rear mounting of hf aerial on prado off spare tyre mount

Submitted: Wednesday, Feb 06, 2008 at 09:35
ThreadID: 54294 Views:4452 Replies:5 FollowUps:4
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I am contemplating mounting the hf aerial off a bracket from the centre of the spare wheel mounting. Has anyone done this successfully. Does it overload the back door. Has it affected the reception of the radio.
The radio is a Codan and the good book says that half of the autotune should be above the roof line of the vehicle.
This makes the aerial very high and the bracket to suit this height
would be huge.
The standard bracket off shelf have the top of the autotune at roof height.
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Reply By: Member - Doug T (FNQ) - Wednesday, Feb 06, 2008 at 09:40

Wednesday, Feb 06, 2008 at 09:40
Have a look at the link on this EO website,

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AnswerID: 285923

Reply By: Member - lyndon K (SA) - Wednesday, Feb 06, 2008 at 10:18

Wednesday, Feb 06, 2008 at 10:18
Hi
I have my Codan NGT aerial mounter to my Kaymar swing away wheel carrier, just about the whole (fat part) aerial is below the roof line. Just how i wanted it so i couldn't catch it on tree's, obviously the whip is quite long so this pokes up about 6ft.
Mine works well.
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AnswerID: 285930

Reply By: Member - Mike DID - Wednesday, Feb 06, 2008 at 11:25

Wednesday, Feb 06, 2008 at 11:25
Codan did some tests a while ago that showed how much the signal dropped from a rear-mounted aerial compared with Bullbar mounted.

The loss varied quite a bit with the direction of the other station.

With the current regulations we don't any choice about mounting autotune antennas.

Moonraker claim their autotune is less affected by metal near the lower part of the antenna.
AnswerID: 285937

Reply By: Member - Phil G (SA) - Wednesday, Feb 06, 2008 at 15:02

Wednesday, Feb 06, 2008 at 15:02
Yep, I made a bracket on my 90series tailgate. Its a bit tricky to get it right - you have the option of buying one - from memory between $125 and $150 (Electric Bug in Adelaide were selling them).

If you want to make your own, the following advice was offered to me by someone with a vast amount of HF experience.

To mount a Codan autotune on the Prado you'll need a bracket that comes out to the LHS of the spare - thats because the Codan aerial is so tall. Barrets can be mounted on the RHS, because the autotune is shorter.

For optimal transmission, the base of the autotune needs to be at least 160mm away from the metalwork. The signal radiates 45degrees upwards from near the bottom of the autotune, so the aerial needs a lot more clearance at the top of the autotune. This extra clearance can be obtained by tilting the aerial backwards a bit. If you skimp on clearance, your transmissions will not be as good.

The bracket itself can be attached to 3 of the 4 holes that hold the spare wheel bracket to the tailgate. Ideally, the backet should lean against the spare tyre as it comes out sideways - this offers additional stability for the bracket, so it doesn't have to be overengineered. Don't mount the autotune too close to the sparetyre because they have steel belts and will affect the signal too.

Also use a big fat earth wire from the autotune to the body of the Prado. The best place to pick up the earth is one of those big bolts for the tailgate hinge that go into the body, not the tailgate. I also made mine, so you had to remove the spare to undo the aerial - just some additional theftproofing.

When you transmit, have the vehicle point towards the base being transmitted to. You'll throw the signal better in a forward direction, with a rear mounted autotune.

If you do all that, you'll transmit as signal thats as good as any front mounted aerial.
AnswerID: 285967

Follow Up By: Mike - Wednesday, Feb 06, 2008 at 19:55

Wednesday, Feb 06, 2008 at 19:55
Phil I have the Codan Auto tune on the rear wheel carrier of my 100 series and was told by a radio expert to have the rear of the vehicle facing the station that I was talking to for the best TX RX, having said that, I get good reception which ever way I am facing
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FollowupID: 551033

Follow Up By: Member - Phil G (SA) - Wednesday, Feb 06, 2008 at 23:27

Wednesday, Feb 06, 2008 at 23:27
Hi Mike,
Like you, I'm just going by what I was told as to which way to face the vehicle. I've looked up my installation manuals and googled a lot, but can't come up with anything that confirms it.
Like you, I receive well no matter what direction.
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FollowupID: 551092

Reply By: Geoff M (QLD) - Wednesday, Feb 06, 2008 at 17:15

Wednesday, Feb 06, 2008 at 17:15
There's a thread on this subject over on the 120 LCOOL site with some good info on the bracket.

Site Link
AnswerID: 285993

Follow Up By: Richard Kovac - Wednesday, Feb 06, 2008 at 23:14

Wednesday, Feb 06, 2008 at 23:14
geoff

link goes to members log in???

Richard
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FollowupID: 551089

Follow Up By: Geoff M (QLD) - Thursday, Feb 07, 2008 at 10:11

Thursday, Feb 07, 2008 at 10:11
....yep Richard, the magic of cookies.

I tested it before I posted, but because I'm an LCOOL member it automatically signs me in.

If you want to see the thread you'll have to register.

Go to lcool.org/ (Click Here)
then go to "Members" and submit your application for membership.



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FollowupID: 551165

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