[Elecraft] K3 and Expert Amp

[Joe Subich, W4TV]

> It sounds like I don't want to use ALC to control power output on
> the  Expert Amp.

You don't want to rely on it to control power.  However, it is best to
connect it, set the level just slightly above the point where it starts
to reduce power from the K3 and allow it to function as a "safety".

> I'd suppose, if I did use the ALC connection, when I hit the half
> power button on the amp it would just cut back the power level on the
> K3 to generate a 500W output from the amp.

The "half power" button should be reducing voltage to the Expert FETs
to reduce current and heat dissipation (most other amps do the same).
You will need to reduce drive at the same time.  Again, if you connect
ALC and set it about 10% above the activation point, it might provide
some protection in case you hit the half-power button and forget to
turn down the power on the K3.

73,

    ... Joe, W4TV


On 9/23/2012 10:36 AM, Gary Slagel wrote:
> Thanks for your responses to my earlier question.  It sounds like I don't want to use ALC to control power output on the Expert Amp.  One more question for the Expert amp users though.
>
> I'd suppose, if I did use the ALC connection, when I hit the half power button on the amp it would just cut back the power level on the K3 to generate a 500W output from the amp.  So, If I'm not using the ALC connection does this make the SPE full/half power button useless?
>
> I know this might be a better discussion for the SPE yahoo group but I've been trying for a couple days to get into that group and my membership is still pending.  Thanks much for any input.
>
> Gary Slagel
> KT0A
>
>
>
>
> ________________________________
> From: Gary Slagel <gdslagel at yahoo.com>
> To: "elecraft at mailman.qth.net" <elecraft at mailman.qth.net>
> Sent: Friday, September 21, 2012 10:37 AM
> Subject: K3 and Expert Amp
>
>
>   I'm looking at the SPE Expert Amp 1K-FA.  The SPE amps both recommend using an ALC connection to automatically control the radio's output power thus preventing amplifier overdrive.
>
> I talked to an SPE rep and I understood him to say that I couldn't use the ALC connection with a K3 and there was an alternative way to allow the SPE to control the K3 output power by manually configuring the SPE to set the K3 output power on a band by band basis.  I looked at the SPE manual and it outlines a method to set up a flex-radio that does not have the ALC connection but doesn't talk about the K3.  I assume the k3 setup would be the same as for the flex-radio.
>
> Does anyone have experience with setting this up with the K3 and SPE 1K-FA.  Or, experience using the K3 ext ALC with and SPE?
>
> Thanks,
>
> Gary Slagel
> KT0A
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