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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