Anyone care to help with grounding?

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Re: Anyone care to help with grounding?

Postby Dave In Herts » Fri Feb 28, 2020 5:33 pm

G4RMT wrote:I'd not thought much about this before, because it never used to be this complicated, but it does strike me that now the mains electricity rules have leaked into our RF systems, the damn situation is stupidly complex. Worse still, where would you find an electrician with Part P certification who understands ANYTHING about RF. The idea of an upstairs grounding system, and the possibility of RF getting into the system and causing havoc would be a nightmare. I'm left wondering if this extra grounding is actually necessary. I wonder if it's just possible to have an RF grounding system and isolate this from the mains side of the installation. Clearly difficult to stop the chassis of a mains powered radio being connected to electrical earth, but maybe with a bit off effort and planning?

I used to work in quite a few studio installations where there was a mains earth but a separate technical earth - how on earth this would fare nowadays I don't know.


Luckily my guy is an old friend and although he does no know RF, at least he bonded it and tested it.

Driving a rod and not bonding it in a PME area is a no-no completely - any faults in the area can set up dangerous voltages in the ground which will then be picked up and sent into the equipment - all rods must be bonded to supply, its complex but well explained online.

Looking at it i can see multiple ground loops, Im already suffering from one on the PC audio line, and the only real way i can see to make this stuff work is lift ALL the shack from supply ground and re-ground it to the star-point and then to the new rod - this however opens more worm-cans and i really do not want to get into tampering with the shack supply grounding.

If i can't fix the audio noise i'm getting now with a little ground-loop isolator i'll probably disconnect all the new grounding until more knowledge or information arises. This does mean that i will NOT be able to run my EFHW grounded, it'll have to run against the coax outer upto the CMC.
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Re: Anyone care to help with grounding?

Postby radiostationx » Fri Feb 28, 2020 9:06 pm

I said at the outset that it was no mean feat to set up a station on the 1st floor and not have some sort of interference coming back via chassis ground.
Here you have some feedback via the gnd of the audio line, Seems like you have a methodical and logical plan Dave by disconnecting the star ground/central chassis ground, and then perhaps re-instate each chassis ground from each piece of eqpt in turn.
You also have the possibility of near field electronics/other unrelated eqpt causing the issue.
The EFHW80-10 will work fine if you choose to omit the option for the ground connection.
The impedance transformer (CMC/Common mode choke) will match your wire without.
In my DIY version of the tranny (which is a slightly different ratio) I inserted a 3kv rated capacitor by Vishay/Cera-Mite which is just visible below the resin.
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Re: Anyone care to help with grounding?

Postby Dave In Herts » Fri Feb 28, 2020 9:30 pm

Yep, its all good clean fun :)

Taking a tip from other sources, I just watched an hour long video from the RSGB on the very subject. :biggrin:

Anyway, i'll try this as it's pretty easy....

Remove my existing ground setup and disconnect the ground rod from everything.
Fit a big 31-mix ferrite choke to the single-point shack supply making a "clean" supply and lowering the risk of feeding RF into the mains as well.
Go internal and disconnect the PSU negative from the supply ground, replace the link with a 1k resistor for static drain.
If needed, choke all the coax feeds.
Bond all the shack stuff with something - he used copper-clad PCB but i have a feeling wide copper tape will do the same as the PCB has no electrical effect here.

Suck-it-and-see :happy: :happy: :happy:
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Re: Anyone care to help with grounding?

Postby radiostationx » Fri Feb 28, 2020 9:59 pm

I know other sources said to bond the coaxial braids at entrance to property but can you imagine the hassle you would have if you had to unbond them all to find the problem.
Thats why I was in favour of not bonding here to facilitate maintenance.
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Re: Anyone care to help with grounding?

Postby Dave In Herts » Fri Feb 28, 2020 10:11 pm

Its easy - they all spilt at the house entrance, the RX feeds are all on F-Type plugs and the TX/RX is PL259, I just used bulkhead joiners mounted on a copper strip. I can easily remove the copper strip again.
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Re: Anyone care to help with grounding?

Postby radiostationx » Fri Feb 28, 2020 10:28 pm

Ahhh Okay, Its just your drawing stated a 10mm bond, at first I thought a 10m2 earthing cable and I envisaged sheaths being nicked and soldered to it or something.. but that must be the copper strip with the bulkhead f couplings and so-239 for your HF. So you have done a little bit of fabbing to make things tidy and easy to maintain..Very Good Dave.
I take it you are using webro ct100/wf100,? That would explain the F type connectors,Its Very good coaxial.
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Re: Anyone care to help with grounding?

Postby Dave In Herts » Fri Feb 28, 2020 10:56 pm

Yep spot on, WF100 an F-Types.

I'll just pull the copper bar and refit the plain joiners, 5 minute job.

Just found some nice 20mm copper braid on the 'bay, that's on the way :happy:
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Re: Anyone care to help with grounding?

Postby Dave In Herts » Sat Feb 29, 2020 10:15 am

Right, i'm heading this way following an excellent video by the RSGB, all equipment bonded but uses the supply earthing. RF hopefully kept outside with CMC's where needed. No ground rods.

http://testsite.davekearley.co.uk/wp-content/uploads/proposed-mk5.png
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Re: Anyone care to help with grounding?

Postby Dave In Herts » Thu Mar 05, 2020 5:50 pm

Have now built the mains supply filter, multi-stage as per presentation, 1st stage is a block-type commercial filter, 2nd stage is a large type 43 core with 8 turns on it then 3rd stage is two oval 31 type cores side-by-side with 4 turns on them, then its out to the radio/pc stuff.

Have also bonded the equipment together as shown in the video, used a wide copper braid as a bus and dropped on to it with smaller braids from each item.

A little disappointed with results as i only got a S0.5 drop in background mush on all bands, to measure, i connected a dummy load and did a before/after test. Only S0.5 but better than nothing and at least now i know my mains is clean in both directions.

The video was a little foggy in one area - do i need to take that bonding strip to supply earth or not?
In practice it already is - via the PSU and PC supply cables.

Already to go i think, should get my callsign next week :smiles: :smiles: :smiles:
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Re: Anyone care to help with grounding?

Postby Dave In Herts » Thu Mar 12, 2020 11:43 am

Finally got my callsign today :) :)

I am now M7DJK

Now to start burning up the airwaves with all of my massive 10 watts of allowed power :)
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