Talk:Antenna tuner

This article currently is fairly specific to amateur radio, rather than being "encyclopedic". This is not suggesting that the current information is not useful, merely that the article covers a very narrow view of its subject to the exclusion of the majority of the topic material. 75.140.243.0 (talk) 14:36, 9 January 2009 (UTC)[reply]

FORMULA ERROR

Here are the formulae copied and pasted from the article...

XL = {(Rsource+jXsource)([Rsource+jXsource]-[Rload+jXload])}0.5

and

XC = (Rload+jXload){(Rsource+jXsource)/([Rload+jXload]−[Rsource+jXsource]}0.5

In the Xc formula, the parantheses are unpaired. I have had to guess what the real meaning is. Here are my interpretation in Excel: (is this right?) Rsource = b2 jXsource= b3 Rload = b4 jXload = b5

XL = SQRT(((B2+C2)^2)-(B4+B5)) XC = =(B4+B5) * SQRT((B2+B3)/((B4+B5)-(B2+B3))) the square root is taken across that entire term. (?)

Also, if the sum b2+b3 is negative, then there is an error (root of a negative number). This can happen if the jXsource is capacitive and large. Or an error can arise if b2+b3 is larger than b4+b5. duh. Baruchatta (talk) 20:31, 25 January 2008 (UTC)[reply]

Need Real World Advice

This article needs some real world advice on how to use an antenna tuner. For example, all of the "how it works" examples show how to match one resistor value (1000 ohms) to another resistive value (50 ohms). BUT IF MY ANTENNA WAS RESISTIVE (RESONANT) I WOULD NOT NEED AN ANTENNA TUNER! I would like to see advice on how a reactive antenna (too short or too long, capacitive or inductive) is matched to a transmitter. Also, if an antenna is resonant at one frequency, what is its resistance and reactance at another frequency. For example, if an antenna is resonant at 5 MHz, what is its values at 3 MHz? --Baruchatta (talk) 14:50, 25 January 2008 (UTC)[reply]

This article could use some discussion about how to build an antenna tuner. It might be useful in this to mention complex conjugate matches. --ssd 04:44, 21 October 2005 (UTC)[reply]

How to

This article used to have a section on how to use an ATU, which I wrote. That has since been removed because "The section on the use of ATUs has been removed becuase [sic] WP should not be how to guides" I expect that also means they should avoid becoming how to build guides as well.

Sigh, I personally think both of these would add value to the community and should really be allowed to stay. This article is now terribly complicated with much math and very little use to someone who might actually want to find out any practical information on ATUs. For the record I think the math section is important as well. But not more than how you may typically operate one.

J3gum 05:46, 12 March 2007 (UTC)[reply]

Somethings wrong in the calculation

In the calculations complex numbers are changed into non-complex numbers.

X_L = j 217.94 Ohms

But later

X_L = 2πfL

L = X_L/(2πf) = 1.239 μH

is incorrect, because there is no "j" in the formula:

L = X_L/(2πf) = j 1.239 μH

Z=R+jX = j*j 217.94 Ohms = - 217.94 Ohms