Earthing

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bigpimp347
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Re: Earthing

Post by bigpimp347 » 24 Mar 2013, 15:04

bear in mind the link is from america where they use 110v power source and they have no earth/grounding on most of their 110v units..

at least we have a lot of appliances earthed..

all i'd say is do it if you think you need to, but i doubt you will need to, or even see any difference..

what are you trying to achieve by grounding ??
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Re: Earthing

Post by JGR » 24 Mar 2013, 15:10

It is something that was drummed into me as an amateur but I never did it with CB radio. And I think it will do no harm either way, but thinking about it in amateur radio terms we are using multiple wires and various antennas which can cause RFI so the grounding does help. But as the operator is using a balanced antenna they can choose to ground or not.
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Re: Earthing

Post by northern35s » 24 Mar 2013, 17:02

JGR wrote:It is something that was drummed into me as an amateur but I never did it with CB radio. And I think it will do no harm either way, but thinking about it in amateur radio terms we are using multiple wires and various antennas which can cause RFI so the grounding does help. But as the operator is using a balanced antenna they can choose to ground or not.
RFI, and it's source, has nothing to do with grounding your equipment.

An Antron 99 isn't a balanced antenna, it is end fed and as such is unbalanced, a properly installed A99 would have to be isolated from it's mast, have it's own elevated radials at the feedpoint, and a properly choked coax, but very few, if any, would bother to do that.
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Re: Earthing

Post by JGR » 24 Mar 2013, 17:16

So I missed a few vital points and made a couple of mistakes along the way, its Sunday and my mind is in a relaxed mode.

And its nice to see you on here as well northern35s.
Do not believe everything that is in black and white.
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Re: Earthing

Post by northern35s » 24 Mar 2013, 17:24

JGR wrote:So I missed a few vital points and made a couple of mistakes along the way, its Sunday and my mind is in a relaxed mode.

And its nice to see you on here as well northern35s.
And you to John, you'll notice a few others as well ;)
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Re: Earthing

Post by JGR » 24 Mar 2013, 17:27

Thundercat scrap the idea of RF grounding / earthing, I was following a myth of a bygone era that has seem to stuck with the hobby.
I have been re-educated and now know better and its not needed.
Do not believe everything that is in black and white.
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Re: Earthing

Post by rpcomms » 19 Jan 2018, 10:52

Depends on what exact equipment you have?

Old school linear DC supply-DC negative bonded to Frame ground (metal chassis)
New school Isolated DC type power supply including switched mode types or linears-DC negative is totally isolated from frame ground?
Old school radio and SO-239 socket is floating against DC negative line?
New school radio the SO-239 is grounded to DC neg line?
Antenna has ground plane or no ground plane?

I ask this because in some cases depending on what item you have for installation and combination
Ive discovered recently you can create earth loops,that can cause certain psu
to be susceptible to DC noise increase/RFI issue if the antenna system is bonded to earth\ground via mast\antenna mount,that grounds the coax braid
If radio has a common chassis SO-239 bonded to the negative lead of set and you use with a new type DC Isolated PSU,most will go noisy and create RFI,plus another issue in some circumstances AC leakage on DC outputs

I say this as a recent issue mainly with the new types of isolated ground psu coming out currently
and very little info as I found from mfr's or proper info on net on this problem.
A company i worked for ,took 2 years to figure and get done to bottom of this,we had people with PHD and alike could not figure this out
mainly due to mfr not telling the whole the truths and bad information,caused some right headaches i cant tell you.

some info on net can be misleading and not applicable any more,its taken me ages to re-train engineers from old school methods of grounding system firmly embedded in brain on this subject.

All i can say until i know,is watch these new DC isolated PSU,you can check them easy with a DVM with power off.
Do a continuity check and see if the DC negative terminal is connected to the metal chassis or earth if its Hi Z its open circuit,should be an isolated type
These isolated types do not like to be ground to earth via the negative DC terminal.Fullstop
I wont go into AC leakage as it will confuse you.

They way they get accidentally grounded is via the coax connected to antenna bracket,now if the mast is bolted mast and mast earthed.
Now depending on what radio you have
Isolated floating So-239 socket-no connection to DC negative
or in most case now modern radio where the SO-239 is bonded to DC negaive

this is where it becomes critical on decision to insulate antenna from mast or
not isolate antenna from mast to prevent a ground loop back to psu via co-ax

only if have a radio that the so-239 is bonded to DC negative and a isolated type psu will you need to isolate antenna from mast
if you have a old school radio where So-239 floats generally you wont have in most cases an issue if antenna is ground to metal mast and antenna mount is bonded to metal mast.

the mast if metal must be earth bonded via copper stake regardless for electrical safety (not antenna performance) purposes regardless of what install equipment.
It just do you isolate antenna from mast or not isolate antenna to mast
Obviously is mast fibre glass pole,not an issue at all

I know this sounds all confusing and its difficult to explain in text sometimes,best way is draw it out on paper ull get it.

I done a lot of research into this,esp with recent Switch mode DC isolated PSU and earth grounding effects in DC operated systems and what causes
the "switchmodes are rubbish for radios" problems partly due to different combination of equipment can cause DC noise on psu to raise,Noise spikes ,Bad RFI radiationon DC line,poor design etc and this new factor of never ground the DC negative to earth we found out on these types of new PSU's
some go really noisy and you prob wouldn't have a clue where to start tracking this down or seeing it unless have right test equipment.

I run here to prove it to other engineers as most dont believe at first ,pre-conceived ideas and gone away rethinking this whole issue
SMP DC isolated PSU (modern 2016 onward) to show you can use them on CB\HF radio (but installation and depending on equipment how antenna earthed.)
its noiseless,No dc noise,no RFI,
because the way i have installed radio kit and prevent this ground loop issue,with that type of psu
I will add also ive reinforced my psu with extra AC line 2 stage AC filters RS Part 704-4031
helps with main borne PLC and stops anything RF going back down and up mains!

My quarter wave ground plane antenna floats,not grounded on fibre pole,the mast in metal is grounded for electrical safety
and work's flawless.

Ill touch on AC leakage on DC outputs later on SMP's another undocumented problem in electronics world.
involves adding special capacitors to dc outputs to earth AC volts out,but dont worry about that for now.

I should also add this note,if antenna is floating,yes you need a ground plane otherwise it wont work,stating the obvious here.
On mine use 3 lengths 2.73metre long of 12AWG wire connected on the braid side\outer PL259,not the earthy end.

so to answer question maybe yes maybe no depends on ur kit you have.

this is why often there conflicting views on this often touchy subject that can get your finger burnt often!

Hope that helps!

And good luck getting on Air

73's Rob

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Re: Earthing

Post by ghost123uk » 21 Jan 2018, 10:48

DOH, must type quicker re ^^^

thundercat wrote:
24 Mar 2013, 12:55
its a homebase installation
Depending on how your homebase installation is set up, it is likely to be earthed to the mains socket anyway. Most CB type power supplies have the -ve terminal connected internally to the case, which, if metal, is by law connected to the earth of the 13A socket. Many of the proper "homebase" (mains powered) radios have the same arrangement. You can test this of course with your multimeter (whilst the whole lot is NOT plugged in to the mains.
I do wonder how much QRM (man made noise) comes in to the set via the mains earth. One could disconnect the earth for a quick test, but doing that may not be recommended !!

I can't see that an earth rod can do any harm, it might even do some good, Try it and let us know your findings.
Thinking out loud now "is a cold water pipe still a good earth, or is the underground run now always plastic"?
John, on the S. Cheshire / N. Shropshire border. Muppet handle "Grey ghost" and on UK C25 most working days.
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Re: Earthing

Post by Mattylad » 29 Jan 2018, 07:13

rpcomms wrote:
19 Jan 2018, 10:52
And good luck getting on Air
Methinks that since 2013 lots may have happened, the Op may not even be around any more. :)

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Re: Earthing

Post by rpcomms » 31 Jan 2018, 00:47

I just posted it up for others for ref ,looks like op alive :)
lots have happened in SMPs,earthing and dc isolation,a lot of books and info out there out of date of misunderstood esp in the use of SMP's for radio's and earthing.
Two problems exist now ...
old school cb with floating radio chassis
new school radios with common DC ground chassis.

Add to that mix with
Old school linear PSU with the DC side Earthed
New school PSU\SMP where negative DC isolated & should never be earthed(via coax,mounting bracket,mast depending on radio type ground used on chassis)

you can see by different combinations of old and new or new and new power supply and radio equipment ,a different outcomes can happen esp on the earthing of mast and antenna system.
Another misnomer is earthing the mast, is really for electrical safety really than performance enhancing the antenna system of verticals
antenna,
perceived improvements can happen due to poorly design antenna system and lack of ground planes on verticals
,esp on freq on low-band vhf where line sight is really primary goal for most cb communications,apart from serious Dxers
needing low angle at height or high angle for sky-wave DX communications.
Ground effect on a vertical will change the angle and reflection,not the mast in earth!


Recently add the AC leakage (where you can measure AC volts from either DC positive or DC negative terminal to frame chassis mains earth)issue now found commonly on poor designed on DC isolated PSU's linear and SMP,
thats add another variable into the mix and yes I have seen this problem and believe me I was amazed the number of professionals in Industrial electronics were not aware of this problem including myself,too quite a while to find a fix for this issue.
add two *680nF 1000V 310VAC Wurth Part 890334027006CS RS Part 871-2629 2off required
the effectiveness is good up to 30V DC
I used solder tag's to psu metal chassis and solder caps on inside of pos and neg DC terminals to the solder tags inside the psu which sit at frame earth ground
The solder tags are nut,bolted,star washered,ensure any paint does not insulated the tag,need a good earth bond.
To check use DVM on Ac turn on PSU,ut one DVM probe to PSU chassis earth,othe DVM prob to pos or neg DC terminal
IF you see anything more than 1 Volts AC upto shock horror over 100 Volts (dont worry its very low uAmps! you wont get a shock!),then try fitting the cap mods.
When fitted around 0.3V AC or less should be seen on repeat test.
This issue can upset CPUs board and random strange outcomes like CPU lockups!
when addling RF transmitting based equipment into this,some funny strange things can happen,hum,sequels,tripping SMP
Ive personally modified about 12 PSU's found with problem and all cured it,all my DC designed PCB incorporate these capacitors on 24V DC industrial electronics involved iin to avoid this problem when customer supplying own brand PSU equipment.


I would encourage the use of Hi quality AC line filters n PSU old or new too when using radio gear.these filters stop anything going into psu or coming back out down the AC line
The ones I use and know work well are
RS Stock No.702-4031 Or
EPCOS Mfr. Part No.B84115EB110 RS Stock No.213-7154

these def help when using RF equipment and (SMPS) switched Mode Power supplies or Linears.#too.

This is one of the main reasons operators and radio engineers can get very confused with contradicted information in books and forums and the equipment been in installed from personal experiences in my engineering work.

I run SMP PSU,with Ac line filters,AC leakage caps when required,with modern DC grounded radios and floating antenna with ground planes
and no issues whats so ever,my mast cannot be earthed due to being fibre glass.
If I had to use steel mast (with modern SMP\DC Linear ISOLATED type PSU) I would use a PTFE or THICK Nylon packing isolator plate mounted to antenna mount and between steel mast so bracket and mast totally isolated to prevent the SMP earthing issues.
The antenna used would either be a ground plane type or a choked RF type cb vertical antenna
The mast would then be earth via thick earth strap and copper rod into ground
The coax,antenna mount sits at DC neg via the cb radio S0239 socket,chassis\PCB,it will not come in contact with earth at all due to the issues doing so ,its design that way for safety.


If on other hand have a old school linear PSU and old school floating chassis type radio like cybernet or superstar,then its fine to electrical earth the mast and connect the antenna mount to the mast pole with no issues.

If unsure to check what type earth on your radio,use a DVM on ohm continuity test
connect black probe to black on dc lead,place red probe of DVM on the bare cb radio chassis or SO239 socket outer,
if it show low ohm 0-2 ohms its common DC ground type,most modern two way radios are.
If it show NIL or Infinity Ohms on DVM you has a floating chassis radio ,inside the DC neg of radios PCB is decoupled to metalwork via ceramic Disc capacitors

One day when I get 5 mins myself ill post some diagrams up as text can be sometimes be interpenetrated incorrectly ,as I often get same troubles explaining this to other radio engineers professionally due to misguided information and the mix up of equipment and power supplies types and not gully understanding the outcomes.

I will add a note not all SMP have AC leakage issues,just ones missing these vital capacitors,TDK SMP PSU's i choose to use had these caps installed and confirmed by mfr's

Another trick i have done is ground the radio chassis internally if its was a floating system type on cb and using a SMP PSU,the antenna isolate from masted (thats earthed),my superstar 3900 was having some hissy fits with ssb carrier leakage,once DC neg was ground to radios chassis internal problem went away and SSB leakage was fine.

UPDATE-Also i have been told you can get special fully isolated 1:1 commercial baluns\isolators (not electrically connected primary and secondary winding) to do same trick of isolation of coax to mast\antenna,but have not validated this technique or used under correct conditions,so I cannot advise\comment on this one.



Ill prob get some flamings too on this?,lol
so to put it in context i had to deal with with a real design headache in industry electronics equipment
it took us a long time to get down to this mystery as as engineers we had preconceived ideas on earthing system,linear VS SMP,Ac leakage it turn out a big can of worms we opened up when we finally got down to bottom of all this,including some so called experts with certificates as long as your arm ,psu manufacturers,the internet ,forums and a lot of red hearings.
After we fix the issues and learnt a lot of things,my curiosity turn to radios and wondered if same issues with earthing masts,smps,different radio earth types had an effect.
And yes after a bit of R&D,I did find under certain circumstance depending on what equipment combinations,you can actually make things worse earthing your antenna under certain circumstance!
Even close friends in industry still question this and some shocked when show practicable test beds and outcomes!

Personally after what i learnt and validated data gathered on this often touchy subject
i try to advise now anyone on pitfalls of antenna isolation from mast and earthing masts with some radio equipment setups and what psu you have more so now than before in old days of radio,mainly where base station installation are involved.
All the radio guys in my group successfully run our equipment this way or make allowances in setup,including the cap mods for AC leakage issues on psu.
Sometimes old school DC isolated types we have come across AC leakage issue now we are aware of it,mods worked fine.



Hope this extra info of some use,and glad OP still alive and kicking on radio!
seems you have read my post so one result :thumbup:

Regards 73's

Rob

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