[RFI] Low RFI Solar Inverters

[K9MA]

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 at sdellington.us