ERF Mirror Mount SWR Problems

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joe jeep
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Thu Aug 04, 2011 8:49 pm

Hello All, some advice needed, I have added some pictures to futher explain my situation, I have an ERF Mirror mount, I have drilled an extra hole in order to attatch it to the diametre of pole i have as the U-bolt required was to big, The upside down aerial, was a pain to get in, using a drill bit i took out some burrs on the inside but it is still a tight squeeze and is catching further down, but i managed to get the aerial all the way down, but i think it might be shorting,not sure what to do, anyway here's the pics which show the setup and the high swr, I have tested it with two radios, both the same.

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Cheers, Hope the pics are ok.
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stampman
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Fri Aug 05, 2011 7:47 am

that looks like a short somewhere on the system i would loses the small ground plane antenna and use 8ft 6" of coax strapped to the mounting bracket then try the swr but defiantly check for a short first


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joe jeep
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Fri Aug 05, 2011 8:39 am

Your the second person to say it could be a short, I will check today again, i checked it briefly yesterday.

I emailed a friend and this is what he suggested.
What fixed it in the end was making the hole in the bar bigger (see picture - red arrow).

The logic is that you need to separate the radiating element from the earth bar/mount/pole and for that reason there's the nylon washer on the radiating side (see little blue arrow). But if the hole is too tight, the element touches the sides of the drilled hole and shorts to the Ground. Enlarge the hole by two or three mill, then CAREFULLY mount the radiating element so that it does not touch the sides.

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I'm thinking that is the problem, at least it was sorted, hopefully. [-o<

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Joseph
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Dragonfly
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Fri Aug 05, 2011 10:54 am

It could be a short but If you look at picture 4 you will see a simple dipole up on the wall of the house behind.
A CB radio simple Dipole needs to be around 8ft 6 inch either side so very large .


You need to set up the small ground antenna pointing downwards as in my diagram.

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stampman
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Fri Aug 05, 2011 3:08 pm

if it was bought new then would be unusual for the antenna to be shorting out on the mount more than likely to be the coax simple to use a wire lead in stead of the small antenna as well



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joe jeep
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Fri Aug 05, 2011 3:34 pm

Dragonfly wrote:A CB radio simple Dipole needs to be around 8ft 6 inch either side so very large .


You need to set up the small ground antenna pointing downwards as in my diagram.

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Does that mean that the mount needs to be at least 8ft 6 inch from the ground, also is there anyway of testing when the small ground antenna is pointing down without bending the mount, the pole is to rigid to bend. i have a right angle connector in order to get the antenna pointed upwards i took that out so it was horizontal with the small ground antenna but that made no difference.

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Joseph
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stampman
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Fri Aug 05, 2011 3:56 pm

no just run it down the pole an out at right angles from the bottom you will find that by moveing it it will alter the swr so find the best place and leave it there

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joe jeep
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Fri Aug 05, 2011 4:04 pm

stampman wrote:no just run it down the pole an out at right angles from the bottom you will find that by moveing it it will alter the swr so find the best place and leave it there

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sorry stampman, run what down the pole and out at right angles??
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Dragonfly
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Fri Aug 05, 2011 4:10 pm

Try the antenna on a piece of wood or insulate the pole from the antenna with ducktape or rubber hose , These ERF antenna are designed to work in a situation were there is no ground pole or metal body.

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Fri Aug 05, 2011 6:24 pm

The part their on is made of fibreglass. I placed a rubber washer between the connector from the coax to the bar of metal, and it has dropped the swr from infinity to just over 5, so getting better, but still not perfect.
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Fri Aug 05, 2011 7:34 pm

Hi joe,,if yer hoping that setup will work well as a homebase,,yer gonna be as disapointed as yer magmount on the garage door...you gotta go silver rod type at the least!!!..i know yer dad wont allow it...but messing around with mobile antennas wont work...

joe jeep
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Fri Aug 05, 2011 7:50 pm

No, this is for when i go camping!!
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Sat Aug 06, 2011 11:37 am

just down the pole glad your getting there

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joe jeep
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Wed Aug 10, 2011 7:01 pm

SORTED!! Sent the ERF mount back and Thunderpole have sent a 5/8 silver rod down, I will then put it on a steel (or alluminium) scaff pole stabbed in the ground with some nylon rope as guy wires and there we go!

Cheers Thunderpole!
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needle bender
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Mon Aug 15, 2011 4:40 pm

great stuff joe...hope it does the business and gets ya out and about....

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