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K3/K3S 10W models with KXPA100

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lstavenhagen

K3/K3S 10W models with KXPA100

Hi all,
May be a bit silly of a question, but how well does the KXPA 100 work with the K3 or K3S 10W model? Reason I ask is I now have 3 10W rigs (K3, K3S and a K2) and may be building a 4th soon (another K2/10). And in the very rare event when do go QRO, it would probably be cheaper to just get one 100W amp to use with them all than 4 100W amp modules for each.

So my idea is a KXPA100 for my QRO ops with each one. So just curious how well this amp works with the K3 and K3S? I would imagine it'd be similar to using it with the K2 or ?

Thanks,
LS
W5QD

Brendon Whateley

Re: K3/K3S 10W models with KXPA100

Ron,

Would it be possible to put some sort of RF detector between the rig and
the amp to trigger the KEY line? That would seem to be a relatively simple
DIY project if need be.

- Brendon
KK6AYI

On Sat, Feb 20, 2016 at 12:15 PM, Ron D'Eau Claire <[hidden email]> wrote:

> I was just informed by the design engineer that it does NOT sense RF to
> transmit, so you need to provide a way to ground the KEY line input to the
> KXPA100 to transmit.
>
> My apologies.
>
> 73, Ron AC7AC
>
> -----Original Message-----
> From: Elecraft [mailto:[hidden email]] On Behalf Of Ron
> D'Eau Claire
> Sent: Saturday, February 20, 2016 11:20 AM
> To: 'lstavenhagen'; [hidden email]
> Subject: Re: [Elecraft] K3/K3S 10W models with KXPA100
>
> It works very well with just about any QRP rig. Complete instructions for
> use with rigs other than the KX3 are included in the Owner's manual,
> available from the Elecraft web site here:
>
>
> http://www.elecraft.com/manual/E740199%20KXPA100%20Owner's%20Manual%20Rev%20
> A5.pdf
>
> It will work well even with QRP rigs that do not have a key line to enable
> the amp. The amp will sense the presence of RF drive and switch to transmit
> automatically.
>
> 73, Ron AC7AC
>
>
>
> -----Original Message-----
> From: Elecraft [mailto:[hidden email]] On Behalf Of
> lstavenhagen
> Sent: Saturday, February 20, 2016 6:25 AM
> To: [hidden email]
> Subject: [Elecraft] K3/K3S 10W models with KXPA100
>
> Hi all,
> May be a bit silly of a question, but how well does the KXPA 100 work with
> the K3 or K3S 10W model? Reason I ask is I now have 3 10W rigs (K3, K3S and
> a K2) and may be building a 4th soon (another K2/10). And in the very rare
> event when do go QRO, it would probably be cheaper to just get one 100W amp
> to use with them all than 4 100W amp modules for each.
>
> So my idea is a KXPA100 for my QRO ops with each one. So just curious how
> well this amp works with the K3 and K3S? I would imagine it'd be similar to
> using it with the K2 or ?
>
> Thanks,
> LS
> W5QD
>
>
>
> --
> View this message in context:
>
> http://elecraft.365791.n2.nabble.com/K3-K3S-10W-models-with-KXPA100-tp761436
> 4.html
> Sent from the Elecraft mailing list archive at Nabble.com.
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Don Wilhelm-4

Re: K3/K3S 10W models with KXPA100

In reply to this post by lstavenhagen

LS,

The KXPA100 will work with any QRP transceiver that produces a KEYOUT
signal.
The K3/10, K3S/10 and the KX3 can do that, it is just a matter of a
proper cable.

The K2/10 does not have a KEYOUT line (although the K2/100 does). I
would recommend that you build the circuit shown on Tom Hammond N0SS
(SK) website at http://www.mmccs.com/mmarc/n0ss/index_k2.html.
Since Tom is SK, no boards are available, but the circuit is easy enough
to build on perfboard. Just follow Tom's board layout which is clearly
identified full scale on his website and connect the wires. If you have
the capabilities for etching your own board, the process is easy since
Tom provided full scale images of his board.
I have built several of the perfboard verions of that circuit and they
work fine.

73,
Don W3FPR

On 2/20/2016 9:25 AM, lstavenhagen wrote:

> Hi all,
> May be a bit silly of a question, but how well does the KXPA 100 work with
> the K3 or K3S 10W model? Reason I ask is I now have 3 10W rigs (K3, K3S and
> a K2) and may be building a 4th soon (another K2/10). And in the very rare
> event when do go QRO, it would probably be cheaper to just get one 100W amp
> to use with them all than 4 100W amp modules for each.
>
> So my idea is a KXPA100 for my QRO ops with each one. So just curious how
> well this amp works with the K3 and K3S? I would imagine it'd be similar to
> using it with the K2 or ?
>
>

Elecraft mailing list

Re: K3/K3S 10W models with KXPA100

In reply to this post by lstavenhagen

Why not a foot switch

George, W6GF

On February 20, 2016, at 6:48 PM, Don Wilhelm <[hidden email]> wrote:

LS,

The KXPA100 will work with any QRP transceiver that produces a KEYOUT
signal.
The K3/10, K3S/10 and the KX3 can do that, it is just a matter of a
proper cable.

The K2/10 does not have a KEYOUT line (although the K2/100 does). I
would recommend that you build the circuit shown on Tom Hammond N0SS
(SK) website at http://www.mmccs.com/mmarc/n0ss/index_k2.html.
Since Tom is SK, no boards are available, but the circuit is easy enough
to build on perfboard. Just follow Tom's board layout which is clearly
identified full scale on his website and connect the wires. If you have
the capabilities for etching your own board, the process is easy since
Tom provided full scale images of his board.
I have built several of the perfboard verions of that circuit and they
work fine.

73,
Don W3FPR

On 2/20/2016 9:25 AM, lstavenhagen wrote:

Elecraft mailing list

Re: K3/K3S 10W models with KXPA100

Curious if 0H0SS amp will work with K3/10? 73 de Dave KJ6CBS

From: george fritkin via Elecraft <[hidden email]>
To: "w3fpr@embarqmail com" <[hidden email]>; lstavenhagen <[hidden email]>; El <[hidden email]>
Sent: Saturday, February 20, 2016 8:58 PM
Subject: Re: [Elecraft] K3/K3S 10W models with KXPA100

Why not a foot switch

George, W6GF

On February 20, 2016, at 6:48 PM, Don Wilhelm <[hidden email]> wrote:

LS,

The KXPA100 will work with any QRP transceiver that produces a KEYOUT
signal.
The K3/10, K3S/10 and the KX3 can do that, it is just a matter of a
proper cable.

The K2/10 does not have a KEYOUT line (although the K2/100 does). I
would recommend that you build the circuit shown on Tom Hammond N0SS
(SK) website at http://www.mmccs.com/mmarc/n0ss/index_k2.html.
Since Tom is SK, no boards are available, but the circuit is easy enough
to build on perfboard. Just follow Tom's board layout which is clearly
identified full scale on his website and connect the wires. If you have
the capabilities for etching your own board, the process is easy since
Tom provided full scale images of his board.
I have built several of the perfboard verions of that circuit and they
work fine.

73,
Don W3FPR

On 2/20/2016 9:25 AM, lstavenhagen wrote:

______________________________________________________________
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Don Wilhelm-4

Re: K3/K3S 10W models with KXPA100

In reply to this post by Elecraft mailing list

George,

A footswitch will work as long as you operate it before transmitting any RF.
I would prefer an amp keying circuit over a footswitch since there can
be occasions of human failure - "I hit the key (or mic PTT) before I
activated the footswitch".

73,
Don W3FPR

On 2/20/2016 9:58 PM, george fritkin wrote:

> Why not a foot switch
>
>
> George, W6GF
>
> On February 20, 2016, at 6:48 PM, Don Wilhelm <[hidden email]> wrote:
>
> LS,
>
> The KXPA100 will work with any QRP transceiver that produces a KEYOUT
> signal.
> The K3/10, K3S/10 and the KX3 can do that, it is just a matter of a
> proper cable.
>
> The K2/10 does not have a KEYOUT line (although the K2/100 does). I
> would recommend that you build the circuit shown on Tom Hammond N0SS
> (SK) website at http://www.mmccs.com/mmarc/n0ss/index_k2.html.
> Since Tom is SK, no boards are available, but the circuit is easy enough
> to build on perfboard. Just follow Tom's board layout which is clearly
> identified full scale on his website and connect the wires. If you have
> the capabilities for etching your own board, the process is easy since
> Tom provided full scale images of his board.
> I have built several of the perfboard verions of that circuit and they
> work fine.
>
> 73,
> Don W3FPR
>
> On 2/20/2016 9:25 AM, lstavenhagen wrote:
>> Hi all,
>> May be a bit silly of a question, but how well does the KXPA 100 work with
>> the K3 or K3S 10W model? Reason I ask is I now have 3 10W rigs (K3, K3S and
>> a K2) and may be building a 4th soon (another K2/10). And in the very rare
>> event when do go QRO, it would probably be cheaper to just get one 100W amp
>> to use with them all than 4 100W amp modules for each.
>>
>> So my idea is a KXPA100 for my QRO ops with each one. So just curious how
>> well this amp works with the K3 and K3S? I would imagine it'd be similar to
>> using it with the K2 or ?
>>
>>
> ______________________________________________________________
> 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]

Edward R Cole

Re: K3/K3S 10W models with KXPA100

In reply to this post by lstavenhagen

Brendon,

Yes, though you would need to construct it.

A simple RF sense ckt would be 1pF coupling cap from the coax line
(maybe use a coax tee and connect the RF sense box to the tee). At
HF the tee will not show significant impedance bump.

The cap feeds a diode like the BAS-16 followed by bypass caps to
ground (0.01uF and 10uF ought to suffice). This feeds thru a 1K
resistor to control a NPN transistor that will key the amplifier to
ground. You might add a 1uH choke in line before the resistor if
concerned that the RF is not completely smoothed to dc. The circuit
I described is used in the W6PQL 2m 80w amplifier for RF sensed PTT
(except different values for bypassing 2m).
http://www.w6pql.com/2_meter_80w_all_mode_amplifier.htm

Another way is to buy a kit. W6PQL sells an ALC detector board which
passes RF thru and detects RF providing a negative voltage. The kit
includes 750-ohm resistor which is good for 1-2w. Probably better to
use a 2K resistor for 10w. I am using this board kit with 10K
resistor to sample 2m 80w RF for a RF output meter.
http://www.w6pql.com/Sampling_RF_Power.htm#alc

Let me also comment about using the KXPA-100 with either K3/10 or
KX3. I recently bought a KXPA-100 for just those two radios and its
a perfect companion. One plus is heat is kept out of either radio
which reduces frequency drift when running digital modes. Of course
digital modes don't need 100w but you can reduce drive to 20w with
either radio driving the KXPA-100. I don't plan to use my K3 outside
the shack but the KX3 may go mobile with the KXPA-100. I
incorporated a PTT switch in my new station control panel to select
either K3 or KX3 PTT which is provided to several accessories
including the KXPA-100.

73, Ed - KL7UW

From: Brendon Whateley <[hidden email]>
Cc: Elecraft Reflector Reflector <[hidden email]>
Subject: Re: [Elecraft] K3/K3S 10W models with KXPA100
Message-ID:
<[hidden email]>
Content-Type: text/plain; charset=UTF-8

Ron,

Would it be possible to put some sort of RF detector between the rig and
the amp to trigger the KEY line? That would seem to be a relatively simple
DIY project if need be.

- Brendon
KK6AYI

73, Ed - KL7UW
http://www.kl7uw.com
"Kits made by KL7UW"
Dubus Mag business:
[hidden email]

______________________________________________________________
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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Vic Rosenthal

Re: K3/K3S 10W models with KXPA100

I don't like circuits like this because they guarantee hot-switching of the amplifier. Unless you have a time-reversal device, the amp won't switch until RF is already flowing. Maybe it wouldn't damage the amplifier in this case, but it would certainly mess up the shaping of CW elements.

Much better to add an amp key circuit to the transceiver if it doesn't have one. If done correctly (like the N0SS circuit for the K2 that was mentioned), the amp key line is activated a few ms before RF is produced.

Vic 4X6GP

> On 21 Feb 2016, at 11:01 AM, Edward R Cole <[hidden email]> wrote:
>
> Brendon,
>
> Yes, though you would need to construct it.
>
> A simple RF sense ckt would be 1pF coupling cap from the coax line (maybe use a coax tee and connect the RF sense box to the tee). At HF the tee will not show significant impedance bump.
>
> The cap feeds a diode like the BAS-16 followed by bypass caps to ground (0.01uF and 10uF ought to suffice). This feeds thru a 1K resistor to control a NPN transistor that will key the amplifier to ground. You might add a 1uH choke in line before the resistor if concerned that the RF is not completely smoothed to dc. The circuit I described is used in the W6PQL 2m 80w amplifier for RF sensed PTT (except different values for bypassing 2m).
> http://www.w6pql.com/2_meter_80w_all_mode_amplifier.htm
>
> Another way is to buy a kit. W6PQL sells an ALC detector board which passes RF thru and detects RF providing a negative voltage. The kit includes 750-ohm resistor which is good for 1-2w. Probably better to use a 2K resistor for 10w. I am using this board kit with 10K resistor to sample 2m 80w RF for a RF output meter.
> http://www.w6pql.com/Sampling_RF_Power.htm#alc
>
> Let me also comment about using the KXPA-100 with either K3/10 or KX3. I recently bought a KXPA-100 for just those two radios and its a perfect companion. One plus is heat is kept out of either radio which reduces frequency drift when running digital modes. Of course digital modes don't need 100w but you can reduce drive to 20w with either radio driving the KXPA-100. I don't plan to use my K3 outside the shack but the KX3 may go mobile with the KXPA-100. I incorporated a PTT switch in my new station control panel to select either K3 or KX3 PTT which is provided to several accessories including the KXPA-100.
>
> 73, Ed - KL7UW
>
> From: Brendon Whateley <[hidden email]>
> Cc: Elecraft Reflector Reflector <[hidden email]>
> Subject: Re: [Elecraft] K3/K3S 10W models with KXPA100
> Message-ID:
> <[hidden email]>
> Content-Type: text/plain; charset=UTF-8
>
> Ron,
>
> Would it be possible to put some sort of RF detector between the rig and
> the amp to trigger the KEY line? That would seem to be a relatively simple
> DIY project if need be.
>
> - Brendon
> KK6AYI
>
>
>
> 73, Ed - KL7UW
> http://www.kl7uw.com
> "Kits made by KL7UW"
> Dubus Mag business:
> [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]

lstavenhagen

Re: K3/K3S 10W models with KXPA100

In reply to this post by Don Wilhelm-4

Hi all,
Ok, thanks for the info. It looked like from the KXPA documentation that one would simply use the "general" hookup with the K3 or K3S, I just wanted to confirm.

Thanks,
LS
W5QD