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Product Idea - 25 Watt PA for the K3

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Product Idea - 25 Watt PA for the K3

Seeing how the KPA- 500 tends to need less than 25 watts to drive it to full output (500 watts) It got me thinking about a 25 watt PA Option.
Would it be possible to replace the existing 10 watt PA board with a 25 watt PA board that would use a larger heatsink instead of the case.

If the stock Filters and Relays can handle the 25 watts it would seem that it would be a more inexpensive option for those who plan on going with the KPA500.

Just a thought...

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ha4zd

Re: Product Idea - 25 Watt PA for the K3

Harry I like this idea.

István, HA4ZD

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Phil Hystad-3

Re: Product Idea - 25 Watt PA for the K3

In reply to this post by Elecraft mailing list

Good idea. I would have went for that if it was available.

73, phil, K7PEH

> On Feb 22, 2017, at 1:25 PM, Harry Yingst via Elecraft <[hidden email]> wrote:
>
>
> Seeing how the KPA- 500 tends to need less than 25 watts to drive it to full output (500 watts) It got me thinking about a 25 watt PA Option.
> Would it be possible to replace the existing 10 watt PA board with a 25 watt PA board that would use a larger heatsink instead of the case.
>
> If the stock Filters and Relays can handle the 25 watts it would seem that it would be a more inexpensive option for those who plan on going with the KPA500.
>
> Just a thought...
>
>
>
>
> ______________________________________________________________
> 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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Aaron Lee

Re: Product Idea - 25 Watt PA for the K3

In reply to this post by Elecraft mailing list

I'm dealing with indoor and hidden antennas for the next few years, 25
watts makes it much easier to stay within uncontrolled exposure limits
than 100 watts. 25 watts is much more appropriate for my confined urban
environment. It's also enough to have fun with the CW and digital modes
I enjoy. I get nervous pushing my KX3 past 5 watts some of the 100% duty
cycle digital modes. However, I would feel much more comfortable with a
desktop rig that could push 25 watts all day long.*

Aaron Lee
AC9OH

* Right now I'm debating between a 100 watt rig and trying to keep my
fingers off of the power knob or saving my money in hopes that something
better is on the market after I move.

On Wed, Feb 22, 2017, at 03:25 PM, Harry Yingst via Elecraft wrote:

>
> Seeing how the KPA- 500 tends to need less than 25 watts to drive it to
> full output (500 watts) It got me thinking about a 25 watt PA Option.
> Would it be possible to replace the existing 10 watt PA board with a 25
> watt PA board that would use a larger heatsink instead of the case.
>
> If the stock Filters and Relays can handle the 25 watts it would seem
> that it would be a more inexpensive option for those who plan on going
> with the KPA500.
>
> Just a thought...
>
>
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]

Ken Arck

Re: Product Idea - 25 Watt PA for the K3

In reply to this post by Elecraft mailing list

Seems to me that IMD might be noticeably worse that way....

At 01:25 PM 2/22/2017, Harry Yingst via Elecraft wrote:

>Seeing how the KPA- 500 tends to need less than
>25 watts to drive it to full output (500 watts)
>It got me thinking about a 25 watt PA
>Option.Â Would it be possible to replace the
>existing 10 watt PA board with a 25 watt PA
>board that would use a larger heatsink instead
>of the case. If the stock Filters and Relays can
>handle the 25 watts it would seem that it would
>be a more inexpensive option for those who plan
>on going with the KPA500. Just a thought...
>______________________________________________________________
>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
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Matthew Cook

Re: Product Idea - 25 Watt PA for the K3

In reply to this post by Elecraft mailing list

To make this idea work you need to make a 25Wpep amplifier that is kept in
it's linear region so that the IMD from this amplifier does not cause
problems in the output of the KPA500.

To make a class A-B 25W amplifier such as this with enough linearity will
result in you designing an amplifier capable of 100Wpep at full smoke. The
non-linear nature of HF PA's is easily found on the net. Having designed
PA's for HF manpacks a number of years ago we simply turned down our
100Wpep design to 25Wpep and pocketed the performance increase at the
expense of cost.

The K3/100 at 25-35W has excellent linearity (highly likely by design, pat
designers on back for this one) which allows a more aggressive approach
within the KPA500 for grunt at the expense of "some" linearity. You're
not increasing the cost of the KPA500 trying to eeek out every last bit of
linearity to get around the rubbish coming from the transceiver.

I'm keen to do some measurements in the near future of the SPE 1.3k-fa
amplifier being driven by a K3/10. Having measured the IMD of my the
K3/100 at 10W (KPA3 disabled) recently I was a little surprised at the
result, it was not as clean as when driven at 30W with the KPA3 enabled.
I'd not be surprised to see some output degradation in the SPE from the
K3/10 c.f K3/100 driven at 20W with a -3dB inline attenuator. This would
certainly explain some of the "wide" local signals that I've been seeing in
my SDR recently.

Engineering is always about compromise, and cascaded amplifiers are one of
the more trickier things to strike the right balance with.

73

Matthew
VK5ZM

On 23 February 2017 at 07:55, Harry Yingst via Elecraft <
[hidden email]> wrote:

>
> Seeing how the KPA- 500 tends to need less than 25 watts to drive it to
> full output (500 watts) It got me thinking about a 25 watt PA Option.
> Would it be possible to replace the existing 10 watt PA board with a 25
> watt PA board that would use a larger heatsink instead of the case.
>
> If the stock Filters and Relays can handle the 25 watts it would seem that
> it would be a more inexpensive option for those who plan on going with the
> KPA500.
>
> Just a thought...
>
>
>
>
> ______________________________________________________________
> 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]

Cameron Francey

Re: Product Idea - 25 Watt PA for the K3

Thumbs up here to this reply!

Also, if you have 25 watts max from the rig then you limit your ability to reduce to 100 watts or less where its more than enough.

Remembering that we use the least amount of power needed to maintain the contact. Just because the gas peddle goes as far as the floor doesn't mean it needs to be pushed that far to get to the shops!

Best regards,

Cameron -AF7DK/GM7LQR

________________________________
From: Elecraft <[hidden email]> on behalf of Matthew Cook <[hidden email]>
Sent: Wednesday, February 22, 2017 7:32 PM
To: Harry Yingst
Cc: Elecraft Reflector
Subject: Re: [Elecraft] Product Idea - 25 Watt PA for the K3

To make this idea work you need to make a 25Wpep amplifier that is kept in
it's linear region so that the IMD from this amplifier does not cause
problems in the output of the KPA500.

To make a class A-B 25W amplifier such as this with enough linearity will
result in you designing an amplifier capable of 100Wpep at full smoke. The
non-linear nature of HF PA's is easily found on the net. Having designed
PA's for HF manpacks a number of years ago we simply turned down our
100Wpep design to 25Wpep and pocketed the performance increase at the
expense of cost.

The K3/100 at 25-35W has excellent linearity (highly likely by design, pat
designers on back for this one) which allows a more aggressive approach
within the KPA500 for grunt at the expense of "some" linearity. You're
not increasing the cost of the KPA500 trying to eeek out every last bit of
linearity to get around the rubbish coming from the transceiver.

I'm keen to do some measurements in the near future of the SPE 1.3k-fa
amplifier being driven by a K3/10. Having measured the IMD of my the
K3/100 at 10W (KPA3 disabled) recently I was a little surprised at the
result, it was not as clean as when driven at 30W with the KPA3 enabled.
I'd not be surprised to see some output degradation in the SPE from the
K3/10 c.f K3/100 driven at 20W with a -3dB inline attenuator. This would
certainly explain some of the "wide" local signals that I've been seeing in
my SDR recently.

Engineering is always about compromise, and cascaded amplifiers are one of
the more trickier things to strike the right balance with.

73

Matthew
VK5ZM

On 23 February 2017 at 07:55, Harry Yingst via Elecraft <
[hidden email]> wrote:

>
> Seeing how the KPA- 500 tends to need less than 25 watts to drive it to
> full output (500 watts) It got me thinking about a 25 watt PA Option.
> Would it be possible to replace the existing 10 watt PA board with a 25
> watt PA board that would use a larger heatsink instead of the case.
>
> If the stock Filters and Relays can handle the 25 watts it would seem that
> it would be a more inexpensive option for those who plan on going with the
> KPA500.
>
> Just a thought...
>
>
>
>
> ______________________________________________________________
> 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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ab2tc

Re: Product Idea - 25 Watt PA for the K3

In reply to this post by Matthew Cook

Hi,

Very good points indeed. I am not surprised at all that the KPA3 is much cleaner at 30W than the K3/10 is at 10W. At 25/30W it's loafing along close to its optimum IMD level and the "driver" (the KPA3/10) is loafing along at 3W or less. So let's face it, neither of these amplifiers are very linear at their rated full power levels. So please don't let KPA500 users worsen their IMD levels by skimping on its driving source.

AB2TC - Knut

Matthew Cook wrote

To make this idea work you need to make a 25Wpep amplifier that is kept in
it's linear region so that the IMD from this amplifier does not cause
problems in the output of the KPA500.

To make a class A-B 25W amplifier such as this with enough linearity will
result in you designing an amplifier capable of 100Wpep at full smoke. The
non-linear nature of HF PA's is easily found on the net. Having designed
PA's for HF manpacks a number of years ago we simply turned down our
100Wpep design to 25Wpep and pocketed the performance increase at the
expense of cost.

The K3/100 at 25-35W has excellent linearity (highly likely by design, pat
designers on back for this one) which allows a more aggressive approach
within the KPA500 for grunt at the expense of "some" linearity. You're
not increasing the cost of the KPA500 trying to eeek out every last bit of
linearity to get around the rubbish coming from the transceiver.

I'm keen to do some measurements in the near future of the SPE 1.3k-fa
amplifier being driven by a K3/10. Having measured the IMD of my the
K3/100 at 10W (KPA3 disabled) recently I was a little surprised at the
result, it was not as clean as when driven at 30W with the KPA3 enabled.
I'd not be surprised to see some output degradation in the SPE from the
K3/10 c.f K3/100 driven at 20W with a -3dB inline attenuator. This would
certainly explain some of the "wide" local signals that I've been seeing in
my SDR recently.

Engineering is always about compromise, and cascaded amplifiers are one of
the more trickier things to strike the right balance with.

73

Matthew
VK5ZM
<snip>

ab2tc

Re: Product Idea - 25 Watt PA for the K3

Hi again,

If I could amplify that a bit further, no pun intended, if you can afford the KPA500, you surely can afford the KPA3 option in the K3. And it is a better driver option for the KPA500.

AB2TC - Knut

ab2tc wrote

Hi,

Very good points indeed. I am not surprised at all that the KPA3 is much cleaner at 30W than the K3/10 is at 10W. At 25/30W it's loafing along close to its optimum IMD level and the "driver" (the KPA3/10) is loafing along at 3W or less. So let's face it, neither of these amplifiers are very linear at their rated full power levels. So please don't let KPA500 users worsen their IMD levels by skimping on its driving source.

AB2TC - Knut
<snip>

Rick WA6NHC-2

Re: Product Idea - 25 Watt PA for the K3

In reply to this post by Cameron Francey

Excellent replies so far.

What we start with is a ten watt radio. We add the KPA3, which provides
a jump in output by 10 db. We can add the KPA500 which provides another
~12 db; because you're now loafing the KPA3, keeping linearity
'manageable'. (Yes, you can push the KPA500 to 600 watts on many bands,
but the IMD gives less return on that power investment.)

This has been very successful as a model for Elecraft. I don't see any
need for it to change (but without restarting another thread, a KPA1500
with a KAT1500 matching tuner *would* be awesome).

If the user wants to run at 25 watts, use a K3(s)/100. It's a simple
macro, computer command or knob twist to reach 25 watts and the signal
will be sparkling clean. But I also note that if 25 watts was a hard
limit, my KPA500 could not be driven to full output on all bands, a
couple require more input.

Let's not mess with success... This is one case that fewer options (not
having a 25 watt amp at max OR having it biased into class A, using more
energy) is a good thing.

73,

Rick wa6nhc

On 2/22/2017 8:30 PM, Cameron Francey wrote:

> Thumbs up here to this reply!
>
> Also, if you have 25 watts max from the rig then you limit your ability to reduce to 100 watts or less where its more than enough.
>
> Remembering that we use the least amount of power needed to maintain the contact. Just because the gas peddle goes as far as the floor doesn't mean it needs to be pushed that far to get to the shops!
>
>
> Best regards,
>
> Cameron -AF7DK/GM7LQR
>
>
> ________________________________
> From: Elecraft <[hidden email]> on behalf of Matthew Cook <[hidden email]>
> Sent: Wednesday, February 22, 2017 7:32 PM
> To: Harry Yingst
> Cc: Elecraft Reflector
> Subject: Re: [Elecraft] Product Idea - 25 Watt PA for the K3
>
> To make this idea work you need to make a 25Wpep amplifier that is kept in
> it's linear region so that the IMD from this amplifier does not cause
> problems in the output of the KPA500.
>
> To make a class A-B 25W amplifier such as this with enough linearity will
> result in you designing an amplifier capable of 100Wpep at full smoke. The
> non-linear nature of HF PA's is easily found on the net. Having designed
> PA's for HF manpacks a number of years ago we simply turned down our
> 100Wpep design to 25Wpep and pocketed the performance increase at the
> expense of cost.
>
> The K3/100 at 25-35W has excellent linearity (highly likely by design, pat
> designers on back for this one) which allows a more aggressive approach
> within the KPA500 for grunt at the expense of "some" linearity. You're
> not increasing the cost of the KPA500 trying to eeek out every last bit of
> linearity to get around the rubbish coming from the transceiver.
>
> I'm keen to do some measurements in the near future of the SPE 1.3k-fa
> amplifier being driven by a K3/10. Having measured the IMD of my the
> K3/100 at 10W (KPA3 disabled) recently I was a little surprised at the
> result, it was not as clean as when driven at 30W with the KPA3 enabled.
> I'd not be surprised to see some output degradation in the SPE from the
> K3/10 c.f K3/100 driven at 20W with a -3dB inline attenuator. This would
> certainly explain some of the "wide" local signals that I've been seeing in
> my SDR recently.
>
> Engineering is always about compromise, and cascaded amplifiers are one of
> the more trickier things to strike the right balance with.
>
> 73
>
> Matthew
> VK5ZM
>
> On 23 February 2017 at 07:55, Harry Yingst via Elecraft <
> [hidden email]> wrote:
>
>> Seeing how the KPA- 500 tends to need less than 25 watts to drive it to
>> full output (500 watts) It got me thinking about a 25 watt PA Option.
>> Would it be possible to replace the existing 10 watt PA board with a 25
>> watt PA board that would use a larger heatsink instead of the case.
>>
>> If the stock Filters and Relays can handle the 25 watts it would seem that
>> it would be a more inexpensive option for those who plan on going with the
>> KPA500.
>>
>> Just a thought...
>>
>>
>>
>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>> Message delivered to [hidden email]
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
> ______________________________________________________________
> Elecraft mailing list
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>
> This list hosted by: http://www.qsl.net
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thelastdb

Re: Product Idea - 25 Watt PA for the K3

In keeping with my purchasing habits (I own the K1/2 and KX line) I'd rather see a compact, efficient, external, 1 W in /25W out (14dB) packer type amp offered to compliment my very versatile station. Just saying.

72
Myron WVØH
Printed on Recycled Data

> On Feb 23, 2017, at 1:00 AM, Rick WA6NHC <[hidden email]> wrote:
>
> Excellent replies so far.
>
> What we start with is a ten watt radio. We add the KPA3, which provides a jump in output by 10 db. We can add the KPA500 which provides another ~12 db; because you're now loafing the KPA3, keeping linearity 'manageable'. (Yes, you can push the KPA500 to 600 watts on many bands, but the IMD gives less return on that power investment.)
>
> This has been very successful as a model for Elecraft. I don't see any need for it to change (but without restarting another thread, a KPA1500 with a KAT1500 matching tuner *would* be awesome).
>
> If the user wants to run at 25 watts, use a K3(s)/100. It's a simple macro, computer command or knob twist to reach 25 watts and the signal will be sparkling clean. But I also note that if 25 watts was a hard limit, my KPA500 could not be driven to full output on all bands, a couple require more input.
>
> Let's not mess with success... This is one case that fewer options (not having a 25 watt amp at max OR having it biased into class A, using more energy) is a good thing.
>
> 73,
>
> Rick wa6nhc
>
>
>> On 2/22/2017 8:30 PM, Cameron Francey wrote:
>> Thumbs up here to this reply!
>>
>> Also, if you have 25 watts max from the rig then you limit your ability to reduce to 100 watts or less where its more than enough.
>>
>> Remembering that we use the least amount of power needed to maintain the contact. Just because the gas peddle goes as far as the floor doesn't mean it needs to be pushed that far to get to the shops!
>>
>>
>> Best regards,
>>
>> Cameron -AF7DK/GM7LQR
>>
>>
>> ________________________________
>> From: Elecraft <[hidden email]> on behalf of Matthew Cook <[hidden email]>
>> Sent: Wednesday, February 22, 2017 7:32 PM
>> To: Harry Yingst
>> Cc: Elecraft Reflector
>> Subject: Re: [Elecraft] Product Idea - 25 Watt PA for the K3
>>
>> To make this idea work you need to make a 25Wpep amplifier that is kept in
>> it's linear region so that the IMD from this amplifier does not cause
>> problems in the output of the KPA500.
>>
>> To make a class A-B 25W amplifier such as this with enough linearity will
>> result in you designing an amplifier capable of 100Wpep at full smoke. The
>> non-linear nature of HF PA's is easily found on the net. Having designed
>> PA's for HF manpacks a number of years ago we simply turned down our
>> 100Wpep design to 25Wpep and pocketed the performance increase at the
>> expense of cost.
>>
>> The K3/100 at 25-35W has excellent linearity (highly likely by design, pat
>> designers on back for this one) which allows a more aggressive approach
>> within the KPA500 for grunt at the expense of "some" linearity. You're
>> not increasing the cost of the KPA500 trying to eeek out every last bit of
>> linearity to get around the rubbish coming from the transceiver.
>>
>> I'm keen to do some measurements in the near future of the SPE 1.3k-fa
>> amplifier being driven by a K3/10. Having measured the IMD of my the
>> K3/100 at 10W (KPA3 disabled) recently I was a little surprised at the
>> result, it was not as clean as when driven at 30W with the KPA3 enabled.
>> I'd not be surprised to see some output degradation in the SPE from the
>> K3/10 c.f K3/100 driven at 20W with a -3dB inline attenuator. This would
>> certainly explain some of the "wide" local signals that I've been seeing in
>> my SDR recently.
>>
>> Engineering is always about compromise, and cascaded amplifiers are one of
>> the more trickier things to strike the right balance with.
>>
>> 73
>>
>> Matthew
>> VK5ZM
>>
>> On 23 February 2017 at 07:55, Harry Yingst via Elecraft <
>> [hidden email]> wrote:
>>
>>> Seeing how the KPA- 500 tends to need less than 25 watts to drive it to
>>> full output (500 watts) It got me thinking about a 25 watt PA Option.
>>> Would it be possible to replace the existing 10 watt PA board with a 25
>>> watt PA board that would use a larger heatsink instead of the case.
>>>
>>> If the stock Filters and Relays can handle the 25 watts it would seem that
>>> it would be a more inexpensive option for those who plan on going with the
>>> KPA500.
>>>
>>> Just a thought...
>>>
>>>
>>>
>>>
>>> ______________________________________________________________
>>> Elecraft mailing list
>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>> Help: http://mailman.qth.net/mmfaq.htm
>>> Post: mailto:[hidden email]
>>>
>>> This list hosted by: http://www.qsl.net
>>> Please help support this email list: http://www.qsl.net/donate.html
>>> Message delivered to [hidden email]
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>> Message delivered to [hidden email]
>> ______________________________________________________________
>> Elecraft mailing list
>> 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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>
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Erlend Grimseid

Re: Product Idea - 25 Watt PA for the K3

+1 on this.
~25w, (optional) built in battery pack and tuner. Integration with the KX2
,KX3 and maybe the K2 and K3(S) for automatic band changing and so on. That
would be awesome.

73
LA4TTA
Erlend

2017-02-23 10:40 GMT+01:00 Myron Schaffer <[hidden email]>:

> In keeping with my purchasing habits (I own the K1/2 and KX line) I'd
> rather see a compact, efficient, external, 1 W in /25W out (14dB) packer
> type amp offered to compliment my very versatile station. Just saying.
>
> 72
> Myron WVØH
> Printed on Recycled Data
>
--
Erlend
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briancom

Re: Product Idea - 25 Watt PA for the K3

In reply to this post by Aaron Lee

Have you done the RF exposure calcs? I have the same issues. It turns out that on all HF bands, it is difficult to exceed the limits at 100 watts. Just 5 to 10 ft from the antenna provides enough distance.
73 de Brian K3KO

Sent from my iPad

> On Feb 22, 2017, at 10:06 PM, Aaron Lee <[hidden email]> wrote:
>
> I'm dealing with indoor and hidden antennas for the next few years, 25
> watts makes it much easier to stay within uncontrolled exposure limits
> than 100 watts. 25 watts is much more appropriate for my confined urban
> environment. It's also enough to have fun with the CW and digital modes
> I enjoy. I get nervous pushing my KX3 past 5 watts some of the 100% duty
> cycle digital modes. However, I would feel much more comfortable with a
> desktop rig that could push 25 watts all day long.*
>
> Aaron Lee
> AC9OH
>
> * Right now I'm debating between a 100 watt rig and trying to keep my
> fingers off of the power knob or saving my money in hopes that something
> better is on the market after I move.
>
>> On Wed, Feb 22, 2017, at 03:25 PM, Harry Yingst via Elecraft wrote:
>>
>> Seeing how the KPA- 500 tends to need less than 25 watts to drive it to
>> full output (500 watts) It got me thinking about a 25 watt PA Option.
>> Would it be possible to replace the existing 10 watt PA board with a 25
>> watt PA board that would use a larger heatsink instead of the case.
>>
>> If the stock Filters and Relays can handle the 25 watts it would seem
>> that it would be a more inexpensive option for those who plan on going
>> with the KPA500.
>>
>> Just a thought...
>>
>>
>>
>>
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john@kk9a.com

Re: Product Idea - 25 Watt PA for the K3

In reply to this post by Elecraft mailing list

I am a little late to the Elecraft party, why does this transceiver use a
separate 100 watt module instead of just having a 100 to 200 watt
transmitter like other manufactures?

John KK9A

Harry Yingst

Seeing how the KPA- 500 tends to need less than 25 watts to drive it to
full output (500 watts) It got me thinking about a 25 watt PA Option.
Would it be possible to replace the existing 10 watt PA board with a 25
watt PA board that would use a larger heatsink instead of the case.

If the stock Filters and Relays can handle the 25 watts it would seem that
it would be a more inexpensive option for those who plan on going with the
KPA500.

Just a thought...

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Jim AB3CV

Re: Product Idea - 25 Watt PA for the K3

I'll take a guess.

All transmitters have multiple stages to get to 100-200 watts. Tapping off
the 10w stage was easy to do and makes a nice QRP rig. I used my K3 for
several years as QRP only before getting the 100w amp and eventually the
KPA/KAT combo.

jim ab3cv

On Thu, Feb 23, 2017 at 9:32 AM, [hidden email] <[hidden email]> wrote:

> I am a little late to the Elecraft party, why does this transceiver use a
> separate 100 watt module instead of just having a 100 to 200 watt
> transmitter like other manufactures?
>
> John KK9A
>
> Harry Yingst
>
> Seeing how the KPA- 500 tends to need less than 25 watts to drive it to
> full output (500 watts) It got me thinking about a 25 watt PA Option.
> Would it be possible to replace the existing 10 watt PA board with a 25
> watt PA board that would use a larger heatsink instead of the case.
>
> If the stock Filters and Relays can handle the 25 watts it would seem that
> it would be a more inexpensive option for those who plan on going with the
> KPA500.
>
> Just a thought...
>
> ______________________________________________________________
> 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: Product Idea - 25 Watt PA for the K3

In reply to this post by john@kk9a.com

John,

Historically, Elecraft has always offered options - on the premise that
"if you don't need/want it, you don't have to buy it".
As a result, the KPA3, KAT3, Bandpass filters for general coverage, 2nd
receiver, DVR, extra roofing filters are optional.

For instance, those who want a transceiver only to drive VHF/UHF
transceivers do not want to buy the 100 watt PA, nor the KAT3. Those
who operate only QRP levels can pay for a K3S without the KPA3.

Certainly, it makes customizing your order a bit more involved, but you
end up with a transceiver that is tailored to your needs and operating
preferences.

73,
Don W3FPR

On 2/23/2017 9:32 AM, [hidden email] wrote:
> I am a little late to the Elecraft party, why does this transceiver use a
> separate 100 watt module instead of just having a 100 to 200 watt
> transmitter like other manufactures?
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Jim AB3CV

Re: Product Idea - 25 Watt PA for the K3

And 25w isn't sufficient to drive the KPA to full power on all bands.

jim ab3cv

On Thu, Feb 23, 2017 at 9:53 AM, Don Wilhelm <[hidden email]> wrote:

> John,
>
> Historically, Elecraft has always offered options - on the premise that
> "if you don't need/want it, you don't have to buy it".
> As a result, the KPA3, KAT3, Bandpass filters for general coverage, 2nd
> receiver, DVR, extra roofing filters are optional.
>
> For instance, those who want a transceiver only to drive VHF/UHF
> transceivers do not want to buy the 100 watt PA, nor the KAT3. Those who
> operate only QRP levels can pay for a K3S without the KPA3.
>
> Certainly, it makes customizing your order a bit more involved, but you
> end up with a transceiver that is tailored to your needs and operating
> preferences.
>
> 73,
> Don W3FPR
>
> On 2/23/2017 9:32 AM, [hidden email] wrote:
>
>> I am a little late to the Elecraft party, why does this transceiver use a
>> separate 100 watt module instead of just having a 100 to 200 watt
>> transmitter like other manufactures?
>>
> ______________________________________________________________
> Elecraft mailing list
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w7aqk

Re: Product Idea - 25 Watt PA for the K3

In reply to this post by Elecraft mailing list

I think this issue of distortion when driving amps at near their limit was
highlighted early on by a change Elecraft made on the K3. Initially the K3
could be dialed up to 110 watts. However, IMD got pretty rough at that
level. So, Elecraft dropped the maximum down to just 100 watts, and the
difference was quite noticeable. I tend to run my K3 (when operating
barefoot) at only about 90 watts hoping I'm doing even better.

I can, and have, run my KPA500 just using a KX3 or KX2 to drive it.
However, that means cranking the little rigs up near maximum to get much out
of the bigger amp. I suspect that is a problem as to IMD. If I put a
KXPA100 in between, I also suspect I am much better off in that department.
So, if I want to play with the little rigs and the big amp, I put the
KXPA100 in the mix. As best as I can tell, everything stays pretty
"linear". The little rigs only need a few watts to drive the KXPA100, and
the KXPA100 only needs about 25 watts to drive the KPA500. Convoluted
perhaps, but kind of fun to play with. It does minimize what I have
directly in front of me on the desk. I love my K3, but there are
times/situations when I don't need everything it gives me.

Dave W7AQK

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Eric Swartz - WA6HHQ

Re: Product Idea - 25 Watt PA for the K3

Administrator

In reply to this post by Jim AB3CV

That is correct. While typically in the 25-35 W range, It can require up to the
low 40 W range in some cases.

Eric
/elecraft.com/

On 2/23/2017 6:59 AM, Jim Miller wrote:

> And 25w isn't sufficient to drive the KPA to full power on all bands.
>
> jim ab3cv
>
> On Thu, Feb 23, 2017 at 9:53 AM, Don Wilhelm <[hidden email]> wrote:
>
>> John,
>>
>> Historically, Elecraft has always offered options - on the premise that
>> "if you don't need/want it, you don't have to buy it".
>> As a result, the KPA3, KAT3, Bandpass filters for general coverage, 2nd
>> receiver, DVR, extra roofing filters are optional.
>>
>> For instance, those who want a transceiver only to drive VHF/UHF
>> transceivers do not want to buy the 100 watt PA, nor the KAT3. Those who
>> operate only QRP levels can pay for a K3S without the KPA3.
>>
>> Certainly, it makes customizing your order a bit more involved, but you
>> end up with a transceiver that is tailored to your needs and operating
>> preferences.
>>
>> 73,
>> Don W3FPR
>>
>> On 2/23/2017 9:32 AM, [hidden email] wrote:
>>
>>> I am a little late to the Elecraft party, why does this transceiver use a
>>> separate 100 watt module instead of just having a 100 to 200 watt
>>> transmitter like other manufactures?
>>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>>
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Elecraft mailing list

Re: Product Idea - 25 Watt PA for the K3

In reply to this post by Jim AB3CV

That's surprising.

The most I need its 20 watts to get 500 watts out

From: Jim Miller <[hidden email]>
To: [hidden email]
Cc: Elecraft Reflector <[hidden email]>; "[hidden email]" <[hidden email]>
Sent: Thursday, February 23, 2017 9:59 AM
Subject: Re: [Elecraft] Product Idea - 25 Watt PA for the K3

And 25w isn't sufficient to drive the KPA to full power on all bands.

jim ab3cv

On Thu, Feb 23, 2017 at 9:53 AM, Don Wilhelm <[hidden email]> wrote:

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