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odd antenna issue

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project1

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I set up an st-4 antenna this weekend and am having strange results. The antenna is at 25' but has less reception than my factory antenna. I put the same setup together for a family member 2 weeks ago with great results. Im no newbe to antennas , Ive been into radios and scanners for 20 years but this is a first for me. Any ideas??
 

DickH

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I set up an st-4 antenna this weekend and am having strange results. The antenna is at 25' but has less reception than my factory antenna. I put the same setup together for a family member 2 weeks ago with great results. Im no newbe to antennas , Ive been into radios and scanners for 20 years but this is a first for me. Any ideas??
Check continuity of the co-ax. There might be an open or a short.
 

LtDoc

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I have to think that the ST-4 should do better than a typical 'supplied' antenna. Not on all bands, naturally, but still still 'better'. Since it isn't doing that, then I have to think that something was missed or there was a goof in putting the thing together (I'm also sure you've thought the same thing). So, have you 'trouble-shot' the thing? Check the antenna, feed line, connectors, etc? How about 'opens' or 'shorts'? Besides the antenna, what else is different?
- 'Doc

(After all that if it doesn't "get better", it's gotta be the color of your socks.)
 

project1

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yes the only thing different is the antenna and feedline. I checked for opens and shorts when I made the feedline. The rain set in on me here in East tx so I will work on it more when the weather clears. Its strange..
 

fineshot1

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yes the only thing different is the antenna and feedline. I checked for opens and shorts when I made the feedline. The rain set in on me here in East tx so I will work on it more when the weather clears. Its strange..
Perhaps you now have front end overload on your scanner from very strong signal levels
from a close by transmitter(perhaps a paging station).

Have you tried your attenuator function to see it it helps the rx issue?
 

project1

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I tried the attenuator with no detectable changes.. Im going to make a new feed line out of lmr 400 and see if that helps..
 

project1

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multiple frequencies. Does that antenna have a matching network inside it?
 
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LtDoc

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The way the thing is made, the relationship between the elements, is what amounts to a matching network. There shouldn't be an additional one.
- 'Doc
 

W2PMX

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Ir's just a disk, a vertical and a cone - there shouldn't be anything else (except a coax connector). If the antenna is shorted, it's because it's defective.
 

project1

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Ok I will Take the antenna down tonight and check for a short at the feed point ..
 

project1

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How can I test for a short on the antenna . If I test the so-239 connector it should show a short from inside to outside rite? If it shows an open that would indicate a problem . Am I correct in my thinking?
 

captclint

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How can I test for a short on the antenna . If I test the so-239 connector it should show a short from inside to outside rite? If it shows an open that would indicate a problem . Am I correct in my thinking?
No, others have said there are no loading/matching coils, so it should be open.
 

jackj

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The ST-4 is a discone antenna. It doesn't have any matching network and a check with an ohmmeter should show an open between the center conductor and the shell of the SO-239. You should show continuity between the SO-239's center conductor and the disk/stinger portion of the antenna as well as continuity between the SO-239's shell and the cone portion.
 

project1

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Ok.. Thanks . I will battle the weather and get it tested tonight.
 

wmbio

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You did not tell us what brand/model scanner you were connecting to the antenna? If it is a newer GRE/RS, Fineshot1 may be on to your problem with overload of the scanners front end by nearby FM/TV/PAGING transmitters.Many threads on the subject here.
Let us know how you make out with your testing?

Enjoy
Wmbio
 

project1

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Ok I got it fixed. It was a bad bnc/so-239 adapter. i changed it out and everything is working fine. Thanks for all the help..
 
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