Until I saw the reference here to the Whirlpool Duet being noisy, I did not
know that to be so...... I've been operating with a pair less than 15 feet
from my basement shack. The washer is very close to the MDP and on its own
circuit along with the matching gas dryer. The shack is on a former 220 VAC
electric range circuit with supplemental ground IAW the NEC, using a eight
foot ground rod driven through the bottom of the perimeter drain sump. A
similar eight foot ground rod is driven through the bottom of the drain sump
for the laundry. Both ground rods are bonded IAW the NEC to the copper cold
water supply which is also bonded to the MDP ground lug. The house is in the
country with both septic system and 200 foot well. The HVAC is air/heat pump
with supplemental gas heat below 30 degrees. The central air / furnace
blower motor is also variable speed and the air filter is electronic. As a
DXer (347/338 Mixed verified) I would not, could not, tolerate electrical
noise in my house / property.
I have a FLEX-1500 operating as a sub-receiver of my OMNI-VII. With the FLEX
in panadapter mode, I can see the noise floor on any given mode and band and
I have never seen noise that I could associate with the washer, dryer, or
HVAC in my house. I have on rare occasions seen noise from tools,
appliances, and equipment on neighboring properties, but usually it does not
last long.... also of note the electrical service is underground and the
noisy electrical tools are usually circular saws or welders.
73 ES DX,
Gary -- AB9M
-----Original Message-----
From: Larry Benko
Sent: Sunday, May 12, 2013 1:41 PM
To: rfi@contesting.com
Subject: Re: [RFI] Comments on RFI from Ductless Air Conditioning Units?
Jeff,
I am a retired EE and worked for years designing communications
equipment for AT&T, medical equipment, and the general aviation industry
communications. All the equipment needed to meet various emissions
standards (FCC part 15 A & B, CISPR 16, 17, 22, DO-160 etc). At
frequencies below 30MHz RF emissions are based on conducted currents and
not field strength measurements with FCC part 15B being slightly less
than 10uA (QUASI peak detector in 9KHz bandwidth). A compliant FCC part
15B device will generally not be heard at distances more than 20-30'
away. Of course there are so many exceptions to any generalizations in
this area but this is a good starting guideline.
I happen to have all the equipment necessary to measure these currents
and I realize that most folk don't so you need an alternate plan. First
of all it is your money and you dictate the terms to a contractor and if
they don't like it find another contractor. Contractors deal with many
suppliers and they need to talk to the manufacturers as to which ones
will stand behind their products as being RF clean. "Green" electrical
appliances do not need to emit RFI that is objectionable. To appease a
contractor get them to take you to a place where they installed the same
product you are interested in and let you listen for interference. In
this case they need to swear to you that you will get the exact same
product and it will be installed the same. That may appease the contractor.
If we don't return noisy appliances (such as the Whirlpool Duet) and
demand better we lose. The FCC seems to have no interest going after
the bad lighting devices which are supposed to meet FCC part 18 and may
actually be 10,000 times (40dB)over the limit. See
http://www.w0qe.com/RF_Interference/grow_light_electronic_ballasts.html
as an example. Devices such as direct drive motors in furnaces and
washing machines are not subject to any requirements in the US but they
are in Europe and many companies who primarily deal in Europe will
design products that are more RF quiet.
73,
Larry, W0QE
On 5/12/2013 11:37 AM, Jeff Stevens wrote:
Has anyone had success specifying a term such as 'RFI Free' when
dealing with a contractor? Whenever there is AC (or worse yet, square
waves) there is going to be SOME level of RFI, no? The question
becomes what level is acceptable for a particular installation. In my
case, if it's VLF/ELF noise or HF noise below the noise floor on
antennas some distance away, I don't really care. I can't, however,
provide a more specific acceptable level such as a particular maximum
field strength. Something like 'RFI Free' seems rather amorphous and
if I were a contractor, I'd be reluctant to accept such a term.
However, if my customer provided concrete criteria (such as a maximum
field strength) I might actually be able to get some specs from the
manufacturer and have some reasonable confidence that I can perform
the install in such a way as to meet my customer's needs.
Just curious if anyone has brought RFI issues up, in writing, with a
contractor and how that worked out.
-Jeff
W7WWA
_______________________________________________
RFI mailing list
RFI@contesting.com
http://lists.contesting.com/mailman/listinfo/rfi
_______________________________________________
RFI mailing list
RFI@contesting.com
http://lists.contesting.com/mailman/listinfo/rfi
_______________________________________________
RFI mailing list
RFI@contesting.com
http://lists.contesting.com/mailman/listinfo/rfi
|