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KPA-1500 wish list

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N4ZR

KPA-1500 wish list

Here's one that I kept running into. My K3/KPA-1500 when operating at
one end of the band on 40 and 80, would work fine, but when I went to
the other end I found that often I would be running over 1500 watts,
and sometimes, the result would be reflected power exceeding 200 watts,
causing a fault. For those of us who have the Aux port cable connected,
wouldn't it be pretty simple for the KPA-1500 to turn down the K3's
power to limit output to 1500 watts?

--

73, Pete N4ZR
Check out the Reverse Beacon Network
at <http://reversebeacon.net>, now
spotting RTTY activity worldwide.
For spots, please use your favorite
"retail" DX cluster.

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Rick Tavan-2

Re: KPA-1500 wish list

I'd love to have something like this, Pete! It's not only frequency
excursions that cause output fluctuations but also warm-up. The gain of the
power transistors is temperature-sensitive. I'd like to be able to set a
target output power (typically 1500w but maybe less on bands with
mismatched antennas or in countries with lower power limits), have
*something* monitor it, and send drive adjustment commands to the K3 via
sharing the serial port. (The commands exist - PC and PO.) It's not the
same as AGC which is analog and real-time and can cause distortion. I've
called it "Slow AGC" because it would only operate every second or so,
perhaps taking multiple cycles to recover a desired output power and
causing no measurable distortion. It would essentially duplicate what we do
manually - keep a sharp eye on the power and tweak the K3 PWR control
appropriately. That's not only a significant drain on brain and muscle
cycles over the course of a long operating session as in contesting but
also useful in less extended situations like the excitement of a DX pileup.
It would require software in the KPA1500 and maybe also an external box or
computer where port sharing would take place. (It could also be done
entirely external to the KPA1500 by replicating its power sensing
circuitry, a bit of a waste.) It's not trivial but I'm convinced it's
possible.

73,

/Rick N6XI

On Mon, Nov 18, 2019 at 8:31 AM N4ZR <[hidden email]> wrote:

> Here's one that I kept running into. My K3/KPA-1500 when operating at
> one end of the band on 40 and 80, would work fine, but when I went to
> the other end I found that often I would be running over 1500 watts,
> and sometimes, the result would be reflected power exceeding 200 watts,
> causing a fault. For those of us who have the Aux port cable connected,
> wouldn't it be pretty simple for the KPA-1500 to turn down the K3's
> power to limit output to 1500 watts?
>
> --
>
> 73, Pete N4ZR
> Check out the Reverse Beacon Network
> at <http://reversebeacon.net>, now
> spotting RTTY activity worldwide.
> For spots, please use your favorite
> "retail" DX cluster.
>
> ______________________________________________________________
> 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]

Doug Turnbull

Re: KPA-1500 wish list

Dear OMs and YLs,
Why not just run 1400 Watts. The difference in power will never be
noticed by anyone you are working. It should reduce stress on the KPA1500
components. Though feedback which is after all what we are talking about
can not only reduce distortion but in some instances introduce distortion;
ALC being just one example. If your SWR forces the return power to over
200 Watts then it seems to me there is the more important problem to
address.

I am sorry if I have stepped on any toes. This is not my intent. I
too run a KPA 1500 which is a delight.

73 Doug EI2CN

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Rick Tavan
Sent: 18 November 2019 17:45
To: N4ZR; Elecraft Reflector
Subject: Re: [Elecraft] KPA-1500 wish list

I'd love to have something like this, Pete! It's not only frequency
excursions that cause output fluctuations but also warm-up. The gain of the
power transistors is temperature-sensitive. I'd like to be able to set a
target output power (typically 1500w but maybe less on bands with
mismatched antennas or in countries with lower power limits), have
*something* monitor it, and send drive adjustment commands to the K3 via
sharing the serial port. (The commands exist - PC and PO.) It's not the
same as AGC which is analog and real-time and can cause distortion. I've
called it "Slow AGC" because it would only operate every second or so,
perhaps taking multiple cycles to recover a desired output power and
causing no measurable distortion. It would essentially duplicate what we do
manually - keep a sharp eye on the power and tweak the K3 PWR control
appropriately. That's not only a significant drain on brain and muscle
cycles over the course of a long operating session as in contesting but
also useful in less extended situations like the excitement of a DX pileup.
It would require software in the KPA1500 and maybe also an external box or
computer where port sharing would take place. (It could also be done
entirely external to the KPA1500 by replicating its power sensing
circuitry, a bit of a waste.) It's not trivial but I'm convinced it's
possible.

73,

/Rick N6XI

On Mon, Nov 18, 2019 at 8:31 AM N4ZR <[hidden email]> wrote:

--
--

Rick Tavan
Truckee and Saratoga, CA
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Bob McGraw - K4TAX

Re: KPA-1500 wish list

At risk of starting a FIRE storm here in the group, why not CORRECTLY
configure the ALC between the amp and radio. Just remember it is not a
power control application but no different than the normal ALC in your
radio. You do use that don't you? And you can see the amp ALC on the
K3S display ALC indication. It will let you know if you are punching it
too hard.

73

Bob, K4TAX

On 11/18/2019 11:55 AM, Doug Turnbull wrote:

> Dear OMs and YLs,
> Why not just run 1400 Watts. The difference in power will never be
> noticed by anyone you are working. It should reduce stress on the KPA1500
> components. Though feedback which is after all what we are talking about
> can not only reduce distortion but in some instances introduce distortion;
> ALC being just one example. If your SWR forces the return power to over
> 200 Watts then it seems to me there is the more important problem to
> address.
>
> I am sorry if I have stepped on any toes. This is not my intent. I
> too run a KPA 1500 which is a delight.
>
> 73 Doug EI2CN
>
> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of Rick Tavan
> Sent: 18 November 2019 17:45
> To: N4ZR; Elecraft Reflector
> Subject: Re: [Elecraft] KPA-1500 wish list
>
> I'd love to have something like this, Pete! It's not only frequency
> excursions that cause output fluctuations but also warm-up. The gain of the
> power transistors is temperature-sensitive. I'd like to be able to set a
> target output power (typically 1500w but maybe less on bands with
> mismatched antennas or in countries with lower power limits), have
> *something* monitor it, and send drive adjustment commands to the K3 via
> sharing the serial port. (The commands exist - PC and PO.) It's not the
> same as AGC which is analog and real-time and can cause distortion. I've
> called it "Slow AGC" because it would only operate every second or so,
> perhaps taking multiple cycles to recover a desired output power and
> causing no measurable distortion. It would essentially duplicate what we do
> manually - keep a sharp eye on the power and tweak the K3 PWR control
> appropriately. That's not only a significant drain on brain and muscle
> cycles over the course of a long operating session as in contesting but
> also useful in less extended situations like the excitement of a DX pileup.
> It would require software in the KPA1500 and maybe also an external box or
> computer where port sharing would take place. (It could also be done
> entirely external to the KPA1500 by replicating its power sensing
> circuitry, a bit of a waste.) It's not trivial but I'm convinced it's
> possible.
>
> 73,
>
> /Rick N6XI
>
> On Mon, Nov 18, 2019 at 8:31 AM N4ZR <[hidden email]> wrote:
>
>> Here's one that I kept running into. My K3/KPA-1500 when operating at
>> one end of the band on 40 and 80, would work fine, but when I went to
>> the other end I found that often I would be running over 1500 watts,
>> and sometimes, the result would be reflected power exceeding 200 watts,
>> causing a fault. For those of us who have the Aux port cable connected,
>> wouldn't it be pretty simple for the KPA-1500 to turn down the K3's
>> power to limit output to 1500 watts?
>>
>> --
>>
>> 73, Pete N4ZR
>> Check out the Reverse Beacon Network
>> at <http://reversebeacon.net>, now
>> spotting RTTY activity worldwide.
>> For spots, please use your favorite
>> "retail" DX cluster.
>>
>> ______________________________________________________________
>> 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]
>
>

Doug Turnbull

Re: KPA-1500 wish list

Bob,
I was thinking of ALC between K3 and an external amplifier. Your
point is taken; first trim the K3 properly.
73 Doug EI2CN

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Bob McGraw K4TAX
Sent: 18 November 2019 18:08
To: [hidden email]
Subject: Re: [Elecraft] KPA-1500 wish list

At risk of starting a FIRE storm here in the group, why not CORRECTLY
configure the ALC between the amp and radio. Just remember it is not a
power control application but no different than the normal ALC in your
radio. You do use that don't you? And you can see the amp ALC on the
K3S display ALC indication. It will let you know if you are punching it
too hard.

73

Bob, K4TAX

On 11/18/2019 11:55 AM, Doug Turnbull wrote:
> Dear OMs and YLs,
> Why not just run 1400 Watts. The difference in power will never
be
> noticed by anyone you are working. It should reduce stress on the
KPA1500
> components. Though feedback which is after all what we are talking about
> can not only reduce distortion but in some instances introduce distortion;
> ALC being just one example. If your SWR forces the return power to over
> 200 Watts then it seems to me there is the more important problem to
> address.
>
> I am sorry if I have stepped on any toes. This is not my intent.
I

> too run a KPA 1500 which is a delight.
>
> 73 Doug EI2CN
>
> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of Rick Tavan
> Sent: 18 November 2019 17:45
> To: N4ZR; Elecraft Reflector
> Subject: Re: [Elecraft] KPA-1500 wish list
>
> I'd love to have something like this, Pete! It's not only frequency
> excursions that cause output fluctuations but also warm-up. The gain of

the
> power transistors is temperature-sensitive. I'd like to be able to set a
> target output power (typically 1500w but maybe less on bands with
> mismatched antennas or in countries with lower power limits), have
> *something* monitor it, and send drive adjustment commands to the K3 via
> sharing the serial port. (The commands exist - PC and PO.) It's not the
> same as AGC which is analog and real-time and can cause distortion. I've
> called it "Slow AGC" because it would only operate every second or so,
> perhaps taking multiple cycles to recover a desired output power and
> causing no measurable distortion. It would essentially duplicate what we
do
> manually - keep a sharp eye on the power and tweak the K3 PWR control
> appropriately. That's not only a significant drain on brain and muscle
> cycles over the course of a long operating session as in contesting but
> also useful in less extended situations like the excitement of a DX
pileup.

> It would require software in the KPA1500 and maybe also an external box or
> computer where port sharing would take place. (It could also be done
> entirely external to the KPA1500 by replicating its power sensing
> circuitry, a bit of a waste.) It's not trivial but I'm convinced it's
> possible.
>
> 73,
>
> /Rick N6XI
>
> On Mon, Nov 18, 2019 at 8:31 AM N4ZR <[hidden email]> wrote:
>
>> Here's one that I kept running into. My K3/KPA-1500 when operating at
>> one end of the band on 40 and 80, would work fine, but when I went to
>> the other end I found that often I would be running over 1500 watts,
>> and sometimes, the result would be reflected power exceeding 200 watts,
>> causing a fault. For those of us who have the Aux port cable connected,
>> wouldn't it be pretty simple for the KPA-1500 to turn down the K3's
>> power to limit output to 1500 watts?
>>
>> --
>>
>> 73, Pete N4ZR
>> Check out the Reverse Beacon Network
>> at <http://reversebeacon.net>, now
>> spotting RTTY activity worldwide.
>> For spots, please use your favorite
>> "retail" DX cluster.
>>
>> ______________________________________________________________
>> 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]
>
>

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ANDY DURBIN

KPA-1500 wish list

In reply to this post by N4ZR

"(It could also be done entirely external to the KPA1500 by replicating its power sensing circuitry, a bit of a waste.) It's not trivial but I'm convinced it's
possible."

I'm no expert on amplifier design but wouldn't it be more appropriate to have (slow) closed loop control of the amplifier gain? Couldn't that be done internal to the KPA1500 without any need to control exciter drive power?

If the gain gain change is caused mainly by PA temperature changes couldn't that be compensated open loop. The finals temperature is already known to the controller.

Why develop a complex closed loop power control system if the problem could be fixed by stabilizing the amplifier gain?

Andy, k3wyc
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Paul Baldock

Re: KPA-1500 wish list

In reply to this post by N4ZR

In my experience for the amplifier gain to be
flat across a band it requires the output SWR to
1.1:1 or better. So the solution is to use the
internal tuner on all frequencies that you do not
have a perfect match. I have manually tweaked
(with amp in standby and running 50W) my auto
learned atu settings to get as close to 0W
reflected power as possible. It takes a while to do this but its worth it.

- Paul; KW7Y

At 08:29 AM 11/18/2019, N4ZR wrote:

>Here's one that I kept running into.Â My
>K3/KPA-1500 when operating at one end of the
>band on 40 and 80, would work fine, but when I
>went to the other endÂ I found that often I
>would be running over 1500 watts, and sometimes,
>the result would be reflected power exceeding
>200 watts, causing a fault.Â For those of us
>who have the Aux port cable connected, wouldn't
>it be pretty simple for the KPA-1500 to turn
>down the K3's power to limit output to 1500
>watts? -- 73, Pete N4ZR Check out the Reverse
>Beacon Network at <http://reversebeacon.net>,
>now spotting RTTY activity worldwide. For spots,
>please use your favorite "retail" DX cluster.
>______________________________________________________________
>Elecraft mailing list Home:
>http://mailman.qth.net/mailman/listinfo/elecraft
>Help: http://mailman.qth.net/mmfaq.htm Post:
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>by: http://www.qsl.net Please help support this
>email list: http://www.qsl.net/donate.html
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Jim Brown-10

Re: KPA-1500 wish list

On 11/18/2019 11:34 AM, Paul Baldock wrote:
> I have manually tweaked (with amp in standby and running 50W) my auto
> learned atu settings to get as close to 0W reflected power as possible.

Yes, and this is exactly what the manual says to do -- before using the
amp, train the tuner by tuning at multiple frequencies in each band, AND
for each antenna that you use on that band. The tuner is smart enough to
select between multiple "trainings" when you use more than one antenna.

73, Jim K9YC
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Bob McGraw - K4TAX

Re: KPA-1500 wish list

Yes and I have trained my tuner to use the same frequency on different
antennas. Thus when I switch antennas it does not require any
re-tuning, only push the ANT selector for the preferred antenna of
choice at the moment.

73

Bob, K4TAX

On 11/18/2019 7:18 PM, Jim Brown wrote:

> On 11/18/2019 11:34 AM, Paul Baldock wrote:
>> I have manually tweaked (with amp in standby and running 50W) my auto
>> learned atu settings to get as close to 0W reflected power as possible.
>
> Yes, and this is exactly what the manual says to do -- before using
> the amp, train the tuner by tuning at multiple frequencies in each
> band, AND for each antenna that you use on that band. The tuner is
> smart enough to select between multiple "trainings" when you use more
> than one antenna.
>
> 73, Jim K9YC
> ______________________________________________________________
> 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]

N4ZR

Re: KPA-1500 wish list

In reply to this post by Jim Brown-10

Jim, I think Paul is talking about something different here. On Page 18
of the manual it describes tapping the ATU Tune button again within 3
seconds of completing the initial tune, to get closer yet. I just tried
it, and it works well so long as you have trained the tuner for both
antennas on every segment. Unfortunately, there appears to be no way to
actually transmit the first character at full power when changing
antennas or QSYing bigly. I understand the tuner bypasses the amp until
it has determined which setting it should use, which it can only do by
learning what the load looks like by actually sending power into it.

73, Pete N4ZR
Check out the Reverse Beacon Network
at <http://reversebeacon.net>, now
spotting RTTY activity worldwide.
For spots, please use your favorite
"retail" DX cluster.

On 11/18/2019 8:18 PM, Jim Brown wrote:

K9MA

Re: KPA-1500 wish list

There are a couple issues here.

First, even if the SWR is 1.2:1, about the best the KP1500 ATU firmware
can do, across the whole band, the power can still vary a lot. It
depends on the actual load impedance, which, at 1.2:1 could be anywhere
from 42 to 60 Ohms. If you happened to be at 42 Ohms when you set the
power to 1500 W, it could possibly go up to 2100 W elsewhere in the
band. (Except, of course, that the KPA1500 won't let you do that.) The
other issue is the temperature dependence: I find I have to reduce drive
by about 20 percent when the amplifier is cold, or it will fault. Both
of these problems could be solved by a slow feedback mechanism which
adjusted the K3 output like we do manually. It might even remember
previous settings as a function of PA temperature and frequency.

The second issue is that this is nothing like conventional ALC, a
relatively fast feedback loop. ALC has proven to be highly problematic,
so let's not go into that again. It's an entirely different issue. Yes,
ALC that really worked well with an amplifier would make the above
unnecessary, but I don't think anyone has figured out how to do that.
Until someone does, a slow feedback loop adjusting drive power would
solve the problem above, not introduce any distortion, and save us
operators the bother of riding the power control.

73,
Scott K9MA

On 11/18/2019 20:32, N4ZR wrote:

> Jim, I think Paul is talking about something different here. On Page
> 18 of the manual it describes tapping the ATU Tune button again within
> 3 seconds of completing the initial tune, to get closer yet. I just
> tried it, and it works well so long as you have trained the tuner for
> both antennas on every segment. Unfortunately, there appears to be no
> way to actually transmit the first character at full power when
> changing antennas or QSYing bigly. I understand the tuner bypasses
> the amp until it has determined which setting it should use, which it
> can only do by learning what the load looks like by actually sending
> power into it.
>
> 73, Pete N4ZR
> Check out the Reverse Beacon Network
> at <http://reversebeacon.net>, now
> spotting RTTY activity worldwide.
> For spots, please use your favorite
> "retail" DX cluster.
>
> On 11/18/2019 8:18 PM, Jim Brown wrote:
>> On 11/18/2019 11:34 AM, Paul Baldock wrote:
>>> I have manually tweaked (with amp in standby and running 50W) my
>>> auto learned atu settings to get as close to 0W reflected power as
>>> possible.
>>
>> Yes, and this is exactly what the manual says to do -- before using
>> the amp, train the tuner by tuning at multiple frequencies in each
>> band, AND for each antenna that you use on that band. The tuner is
>> smart enough to select between multiple "trainings" when you use more
>> than one antenna.
>>
>> 73, Jim K9YC
>> ______________________________________________________________

--
Scott K9MA

[hidden email]

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Paul Baldock

Re: KPA-1500 wish list

By "manually tuning" I mean using KPA1500 Utility
program to tweak the L and C. In most cases you
can get closer to zero reflected power than the
automatic routine can. Getting the SWR down as
close as possibly to 1.0:1 at all frequencies
most certainly flattens the gain/frequency response.

If you know how to use the Utility program try it. You might be surprised.

You should also investigate the ^PB command, very
useful if you have a high Q antenna. The ^PB
command chooses the stored setting for the lowest
SWR within a segment. I have this mapped to PF1
on the front panel and use it on 160M where the
tuning segments are wide compared to the fast
changing SWR (high Q) of my antenna. I also have
WET and DRY settings for one of my antennas that are selected by PF1 (^PB).

- Paul KW7Y

at 07:19 PM 11/18/2019, K9MA wrote:

>There are a couple issues here. First, even if
>the SWR is 1.2:1, about the best the KP1500 ATU
>firmware can do, across the whole band, the
>power can still vary a lot. It depends on the
>actual load impedance, which, at 1.2:1 could be
>anywhere from 42 to 60 Ohms. If you happened to
>be at 42 Ohms when you set the power to 1500 W,
>it could possibly go up to 2100 W elsewhere in
>the band. (Except, of course, that the KPA1500
>won't let you do that.) The other issue is the
>temperature dependence: I find I have to reduce
>drive by about 20 percent when the amplifier is
>cold, or it will fault. Both of these problems
>could be solved by a slow feedback mechanism
>which adjusted the K3 output like we do
>manually. It might even remember previous
>settings as a function of PA temperature and
>frequency. The second issue is that this is
>nothing like conventional ALC, a relatively fast
>feedback loop. ALC has proven to be highly
>problematic, so let's not go into that again.
>It's an entirely different issue. Yes, ALC that
>really worked well with an amplifier would make
>the above unnecessary, but I don't think anyone
>has figured out how to do that. Until someone
>does, a slow feedback loop adjusting drive power
>would solve the problem above, not introduce any
>distortion, and save us operators the bother of
>riding the power control. 73, Scott K9MA On
>11/18/2019 20:32, N4ZR wrote: > Jim, I think
>Paul is talking about something different
>here.Â On Page > 18 of the manual it describes
>tapping the ATU Tune button again within > 3
>seconds of completing the initial tune, to get
>closer yet.Â I just > tried it, and it works
>well so long as you have trained the tuner for >
>both antennas on every segment. Unfortunately,
>there appears to be no > way to actually
>transmit the first character at full power
>when > changing antennas or QSYing bigly.Â I
>understand the tuner bypasses > the amp until it
>has determined which setting it should use,
>which it > can only do by learning what the load
>looks like by actually sending > power into
>it. > > 73, Pete N4ZR > Check out the Reverse
>Beacon Network > at <http://reversebeacon.net>,
>now > spotting RTTY activity worldwide. > For
>spots, please use your favorite > "retail" DX
>cluster. > > On 11/18/2019 8:18 PM, Jim Brown
>wrote: >> On 11/18/2019 11:34 AM, Paul Baldock
>wrote: >>> I have manually tweaked (with amp in
>standby and running 50W) my >>> auto learned atu
>settings to get as close to 0W reflected power
>as >>> possible. >> >> Yes, and this is exactly
>what the manual says to do -- before using >>
>the amp, train the tuner by tuning at multiple
>frequencies in each >> band, AND for each
>antenna that you use on that band. The tuner
>is >> smart enough to select between multiple
>"trainings" when you use more >> than one
>antenna. >> >> 73, Jim K9YC >>
>______________________________________________________________
>-- Scott K9MA [hidden email]
>______________________________________________________________
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K9MA

Re: KPA-1500 wish list

On 11/18/2019 21:52, Paul Baldock wrote:
> I also have WET and DRY settings for one of my antennas that are
> selected by PF1 (^PB).

Ah, but there can be more than two setting. A little wet, or a lot wet.
Or, in the case of one of my antennas, varying amounts of frost.

73,

Scott K9MA

--
Scott K9MA

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ANDY DURBIN

Re: KPA-1500 wish list

In reply to this post by ANDY DURBIN

"Yes, ALC that really worked well with an amplifier would make the above
unnecessary, but I don't think anyone has figured out how to do that.
Until someone does, a slow feedback loop adjusting drive power would
solve the problem above, not introduce any distortion, and save us
operators the bother of riding the power control."

The significant problem with implementing closed loop power control is that it would only work (if it could work at all) with an Elecraft transceiver connected by the AUX cable. The KPA1500 is marketed as being compatible with non-Elecraft transceivers.

Gain control contained within the KPA1500 would be an advantage to all KPA1500 owners, not just those with a fully integrated Elecraft transceiver.

Andy, k3wyc

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K9MA

Re: KPA-1500 wish list

Gain control within the KPA1500 just wouldn't be practical. It would
require addition of some sort of high power variable attenuator. Slow
feedback to the K3, however, only requires some added firmware. No, it
wouldn't work with other transceivers, but that's life. Perhaps someone
would like to design an external box or write some PC software to
perform that function.

73,
Scott K9MA

On 11/19/2019 06:55, Andy Durbin wrote:

> "Yes, ALC that really worked well with an amplifier would make the above
> unnecessary, but I don't think anyone has figured out how to do that.
> Until someone does, a slow feedback loop adjusting drive power would
> solve the problem above, not introduce any distortion, and save us
> operators the bother of riding the power control."
>
> The significant problem with implementing closed loop power control is that it would only work (if it could work at all) with an Elecraft transceiver connected by the AUX cable. The KPA1500 is marketed as being compatible with non-Elecraft transceivers.
>
> Gain control contained within the KPA1500 would be an advantage to all KPA1500 owners, not just those with a fully integrated Elecraft transceiver.
>
> Andy, k3wyc
>
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
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>
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K8TE

Re: KPA-1500 wish list

In reply to this post by N4ZR

Another issue not explicitly mentioned is using an external antenna switch
with different conjugate matches already trained withing the KPA1500 ATU.
Those different matches mean when one selects a "new" (different) antenna
than already selected on a particular frequency (same band or not), the
KPA1500 doesn't know this fact until power is applied. Then, due to a high
VSWR, the amplifier faults.

With just two antenna ports on the KPA1500, there are only two quickly
accessible tuning solutions per frequency if using both ports. If using
only one port and an external antenna switch, a common choice in many
stations, finding the correct tuning solutions can't be done fast enough to
prevent a fault.

As alluded to in previous messages on this topic, perhaps the solution,
unfortunately, is an external box that could contain the appropriate data so
that, when a new frequency/antenna combination, that has a previously tuning
solution, is selected, the external box will tell both the KPA1500 ATU to
select the appropriate solution and transceiver to make appropriate power
level adjustments, both PRIOR to actually transmitting.

This is done (approximately, but with no power level changes) by the KAT500
in selecting one of the three antenna ports and the appropriate tuning
solution. This assumes no other antenna choices on each of the three ports
for the same frequency. The KPA1500/K3S combination is (currently) not
sufficiently "smart" to accomplish this.

Of course, if we had "perfect" antennas that provided resonant matches on
all bands/frequencies, we wouldn't be discussing this. If we had those, we
wouldn't need the KPA1500 ATU either. 73, Bill, K8TE

--
Sent from: http://elecraft.365791.n2.nabble.com/
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Lyn WØLEN

Re: KPA-1500 wish list

In reply to this post by K9MA

Now you've done it ... created a whole new category of products to wish for
... at least for those of us in the frozen North:

THE ANTENNA DE-ICER!

Imagine, if you will, a device that would initiate a series of super slow CW
(Testing + <your call sign> + + ) transmissions at full legal power
combined with a short, quick back-and-forth rotator motion sequence designed
to loosen - and then shake - the ice off your beam as the long, gangly
elements wobble in a pre-determined fashion.

Imagine also all the problems and design challenges to be overcome with
respect to the involved components.

The possibilities are staggering!

73

Lyn, WØLEN

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of K9MA
Sent: Monday, November 18, 2019 10:00 PM
To: Paul Baldock; [hidden email]
Subject: Re: [Elecraft] KPA-1500 wish list

On 11/18/2019 21:52, Paul Baldock wrote:

> I also have WET and DRY settings for one of my antennas that are

> selected by PF1 (^PB).

Ah, but there can be more than two setting. A little wet, or a lot wet.

Or, in the case of one of my antennas, varying amounts of frost.

73,

Scott K9MA

--

Scott K9MA

[hidden email]

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K9MA

Re: KPA-1500 wish list

In reply to this post by K8TE

Bill is touching on an issue I've raised before: A way to select
multiple ATU settings for the same frequency and antenna output. I had
to build a tri-band tuner to switch between my two tribanders so they
would both present the amplifier with the same impedance. The internal
ATU would have been able to do that, if only there were a way to store
and recall two different sets of settings. In the case of automated
antenna switching systems like mine, there also has to be a way to
electronically tell the amplifier which settings to use: Having to press
a front panel switch is not acceptable, as that would require two
operations to switch antennas, which is way too slow. (I sometimes have
to flip the antenna switch several times during a call to determine
which antenna to use.)

73,
Scott K9MA

On 11/19/2019 13:02, K8TE wrote:

> Another issue not explicitly mentioned is using an external antenna switch
> with different conjugate matches already trained withing the KPA1500 ATU.
> Those different matches mean when one selects a "new" (different) antenna
> than already selected on a particular frequency (same band or not), the
> KPA1500 doesn't know this fact until power is applied. Then, due to a high
> VSWR, the amplifier faults.
>
> With just two antenna ports on the KPA1500, there are only two quickly
> accessible tuning solutions per frequency if using both ports. If using
> only one port and an external antenna switch, a common choice in many
> stations, finding the correct tuning solutions can't be done fast enough to
> prevent a fault.
>
> As alluded to in previous messages on this topic, perhaps the solution,
> unfortunately, is an external box that could contain the appropriate data so
> that, when a new frequency/antenna combination, that has a previously tuning
> solution, is selected, the external box will tell both the KPA1500 ATU to
> select the appropriate solution and transceiver to make appropriate power
> level adjustments, both PRIOR to actually transmitting.
>
> This is done (approximately, but with no power level changes) by the KAT500
> in selecting one of the three antenna ports and the appropriate tuning
> solution. This assumes no other antenna choices on each of the three ports
> for the same frequency. The KPA1500/K3S combination is (currently) not
> sufficiently "smart" to accomplish this.
>
> Of course, if we had "perfect" antennas that provided resonant matches on
> all bands/frequencies, we wouldn't be discussing this. If we had those, we
> wouldn't need the KPA1500 ATU either. 73, Bill, K8TE
>
>
>
> --
> Sent from: http://elecraft.365791.n2.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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> Message delivered to [hidden email]

N4ZR

Re: KPA-1500 wish list

I hope that the amp guys at Elecraft will reply to this thread. I've
been working with them for several weeks trying to address just this
problem. The latest beta firmware seems to handle it pretty well, so
long as I make sure I've trained the ATU on every band segment.

I'd love to have 50-ohm resonant antennas on every band. Short of that,
there does not appear to be any way around the ATU's need to identify
which antenna is selected by the external switch, before it can decide
which stored setting to apply. This takes a measurable amount of time,
as much as one character of 30 WPM CW, and I'm told that until this
process is completed, the amplifier is bypassed. I've observed, for
example, that when I pounce on a CQer significantly far away from the
frequency of my last QSO, the "N" in my call becomes "E", or goes away
entirely, as heard by the other station.

73, Pete N4ZR
Check out the Reverse Beacon Network
at <http://reversebeacon.net>, now
spotting RTTY activity worldwide.
For spots, please use your favorite
"retail" DX cluster.

On 11/19/2019 3:56 PM, K9MA wrote:

> Bill is touching on an issue I've raised before: A way to select
> multiple ATU settings for the same frequency and antenna output. I had
> to build a tri-band tuner to switch between my two tribanders so they
> would both present the amplifier with the same impedance. The internal
> ATU would have been able to do that, if only there were a way to store
> and recall two different sets of settings. In the case of automated
> antenna switching systems like mine, there also has to be a way to
> electronically tell the amplifier which settings to use: Having to
> press a front panel switch is not acceptable, as that would require
> two operations to switch antennas, which is way too slow. (I sometimes
> have to flip the antenna switch several times during a call to
> determine which antenna to use.)
>
> 73,
> Scott K9MA
>
>
>
> On 11/19/2019 13:02, K8TE wrote:
>> Another issue not explicitly mentioned is using an external antenna
>> switch
>> with different conjugate matches already trained withing the KPA1500
>> ATU.
>> Those different matches mean when one selects a "new" (different)
>> antenna
>> than already selected on a particular frequency (same band or not), the
>> KPA1500 doesn't know this fact until power is applied. Then, due to
>> a high
>> VSWR, the amplifier faults.
>>
>> With just two antenna ports on the KPA1500, there are only two quickly
>> accessible tuning solutions per frequency if using both ports. If using
>> only one port and an external antenna switch, a common choice in many
>> stations, finding the correct tuning solutions can't be done fast
>> enough to
>> prevent a fault.
>>
>> As alluded to in previous messages on this topic, perhaps the solution,
>> unfortunately, is an external box that could contain the appropriate
>> data so
>> that, when a new frequency/antenna combination, that has a previously
>> tuning
>> solution, is selected, the external box will tell both the KPA1500
>> ATU to
>> select the appropriate solution and transceiver to make appropriate
>> power
>> level adjustments, both PRIOR to actually transmitting.
>>
>> This is done (approximately, but with no power level changes) by the
>> KAT500
>> in selecting one of the three antenna ports and the appropriate tuning
>> solution. This assumes no other antenna choices on each of the three
>> ports
>> for the same frequency. The KPA1500/K3S combination is (currently) not
>> sufficiently "smart" to accomplish this.
>>
>> Of course, if we had "perfect" antennas that provided resonant
>> matches on
>> all bands/frequencies, we wouldn't be discussing this. If we had
>> those, we
>> wouldn't need the KPA1500 ATU either. 73, Bill, K8TE
>>
>>
>>
>> --
>> Sent from: http://elecraft.365791.n2.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]
>
>

K9MA

Re: KPA-1500 wish list

When you QSY, without switching antennas, it seems to take half a second
or so after you stop tuning for the ATU to switch. (Assuming it's been
"trained".) As far as I can tell, after that delay the ATU is stable, so
it shouldn't affect outgoing CW. However, as Pete says, when you switch
antennas there can be a delay, since the only way the ATU knows you have
switched antennas is the high SWR when you start transmitting. The
solution is a way to tell the ATU that you have switched antennas BEFORE
transmitting, for example, by tying it into the switch(es) which
controls the external antenna relays.

Imagine this scenario: You hear a weak signal calling CQ, flip your
antennas switch a couple time to figure out where it is coming from, and
then you have about 100 ms to start calling. Otherwise it's too late.
With two tribanders, this happens to me all the time. How can the
KPA1500 ATU be made to switch that fast? It's relays certainly can; it's
just a matter of getting that control signal to them.

I doubt there is any way to modify the KPA1500 to make this happen
without changes to firmware.

73,
Scott K9MA

On 11/20/2019 08:40, N4ZR wrote:

> I hope that the amp guys at Elecraft will reply to this thread. I've
> been working with them for several weeks trying to address just this
> problem. The latest beta firmware seems to handle it pretty well, so
> long as I make sure I've trained the ATU on every band segment.
>
> I'd love to have 50-ohm resonant antennas on every band. Short of
> that, there does not appear to be any way around the ATU's need to
> identify which antenna is selected by the external switch, before it
> can decide which stored setting to apply. This takes a measurable
> amount of time, as much as one character of 30 WPM CW, and I'm told
> that until this process is completed, the amplifier is bypassed. I've
> observed, for example, that when I pounce on a CQer significantly far
> away from the frequency of my last QSO, the "N" in my call becomes
> "E", or goes away entirely, as heard by the other station.
>
> 73, Pete N4ZR
> Check out the Reverse Beacon Network
> at <http://reversebeacon.net>, now
> spotting RTTY activity worldwide.
> For spots, please use your favorite
> "retail" DX cluster.
>
> On 11/19/2019 3:56 PM, K9MA wrote:
>> Bill is touching on an issue I've raised before: A way to select
>> multiple ATU settings for the same frequency and antenna output. I
>> had to build a tri-band tuner to switch between my two tribanders so
>> they would both present the amplifier with the same impedance. The
>> internal ATU would have been able to do that, if only there were a
>> way to store and recall two different sets of settings. In the case
>> of automated antenna switching systems like mine, there also has to
>> be a way to electronically tell the amplifier which settings to use:
>> Having to press a front panel switch is not acceptable, as that would
>> require two operations to switch antennas, which is way too slow. (I
>> sometimes have to flip the antenna switch several times during a call
>> to determine which antenna to use.)
>>
>> 73,
>> Scott K9MA
>>
>>
>>
>> On 11/19/2019 13:02, K8TE wrote:
>>> Another issue not explicitly mentioned is using an external antenna
>>> switch
>>> with different conjugate matches already trained withing the KPA1500
>>> ATU.
>>> Those different matches mean when one selects a "new" (different)
>>> antenna
>>> than already selected on a particular frequency (same band or not), the
>>> KPA1500 doesn't know this fact until power is applied. Then, due to
>>> a high
>>> VSWR, the amplifier faults.
>>>
>>> With just two antenna ports on the KPA1500, there are only two quickly
>>> accessible tuning solutions per frequency if using both ports. If using
>>> only one port and an external antenna switch, a common choice in many
>>> stations, finding the correct tuning solutions can't be done fast
>>> enough to
>>> prevent a fault.
>>>
>>> As alluded to in previous messages on this topic, perhaps the solution,
>>> unfortunately, is an external box that could contain the appropriate
>>> data so
>>> that, when a new frequency/antenna combination, that has a
>>> previously tuning
>>> solution, is selected, the external box will tell both the KPA1500
>>> ATU to
>>> select the appropriate solution and transceiver to make appropriate
>>> power
>>> level adjustments, both PRIOR to actually transmitting.
>>>
>>> This is done (approximately, but with no power level changes) by the
>>> KAT500
>>> in selecting one of the three antenna ports and the appropriate tuning
>>> solution. This assumes no other antenna choices on each of the
>>> three ports
>>> for the same frequency. The KPA1500/K3S combination is (currently) not
>>> sufficiently "smart" to accomplish this.
>>>
>>> Of course, if we had "perfect" antennas that provided resonant
>>> matches on
>>> all bands/frequencies, we wouldn't be discussing this. If we had
>>> those, we
>>> wouldn't need the KPA1500 ATU either. 73, Bill, K8TE
>>>
>>>
>>>
>>> --