[Premium-Rx] Grounding Receivers

[Carcia, Francis A HS]

Ben Dover was (Skunk Works Boss) Ben Rich's cover name. 
I've been doing some lightning testing and there is a reason for NEC ground
systems. 
#1 after a transformer you need to reestablish a ground. I would prefer a
240 volt transformer center tap to take advantage of the CMRR of the
transformer yet still have a safety ground.

-----Original Message-----
From: w3jn [mailto:w3jn at direcway.com]
Sent: Monday, April 04, 2005 7:31 PM
To: Blair Batty; premium-rx at ml.skirrow.org
Subject: Re: [Premium-Rx] Grounding Receivers


You might want to check your fire insurance before you decide to go with the

illegal setup.

Do you bond the neutral and ground at the secondary of the isolation 
xformer, and bond that to the service entrance ground?  If not, I believe 
that is contrary to the NEC.  You also need load disconnect (circuit 
breaker[s]) at the secondary if you're distributing it as in a permanent 
installation.  Would be a good idea to do so anyway.

Grounding and understanding thereof is a big issue and not well understood; 
I have one of those books explaining the NEC that admits same.  Covering 
this topic properly will go way beyond the patience of the list members; I 
strongly recommend you go to Borders or equivalent and get one of these 
books.

This is NOT something you want to get wrong.  As you may know, improperly 
grounded equipment can kill you DEAD, and especially in a receiving 
installation where you have a large outside antenna (read "lightning 
magnet"), you need to get it right.  The NEC is literally written in blood, 
and I believe your insurance company will shrug and tell you whatever you do

is at your (not THEIR) risk if you violate same.

Mr. Ben Dover:  like your name.  Any relation to a certain Mr. Hunt?

73 John

----- Original Message ----- 
From: "Blair Batty" <Blair at OntarioRocks.ca>
To: <premium-rx at ml.skirrow.org>
Sent: Monday, April 04, 2005 4:34 PM
Subject: Re: [Premium-Rx] Grounding Receivers


>
>>Next, an isolation transformer to power the receiver is a big help,
>>especially if
>>it has low interwinding capacitance and / or Faraday shielding. Much of 
>>the
>>RFI on
>>longwave is capacitively coupled into the receiver thru the AC line,
>>especially the
>>15.734 KHz horizontal oscillators in TV sets, and the COPIOUS harmonics of
>>same!
>>
>>Finally...  if possible, make sure that your receiver ground is TOTALLY
>>isolated from the AC power company ground.
>
> Hi Ben:
>
> Grounding is something I've been puzzling with.
>
> The AC power for my shack goes to a 240v, 15 amp Sola Isolation
> transformer, which isolates and voltage regulates my shack power.
> The Sola metal cabinet is bonded to the Utility ground wire. The heavy
> transformer inductance also kills any rfi and spikes.
>
> The ground wire of the Sola secondary output cable is connected
> to the shack's RF, antenna and equipment common bonding
> point (connected to ground rods), before going to AC outlets. So all
> equipment, antennas, and AC ground was isolated from the Utility
> supplied ground; and Utility power noise on the AC lines didn't get into
> the shack power.
>
> Unfortunately that arrangement is illegal. So I've connected the utility
> ground to the shack AC power ground by jumpering at the Sola
> Transformer. So my question is, do I leave the jumper in or not?
> I don't mind being illegal, if it's quieter and safe.
>
> Sincerely
> Blair
>
> p.s. Please reply directly, if you feel it's off topic.
>
>
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