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Marconi
| | Posted on Sunday, December 23, 2001 - 4:24 pm: | 
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Tech group and members, assume that a Wilson 1000 magnet mount antenna is set to resonance in the middle of 11 meters, system is working correctly, the antenna is not being affected by anything nearby, and is installed on an adequate ground surface.
If I used an MFJ 259B meter on this Wilson 1000 magnet mount antenna, generally speaking, what kind of readings (R & X) would one expect to see with this antenna. Would you expect to see at or near 50 ohms with little or no reactance and as low an SWR as possible at 27.195?
Question is for anyone that has or uses one of these meters. What kind of information are you getting? Assuming you can tune the resonance of the antenna a bit by moving the stinger up or down, specifically what do you look for then tuning with this meter in a mobile installation?
Marconi 39ZERO
TS-50/Cobra 148GTL
Sigma IV/Starduster
Flatside 5EL-Yagi
No Amps here! |
Scrapiron63
| | Posted on Sunday, December 23, 2001 - 7:43 pm: |
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I should have added this in my other post, you can go to MFJ's web page and read more, the 259b is a later version of my 259, they have added the LCD displays, mine just has the Freq meter in that slot. Looks like the price has gone up about 60 or 70 bucks also since I bought mine.
http://www.mfjenterprises.com/products.php?prodid=MFJ-259B |
Scrapiron63
| | Posted on Sunday, December 23, 2001 - 6:20 pm: |
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Marconi, some of the techs might answer you better, but I own one of the MFJ 259 analyzers, and have used it for 2 or 3 years. With this meter, you hook the coax from any antenna, right to the meter, the radio does not connect to the meter. The meter has a frequence display, plus a resistance meter and a seperate SWR meter. If you wanted your antenna resonance at 27.195, after hooking the coax to the meter, tune the freq counter to 27.195. You can then read the resistance and swr, of course the idea is to get the resistance as close to 50 ohms with as low swr as possible. Before you even start adjusting the stinger in the Wilson, you can tune the freq display up and down freq, to see if you need to shorten or lenthen the stinger. You will find the SWR curve is not as long as we think by just using a regular SWR meter. Most any antenna will tune just for the 40 channels, but if you want to talk above 40 and below 40, you will have quite a bit more resistance than 50 ohms at one end or the other. Now weather a 1.5 or even higher SWR really hurts you much is another argument. Hope you can make sense of this. ScrapIron |
Marconi
| | Posted on Tuesday, December 25, 2001 - 1:48 pm: |
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Thanks ScrapIron. Would you elabarate a little on your comments below,
"You will find the SWR curve is not as long as we think by just using a regular SWR meter. Most any antenna will tune just for the 40 channels, but if you want to talk above 40 and below 40, you will have quite a bit more resistance than 50 ohms at one end or the other. Now weather a 1.5 or even higher SWR really hurts you much is another argument. Hope you can make sense of this. ScrapIron"
I guess you also find that inline meters do not typically show you as narrow a bandwidth as the analyzer's do?
The following questions are for both ScrapIron and anyone else that responds. What do you do with the meter to make real sure you are at true resonance? How do you approach your antenna checks?
Marconi |
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