[Elecraft] K3 Internal Tuner Question

[Ron D'Eau Claire]

Quite right. 

There a couple of impedance transformations that occur between the
collectors (or plates) of the power amplifiers and the antenna. The first is
done by the output filters. In modern rigs, they are fixed tuned and
designed in common Ham rigs to convert the impedance at the collectors to 50
ohms, resistive. 

If your antenna presents that impedance, no further conversion is necessary.
But many antennas don't.

In the "old" days the output network was adjustable and we simply did the
necessary adjustments and all was good. 

Nowadays, with fixed tuned amplifier output networks, we need another
matching network to handle the conversion when the antenna doesn't present a
50 ohms resistive load. 

Enter the "antenna tuner" that converts what the antenna shows to the 50
ohms needed by the output filter. The built in SWR meter displays the SWR on
the link between the tuner and the output filter. 

Ron AC7AC

-----Original Message-----
From: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Tom Azlin N4ZPT
Sent: Monday, January 02, 2012 6:19 PM
To: elecraft at mailman.qth.net
Subject: Re: [Elecraft] K3 Internal Tuner Question

Thanks Matthew. I should not have spoken like that. Should just
have said the meter in the line would not change just because a radio
tuner transformed impedance to make the radio happy. 73, tom n4zpt

On 1/2/2012 9:11 PM, Matthew Pitts wrote:
> Tom,
>
> All an antenna tuner does is show the radio the load it expects; the
> SWR will still be high at the output of the tuner, and an SWR meter
> in the coax at that output will show it as it actually is at that
> point, not as it is on the input of the tuner/output of the radio.
>
> Matthew Pitts N8OHU