER QUESTIONS.......

And now the voice of caution.

I think the KPA500 with the KAT500 and my Flex are a wonderful combination.
That said, my KPA500 stopped working. It appears, after reviewing the logs,
I hit it with 75 watts and probably blew one of the diodes in the front
end. I can dig up the explanation if needed. It may have been a case where
it took me a while to realize what I was doing. In fact, I can't remember
the event other than it was logged by the KPA500. By the way... just having
that log available is valuable.

I now have the Flex set to 25 watts max out.

73,
Kev K4VD

On Thu, Feb 28, 2019 at 4:22 PM Barry Simpson <[hidden email]> wrote:

> I have had my KPA500 for around 5 years. I frequently feed through 200w
> from my TS990S.
>
> I have also accidentally abused it many times by putting 100w or more into
> it or using the wrong antenna or some such operator error.
>
> It has always just faulted appropriately and come back up smiling.
>
> It is a tough little cookie !
>
> Barry VK2BJ
>
> Sent from my iPad
>
> > On 1 Mar 2019, at 06:12, Bob McGraw K4TAX <[hidden email]> wrote:
> >
> > Yes, improperly or incorrectly using ALC with any amp or any
> transceiver, for that matter, can and usually does produce distortion and
> splatter. Just look at some of the signals on the bands and observe the
> ALC overshoot which exists with many radios. And it is made worse by the
> addition of an amplifier in line. It isn't pretty!. Yet it has little
> impact on the on frequency signal as heard and thus the "great signal"
> complements follow. But look at the other factors where you will find "NOT
> so great signal". These points should be addressed as well.
> >
> > 73
> >
> > Bob, K4TAX
> >
> >
> >> On 2/28/2019 1:04 PM, [hidden email] wrote:
> >> I have not used ALC with any amplifier since transceivers switched to
> transistor finals. From what I have read on this list, using ALC improperly
> can cause distortion. Just be very careful with your drive level. I
> believe that the KPA500 can handle 100 watts in bypass, 200 watts may be
> pushing it. The KPA500 is a very nice amp and it is easy to use with any
> transceiver.
> >>
> >> GL,
> >> John KK9A
> >>
> >>
> >> JIM LAGESON N0UR wrote
> >> _Thu Feb 28 13:07:27 EST 2019_
> >>
> >>
> >> -------------------------
> >>
> >> I have never owned an amp before and recently put together a KPA500. All
> >> seems to be working well, but I have a few questions. I am using with a
> >> IC-7300.
> >>
> >> How important is the ALC cable? I notice it is not included in the Basic
> >> Cabling Diagram in the manual but is discussed later in the manual.
> >>
> >> If I were accidently to run 100 watts into the KPA500 will the PWRIN HI
> >> Hard Fault/STBY protect itself before any damage is done. Would ALC
> protect
> >> me from that?
> >>
> >> Is it standard procedure to keep the KPA500 in line when turned off and
> not
> >> in use? I see you may run up to 200 through the KPA500 in STBY.
> >>
> >> Is there any concerns or settings on radio when running full break in
> on CW?
> >>
> >> Thanks
> >> Jim-N0UR
> >> ______________________________________________________________
> >> 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]
> >
> > 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]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

K9MA

Re: [ELECRAFT] KPA500 NEW OWNER QUESTIONS.......

In reply to this post by Bob McGraw - K4TAX

Many years ago, I built a tube amplifier with what I thought was a
fairly sophisticated ALC circuit. I could never get the ALC loop to be
stable. I know a lot more about control systems now, but I still don't
know how to get ALC around an amplifier to work, and apparently neither
does anyone else. What I don't understand is why it's so hard with an
external amplifier, as every transmitter has ALC for its internal 100 W
amplifier, and that works fine. Why the same design doesn't work with an
external amplifier is the mystery.

The problem with just limiting the drive power and using the
transmitter's ALC is that, especially for solid state amplifiers, the
required drive power can vary considerably with SWR and temperature.
That requires either riding the power control continuously or running
your amplifier well below rated output most of the time. (Unless, of
course, you're running a 2.5 kW amplifier, but that kind of margin is
expensive.) So, if anyone could figure out how to get ALC to really work
with an amplifier, I think that would be worth paying extra for.

73,
Scott K9MA

On 2/28/2019 13:12, Bob McGraw K4TAX wrote:

> Yes, improperly or incorrectly using ALC with any amp or any
> transceiver, for that matter, can and usually does produce distortion
> and splatter.   Just look at some of the signals on the bands and
> observe the ALC overshoot which exists with many radios. And it is
> made worse by the addition of an amplifier in line. It isn't
> pretty!.   Yet it has little impact on the on frequency signal as
> heard and thus the "great signal" complements follow. But look at the
> other factors where you will find "NOT so great signal".   These
> points should be addressed as well.
>
> 73
>
> Bob, K4TAX
>
>
> On 2/28/2019 1:04 PM, [hidden email] wrote:
>> I have not used ALC with any amplifier since transceivers switched to
>> transistor finals. From what I have read on this list, using ALC
>> improperly can cause distortion. Just be very careful with your
>> drive level. I believe that the KPA500 can handle 100 watts in
>> bypass, 200 watts may be pushing it. The KPA500 is a very nice amp
>> and it is easy to use with any transceiver.
>>
>> GL,
>> John KK9A
>>
>>
>> JIM LAGESON N0UR wrote
>> _Thu Feb 28 13:07:27 EST 2019_
>>
>>
>> -------------------------
>>
>> I have never owned an amp before and recently put together a KPA500. All
>> seems to be working well, but I have a few questions. I am using with a
>> IC-7300.
>>
>> How important is the ALC cable? I notice it is not included in the Basic
>> Cabling Diagram in the manual but is discussed later in the manual.
>>
>> If I were accidently to run 100 watts into the KPA500 will the PWRIN HI
>> Hard Fault/STBY protect itself before any damage is done. Would ALC
>> protect
>> me from that?
>>
>> Is it standard procedure to keep the KPA500 in line when turned off
>> and not
>> in use? I see you may run up to 200 through the KPA500 in STBY.
>>
>> Is there any concerns or settings on radio when running full break in
>> on CW?
>>
>> Thanks
>> Jim-N0UR ml

--
Scott K9MA

[hidden email]

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Bob McGraw - K4TAX

Re: [ELECRAFT] KPA500 NEW OWNER QUESTIONS.......

This fellow seems to have a good handle on the ALC issue as it relates
to overshoot in the transceiver.

https://www.w8ji.com/alc_exciter_power_overshoot.htm

Here Tom goes into the discussion of good ALC vs. bad ALC systems.

https://www.w8ji.com/ameritron_alc_adjustment.htm

73
Bob, K4TAX

On 2/28/2019 8:51 PM, K9MA wrote:

> Many years ago, I built a tube amplifier with what I thought was a
> fairly sophisticated ALC circuit. I could never get the ALC loop to be
> stable. I know a lot more about control systems now, but I still don't
> know how to get ALC around an amplifier to work, and apparently
> neither does anyone else. What I don't understand is why it's so hard
> with an external amplifier, as every transmitter has ALC for its
> internal 100 W amplifier, and that works fine. Why the same design
> doesn't work with an external amplifier is the mystery.
>
> The problem with just limiting the drive power and using the
> transmitter's ALC is that, especially for solid state amplifiers, the
> required drive power can vary considerably with SWR and temperature.
> That requires either riding the power control continuously or running
> your amplifier well below rated output most of the time. (Unless, of
> course, you're running a 2.5 kW amplifier, but that kind of margin is
> expensive.) So, if anyone could figure out how to get ALC to really
> work with an amplifier, I think that would be worth paying extra for.
>
> 73,
> Scott K9MA
>

NK7Z

Re: [ELECRAFT] KPA500 NEW OWNER QUESTIONS.......

In reply to this post by k4vd

Logs? Can you expand on that a bit? Does the KPA500 keep logs? How
are they available please?

73s and thanks,
Dave (NK7Z)
https://www.nk7z.net
Award Manager, 30MDG Grid Awards
ARRL Technical Specialist
ARRL Volunteer Examiner
ARRL OOC for Oregon

On 2/28/19 1:35 PM, Kevin der Kinderen wrote:

It appears, after reviewing the logs, I hit it with 75 watts and
probably blew one of the diodes in the front end.
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bdenley

Re: [ELECRAFT] KPA500 NEW OWNER QUESTIONS.......

In reply to this post by Bob McGraw - K4TAX

Thanks for that. I never understood the Ameritron ALC instruction for my ALS-600 so I just never used the ALC. That attached instruction was much clearer and made sense.

Brian Denley
KB1VBF
Sent from my iPad

> On Feb 28, 2019, at 10:19 PM, Bob McGraw K4TAX <[hidden email]> wrote:
>
> This fellow seems to have a good handle on the ALC issue as it relates to overshoot in the transceiver.
>
> https://www.w8ji.com/alc_exciter_power_overshoot.htm
>
>
> Here Tom goes into the discussion of good ALC vs. bad ALC systems.
>
> https://www.w8ji.com/ameritron_alc_adjustment.htm
>
>
> 73
> Bob, K4TAX
>
>
>
>> On 2/28/2019 8:51 PM, K9MA wrote:
>> Many years ago, I built a tube amplifier with what I thought was a fairly sophisticated ALC circuit. I could never get the ALC loop to be stable. I know a lot more about control systems now, but I still don't know how to get ALC around an amplifier to work, and apparently neither does anyone else. What I don't understand is why it's so hard with an external amplifier, as every transmitter has ALC for its internal 100 W amplifier, and that works fine. Why the same design doesn't work with an external amplifier is the mystery.
>>
>> The problem with just limiting the drive power and using the transmitter's ALC is that, especially for solid state amplifiers, the required drive power can vary considerably with SWR and temperature. That requires either riding the power control continuously or running your amplifier well below rated output most of the time. (Unless, of course, you're running a 2.5 kW amplifier, but that kind of margin is expensive.) So, if anyone could figure out how to get ALC to really work with an amplifier, I think that would be worth paying extra for.
>>
>> 73,
>> Scott K9MA
>>
>
> ______________________________________________________________
> Elecraft mailing list
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Rick WA6NHC-2

Re: [ELECRAFT] KPA500 NEW OWNER QUESTIONS.......

In reply to this post by NK7Z

You can pull them via the KPA500 utility; Configuration Tab, Fault table.

Rick nhc

On 2/28/2019 9:08 PM, Dave Cole (NK7Z) wrote:

> Logs? Can you expand on that a bit? Does the KPA500 keep logs? How
> are they available please?
>
> 73s and thanks,
> Dave (NK7Z)
> https://www.nk7z.net
> Award Manager, 30MDG Grid Awards
> ARRL Technical Specialist
> ARRL Volunteer Examiner
> ARRL OOC for Oregon
>
> On 2/28/19 1:35 PM, Kevin der Kinderen wrote:
>
> It appears, after reviewing the logs, I hit it with 75 watts and
> probably blew one of the diodes in the front end.
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
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Don Wilhelm

Re: [ELECRAFT] KPA500 NEW OWNER QUESTIONS.......

In reply to this post by Bob McGraw - K4TAX

In this discussion about ALC, I have to inject a bit of fact.
The Elecraft transceivers K2/K3/K3S/KX2/KX3 use a power control system
that is different from all other amateur transceivers, and unless there
is a problem with the transceiver, there is no power overshoot. In
fact, after a band change or a power setting change, the RF starts at a
low level and builds up to the power knob setting after a dit time or a
few syllables on voice.

That means amplifier ALC is not necessary, and if used should never be
used for power level control (doing that will cause distortion).

W8JI - Tom Rauch is responding to operation with most transceivers
driving the amplifier. With the Elecraft transceivers, the amplifier's
ALC indicator should never come on unless there is an amplifier fault
condition - high SWR, no antenna, etc.
Tom W8JI should know - he designed several of the Ameritron amplifiers.

Operated properly, there is no need for ALC at all, especially with
those amplifiers employing cathode or grid detection of overload. For
the amplifiers with more sophisticated fault detection, connecting the
ALC line to the driving transceiver is OK because it allows the
amplifier to shut down (or reduce power) the transceiver if a fault is
detected.

As Tom pointed out in at the end of his article, ALC should not be used
as a power control mechanism - doing so will only lead to distortion.

73,
Don W3FPR

On 2/28/2019 10:19 PM, Bob McGraw K4TAX wrote:
> This fellow seems to have a good handle on the ALC issue as it relates
> to overshoot in the transceiver.
>
> https://www.w8ji.com/alc_exciter_power_overshoot.htm
>
>
> Here Tom goes into the discussion of good ALC vs. bad ALC systems.
>
> https://www.w8ji.com/ameritron_alc_adjustment.htm
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