[Amps] what is a 4 wire 240VAC service?

Sun Apr 3 09:48:25 PDT 2011

Altho the 4 wire has been SOP in industrial sites for ages it is a result of 
nanny state busybodies where it is now mandated in our homes with appliances 
that also require 120V. The old appliances that are in the house now are 
grandfathered.

Before your dryer ran the 120V motor and SS LV transformers between the hot 
side and a neutral/ground and it worked fine for 60 or so years with a 3 
wire feed.

This is the same as Henry, Alpha, Johnson, maybe others, and plenty of 
homebrewers did as well and most are probably still running that way without 
fried hams making the news.

Yes, today it is not considered "good engineering practice" and its easily 
remedied with transformers that are wound with 120/240 options by placing 
the 120V needs across one of the primaries. Those with 240V only 
transformers are left with a decision.....do it the easy way or run a 
separate 120V line plus separate switching.

Carl
KM1H

----- Original Message ----- 
From: "Jim W7RY" <w7ry at inbox.com>
To: "Charles Harpole" <k4vud at hotmail.com>; <w9ac at arrl.net>; 
<at6c at bellsouth.net>; <amps at contesting.com>
Sent: Sunday, April 03, 2011 11:07 AM
Subject: Re: [Amps] what is a 4 wire 240VAC service?

>2 hots, 1 neutral and 1 ground.  Not really the proper term though. It's
> more properly named 120/240 single phase. With 120/240, you need a 
> neutral.
> And a ground of course.
>
> 73
> Jim W7RY
>
>
> --------------------------------------------------
> From: "Charles Harpole" <k4vud at hotmail.com>
> Sent: Sunday, April 03, 2011 7:57 AM
> To: <w9ac at arrl.net>; <at6c at bellsouth.net>; <amps at contesting.com>
> Subject: [Amps] what is a 4 wire 240VAC service?
>
>>
>> Maybe being in Thailand, where 230vac is supplied with TWO wires, makes 
>> me
>> ask.... what is 4-wire 240vac service?
>>
>> Charles Harpole k4vud at hotmail.com
>>
>>
>>
>>> From: w9ac at arrl.net
>>> To: at6c at bellsouth.net; Amps at contesting.com
>>> Date: Sun, 3 Apr 2011 10:35:01 -0400
>>> Subject: Re: [Amps] Alpha vs Henry
>>>
>>> George,
>>>
>>> If 160m is of interest to you, may want to re-evaluate Henry amps,
>>> including
>>> the 5K.
>>>
>>> Concerning mods for the 77Dx/Sx: few mods have been published and either
>>> version of the 77 is fine as it is. I own a 77Dx and have avoided a
>>> conversion to the Sx for several reasons:
>>>
>>> 1) Added cost of an 8877 during replacement;
>>> 2) Slightly added difficulty in isolating trouble with a pair of tubes. 
>>> A
>>> minor issue;
>>> 3) The added class of power really requires changing the RF output
>>> connector
>>> to a DIN type;
>>> 4) Fuse holders should be upgraded;
>>> 5) Relatively poor Ep regulation of the Sx version unless an outboard
>>> Hypersil transformer is used. Some folks have reported better regulation
>>> with a direct- replacement Dahl type although it's a snug fit;
>>> 6) The Dx already has way more reserve than needed for most operating
>>> modes
>>> in American-licensed service.
>>>
>>> Added together, I just can't justify the change. However, I did make the
>>> following changes to my 77Dx:
>>>
>>> 1) Isolated neutral from chassis ground. As it stands, these Alpha amps
>>> are
>>> not UL compliant. Although not compliant with the NEC, the NEC is
>>> factually
>>> a premise wiring standard -- not a product wiring standard. The mod is
>>> super-easy since it involves only cutting a jumper on the Cinch-Jones
>>> power
>>> plug. However, 4-wire service and 4-wire power cord is required. If you
>>> have not already added 4-wire 240V service, consider it if you plan on
>>> using
>>> older Alpha and Henry amps;
>>>
>>> 2) Elevated the filament return off the chassis. I detest the chassis
>>> being
>>> used for high-current filament returns -- even more of a concern with 
>>> the
>>> Sx
>>> as 20A of current flows in the chassis. It's a personal bias of mine;
>>> many
>>> Alpha amps have run for decades without issues;
>>>
>>> 3) Added a filament choke. A side benefit is that there's just enough of
>>> an
>>> IR drop through the choke as a result of my 250VAC mains to ensure that
>>> the
>>> filaments run at 5.0V. Before adding the choke, my filament voltage ran
>>> above Eimac's specification and I was replacing tubes way too often
>>> because
>>> of filament issues. High filament voltage combined with many 
>>> intermittent
>>> on/off cycles leads to these failures. Also, after inclusion of the
>>> choke,
>>> I did not tie the filament to the cathode (e.g., AL-1500) although that
>>> could be done if I were convinced of the necessity. I've seen arguments
>>> both ways (primarily fault related) from respected amp designers as well
>>> as
>>> former Eimac engineers. It stays unconnected for now;
>>>
>>> 4) Added gas discharge tubes to the filament and cathode terminals, and
>>> added bypass caps to the filaments connections.
>>>
>>> Just my $0.02, and I'm sure others will disagree with me on some of 
>>> these
>>> changes. Good thing I'm not writing article for QST!
>>>
>>> Paul, W9AC
>>>
>>> ----- Original Message ----- 
>>> From: "George Steube" <at6c at bellsouth.net>
>>> To: <Amps at contesting.com>
>>> Sent: Sunday, April 03, 2011 7:58 AM
>>> Subject: [Amps] Alpha vs Henry
>>>
>>>
>>> > Looking at purchasing an Alpha SX/DX or Henry 5K for my amp 
>>> > collection.
>>> > Any
>>> > advice/comments on these amps would be appreciated. My biggest concern
>>> > with
>>> > the Henry would be future tube replacement. Any recommend mods for
>>> > either
>>> > amp? Thanks.
>>> > George
>>> > W2GS
>>> >
>>> >
>>>
>>>
>>> --------------------------------------------------------------------------------
>>>
>>>
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>>> >
>>>
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>>
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