K2 driving KPA500 / KAT500

[Edward A. Dauer]

 Having used the KPA1500 long enough to be confident that mine has no obvious bugs, I am trying to decide whether to keep my KPA500 / KAT500 or put it up for sale.

One possibility would be to use the 500s with a K2.  I have a K2 with the integral KPA100, and two without.  The K2/100 has an RCA jack for the amp keying line which should make things easy - just connect one end to the KPA100 and the other to the KPA500, yes?  

Using a K2 alone as driver for the KPA500 is the question.  There must be an amplifier keying line somewhere in the K2 circuitry, since it can key a KPA500 in the two-box "twins" configuration; but there is no mechanical output for it.  Anyone done this who can help with ideas?  

What kind of output from the KPA500 is possible with a barefoot K2 driving it?  Anything else I should know before trying this out?

The band data is not a problem in either case, since the KPA500 has a one-dit sensing circuit which will be adequate.  (It also has band selection buttons, of course.)

Tnx, as always, for any advice,

Ted, KN1CBR

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[Lou Voerman W2ROW]

Ted,

Elecraft did publish an add on circuit to drive an amp from the K2. The bad
news is that I can not find it on their new website. Tom Hammond N0SS (SK)
designed a PC Board for an amp keying circuit which is no longer available.
However he published the schematic which you can find here:

N0SS K2 amp keying circuit
<http://www.mmccs.com/mmarc/n0ss/k2_t-r_rly_drvr.pdf>  

I hope the link works. I have not tried this circuit with a KPA500.

Lou W2ROW



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[Don Wilhelm]

The link is good.  This one was never on the Elecraft website.
Thank the Mid Misouri ham club for preserving most of Tom's website on
their site.

73,
Don W3FPR

On 10/22/2018 10:43 AM, Lou Voerman W2ROW wrote:

> Ted,
>
> Elecraft did publish an add on circuit to drive an amp from the K2. The bad
> news is that I can not find it on their new website. Tom Hammond N0SS (SK)
> designed a PC Board for an amp keying circuit which is no longer available.
> However he published the schematic which you can find here:
>
> N0SS K2 amp keying circuit
> <http://www.mmccs.com/mmarc/n0ss/k2_t-r_rly_drvr.pdf>
>
> I hope the link works. I have not tried this circuit with a KPA500.
>
> Lou W2ROW
>
>
>
> --
> Sent from: http://elecraft.365791.n2.nabble.com/
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> Post: mailto:[hidden email]
>
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> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>

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[Steve Witt]

On Mon, Oct 22, 2018 at 07:43:07AM -0700, Lou Voerman W2ROW wrote:

> Ted,
>
> Elecraft did publish an add on circuit to drive an amp from the K2. The bad
> news is that I can not find it on their new website. Tom Hammond N0SS (SK)
> designed a PC Board for an amp keying circuit which is no longer available.
> However he published the schematic which you can find here:
>
> N0SS K2 amp keying circuit
> <http://www.mmccs.com/mmarc/n0ss/k2_t-r_rly_drvr.pdf>  
>
> I hope the link works. I have not tried this circuit with a KPA500.
>
> Lou W2ROW
>

I built the circuit provided by Elecraft a few months ago to add a
KXPA100 amp to my K2. Its been working great once I got it built
properly. I used two sources of info, the Elecraft circuit
<http://web.archive.org/web/20180316034045/www.elecraft.com/Apps/Amp_keying_ckt.htm>
and another page that added some information to the Elecraft page
<http://www.mwrs.org.au/2014/04/20/elecraft-k2-amplifier-keying-circuit/>.

In the Elecraft page they mentioned that both transistors can be
2N2222, which is what I did.

The first link is through the Internet Archive site that allows access
to old, saved websitess to allow access to the old Elecraft
site. Someone posted about this just a few days ago, which is how I
learned of it.

73
Steve N6SAW
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