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Amp for a K2

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Ken Miller K6CTW

Amp for a K2

All,

Have updated the firmware and put in the keying mods on my K2. Also had
a friend with some great test equipment verify that the new keyinh
waveform is as it should be to prevent key clicks when using an amp.

Now the dilemma. Torn between the K2/100 amp, and maybe a KAT100 in a
separate EC2 case or a KXPA100.

I'd like to hear comments from those that have used the KXP100 with or
without the tuner to amplify a K2.

Are there any special considerations that need to be taken into account
when using the KXPA100?

How easy is it to add the tuner later to the KXPA100?

Thanks in advance for any/all comments.

73 - Ken Miller, K6CTW K2 # 455

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vk2rq

Re: Amp for a K2

I use the KXPA100+KXAT100 built in tuner with my K2, and it works great. Of course, the integration isn't quite as tight as it is with the KPA100+KAT100. For example, when I change bands, I need to hit the "dit" paddle to give the amp/tuner a squirt of RF and let it know my new QRG. But the tuner immediately selects the right antenna and recalls the last tuning solution for that band segment. I also set the power knob to 3W when doing a tuning cycle, and then maybe crank it up to 5W if I want a full 100W out of the amp.

In order to make the amp work the the K2, you need a key out line. The basic K2 doesn't have this, but it is easy to add one. Here is what I did, based on an article from the Elecraft website:
http://www.mwrs.org.au/2014/04/20/elecraft-k2-amplifier-keying-circuit/

The benefit of using KXPA100 solution is that I can leave it at home if I want to take my K2+built in QRP ATU out into the field, or I can bring it along. I can also use the KXPA100 with my KX3, in which case it is a fully integrated solution. The KXPA100 is completely silent, with no fans, and relays only used for antenna selection/tuning/protection, whereas I understand the KPA100 has some noisy fans when it warms up.

Whichever way you go, the K2 is a lot of fun :-)

73,
Matt VK2RQ

> On 16 Nov 2014, at 6:33 am, Ken Miller <[hidden email]> wrote:
>
> All,
>
> Have updated the firmware and put in the keying mods on my K2. Also had
> a friend with some great test equipment verify that the new keyinh
> waveform is as it should be to prevent key clicks when using an amp.
>
> Now the dilemma. Torn between the K2/100 amp, and maybe a KAT100 in a
> separate EC2 case or a KXPA100.
>
> I'd like to hear comments from those that have used the KXP100 with or
> without the tuner to amplify a K2.
>
> Are there any special considerations that need to be taken into account
> when using the KXPA100?
>
> How easy is it to add the tuner later to the KXPA100?
>
> Thanks in advance for any/all comments.
>
> 73 - Ken Miller, K6CTW K2 # 455
>
>
>
>
> ______________________________________________________________
> 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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vk2rq

Re: Amp for a K2

One other thing I forgot to mention, with KPA100, you get a KIO2 RS232 CAT interface "for free". I had to pay extra to add one into my QRP K2. Of course if you are swapping the top of your K2 to change between "QRP" and "QRO" modes, then you might want a KIO2 for the QRP lid anyway. Of course, you can run a K2 fitted with a KPA100 in QRP mode by powering it off the coaxial power connected instead of the Anderson power pole input, but then you won't have a KAT2 ATU, and will need something external.

Anyway, you can see we are spoiled for choices :-)

73,
Matt VK2RQ

> On 16 Nov 2014, at 7:09 am, Matt VK2RQ <[hidden email]> wrote:
>
> I use the KXPA100+KXAT100 built in tuner with my K2, and it works great. Of course, the integration isn't quite as tight as it is with the KPA100+KAT100. For example, when I change bands, I need to hit the "dit" paddle to give the amp/tuner a squirt of RF and let it know my new QRG. But the tuner immediately selects the right antenna and recalls the last tuning solution for that band segment. I also set the power knob to 3W when doing a tuning cycle, and then maybe crank it up to 5W if I want a full 100W out of the amp.
>
> In order to make the amp work the the K2, you need a key out line. The basic K2 doesn't have this, but it is easy to add one. Here is what I did, based on an article from the Elecraft website:
> http://www.mwrs.org.au/2014/04/20/elecraft-k2-amplifier-keying-circuit/
>
> The benefit of using KXPA100 solution is that I can leave it at home if I want to take my K2+built in QRP ATU out into the field, or I can bring it along. I can also use the KXPA100 with my KX3, in which case it is a fully integrated solution. The KXPA100 is completely silent, with no fans, and relays only used for antenna selection/tuning/protection, whereas I understand the KPA100 has some noisy fans when it warms up.
>
> Whichever way you go, the K2 is a lot of fun :-)
>
> 73,
> Matt VK2RQ
>
>> On 16 Nov 2014, at 6:33 am, Ken Miller <[hidden email]> wrote:
>>
>> All,
>>
>> Have updated the firmware and put in the keying mods on my K2. Also had
>> a friend with some great test equipment verify that the new keyinh
>> waveform is as it should be to prevent key clicks when using an amp.
>>
>> Now the dilemma. Torn between the K2/100 amp, and maybe a KAT100 in a
>> separate EC2 case or a KXPA100.
>>
>> I'd like to hear comments from those that have used the KXP100 with or
>> without the tuner to amplify a K2.
>>
>> Are there any special considerations that need to be taken into account
>> when using the KXPA100?
>>
>> How easy is it to add the tuner later to the KXPA100?
>>
>> Thanks in advance for any/all comments.
>>
>> 73 - Ken Miller, K6CTW K2 # 455
>>
>>
>>
>>
>> ______________________________________________________________
>> 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]

Kevin Stover

Re: Amp for a K2

In reply to this post by Ken Miller K6CTW

KPA100 wins hands down.
The KXPA100 won't integrate with the K2 nearly as well as the KPA100
which was designed for the K2.
There's nothing the KXP100 can do for the K2 that the KPA100 can't
do....better.

--
R. Kevin Stover
AC0H
ARRL
FISTS #11993
SKCC #215
NAQCC #3441

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Phil Wheeler-2

Re: Amp for a K2

Except the KXPA100 will work with the KX3 and other rigs, which can be a big plus.

Phil - Sent from my iPad

> On Nov 15, 2014, at 15:46, Kevin Stover <[hidden email]> wrote:
>
> KPA100 wins hands down.
> The KXPA100 won't integrate with the K2 nearly as well as the KPA100 which was designed for the K2.
> There's nothing the KXP100 can do for the K2 that the KPA100 can't do....better.
>
> --
> R. Kevin Stover
> AC0H
> ARRL
> FISTS #11993
> SKCC #215
> NAQCC #3441
>
> ______________________________________________________________
> 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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Johnny Siu

回覆﹕ Re: Amp for a K2

In reply to this post by Kevin Stover

I would prefer kxpa100 which is more flexible if u have other rigs. In future, if surplus to your requirements, it is far more easy to sell the kxpa100. 73 johnny vr2xmc

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Don Wilhelm-4

Re: Amp for a K2

In reply to this post by Ken Miller K6CTW

Ken,

I have not used my KXPA100 and KXAT100 with my K2, but it can be done if
you add a keying output circuit to your K2.

The KXPA100 (and KXAT100) take a dit or two to 'sync up' with the K2,
but other than that it works quite nicely.

OTOH, the KPA100 and KAT100 follow the K2 band changes automatically.
But if you are mounting the KPA100 and KAT100-2 in an external EC2
enclosure, you will need the KIO2 (or a special cable to pipe the
required internal signals to the EC2 enclosure if you do not wish to
have a computer control connection). You do not need the amp keying
circuit with the KPA100.

So those are the requirements for either setup, take your pick. The
price of the KPA100, KAT100-2 and EC2 enclosure is about 3/4 the cost of
the KXPA100 and KXAT100 kits - no soldering with the latter.

73,
Don W3FPR

On 11/15/2014 2:33 PM, Ken Miller wrote:

> All,
>
> Have updated the firmware and put in the keying mods on my K2. Also had
> a friend with some great test equipment verify that the new keyinh
> waveform is as it should be to prevent key clicks when using an amp.
>
> Now the dilemma. Torn between the K2/100 amp, and maybe a KAT100 in a
> separate EC2 case or a KXPA100.
>
> I'd like to hear comments from those that have used the KXP100 with or
> without the tuner to amplify a K2.
>
> Are there any special considerations that need to be taken into account
> when using the KXPA100?
>
> How easy is it to add the tuner later to the KXPA100?
>
> Thanks in advance for any/all comments.
>
> 73 - Ken Miller, K6CTW K2 # 455
>
>
>
>
> ______________________________________________________________
> 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]
>

Guy Olinger K2AV

Re: Amp for a K2

In reply to this post by Kevin Stover

I have a KPA100 and KAT100 in an EC2 to go behind my K2/10 + battery when I
am using it in the shack. It is absolutely seamless.

There are some danger, danger issues with the cabling, like do not use a
normal RS232 cord from it to a PC...destructions. Only the three basic
RS232 leads are for computer. The rest of the pins are used to talk to the
KPA100 and KAT100. The DB9 connection on the back of the K2 is proprietary,
period. I have a split cable that breaks up into a regular three wire RS232
From K2 to the computer, and another cable from K2 to the KPA/KAT100.

You can build it or occasionally an already built KPA/KAT100/EC2 will show
up for sale, or a WTB posting can stir up one gone surplus. The latter is
how I got mine, third hand, originally built by one of the first to ever
make one.

I don't have anything else like my K2/10/Battery. In simply awful 160/80m
situations very close to 50 kW BC stations, where the analyzers just give
up, I can use the portable battery K2 and tune something by SWR. Can
directly test an antenna and listen to received signals. I'll be keeping
mine. The only conversion I might try is to a lithium ion battery pack with
smart charger and solar panel controller to replace the stock SLA.

So the back-end PA/tuner allows me to use the K2/10 in the station with a
very simple hookup to the EC2, and the EC2 retains all the fixed station
hookups. The K2 with the back-end is a good 2nd radio in a contest. And
plenty good enough for casual if the K3 goes on a trip.

73, Guy K2AV

On Sat, Nov 15, 2014 at 6:46 PM, Kevin Stover <[hidden email]>
wrote:

> KPA100 wins hands down.
> The KXPA100 won't integrate with the K2 nearly as well as the KPA100 which
> was designed for the K2.
> There's nothing the KXP100 can do for the K2 that the KPA100 can't
> do....better.
>
> --
> R. Kevin Stover
> AC0H
> ARRL
> FISTS #11993
> SKCC #215
> NAQCC #3441
>
> ______________________________________________________________
> 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]
>