[Elecraft] K3, KPA500, KAT500 and 2M brick amp keying

[Joel Hallas]

Mike,

I have a K3/KPA-500/KAT-500 and also have an amplifier following the
internal 2-meter transverter. Rather than a non-linear "brick," I have the
80/100 W linear amplifier described in the QST article by W6PQL (May 2013 -
Build a Linear 2 Meter 80 W All Mode Amplifier), but the issues are the
same. 

My solution is to tie the key lines in parallel and turn off the power to
the one I am not using. If I forget, they both key, but nothing happens to
the one without drive, as Don notes. I have been doing this for some years
without issue. 

Joel Hallas, W1ZR 
------------------------------

Message: 23
Date: Wed, 29 May 2019 10:32:19 -0400
From: Don Wilhelm <donwilh at embarqmail.com>
To: Mike Sanders <k0az at centurytel.net>,	Elecraft Reflector
	<elecraft at mailman.qth.net>
Subject: Re: [Elecraft] K3, KPA500, KAT500 and 2M brick amp keying
Message-ID: <ab32b133-0176-b613-a55c-d1c2e3c260b5 at embarqmail.com>
Content-Type: text/plain; charset=utf-8; format=flowed

Mike,

The real answer to your question is - do you have a problem with the 
KPA500 and your 2M brick amplifier being keyed at the same time?
There should be no RF input to the KPA500 when on 2M, and when on HF+6M 
there should be no RF input to your 2M amplifier.

So, are you OK with keying both amplifiers all the time no matter which 
band is selected?  If so, then just connect the KEYOUT line to your 2M 
amp and make no changes to the connection to the KAT500/KPA500.

OTOH, if you do not wish to key both amplifiers all the time, you will 
need to use the Keyline interrupter and cable the KeyOut from the K3 to 
some sort of switching arrangement (could be manual or automated through 
a band decoding device) so the K3 KEYOUT line is routed to the 2M amp 
when 2M is selected and to the KAT500/KPA500 when 2M is NOT selected.

The decision depends on your desires.

Do NOT use both the AUX cable without the keyline interrupter and the 
RCA keyline connections to the KAT500/KPA500 - strange things can occur.

73,
Don W3FPR

On 5/29/2019 9:10 AM, Mike Sanders wrote:
> I have a K3 with built in 2M transverter. The K3 drives the KPA500 and 
> KAT500 with the KPAK3AUX. Everything works
> 
> fine. I do not have the key line interrupter installed. Reading notes 5 
> and 6 on the KPAK3AUX I am a bit confused.
> 
> I want to key a 2M brick amplifier with the key out line on the K3. Can 
> this be done without the key line interrupter in place?
> 
> Or is the interrupter necessary to do this.


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End of Elecraft Digest, Vol 181, Issue 48
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