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Old December 5th 13, 10:13 AM posted to rec.radio.amateur.antenna
Helmut Wabnig[_2_] Helmut Wabnig[_2_] is offline
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First recorded activity by RadioBanter: Sep 2007
Posts: 135
Default MFJ259 conversion help

On Wed, 04 Dec 2013 08:39:56 -0600, amdx wrote:

On 12/4/2013 6:14 AM, Helmut Wabnig wrote:
On Wed, 04 Dec 2013 04:25:29 -0600, amdx wrote:


Ever heard about OHM'S LAW?


w.


Yes Helmut I have. Obviously you don't have any understanding
of my question or you wouldn't have ask a smart ass question.
An MFJ259 is an antenna analyzer, it has two analog meters on it,
one displays the resistance of the load and the other the SWR.
Both meters have a non linear scale on the faceplate.

One would normally think a 50 ohm resistor would display a ratio
of 2 to 1 when compared to a 100 ohm resistor. As you can see the ratio
is 1.3 to 1. Also a 500 ohm and a 50 ohm resistor have a ratio of 10.
But the voltage ratio is 3.56.
So, do you have any other ideas?
Mikek


Could it be you don't know how to calculate an SWR?
Then look at this:
https://sites.google.com/site/tapeme...wave-ratio-swr


w.

I haven't started with SWR yet.
I'm reading the voltage across the meter that displays the R of the
load. The analog meter is fairly accurate, but the distance between 0
and 50 is the same as the distance between 50 and 500. It makes reading
an R of 275 ohms difficult. I was just hoping I could put a digital
meter on the unit and be able to get a bit more detailed numbers. But,
alas, now that I have the voltage readings, the only way I know how to
make sense of them is a conversion chart.
If 50mv = 50 ohms and 100mv = 100 ohms this would make sense but the
voltage vs resistance is non linear.
Thanks, Mikek
chart.



Ah..now I think I understand

It looks like this:
http://img203.imageshack.us/img203/4766/863l.gif


w.