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Re: [TenTec] High speed washer hum/whine

To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Subject: Re: [TenTec] High speed washer hum/whine
From: "Jim Brown K9YC" <k9yc@audiosystemsgroup.com>
Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Thu, 04 Feb 2010 10:16:36 -0800
List-post: <tentec@contesting.com">mailto:tentec@contesting.com>
On Wed, 03 Feb 2010 19:51:56 -1000, Ken Brown wrote:

>I believe the present NEC allows three wires for 240 VAC service. Two 
>hot leads and one ground. There is not neutral run on a modern 240 VAC 
>service feed, because it is no longer allowed to run any 120 VAC loads 
>inside a 240 VAC operated device by using one hot lead and the neutral. 

NO!  It all comes down to how the 240V appliance uses power. Certainly 
240V for the heating element, so that's two hots and a ground. It's easy 
to make a motor that runs on 240V, so no neutral would be needed. 
Remember -- most of the world outside of North America runs on 240V!  

Now, if the appliance has a 120V motor, it DOES need a neutral (that is, 
four wires), because is IS ILLEGAL to draw current between hot and 
GROUND.  AND -- any current drawn between hot and ground will set up a 
magnetic field that will drive you nuts for hum and buzz, both in your 
ham station and in your hi-futility rig. 

Remember my drawing showing how Ten Tec properly uses a center tap on 
the primary of the 240V power transformer to run the 120V fan in the 
Titan 425?  The Titan can run on 120V or 240V by changing the wiring of 
the power transformer primary. That drawing is on my website. 

http://audiosystemsgroup.com/publish.htm

73,

Jim K9YC


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