A result of tying neutrals to each house ground is that there can be
sizeable voltage differences between two house's grounds. Years ago I had an
"informal" TV cable system with two amplifiers each at about 300 feet along
the coax run. I was feeding 24V AC for both amplifiers through the coax at
my end. One day my 24V transformer became disconnected but the two
amplifiers were still working! I discovered that there was a 20 V AC
difference between my house's ground and the house ground at the end of the
line.
John, KU6X
-----Original Message-----
From: Amps [mailto:amps-bounces@contesting.com] On Behalf Of
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Sent: Thursday, September 19, 2013 9:25 PM
To: amps@contesting.com
Subject: Amps Digest, Vol 129, Issue 37
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Today's Topics:
1. Re: Direct rectification of AC mains to derive the amp, VDD,
supply (Roger (K8RI))
2. Re: Re Direct rectification of AC mains to derive the amp,
VDD, supply (Peter Voelpel)
3. Re: Direct rectification of AC mains to derive the amp, VDD,
supply (qrv@kd4e.com)
4. Re: Re Direct rectification of AC mains to derive the amp,
VDD, supply (peter chadwick)
5. Re: Re Direct rectification of AC mains to derive the amp,
VDD, supply (Bill Turner)
6. Re: Re Direct rectification of AC mains to derive the amp,
VDD, s (Steve Thompson)
7. Re: WTB: Matched pair of 8122 or 8122W's (Randall, Randy)
8. Re: WTB: Matched pair of 8122 or 8122W's (Carl)
----------------------------------------------------------------------
Message: 1
Date: Thu, 19 Sep 2013 15:14:54 -0400
From: "Roger (K8RI)" <k8ri@rogerhalstead.com>
To: amps@contesting.com
Subject: Re: [Amps] Direct rectification of AC mains to derive the
amp, VDD, supply
Message-ID: <523B4D2E.5090806@rogerhalstead.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
On 9/19/2013 11:37 AM, Manfred Mornhinweg wrote:
> Roger,
>
> the near electrocution you describe was due to several concurrent
> problems: The short circuit due to a poor solder job, lack of a ground
I know what contributed to the problem, but much of the technology and
wiring was not available.
> fault interrupter, and poor grounding of the equipment.
>
> If there had been a GFI, it would have tripped as soon as the solder
This was in the late 60s. I'd never heard of a GFI back then and don't
think they were available. Thing is, there are still many homes that do
not have GFIs. The only GFIs in this home are those we have installed
and when you are working with older wiring you are taking a lot on
faith. Even after tracing out circuits you have no gurantee that there
isn't a branch running off somewhere. Perhaps an infinished project.
Nealy all equipment back then had a 3 wire cord, grounding the case to
the electrical ground, so the 101B with the 2 wire power cord and no
ground was an anomaly to most of us.
> blob made a short, as long as the radio was connected to any sort of
> ground, even a poor one. And if there was no ground at all, the GFI
> would still have tripped, as soon as you touched that radial wire.
>
> This shows how important GFIs are. For anyone who has no particular
> interest in getting electrocuted because of any stupid little failure,
> it's imperative to have GFIs on every circuit, even in those countries
> where they are not yet mandatory.
>
> The incident you describe was in the sixties. I don't think GFIs were
> around back then. But today they are, and they are quite inexpensive
> (the ones I used in my home cost about 12 dollars each, I have 4 of
> them). So anyone who wants to prevent such an occurrence, can do so.
I replace the first outlet on a circuit with a GFI which protects the
entire circuit..."IF" the circuit is properly wired. GFI circuit
breakers are also available for panel installation, but those are not cheap.
My entire shop is wired that way (GFI outlet first on the circuit)
except for the 240 with all the wiring in surface mounted EMT.
OTOH I have to admit, that I've had two GFI outlets fail.
73
Roger (K8RI)
>
> Manfred
>
> ========================
> Visit my hobby homepage!
> http://ludens.cl
> ========================
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>
------------------------------
Message: 2
Date: Thu, 19 Sep 2013 21:18:18 +0200
From: "Peter Voelpel" <dj7ww@t-online.de>
To: <amps@contesting.com>
Subject: Re: [Amps] Re Direct rectification of AC mains to derive the
amp, VDD, supply
Message-ID: <B62F946A298B434DB5A2DAF01F82076A@amateurfunk>
Content-Type: text/plain; charset="us-ascii"
Jim, you will not find any house in Germany being fed from a center-tapped
transformer.
3 phases + neutral is standard, very few houses are still single phase +
neutral.
The distribution transformers are all star connected three phase
transformers with 400V secondary.
73
Peter
-----Original Message-----
From: Amps [mailto:amps-bounces@contesting.com] On Behalf Of Jim Brown
On 9/19/2013 9:01 AM, Bill Turner wrote:
> Could you elaborate on this a bit? I assume the difference is
> how the neutral is used or not used. Is that correct?
The key differences in power distribution around the world boil down to
four factors. 1) Voltage and frequency 2) How and where the neutral and
earth conductors are bonded together, and how they are distributed
around the building; 3) the plugs used; 4) protection devices like
GFCIs. In EU, power is at double our voltage and is fed from
center-tapped transformers, but because the line voltage is 220-240V,
few homes need both sides of the transformer. Also, most of EU places
serious limits on Power Factor, mostly looking at the Harmonic component
of load current.
------------------------------
Message: 3
Date: Thu, 19 Sep 2013 15:29:32 -0400
From: "qrv@kd4e.com" <qrv@kd4e.com>
To: amps@contesting.com
Subject: Re: [Amps] Direct rectification of AC mains to derive the
amp, VDD, supply
Message-ID: <523B509C.9090007@kd4e.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
If you want "sensitive" try the newest breaker technology - mandated in
many places AFCI.
Local contractors say they are so hyper-sensitive they install them for
inspection then replace them with GFI's.
>> the near electrocution you describe was due to several concurrent
>> problems: The short circuit due to a poor solder job, lack of a ground
>
> I know what contributed to the problem, but much of the technology and
> wiring was not available.
>> fault interrupter, and poor grounding of the equipment.
>>
>> If there had been a GFI, it would have tripped as soon as the solder
>
> This was in the late 60s. I'd never heard of a GFI back then and don't
> think they were available. Thing is, there are still many homes that do
> not have GFIs. The only GFIs in this home are those we have installed
> and when you are working with older wiring you are taking a lot on
> faith. Even after tracing out circuits you have no gurantee that there
> isn't a branch running off somewhere. Perhaps an infinished project.
>
> Nealy all equipment back then had a 3 wire cord, grounding the case to
> the electrical ground, so the 101B with the 2 wire power cord and no
> ground was an anomaly to most of us.
>
>> blob made a short, as long as the radio was connected to any sort of
>> ground, even a poor one. And if there was no ground at all, the GFI
>> would still have tripped, as soon as you touched that radial wire.
>>
>> This shows how important GFIs are. For anyone who has no particular
>> interest in getting electrocuted because of any stupid little failure,
>> it's imperative to have GFIs on every circuit, even in those countries
>> where they are not yet mandatory.
>>
>> The incident you describe was in the sixties. I don't think GFIs were
>> around back then. But today they are, and they are quite inexpensive
>> (the ones I used in my home cost about 12 dollars each, I have 4 of
>> them). So anyone who wants to prevent such an occurrence, can do so.
>
> I replace the first outlet on a circuit with a GFI which protects the
> entire circuit..."IF" the circuit is properly wired. GFI circuit
> breakers are also available for panel installation, but those are not
> cheap.
>
> My entire shop is wired that way (GFI outlet first on the circuit)
> except for the 240 with all the wiring in surface mounted EMT.
>
> OTOH I have to admit, that I've had two GFI outlets fail.
>
> 73
>
> Roger (K8RI)
--
Thanks! & 73, KD4E.com
David Colburn - Nevils, Georgia USA
Search with: duckduckgo.com
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Restored to design-spec at Heaven's gate 1Cor15:22
------------------------------
Message: 4
Date: Thu, 19 Sep 2013 22:10:29 +0200
From: peter chadwick <g8on@fsmail.net>
To: Bill Turner <dezrat1242@yahoo.com>, Amps <amps@contesting.com>
Subject: Re: [Amps] Re Direct rectification of AC mains to derive the
amp, VDD, supply
Message-ID: <22825207.26271379621429159.JavaMail.www@wwinf3718>
Content-Type: text/plain; charset=UTF-8
Bill,
We start off with a 3 phase star (wye) connected supply at nominally 415
volts per phase. Each house gets one phase and the neutral i.e. 240 volts
give or take. The neutral is grounded (earthed) at the substation. Along the
distribution, the neutral is grounded at various places. When distribution
tended to be lead sheathed or steel armoured wire cable, the sheath or cable
was the neutral. Clamped in cast iron junction boxes, in certain soils, the
neutral return resistance could be problematical. The argument was that to
'use higher technology cabling' - i.e. cheaper! - where there were three
conductors and a metallic sheath, said sheath would be neutral and earth. To
avoid problems with neutral and earth being at different potentials and to
make sure the 'earth' was earth, earth and neutral are tied at the entrance
to the property. Now if neutral is ruptured, the neutrals connected to the
various equipment float up in voltage. So all earths are tied to the neutral
in the h
ouse. The problem then comes if you bring in an external earth.....
Fortunately, you can insist on having a local earth and no connection to the
neutral. So the power pole feeding my house - right at the end of the line -
has a ground wire and stake grounding the neutral. I have all the ground
pins of my house taken to separate ground and as they are tied back to the
station RF ground, it gives under 10% of the approved ground stake
resistance.
But if you have a grounded neutral and you go outside and touch something
connected to the internal earth pin when there's a ruptured neutral fault,
you can be in very deep sh*t! So certainly here, it's safer no to assume you
can ground the neutral.
Now in the US, if you get a ruptured neutral, the two sides of the line
divide the voltage between them. The side with the lowest resistance will
float towards 120 on both sides....not necessarily actually getting there,
but maybe well above 120 volts. But the in-balance if you have a 'grounded'
neutral then depends on how good the ground is and what the load is.
Does this explain it for you? I regret it isn't easy...Hell, standards
people are involved and making it easy mean they aren't needed. I know -
until June, I was one - although not in this field.
73
Peter G3rzp
========================================
Message Received: Sep 19 2013, 05:02 PM
From: "Bill Turner" <dezrat1242@yahoo.com>
To: "Amps" <amps@contesting.com>
Cc:
Subject: Re: [Amps] Re Direct rectification of AC mains to derive the amp,
VDD, supply
ORIGINAL MESSAGE: (may be snipped)
On Thu, 19 Sep 2013 12:44:45 +0200, Peter wrote:
>The 240 volt EU supply is a very different animal to the US 120-0-120.
REPLY:
Hello Peter: Could you elaborate on this a bit? I assume the difference is
how the neutral is used or not used. Is that correct?
In the US the typical wiring is two 120 "hot" wires, a neutral and an earth
ground. In the proposed power supply, the neutral would not be used at all.
Just the two 120 hots and the cabinet would be earth grounded.
Thank you,
73, Bill W6WRT
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------------------------------
Message: 5
Date: Thu, 19 Sep 2013 13:52:36 -0700
From: Bill Turner <dezrat1242@yahoo.com>
To: Amps <amps@contesting.com>
Subject: Re: [Amps] Re Direct rectification of AC mains to derive the
amp, VDD, supply
Message-ID: <bsom39hc5bqpq6rr16eag02tvu1tther58@4ax.com>
Content-Type: text/plain; charset=us-ascii
ORIGINAL MESSAGE: (may be snipped)
On Thu, 19 Sep 2013 22:10:29 +0200, Peter wrote:
>Does this explain it for you? I regret it isn't easy...Hell, standards
people are involved and making it easy mean they aren't needed. I know -
until June, I was one - although not in this field.
REPLY:
Just one question: What is the voltage relationship between neutral and each
side of the 240 V lines? Is it split down the middle like in the US or is it
connected to one side? Or something else?
Thanks,
73, Bill W6WRT
------------------------------
Message: 6
Date: Thu, 19 Sep 2013 21:58:51 +0100
From: Steve Thompson <g8gsq72@gmail.com>
To: amps@contesting.com
Subject: Re: [Amps] Re Direct rectification of AC mains to derive the
amp, VDD, s
Message-ID: <523B658B.2000609@gmail.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Likewise in the UK. It's unusual for any individual house to have
three phase as standard, single phase plus N is normal but the
distribution network is three phase plus neutral.
Steve
> Jim, you will not find any house in Germany being fed from a center-tapped
> transformer.
>
> 3 phases + neutral is standard, very few houses are still single phase +
> neutral.
> The distribution transformers are all star connected three phase
> transformers with 400V secondary.
>
> 73
> Peter
------------------------------
Message: 7
Date: Thu, 19 Sep 2013 21:47:43 +0000
From: "Randall, Randy" <Randy.Randall@uchealth.com>
To: Carl <km1h@jeremy.mv.com>, "amps@contesting.com"
<amps@contesting.com>
Subject: Re: [Amps] WTB: Matched pair of 8122 or 8122W's
Message-ID:
<1F32B6A6D50F1441BBC09E26B35C500F0F66F6@UCH-LAVERN.healthall.com>
Content-Type: text/plain; charset="us-ascii"
Just out of curiosity, what is the issue with RCA 8122's in the 60's other
than age? Were there manufacturing issues???
Thanks,
Randy
Please note: Upcoming Vacation: December 21 - January 5, 2014
Randy E. Randall AB9GO
Network Architect
UC Health
Randy.Randall@UCHealth.com
Phone 513-585-7146
Fax 513-585-7159
-----Original Message-----
From: Amps [mailto:amps-bounces@contesting.com] On Behalf Of Carl
Sent: Thursday, September 19, 2013 3:12 PM
To: amps@contesting.com
Subject: [Amps] WTB: Matched pair of 8122 or 8122W's
Burle and Eimac preferred, NOS in sealed boxes or guaranteed good, full
output used OK with no screen current drift.
RCA's must have stable screen current, NOS or used, no 60's date codes.
To be used in a fully rebuilt NCL-2000.
Carl
KM1H
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________________________________
Confidentiality Notice: This e-mail message, including any attachments, is
for the sole use of the intended recipient(s) and may contain confidential
and privileged information. Any unauthorized review, use, disclosure or
distribution is prohibited. If you are not the intended recipient, please
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message.
------------------------------
Message: 8
Date: Thu, 19 Sep 2013 20:48:46 -0400
From: "Carl" <km1h@jeremy.mv.com>
To: "Randall, Randy" <Randy.Randall@uchealth.com>,
<amps@contesting.com>
Subject: Re: [Amps] WTB: Matched pair of 8122 or 8122W's
Message-ID: <BD6252CFE4344E9A842B688D9A14F2CA@computer1>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
Several manufacturing issues. Pre mid 1967 the screen was not supported and
when running current would lean into the anode.
Other problems were incomplete gettering and a short try at pink ceramic
which RCA used OK with even larger tubes. I doubt they told anyone at
National the full story but it gave the amp a very bad reputation.
Burle took over around the late mid to 80's when RCA went belly up.
Carl
KM1H
----- Original Message -----
From: "Randall, Randy" <Randy.Randall@uchealth.com>
To: "Carl" <km1h@jeremy.mv.com>; <amps@contesting.com>
Sent: Thursday, September 19, 2013 5:47 PM
Subject: RE: [Amps] WTB: Matched pair of 8122 or 8122W's
Just out of curiosity, what is the issue with RCA 8122's in the 60's other
than age? Were there manufacturing issues???
Thanks,
Randy
Please note: Upcoming Vacation: December 21 - January 5, 2014
Randy E. Randall AB9GO
Network Architect
UC Health
Randy.Randall@UCHealth.com
Phone 513-585-7146
Fax 513-585-7159
-----Original Message-----
From: Amps [mailto:amps-bounces@contesting.com] On Behalf Of Carl
Sent: Thursday, September 19, 2013 3:12 PM
To: amps@contesting.com
Subject: [Amps] WTB: Matched pair of 8122 or 8122W's
Burle and Eimac preferred, NOS in sealed boxes or guaranteed good, full
output used OK with no screen current drift.
RCA's must have stable screen current, NOS or used, no 60's date codes.
To be used in a fully rebuilt NCL-2000.
Carl
KM1H
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Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
________________________________
Confidentiality Notice: This e-mail message, including any attachments, is
for the sole use of the intended recipient(s) and may contain confidential
and privileged information. Any unauthorized review, use, disclosure or
distribution is prohibited. If you are not the intended recipient, please
contact the sender by reply e-mail and destroy all copies of the original
message.
-----
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