Help on getting better reception?

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eddieturtle

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Hello.

I recently installed, on my chimney, a 1/4 Wave Ground Plane Base Antenna with a chimney mount. The antenna purchased is CENTERFIRE Antenna 1/4 wave VHF Base station antenna page

I am running a VX-4000 VHF Mobile Radio off it it. I had a replaced a normal vehicle-type mount antenna with this one as it is supposed to have better reception, when in fact it seems as though it doesn't pick up frequencies from as far away as the other one did.

I am using LMR-400 cable.

Does anyone have any recomendations? Is this antenna simply not whats it says it does and I should go with something else?

Thanks
 

majoco

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It may be that your vehicle-mount antenna was a 5/8 wave - on a good ground plane such as a vehicle roof they tend to have a lower angle of radiation. A 1/4 wave with the sloping radials (to get the impedance down to 50ohms) has a higher angle therefore less on the ground.
 

eddieturtle

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So, if I would be a 5/8 wave with the radilas it would probably pick up better?
 

majoco

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Just 4 wires for a ground plane are not as good as sheet metal.

If you still have the original antenna you could do some comparisons on a known station - don't forget that propogation conditions can change from day to day depnding on rain, humidity etc so you may want to keep a log over a few days of the stations you receive. Then replace the antenna and repat the test - then you can carry out a good comparison.
 

eddieturtle

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majoco, Thanks for the help.

This particular antenna has been installed since before Christmas, likely early last fall, so maybe 9 months or so now.

Here is how I have it installed... so if you have time let me know if this is good enough or if there is something else I could add to help reception...

I have the chimney mount (Ronard 1218 Chimney Mount 18 ft. Stainless Steel (1218) - Ronard - 1218 -) around my chimney with a aluminum pole like shown in the picture on the above link with the antenna attached to it with LMR-400... I don't have it grounded for lightning or anything (which I am sure that I probably should). Is there anything else I could do with this particluar setup to help it out?

Thanks
 

kb2vxa

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"Is this antenna simply not whats it says it does and I should go with something else?"
I don't understand your statement, I don't see any performance claims in the ad. Before you go with something else there are other things to consider.

"So, if I would be a 5/8 wave with the radials it would probably pick up better?"
Only while standing on the roof with the coax in your mouth. (;->)
I know you meant "it" so getting serious here; that depends on terrain, surrounded by high elevation the higher vertical angle of a ground plane tends to get you out of the hole. On higher elevation or flat terrain a 5/8 wave or collinear having a lower angle will extend your radio horizon.

"Just 4 wires for a ground plane are not as good as sheet metal."
Sorry Eddie, if that were so the ground plane counterpoise surface would be sheet metal. Fine for a mobile but not needed for a base antenna.

Now for the major point of consideration. Have you tuned the antenna for the center of the band you wish to cover? If so how? Haphazard assembly without tuning will put reception out of the ballpark meaning the antenna is below par for its intended use. This is the prime consideration before you discount this antenna as a dud and waste time and money going for something else. First things first, don't jump the queue.

"Is there anything else I could do with this particular setup to help it out?"
No, nothing besides the above and grounding the mast for your safety and protection of the home. Proper grounding has been discussed to death here, as long as you can sort all the opinions and go with the National Electrical Code (NEC) requirements. Seek and ye shall find.
 
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