[RFI] RFI from Inverter Technology in Split AC Systems?

kd4e doc at kd4e.com
Wed Feb 17 13:32:06 PST 2010


Do you use wireless mics?

Any chance you could bring a portable SW receiver
and see what might be on those freqs?

It would be good to know if 6M is clean - do you have
a TV on a set-top antenna?

So. Korea manufacture sure is far better than China!

> Years ago, I had a lot of bad experiences with variable speed motor 
> drives, but those were in industrial applications.  I know that technology 
> has improved EMC performance in many ways, and any that are rated for 
> residential applications might (not certain!) have some greater degree of 
> noise reduction than industrial systems.  I can tell you that last year, 
> the church I attend had eight (8) systems similar to yours installed to 
> provide air conditioning and extra heat to our 105 year old building in 
> eastern Iowa.  I am the sound system engineer for the church (as well as 
> one of the Trustees who had to decide on whether to buy the systems) and 
> had a lot of worries about hash getting into the audio system.  No problem 
> to date, even though the power feeds to some of the heat pump systems are 
> in the same power panel as feeds power to the audio system.
> 
> Yes, I know that an audio system is not a radio system, but it does have a 
> lot of wiring (a.k.a. "antennas) running around with low level signals.  I 
> have been impressed with the fact that since each of the 8 systems 
> operates independantly of the others, on-off switching and varying of 
> blower speeds is random and could be happening many times per hour.  Our 
> units are not the same brand as yours, but they are from a South Korean 
> manufacturer.  They otherwise seem very similar to what you are 
> considering.  We've been  happy with the rebate we got from the power 
> company and the first winter's savings in cost of heating an old building 
> here in the Midwest. 
> 
> 73, Dale
> WA9ENA
> 
> To
> rfi at contesting.com
> cc
> 
> Subject
> [RFI] RFI from Inverter Technology in Split AC Systems?
> 
> We are looking at the Sanyo Flexi-Multi Series CMH3172
> 30,600 BTU Multi-System Heat Pump Ductless Split Outdoor 
> Unit with DC Inverter, Microprocessor Control and Auto Fan 
> Speeds.
> 
> http://www.ajmadison.com/cgi-bin/ajmadison/CMH3172.html
> 
> It seems efficient, will handle our somewhat unique layout,
> and is low-profile.
> 
> I am concerned about the "inverter technology" as I worry
> it may generate a *lot* of RFI.  Is that a reasonable
> concern?
> 
> WDYT?
> 

-- 

.Thanks! & 73, doc, KD4E
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