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 Mag Mounts 
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Are mag mounts any good for HF /HF/VHF.
I have gone and purchased a 2011 Vauxhall Astra Estate with no place due to the shape of the tailgate
to secure a boot mount. I am wanting to put in a multiband set but until I find where to secure the antenna too
its on hold at the moment.
Using a mag mount with an HF whip stationary is a counter poise needed?

73
Keith.

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Tue Apr 14, 2015 12:36 pm
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Post Re: Mag Mounts
Advent wrote:
Are mag mounts any good for HF /HF/VHF.
I have gone and purchased a 2011 Vauxhall Astra Estate with no place due to the shape of the tailgate
to secure a boot mount. I am wanting to put in a multiband set but until I find where to secure the antenna too
its on hold at the moment.
Using a mag mount with an HF whip stationary is a counter poise needed?

73
Keith.

Its an old chestnut!
Some will say they have used them with no problems, wherever, others will poo poo them as terrible and only fit for keeping your old washers and screws stuck to!
A lot depends on the size and quality of the magnetic base/feeder and the extent of its indirect RF coupling to the metal beneath it, and indeed the amount of metal it is sat on!
A mag mount on a large metal vehicle, will produce better coupling and results to the same magmount stuck on a biscuit tin!
I have never used a mag mount for lower HF mobile, I have never bothered with lower HF mobile unless you include 10 metres, which was fixed mounted to a boot lid!
I have used several magmounts for small dual band 2/70 antennas, and indeed a quarter wave 4 metre one, that seemed to work quite reasonably stuck in the middle of the roof, the largest metal expanse!

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Tue Apr 14, 2015 2:13 pm
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 Mag Mounts 
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I've used Mag Mounts in the past; they can scratch the paintwork if you are not careful. I had a Mag Mount fly off at speed which caused damage to the car. Since then, I've used one 1/2 of a Roof Rack and bolted my Antennas to that.

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Tue Apr 14, 2015 2:27 pm
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 Mag Mounts 
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Thanks Dave for your reply...
I was thinking along the lines of say a crocodile clip connect to bare metal on the car
with the other end connected to the base of the mag mount. That way there will be an amount
contact on the ground side. How about a counterpoise would one be needed.
I do have means of putting a mast up and say a Dipole longwire whatever,
but what I don't want to do is carry all the gear in the boot of the car all of the time.
Whereas several mobile antennas for the band of interest can be slipped inside the car with minimal of fuss.
Keith.

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Tue Apr 14, 2015 2:29 pm
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Post Re: Mag Mounts
G4NVB wrote:
I've used Mag Mounts in the past; they can scratch the paintwork if you are not careful. I had a Mag Mount fly off at speed which caused damage to the car. Since then, I've used one 1/2 of a Roof Rack and bolted my Antennas to that.

Good point, whether something stays stuck or not depends on strength of magnet, and windloading of what its trying to hold aloft!
None of my antennas used on a magmount have been particularly long, and thus have small wind loading effect!
On the temporary attached couterpoises for fixed stationary lower HF operation, probably would work wonders!
It certainly would not hurt, and may dependant on car metal mass and base coupling, offer an easier tuning solution!

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Tue Apr 14, 2015 2:33 pm
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David thanks also for your suggestion.
A pair of roof bars for my car Vauxhall are not cheap.
Running around with one roof bar on makes the car look
unsightly, thats my opinion...
I'll consider your suggestion and maybe I will take it up.

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Tue Apr 14, 2015 2:36 pm
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Any one out with a car similar to mine a Vauxhall Astra Estate new style (Mk J ) 2010 on.
Have fitted antennas to their tailgate how and what did you use?

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Tue Apr 14, 2015 2:41 pm
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Advent wrote:
Running around with one roof bar on makes the car look unsightly, thats my opinion...


It does look a little different, although I mount mine probably a little further back than normal.

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Tue Apr 14, 2015 2:46 pm
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Advent wrote:
Thanks Dave for your reply...
I was thinking along the lines of say a crocodile clip connect to bare metal on the car
with the other end connected to the base of the mag mount. That way there will be an amount
contact on the ground side..


Wasting your time. Good for DC, pointless for RF. The coupling of the magnet will already be better than a wire.

Basically how well it'll work is determined by the surface area of the magmounts and the thickness of the metal its attached to.

20-10m you probably won't notice any issues. 40m starts to get a bit flakey, on 80m with a triple magmount I was getting my TS480 rebooting every time I tried to run more than 50W on SSB. I drilled a hole in the roof and solved the problem.

Magmounts will scratch the paint and if you put something on the roof to stop that the coax will still scratch the paint. No matter how tight you get it it is impossible to stop the coax flapping around unless you gaffer tape it to the roof.

Roof bars are a crap place to mount your antenna. No matter the DC continuity your ground plane is the bar when you want it to be the vehicle body.

The best solution? Get the drill out and put a mount in the roof, preferably one of the Breedlove 3" or 4" puck mounts. Put it towards the rear of the roof, a couple of feet in front of the existing roof antenna. You'll need to strengthen the roof with a bit of sheet metal under it as its a bit thin on post 2005 Astras. When it comes to sell the car remove the mount and fill the hole with a colour coded sharkfin antenna for DAB and sell it as a bonus.

As for the tailgait, forget it.


Tue Apr 14, 2015 3:47 pm

 Mag Mounts 
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I once (last year) drove out to a quiet place to play with my radio gear and set up a magmount just to trial a few things. As I started home I though "shall I pop the mag mount in tha car or leave it up, aerial and all? If I drive sensibly it'll be fine. ha ha (I thought) it'd take a fat pigeon to hit me to knock it off"

So I drove home carefully and I was right.

A blasted pigeon came straight at me, hit the aerial and took the lot off the car, bounced along the body work and dragged down the road.


Next time I'll think to myself "ha ha, it'd take a naked 25 year old blonde nymphomaniac to knock it off"

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Tue Apr 14, 2015 4:15 pm
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 Mag Mounts 
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Post Re: Mag Mounts
Sirio 145 mag is a decent magmount with a good quality magnet. Held six and half foot aerials on at motorway speeds. It is an SO239 connector.

Rubber boot shouldn't scratch the paint work, but if you're worried, get a polythene food bag and an elastic band or tie, to on the mag.

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Tue Apr 14, 2015 10:00 pm
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M0GVZ wrote:
As for the tailgait, forget it.


Don't agree, a decent mount on the tailgate is more than adequate even up to 80m, I have 2 on my tailgate one for HF and one for VHF/UHF.

I have the luxury of being able to mount all the equipment in the boot underneath the boot tray which is where the manufacturer also has mounted the Mobile phone / Satnav / DAB and has left a few "holes" and mounting / earthing lugs.

Make sure that:-

1, paint is removed by the grub screws on the mount(s)
2, ATU (if used) is earthed
3, radio is earthed
4, Coax as short as practicable
5, battery leads (if battery is in boot like mine) as short as possible and fused - if not get earth wire direct to chassis

The setup works, only 1 wire into the cabin for the remote head unit (speaker hidden under passenger seat), QSL cards to prove it radiates.

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Wed Apr 15, 2015 7:21 am
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Road_Hog wrote:
Rubber boot shouldn't scratch the paint work, but if you're worried, get a polythene food bag and an elastic band or tie, to on the mag.
In my experience, no matter what you try to do, you invariably end up with fine scratch marks on the roof; small dust particles is all it takes.

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Wed Apr 15, 2015 7:44 am
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Post Re: Mag Mounts
G4NVB wrote:
Road_Hog wrote:
Rubber boot shouldn't scratch the paint work, but if you're worried, get a polythene food bag and an elastic band or tie, to on the mag.
In my experience, no matter what you try to do, you invariably end up with fine scratch marks on the roof; small dust particles is all it takes.

Thats true, the stronger the magnet the more the problem!
As when you try an lift it off, inveitably there is a bit of sideways slide, and any dirt, or worse still fine metal particles stuck to even the rubber booted type, work like fine emery cloth!
If like me its an old work horse vehicle, no real bother, if its your latest brand new expensive pride and joy, a bit of a worry!
After all shinier the car, more the scratched bits stand out like a sore thumb! :)

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Wed Apr 15, 2015 7:50 am
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Post Re: Mag Mounts
Hi

I thought this was my biggest challenge of going mobile HF trying to find a suitable antenna mount, If you have a tow bar there is a chap on fleabag that makes tow bar mounts to your required specification cost aprox 20-25 quid. I got one for the hilux as the boss wasn't to happy with an antenna mounted on the work vehicle, even though I have it for personal use there was no holes drilled.
Takes about 5 mins to fit and assemble when needed, I have tried a few so called hatch/trunk mounts and ended up with one coming apart, the one remaining I have had for 6 months and is now starting to rust I use this for vhf. Tried using a tripple mag mount but the rubber protection covers didn't last long.

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Wed Apr 15, 2015 9:33 am
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