[AusNOG] Positive ground

[Jonathan Brewer]

Hi Rhys,

First thing to check is whether the radio transmitter chassis is bonded to
the positive terminal. A continuity test on a multimeter will tell you
that. If your transmitter chassis is bonded to positive, then your mast and
earth will be positive earth (or something will go bang). You don't want
that transmitter sharing a mast or rack with any +12/24V gear, which is
most WISP gear. There is only one Netonix model I know of that should be
able to share a positive earth rack - the WS-26-400-IDC.

If your chassis is isolated, it's fine to use an isolated DCDC converter.
I've done this both ways - to install +12/12V equipment in cell sites
(which are usually -48V). And I've done this to power Ve+ microwave radios
from +24V.

I have worked on some mixed sites in New Zealand where there are isolated
-48V racks that have their own earth return to the building rectifier's
positive terminal. The earth bars are painted red to make it obvious.
Sketchy but it works.

Best of luck keeping that smoke in.

Cheers,

Jon

On Thu, 25 Jun 2020 at 15:19, Rhys Cuff (Speedweb Internet) <
Rhys at team.speedweb.com.au> wrote:

> Hi Group
>
>
>
> We just purchased a radio transmitter that requires Positive Ground.
>
> We normally power with a Netonix but the Pin out is different so that’s a
> no go.
>
>
>
> I can power with DC cable, problem is the unit is positive ground,
> everything else is negative ground.
>
> It’s an off grid site, all 24v dc
>
>
>
> What are my options for powering this?
>
> I “Think” I can just use an isolated DCDC converter but don’t want to risk
> letting the magic smoke out.
>
>
>
> Thanks  for any help.
>
>
>
> Rhys
>
>
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