[OZAPRS] Need a hand

[Glen English VK1XX]

OK good stuff thanks for the answers.

1) Magbase has insufficient capacitance at 10 MHz to give you any sort 
of ground. I wouldnt recommend a base base below 60 MHz or so, depending 
on the construction and the antenna.

2) Bonnet mount good but are the screws deep into your paintwork right 
through to the base metal  to get a good ground? probably not.

suggest take a earth wire off the baseof the magbase body or the bonnet 
mount to a chassis  or panel bolt, this probably means relocating the 
antenna, maybe. if onto the bonnet you might want to connect to the 
bonnet and then connect the bonnet to a bolt in the engine bay to ground 
that panel (rather than the hinges) . some vehicles have ground straps 
for that.  the wire to the immediate ground should be a good choice for 
the RF compared to the coax , so maybe something at least 2.5mm2 or flat 
strap and less than a meter long.

you'll need to re evaluate the antenna location/ mountaing to get a 
suitable immediate ground connection for the antenna (as the ground is 
half of the antenna, without it, the antenna wont feed)



On 3/12/2017 8:22 PM, Andrew Rich wrote:
> Both a bonnet mount and maggy mount in center of roof
>
> Diamond 30 meter vertical
>
> Radio is only connected via cigarette lighter
>
> Getting 6:1 and 9:1
>
> Vna dips but vswr is 6:1
>
> Might try my vhf whip on vna
>
> Not sure car and antenna base are grounded
>
> Like something is floating
>
> I need to measure ohms to chassis
>
> Rg58 only 4 Meters
>
> Radio ground only by power lead
>
> Vna is floating
>
> Not tried any ground straps yet
>
> A
>
>
> Sent from my iPhon
>
>> On 3 Dec 2017, at 5:56 pm, Glen English VK1XX <glenlist at pacificmedia.com.au> wrote:
>>
>> hi Andrew
>>
>> Please do ya best to answer the following barrage of questions and I may be able to assist :
>>
>> but all questions need to be answered to solve the crossword...
>>
>> 1) what is the whip.
>>
>> 2) where is it located, precisely
>>
>> 3) does the ground on the base of the whi[ measure 0 ohms to the chassis ?
>>
>> 4) how long RG58 lead in ?
>>
>> 5) Is the radio grounded via a local ground short strap/thick wire to earth bolt or only its negative power lead ?
>>
>> 6) does it dip below 2:1 VSWR anywhere when you sweep it with a VNA ?
>>
>> 7) With the VNA, is the VNA grounded, or floating on the end of the  coax?
>>
>> 8) With the VNA, if floating, does the VNA indicated sweep/match change if you ground the outer of the VNA coax connector to a local ground like ground bolt ona  door hinge etc
>>
>>
>>
>>
>>> On 3/12/2017 6:42 PM, Andrew Rich wrote:
>>> I bought a 30 m whip for the car
>>>
>>> Can’t get better than vswr 6:1
>>>
>>> I was told I need to ground the base
>>>
>>> Also cigarette lighter maybe not enough current ?
>>>
>>> 10.147 MHz
>>>
>>> Andrew
>>>
>>> Sent from my iPhone
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