[OZAPRS] Grounding of HF Antenna for APRS

[Matthew Cook]

For braid you want wide and flat to keep the L low.

Make sure the braid it can't touch your paintwork or you'll find all sorts
of scratches in your roof paintwork (think sand paper) by the time you get
to where you're going...  Covering it in heatshrink gives it too much mass
and will make it thump the roof as you drive, tends to drive you nuts.

If your mag base is less than 140mm in diameter be careful with a 1.4m whip
in the centre of your roof, the first road train you pass going the other
way will likely see the magbase come through a window if you are not
careful.

Guards, brackets, roof rails, roof racks, screws and bolts et al are your
friend...

73

Matthew
VK5ZM

On 4 December 2017 at 11:28, <vk4tec at tech-software.net> wrote:

> I went to see an engineer mate
>
> He gave me some brass plate
>
> I am cutting out a plate that will have a braid strap coming off it
>
> That should do the trick - he said the VSWR should come down even further
>
> Nudge bars are $1000
>
> Andrew
>
> -----Original Message-----
> From: OZAPRS [mailto:ozaprs-bounces at aprs.net.au] On Behalf Of Glen
> English VK1XX
> Sent: Monday, 4 December 2017 7:35 AM
> To: ozaprs at aprs.net.au
> Subject: Re: [OZAPRS] Need a hand
>
> yeah that will work. it would be out of the weather, and get covered with
> oil/grease and probably weather seal it.
>
> being close to the feedpoint actually isnt that necessary, maybe no more
> than 1/20 of a wavelength, though , that is probably a good number. so max
> strap length 1.5m for that freq.
>
>
> On 4/12/2017 8:27 AM, vk4tec at tech-software.net wrote:
> > Glen
> >
> > I am thinking that maybe just a strap that fits in the gap between the
> bonnet and the side wall.
> >
> > I can sink a screw into the bonnet just inside
> >
> > That way it would be as close to the feed point as possible
> >
> > I would drill into the top side of the bonnet but that equals a
> > divorce LOL
> >
> > -----Original Message-----
> > From: OZAPRS [mailto:ozaprs-bounces at aprs.net.au] On Behalf Of Glen
> > English VK1XX
> > Sent: Monday, 4 December 2017 7:23 AM
> > To: ozaprs at aprs.net.au
> > Subject: Re: [OZAPRS] Need a hand
> >
> > In looking for a place to attach a ground strap, consider that ideally,
> you want the largest continous area of metal. That is probably the engine
> bay firewall (which would attach to the upper body, roof etc) , fender
> mounts,  or in the rear, hinge mounts of the rear hatch, etc.
> >
> > Anyone else have any input here  on where to connect on a modern vehicle
> to maximise surface area ?
> >
> > comeon. ???
> >
> > I am a bit out of tough on modern vehicles. (I have a 2005 XC90 which
> > if you pass a RG58 through a door seal will squash it flat and cause a
> > short... hence requiring coax entry through a bung in the spare tyre
> > well under the vehicle)
> >
> >
> >
> >
> >
> >
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> >
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