The amount of MF radio garbage that is running around common mode on power
lines, phone lines, metallic pipes, etc, is pretty amazing. I've walked
around with my battery K2 listening next to power pole ground wires, buried
power lines where they enter the ground.
The garbage level goes down very quickly as you move away from the wire. A
lot of it can't be heard above atmospherics if the antenna listened on
doesn't hear anything from its own feed coax shield.
Think of it like a network of hoses with leaks all over the place, where
the leaks work in reverse and you don't want anything getting in.
Grounded, bonded together, common mode chokes plugs all the leaks INTO your
signal coax wiring and into your equipment via power and signal wiring.
Power line buzz does not always use regular propagation to your receiver.
It can come in common mode on power lines whose
entirely satisfactory-for-power-purposes entry ground happens not to be
particularly effective at RF.
You will never know your real noise floor until the shack, wiring, antennas
and feedlines are grounded, bonded and blocked as needed.
73, Guy K2AV
On Wednesday, October 28, 2015, Steve Ireland <vk6vz@arach.net.au> wrote:
> Hi Jim (Murray)
>
> Jim K9YC is absolutely right - I live in a similar situation to you and
> the problems have been markedly improved by getting the grounding and
> bonding to earth improved around the house - wish I had taken Jim's advice
> years ago. House earths are often very simple at best and whilst they may
> be good enough to save your life, they are often not good enough in terms
> of RF
>
> Have a look at Jim's book (there are some great diagrams) and get an
> professional electrician in to beef up/improve the house earth/improve the
> equipment bonding.
>
> The likelihood is you win both ways - probably be safer and the RF noise
> will be lower.
>
> Vy 73
>
> Steve, VK6VZ
>
> On Sun,10/25/2015 8:59 PM, Jim Murray via Topband wrote:
>
>> Tomorrow I will walk the line and see if I can come up with anything.
>>
>
> Jim,
>
> I STRONGLY suggest that you check out grounding and bonding in your home
> before looking for noise sources. Poor or missing grounding and bonding
> will bring noise into your home, so you need to get that right FIRST.
>
> 73, Jim K9YC
>
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