In article ,
Ian Jackson wrote:

In message
,
Telamon writes
In article
,
RHF wrote:

On Dec 28, 8:36*pm, Telamon
wrote:
In article ,
*John Smith wrote:

SNIP

I never even commented on where the placement of the matchbox would be,
and, as everyone knows, anywhere along the line you can place it. *The
best place would be between the coax (feedline) and the antenna-

Right. That's because you are to stupid to understand a concept until
someone rubes your nose in it. This would not even occur to you until
someone else brought it up.

-that is, taking for granted that the match from your rig to the
feedline is perfect.

SNIP

You are really worried about the match of 50 ohm *coax to your radios 50
ohm output? Now that's funny.


IIRC - The Characteristically 50 Ohm Impedance
Coax Cable is 'only' 50 Ohms nominal . . .
Until you attach something to it.

SNIP

Nope. The cable itself has a characteristic impedance of some design
value. The spacing and size of the conductors along with the dielectric
constant of the insulator between them dictates the impedance of the
coax.

You are confusing the characteristic impedance of the coax with its
ability to be an effective transmission line. The coax only behaves as
an effective transmission line when both ends of it are terminated at
its characteristic impedance.

Are you really sure about this sweeping statement?

Yes. It is basic transmission line theory. RF energy entering or leaving
a coax line has to be at the same impedance or energy is reflected. That
is a basic rule.

For starters, please define 'effective'.

The word effective was used in the context of the coax meeting its
specifications within reason.

And are you sure that transmitter output impedances are 50 ohms (or
whatever)?

If it is specified to be 50 ohms and it is not then it should find its
way back to the manufacturer for repair or redesign.

--
Telamon
Ventura, California