Hi Frank,
Do you know if the widely available Corcom AC
line filters (presumed to be differential mode
filters only) use the appropriate capacitor
classes? I have a few of them, not yet installed
anywhere, but your trenchant advice prompts
my question.
Thanks for the alert!
73,
Mike, K8CN
________________________________
From: RFI <rfi-bounces+mike.carter=unh.edu@contesting.com> on behalf of
nlsa@nlsa.com <nlsa@nlsa.com>
Sent: Friday, October 20, 2023 4:00 PM
To: 'Frank W3LPL' <donovanf@starpower.net>; 'Rfi List' <rfi@contesting.com>
Subject: Re: [RFI] Filtering 220VAC : Success
CAUTION: This email originated from outside of the University System. Do not
click links or open attachments unless you recognize the sender and know the
content is safe.
Dear Frank,
You got my attention! I will correct my mistake right away.
W9IP
-----Original Message-----
From: Frank W3LPL <donovanf@starpower.net>
Sent: Friday, October 20, 2023 3:26 PM
To: Rfi List <rfi@contesting.com>
Cc: nlsa@nlsa.com; Mike Martin <mike@rfiservices.com>
Subject: Re: [RFI] Filtering 220VAC : Success
Please be very careful about applying W9IP's experience before his good advice
causes major property loss or someone gets badly hurt or worse...
Capacitors must never -- must never! -- be connected to AC mains unless they
are clearly marked as X-Class or Y-Class.
No exceptions! Human life is at stake!
Capacitors not clearly marked as X-Class or Y-Class must never --must never!--
be connected to AC line voltage. They must -- must! -- be behind a fuse or
circuit breaker or other suitable AC line protection device.
No exceptions! Human life is at stake!
Capacitors connected between AC line voltage and the AC neutral line must --
must! -- have self-healing properties in case of arc-over.
Acceptable capacitors are always very clearly marked as X-Class,
Capacitors connected between AC line voltage and ground must -- must-- use a
capacitor that will never -- will never! -- fail as a short circuit from AC
line to ground, which can compromise safety and human life. Capacitors
designed for safe connection between AC lines and ground are always clearly
marked as Y-Class
Safety first. Please!
73
Frank
W3LPL
On Fri, Oct 20, 2023, 2:32 PM <nlsa@nlsa.com> wrote:
> Dear friends,
>
> After re-winding the 3-core toroidal choke and adding some 1,000pF
> bypass capacitors to the AC input and VFD output, there is virtually
> no increase in my noise floor when the elevation subsystem is powered
> up. Maybe 0.1-0.2 dB but I can't be sure.
>
> It appears that my EME system* has almost zero self-inflicted noise.
> Six weak spurs in the range 144.1-144.150 MHz. I'm happy.
>
> W9IP
>
> * (7) Raspberry Pi 3B
> (1) Intel NUC
> (1) Netgear ethernet switch
> Anan SDR, Homebrew: transverter, 1.5kW SSPA, TX polarity
> switch, and LNA
> Mitsubishi VFDs for Az & El
> APC switched rack PDU
> ... and their SMPS (no wall warts however)
> ...all mounted in the EME antenna's near field and controlled
> over fiber
>
>
>
>
> -----Original Message-----
> From: RFI <rfi-bounces+nlsa=nlsa.com@contesting.com> On Behalf Of Don
> Kirk
> Sent: Friday, October 20, 2023 7:24 AM
> To: jim@audiosystemsgroup.com
> Cc: Rfi List <rfi@contesting.com>
> Subject: Re: [RFI] Filtering 220VAC
>
> Hi Jim,
>
>
> You said "The neutral is NOT run to a 240V outlet, only the two phase
> (hot) conductors and green" and I think there needs to be a little
> clarification, especially for those that might be dealing with outlets
> that feed Ranges or Dryers.
>
> Back in the late 80's or possibly early 90's NEC required that for new
> construction 220 volt outlets for Ranges and Clothes Dryers must be 4
> wire outlets (2 hot wires, Neutral, Ground) whereas before that time
> 220 volt outlets for Ranges and Dryers were normally 3 wires (2 hot
> wires and Neutral). Notice I said 3 wire 220 volt outlets used a
> Neutral (not ground), but in function there was very little difference
> since the Neutral eventually does tie back to ground in the panel box.
> I'm not an expert on the NEC rules so I don't know what if any additional
> changes have occurred.
> I do believe there is an exception (Grandfather Rule) to the 4 wire
> outlet situation if you buy a modern Range or Dryer if your house was
> built with a
> 3 wire 220 Volt outlet that allows you to use a conversion kit or
> follow instructions provided with the appliance that ties the Neutral
> and case Ground back together in the appliance.
>
> I only mention the above because I was recently asked about it by a
> friend who purchased a new Range and his house was an older home
> equipped with a 3 wire 220 volt outlet so the information is still somewhat
> fresh in my mind.
>
> Just FYI, and 73.
> Don (wd8dsb)
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