Home |
Search |
Today's Posts |
|
#1
|
|||
|
|||
MFJ259 conversion help
On 12/4/2013 3:07 AM, Helmut Wabnig wrote:
On Tue, 03 Dec 2013 21:07:35 -0600, amdx wrote: I may be asking for something that doesn't have an answer. I connected a voltmeter to the R meter of my MFJ259. I checked a bunch of resistors and recorded the voltages. Now I have all these voltage readings vs. Resistance and don't know how to relate them except for a conversion graph. Is there a math function that relates these voltages to Resistance? Load Resistance Voltage reading 7.5 ohms 0.0388 volts 15 0.0444 volts 25.5 0.0478 volts 39 0.0577 volts 50 0.0614 volts 100 0.0807 volts 140 0.0891 volts 174 0.0935 volts 221 0.0980 volts 249 0.0100 volts 365 0.0106 volts 498 0.0109 volts If you can figure this out, I'll reward you with the SWR chart :-) Thanks, Mikek 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 |
#2
|
|||
|
|||
MFJ259 conversion help
On 12/4/2013 4:25 AM, amdx wrote:
On 12/4/2013 3:07 AM, Helmut Wabnig wrote: On Tue, 03 Dec 2013 21:07:35 -0600, amdx wrote: I may be asking for something that doesn't have an answer. I connected a voltmeter to the R meter of my MFJ259. I checked a bunch of resistors and recorded the voltages. Now I have all these voltage readings vs. Resistance and don't know how to relate them except for a conversion graph. Is there a math function that relates these voltages to Resistance? Load Resistance Voltage reading 7.5 ohms 0.0388 volts 15 0.0444 volts 25.5 0.0478 volts 39 0.0577 volts 50 0.0614 volts 100 0.0807 volts 140 0.0891 volts 174 0.0935 volts 221 0.0980 volts 249 0.0100 volts 365 0.0106 volts 498 0.0109 volts If you can figure this out, I'll reward you with the SWR chart :-) Thanks, Mikek 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 I noticed I slipped a decimal point on the last few measuements. 7.5 ohms 0.0388 volts 15 0.0444 volts 25.5 0.0478 volts 39 0.0577 volts 50 0.0614 volts 100 0.0807 volts 140 0.0891 volts 174 0.0935 volts 221 0.0980 volts 249 0.1000 volts 365 0.1060 volts 498 0.1090 volts The last Ratio I posted as 3.56 to 1 should be 2.8 to 1. |
#3
|
|||
|
|||
MFJ259 conversion help
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. |
#4
|
|||
|
|||
MFJ259 conversion help
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. |
#5
|
|||
|
|||
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. |
#6
|
|||
|
|||
MFJ259 conversion help
On 12/5/2013 4:13 AM, Helmut Wabnig wrote:
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. Yes! and this is one way I could handle this is to add more grid lines and just use the graph to find R by finding were V crosses. I posted new info using the formula John S developed, as you may read the formula does not come out as accurate as I'd like, I'm not sure why. Thanks for the interest, Mikek |
Reply |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
CB to 10M conversion | Homebrew | |||
cb to 10m conversion | Homebrew | |||
FRS CONVERSION?? | Boatanchors | |||
DC-to-DC conversion | General | |||
MFJ259/269 Math | Antenna |