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Re: [TenTec] TT 940 Power Supply

To: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Subject: Re: [TenTec] TT 940 Power Supply
From: denton sprague <denton@oregontrail.net>
Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Tue, 2 Sep 2014 18:06:32 -0700
List-post: <tentec@contesting.com">mailto:tentec@contesting.com>
My big Cyberpower is still under warranty…they don't even want you running an 
extension cord out of the socket!
When I was testing it, I noticed rf hash in spots throughout 80 and 40 
meters….and I ordered it new specifying for telecommunications use!
Will keep in mind what you typed below when I pull the case apart for twice 
annual dust bunny removal next winter. 
On Sep 2, 2014, at 12:31 PM, "Bob McGraw - K4TAX" <RMcGraw@Blomand.net> wrote:

> You raise a point regarding "industrial grade sine wave ups".   I have one of 
> those and in my chasing a noise issue, I opened the case to find the output 
> receptacles each have the neutral terminal {white wire} and the 3rd pin 
> ground terminal {green wire}connected by a solid strap.  This then says the 
> neutral is connected to 3rd pin ground at several points, both on the input 
> and output.  I seem to recall this is not correct according to NEC.
> 
> Anyway, I removed the straps and my noise went away.  Now, this does leave 
> the 3rd pin AC ground terminal on the LOAD side of the UPS connected to the 
> 3rd pin ground on the INPUT side of the UPS.  The neutral however is not 
> connected from the LOAD side to the INPUT side, thus there is significant 
> isolation between input and output of the UPS.  As it should be in my 
> thinking.
> 
> Is there some UL requirement, say UL1499, or other international standard 
> that I'm not aware that mandates the load neutral and 3rd pin AC must be 
> bonded?  It has been too many years since I worked in this part of the safety 
> discipline.
> 
> Comments anyone?
> 
> 73
> Bob, K4TAX
> 
> 
> 
> 
> 

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