C-L vs L-C?

[Cady, Fred]

Hi all,
The K3, KX3 and KAT500 tuners use an L-C network with a series L and a parallel C. It can be configured with the shunt C on the transmitter side or the antenna side.
I can write the transfer functions for both of these configurations (both being low pass, as pointed out by K9YC), one has two zeros and one pole and the other two poles and one zero. I'm wondering under what conditions the C at the tx side is preferable to C at the antenna side. Does it have something to do with the impedance of the load that the tuner is trying to match.

Cheers and 73,
Fred KE7X



Fred Cady
fcady at ieee dot org

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

[Don Wilhelm-4]

Fred,

Yes, it has everything to do with the impedance range to be matched.
In general, if the impedance is less than 50 ohms, the capacitor will be
on the TX side, but if th eimpedance is greater than 50 ohms, it will be
on the feedline side.

Look at the equations and conditions for an L-Network and that should be
clear.

73,
Don W3FPR

On 8/20/2013 1:57 PM, Cady, Fred wrote:
> Hi all,
> The K3, KX3 and KAT500 tuners use an L-C network with a series L and a parallel C. It can be configured with the shunt C on the transmitter side or the antenna side.
> I can write the transfer functions for both of these configurations (both being low pass, as pointed out by K9YC), one has two zeros and one pole and the other two poles and one zero. I'm wondering under what conditions the C at the tx side is preferable to C at the antenna side. Does it have something to do with the impedance of the load that the tuner is trying to match.
>
>

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

[Wes (N7WS)]

Of course.

On 8/20/2013 10:57 AM, Cady, Fred wrote:
> Hi all,
> The K3, KX3 and KAT500 tuners use an L-C network with a series L and a parallel C. It can be configured with the shunt C on the transmitter side or the antenna side.
> I can write the transfer functions for both of these configurations (both being low pass, as pointed out by K9YC), one has two zeros and one pole and the other two poles and one zero. I'm wondering under what conditions the C at the tx side is preferable to C at the antenna side. Does it have something to do with the impedance of the load that the tuner is trying to match.
>
> Cheers and 73,
> Fred KE7X
>
>
>

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html