[1000mp] Groundsystem and RFI-problems with FT-1000MP

[John]

Hans,

Thanks for your reply.  I did not intend for my initial e-mail to go to the
entire list, however, since it did (I tend to forget how this list operates
when thinking about something else.), I'll also post this to make sure
everyone knows I had no intention of inferring any pigheadedness on your
part!  My questions were meant to help me better understand your
perspective.  I've seen information from other EU hams having a similar
isolated grounding system and wanted to figure out why we come to different
solutions.  I know that splitting the grounds can help with some forms of
RFI.

The quotes from the ARRL Handbook points out well how there can be
conflicting considerations on grounding.   The fact that your station has
survived two lightning hits indicates you are probably doing something
right!  I'll have to think more about using an isolation transformer,
however, I can see how it would help.

Appreciate if you could pass along the specifications on your isolation
transformer, especially the maximum voltage between the primary and
secondary that the insulation can survive without breakdown.

Please respond to my e-mail address direct as we are probably not covering a
subject intimately related to our "MP's".

73,

John  W0DC

----- Original Message -----
From: <hans@remeeus.nl>
To: <1000mp@mailman.qth.net>
Sent: Saturday, August 24, 2002 10:25 AM
Subject: [1000mp] Groundsystem and RFI-problems with FT-1000MP


> Dear John (Morris and others),
>
> > Please explain what the term "double pulse" (ground) means.
>
> Language problem!
>
> I mean: "double ground rod". We used two ground rods in an angle of about
90
> degrees. One ground rod in an angle of about 45 degrees to the house and
one
> rod in an angle of about 45 degrees from the house. Both rods are tight
> together and are connected to the antenna mast.
>
> > If the antenna/shack ground system is separated from the houses
electrical
> > ground, won't a lightning hit to your antenna result in a very large
> voltage
> > difference between the equipment ground and the AC input?  (start a
fire?)
> > In the U.S., when the antenna and AC grounds are tied together well, the
> AC
> > line voltage rises with the ground voltage rise due to the center tap of
> the
> > AC transformer being tied to the ground.  This reduces the amount
ofarcing
> > that would occur.  Perhaps lightning is not a big problem there as it is
> > here, sometimes even in the Winter.  (Or maybe I'm am not understanding
> > something!)
>
> Very interesting!
>
> I quote the ARRL handbook for radio amateurs 2000, page 28.7 'GROUNDS':
>
> ...Many amateur stations have several grounds: a safety ground that is
part
> of the ac-wiring system, another at the antenna for lightning protection
and
> perhaps another at the station for EMI control. These grounds can interact
> with each other in ways that are difficult to predict.
>
> Ground Loops
> All of these station grounds can form a large ground loop. This loop can
act
> as a large loop antenna, with increased susceptibility to lighting or EMI
> problems...
>
> ARRL handbook for radio amateurs 2000, page 22.2 'THE STATION GROUND':
>
> ...The second job the ground system must perform is to provide a
> low-impadance path to ground for any stray RF current inside the station.
> Stray RF can cause equipment to malfunction and contributes to RFI
problems.
> This low-impedance path is usually called RF ground. In most stations, dc
> ground and RF ground are provided by the same system....
>
> ARRL handbook for radio amateurs 2000, page 9.7 'GROUNDS':
>
> ...Some think that RF grounds should be isolated from the safety ground
> system - that is not true! All grounds, including safety, RF, lightning
> protection and commercial communications, must be bonded together in order
> to protect life and property...
>
> Unquote
>
> The text on page 9.7 is equal to what you wrote.
>
> However; I am not able to bond my RF-groundsystem together to the
ac-wiring
> groundsystem! Oh yes I can; in my shack, but does this make sense? I use
an
> 'EXTREME ISOLATION TRANSFORMER' to "seperate" the ac-wiring of our house
> from the equipment in the shack.
>
> Please your advise (it is not my intention to be pigheaded).
>
> We had two direct lightning strikes sofar, without any damage to the radio
> equipment. But this does not mean that it is not necessary to improve the
> groundsystem in the way you describe it.
>
> Thanks and 73!
> Hans.
>
> Ham Radio:
> PA1HR
>
> Sites:
> www.remeeus.nl
> www.qsl.net/pa1hr
>
> e-mail:
> hans@remeeus.nl
>
>
>
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