[OZAPRS] 10.147 MHz antenna

Peter Dodd dodd.pc at bigpond.com
Sun Dec 10 16:11:01 AEDT 2017

Hi Glen,

Using copper strap because I had it.

Coax shield will be backup it strap is impractical at a particular 

Thanks for other info


----- Original Message ----- 
From: "Glen English VK1XX" <glenlist at pacificmedia.com.au>
To: <ozaprs at aprs.net.au>
Sent: Sunday, December 10, 2017 8:11 AM
Subject: Re: [OZAPRS] 10.147 MHz antenna

> (this info for everyone)
> Peter, on your copper straps- be sure to use a zinc based jointing 
> compound between the copper and aluminium... or a large Zinc(Gal) washer. 
> ...and avoid stainless in there. The Gal washer works well.
> On a more practical note, on the copper straps, given that the the ground 
> you are trying to connect to is 10 to 20 ohms, an ohm of RF resistance 
> wont hurt ! wide copper is not necessary... so something like a couple of 
> 4mm2 wires soldered to crimp lugs (as the Cu-Zn-Al interface) will do the 
> job.
> Depending on the length.
> 3mm2, like RG213 inner is approx 132 milli ohms per meter at 10 MHz.
> so you dont need much ..
> 1mm2 about 230 milliohms per meter at 10 MHz
> glen
> On 9/12/2017 10:58 PM, Peter Dodd wrote:
>> Hi Andrew,
>> SO239 base is mounted on approx 200 x 200 mm sheet of aluminium which is 
>> bolted to the rack.
>> Rack is providing a counterpoise of sorts.
>> At this time rack does not have a good dc path to chassis (fibreglass 
>> canopy in the way).
>> In process of making earthing straps using copper strips approx 25 mm 
>> wide to remedy this.
>> Shifted antenna late yesterday and haven't redone sweep yet.
>> Should be able to get back to it tomorrow.
>> Heard by vk4mq-4 1600km so it is operational but probably not ideal
>> Regards
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