It's hard to compare noise levels, as it depends on bandwidth, S-meter
calibration, etc. I can tell you that my noise level went down 5-19 dB
on 10-20 meters during a recent power outage, so it's probably that much
above that of a quiet rural location. The level depends on band and
direction. On 20 meters, on a good day towards EU, it is about -146
dBm/Hz, according to the K4 spectrum display. That would be about S3 at
a 2 kHz bandwidth, at 6 dB per S-unit. At 3 dB/S-unit, typical of Icom
and others, that would be below S0.
Generac generators may be OK; it's just the electronics associated with
their solar systems that seems to be the problem.
73,
Scott K9MA
On 1/7/2025 9:46 AM, bill ny9h via RFI wrote:
your comment " Note that I have a typical urban noise level, so it is
possible these systems would cause noticeable RFI in a quiet location"
leads me to ask what IS your urban level...by band..
I now enjoy an S2-3 on 80 with A DIPOLE ... k4 no preamps on...(
dipole is 50 feet from the house , up 45 feet)
and my 10 year old SMA inverters make not a peep & my 18kw Generac
makes no noise \
Bill now in the boonies with occasional light electric fence
rfi...( NB fixes that)
On 1/6/2025 6:12 PM, K9MA wrote:
I now know two manufactures of solar inverters which are apparently
free of RFI.Both are microinverter systems.
Enphase IQ7 Series:
I have these on my system, as does my immediate neighbor, 20 meters
from my tower. both systems have ferrite chokes on the cables, which
may not be necessary. Another neighbor, about 110 meters away at 330
deg. has an Enphase system without chokes, which causes no interference.
AP Systems DS3-S:
No interference detected 100 meters from tower. This neighbor is to
the NE, where I often have my beam pointed.
---
Note that I have a typical urban noise level, so it is possible these
systems would cause noticeable RFI in a quiet location. Of course,
hams in such locations are unlikely to have neighbors so close.
On the other hand, the Generac system 650 meters away has been shut
down since last summer, as Generac tries to find a solution. I must
recommend avoiding Generac systems at all cost.
73,
--
Scott K9MA
k9ma@sdellington.us
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