Elecraft

Amp comparisons

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john@kk9a.com

Amp comparisons

K7ERQ left EHAM reviews on both, it would be nice if he wrote a
comparison. A couple things not mentioned below is that the Flex amp is
SO2R capable and has a higher list price.

John KK9A

K9MA wrote:

On 7/23/2018 21:37, Gary K9GS wrote:
> Any side by side with the KPA1500 and the Flex Power Genius yet?
>
I haven't seen any yet. I did have a conversation last year with 4O3A,
designer of the Power Genius. From what Ranko said, the Flex amp seemed
to have more headroom than the KPA1500, which might result in better
linearity at 1.5 kW, albeit at the expense of efficiency. (The specs say
"capable of 2 kW.") There is some scheme to dynamically adjust the
supply voltage for higher efficiency at lower power, I presume for CW
and RTTY, where linearity isn't a big issue. I read somewhere that
supply voltage is NOT modulated in SSB mode, which I imagine would cause
lots of nonlinearity. The Flex amp can do predistortion with their
radios. However, the KPA1500 also has an output sampling port, which
should allow it to do predistortion also with a radio capable of it,
probably including the Flex. (I wouldn't be surprised if Elecraft came
out with that feature eventually. Could that be the reason it has that
sampling port?)

The Flex amp has an external ATU, which 4O3A strongly favors, but I
think that's a personal preference. For most stations, with antennas
that aren't always below 1.5:1, a solid state amplifier without an ATU
is pretty useless, so I think Elecraft's decision to integrate it makes
sense.

While the Flex amp can certainly be made to work with Elecraft radios,
the seamless integration with the KPA1500 is very attractive. I'm happy
with mine so far.

73,

Scott K9MA

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Larry (K8UT)

Re: Amp comparisons

The most important difference between the Elecraft KPA1500 and the
FlexRadio PowerGenius XL is that you can actually buy one of the
KPA1500s.

According to the FlexRadio website, the PowerGenius - announced over two
years ago - is still just taking reservations.

-larry (K8UT)

------ Original Message ------
From: "[hidden email]" <[hidden email]>
To: [hidden email]
Sent: 2018-07-24 08:12:53
Subject: [Elecraft] Amp comparisons

>K7ERQ left EHAM reviews on both, it would be nice if he wrote a
>comparison. A couple things not mentioned below is that the Flex amp
>is
>SO2R capable and has a higher list price.
>
>John KK9A
>
>
>K9MA wrote:
>
>
>On 7/23/2018 21:37, Gary K9GS wrote:
>>Any side by side with the KPA1500 and the Flex Power Genius yet?
>>
>I haven't seen any yet. I did have a conversation last year with 4O3A,
>designer of the Power Genius. From what Ranko said, the Flex amp seemed
>to have more headroom than the KPA1500, which might result in better
>linearity at 1.5 kW, albeit at the expense of efficiency. (The specs
>say
>"capable of 2 kW.") There is some scheme to dynamically adjust the
>supply voltage for higher efficiency at lower power, I presume for CW
>and RTTY, where linearity isn't a big issue. I read somewhere that
>supply voltage is NOT modulated in SSB mode, which I imagine would
>cause
>lots of nonlinearity. The Flex amp can do predistortion with their
>radios. However, the KPA1500 also has an output sampling port, which
>should allow it to do predistortion also with a radio capable of it,
>probably including the Flex. (I wouldn't be surprised if Elecraft came
>out with that feature eventually. Could that be the reason it has that
>sampling port?)
>
>The Flex amp has an external ATU, which 4O3A strongly favors, but I
>think that's a personal preference. For most stations, with antennas
>that aren't always below 1.5:1, a solid state amplifier without an ATU
>is pretty useless, so I think Elecraft's decision to integrate it makes
>sense.
>
>While the Flex amp can certainly be made to work with Elecraft radios,
>the seamless integration with the KPA1500 is very attractive. I'm happy
>with mine so far.
>
>73,
>
>Scott K9MA
>
>______________________________________________________________
>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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Elecraft mailing list

Re: Amp comparisons

Larry:

> On Jul 24, 2018, at 8:50 AM, Larry (K8UT) <[hidden email]> wrote:
>
> The most important difference between the Elecraft KPA1500 and the FlexRadio PowerGenius XL is that you can actually buy one of the KPA1500s.
>
> According to the FlexRadio website, the PowerGenius - announced over two years ago - is still just taking reservations.

Perhaps it is a question of semantics, but Flex did start shipping the PGXL starting in May (the week after Hamvention). I received mine the week after Memorial Day.

However, on 5 JUL 18 FlexRadio Systems released an e-mail that states in part,

"Last month, as more users began exercising the 6-meter (6M) band in the exciting new FT8 mode, units began showing stress in a way not previously experienced. As a result, an issue in the post-amplifier 6M filter was identified. Our engineering team has already identified root cause and incorporated changes into the design to resolve the stress issues with the amp.

Unfortunately, this has further delayed our delivery plan, and at this time we expect to resume shipments in approximately 8 - 10 weeks.”

Arrangements are also being made for PGXL owners to ship their units back for repair at Flex’s expense and the two-year warranty will be reset to when the unit is returned to the owner following update. In the meantime, FRS suggests that owners not run their PGXL above 500 Watts on Six Meters. I have not yet been contacted by Flex to ship my unit back; I presume they’re spacing returns in order to minimize turn around time. As I don’t have a six meter antenna, this limitation doesn’t impact my current operation. I also have an Elecraft station at the same QTH (K3-P3-KPA500-KAT500, Remote Rig for use with the K3/I0 located elsewhere) and obviously don’t operate six meters with it as well.

So yes, a PGXL ordered today will not be immediately delivered and I have no idea at this point as to their order backlog, but FRS did initiate deliveries in May and from I’ve heard from those that have them are really excited about the amp. What is more concerning to me is that the automatic tuner to accompany the PGXL is still under development. Given the lack of a tuner that can handle the PGXL, I’m essentially limited to use of my tri-bander whereas the KAT500 allows me to tune up the EFHW I have for whatever band segment I want for use with the K3/KPA500.

Bottom line is that for remote operation (my primary means of operating HF), there are significant advantages in using the FRS approach to product design, but there are other advantages with using the Elecraft product line which is why I’m keeping my Elecraft setup. In my mind, the ‘perfect remote setup’ would be a blending of the two systems… ;-)

FWIW,

Barry, WD4ASW
Keller, TX
(Currently in Columbia, SC)

>
> -larry (K8UT)
>
> ------ Original Message ------
> From: "[hidden email]" <[hidden email]>
> To: [hidden email]
> Sent: 2018-07-24 08:12:53
> Subject: [Elecraft] Amp comparisons
>
>> K7ERQ left EHAM reviews on both, it would be nice if he wrote a
>> comparison. A couple things not mentioned below is that the Flex amp is
>> SO2R capable and has a higher list price.
>>
>> John KK9A
>>
>>
>> K9MA wrote:
>>
>>
>> On 7/23/2018 21:37, Gary K9GS wrote:
>>> Any side by side with the KPA1500 and the Flex Power Genius yet?
>>>
>> I haven't seen any yet. I did have a conversation last year with 4O3A,
>> designer of the Power Genius. From what Ranko said, the Flex amp seemed
>> to have more headroom than the KPA1500, which might result in better
>> linearity at 1.5 kW, albeit at the expense of efficiency. (The specs say
>> "capable of 2 kW.") There is some scheme to dynamically adjust the
>> supply voltage for higher efficiency at lower power, I presume for CW
>> and RTTY, where linearity isn't a big issue. I read somewhere that
>> supply voltage is NOT modulated in SSB mode, which I imagine would cause
>> lots of nonlinearity. The Flex amp can do predistortion with their
>> radios. However, the KPA1500 also has an output sampling port, which
>> should allow it to do predistortion also with a radio capable of it,
>> probably including the Flex. (I wouldn't be surprised if Elecraft came
>> out with that feature eventually. Could that be the reason it has that
>> sampling port?)
>>
>> The Flex amp has an external ATU, which 4O3A strongly favors, but I
>> think that's a personal preference. For most stations, with antennas
>> that aren't always below 1.5:1, a solid state amplifier without an ATU
>> is pretty useless, so I think Elecraft's decision to integrate it makes
>> sense.
>>
>> While the Flex amp can certainly be made to work with Elecraft radios,
>> the seamless integration with the KPA1500 is very attractive. I'm happy
>> with mine so far.
>>
>> 73,
>>
>> Scott K9MA
>>
>> ______________________________________________________________
>> 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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Jim Brown-10

Re: Amp comparisons

In reply to this post by john@kk9a.com

On 7/24/2018 5:12 AM, [hidden email] wrote:
> A couple things not mentioned below is that the Flex amp is
> SO2R capable and has a higher list price.

Is it being shipped?

73, Jim K9YC

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