[Elecraft] running an external amp?

[Don Brown]

Hi

If you build the KPA100 into an EC2 box externally and your K2 has a KAT2 
the firmware will place the KAT2 into bypass mode and select Ant 1. This is 
the same as using a amp made by some other supplier except the K2 will not 
be able to detect the amp. The KAT2 bypass mode and Ant 1 can be selected 
manually in this case. Another option would be to disconnect the RF cable to 
the KAT2 and just use the BNC output on the back of the K2.

Don Brown
KD5NDB


----- Original Message ----- 
From: "Vic K2VCO" <vic at rakefet.com>
To: <k6mr at pacbell.net>
Cc: <Elecraft at mailman.qth.net>
Sent: Wednesday, November 02, 2005 10:17 PM
Subject: Re: [Elecraft] running an external amp?


> K6MR wrote:
> > Not sure if you mean the KAT-2 or the KAT-100, but I drive both my amps
> > with the KAT-100s in line from both radios.  I don't know how the tuner
> > would know the difference between an antenna or an amplifier input
> > network.  I just let the tuner cycle (it's real quick) using the tune
> > button the first time I activate the amp.  Then use the keyer to tune
> > with dits.
>
> The KAT2 and KAT100 are pretty similar.  The difference between an
> antenna and an amplifier input network is that the impedance seen when
> driving an amplifier changes as the amplifier is driven harder!  So you
> can get a sort of unstable condition in which the tuner tries to match a
> varying impedance.  This is probably not harmful since you are tuning at
> reduced power, but it's not clear that the tuner will find an
> appropriate match.  That's why I recommend tuning the K2 into a 50-ohm
> dummy load first, and then using it to drive the amp.
>
> -- 
> 73,
> Vic, K2VCO
> Fresno CA
> http://www.qsl.net/k2vco