• Effective immediately we will be deleting, without notice, any negative threads or posts that deal with the use of encryption and streaming of scanner audio.

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swaping ants.

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motolover

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I had a Diamond F23A 144 MHz Single Band Vertical
about 30 feet in a tree and i swaped it with a Diamond X510NA 144~148/435~450 MHz Dual Band Vertical. all my s readings went down i dont understand what happen. the only thing i can think of is that i put a Comet CA-712EFC VHF 153-157MHz & UHF 460-470 MHz Gain right next to it could that be a problom some how ?
 

iMONITOR

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What bands/frequencies are you primarily interested in receiving? How close are the antenna's to each other?
 

motolover

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I use the
Diamond X510NA for 2 meters and 440.
and i use the Comet CA-712EFC for gmrs. and they are like 4 inches apart.
 

fredg

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In another thread someone stated to space antennas one half wavelength, at least I think that is what they meant:

So:

"492 divided by frequency in MHz will give you the length of one half wavelength in space expressed in feet."

Using 144 MHz you would want them about 3.5 feet apart....

I may be way off but that seems like it would be reasonable..... 4 inches seems waaaay to close
 

motolover

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even if one is transmiting and the other is not hooked up to anything would it still be a prob?
 

fredg

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At 4 inches the antennas would reflect signal off each other whether transmitting or recieving. Think of a Yagi antenna, I am far from an expert but I can see where it could be a problem. The antennas so close screw up the pattern.

Do a Google Images search for: "antenna pattern" and look at some of the pics... maybe that will give you a picture of how they can interfere with each other....
 

kb1awi

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motolover said:
even if one is transmiting and the other is not hooked up to anything would it still be a prob?
The way I see it is that your transmitting on your "driver" and your other antenna is acting as a "reflector" or a "director" (a Yagi type Antenna) causing your problems and I'm sure your SWR's are very high. Space them well apart and you should be ok.
 
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