ORIGINAL MESSAGE:
On Fri, 09 Apr 2010 02:16:29 -0400, Roger <sub1@rogerhalstead.com>
wrote:
>
>Now I can understand the case of the multi tube amp where the plate
>impedance = the radiation resistance of the antenna. I can understand
>how to get there when they are close, but HOW do you get a tube or tubes
>with a plate impedance in thousands of ohms to match a very low
>resistance reactive load? (IE a mobile antenna)
REPLY:
In this case, we are dealing with an end-fed half wave vertical, which
has a feedpoint impedance of several thousand ohms, essentially the
same as the tube's plate load impedance. Thus no matching network is
needed. Also no transmission line is needed if the end of the antenna
is connected directly through a DC blocking cap to the tube's plate.
To answer the question in the latter part of your message, that is
what a pi-network does, but you already knew that. Am I missing your
real question there?
73, Bill W6WRT
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|