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Re: [RFI] "Inverter Technology" microwave ovens

To: "'Don Nelson'" <n0ye@comcast.net>, <rfi@contesting.com>
Subject: Re: [RFI] "Inverter Technology" microwave ovens
From: "Gene Langendorff" <k6ttm@sbcglobal.net>
Date: Fri, 17 Dec 2010 12:51:00 -0800
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>
I have a Panasonic "Inverter Technology" microwave oven and really love it.
As Dave said, the magnetron operates at reduced power when you set it for
reduced power -- not like other microwaves that use 100% magnetron power
with sometimes a very long duty cycle.  My daughter has a GE (I think) that
has about a 10 second duty cycle.  For 50% she gets about 5 secs on, then 5
secs off.  When she was younger we used to make S'mores in our old Amana and
we could watch the marshmallow "breath," getting larger and then shrinking
with each cycle of the microwave's reduced power setting.  Fortunately the
duty cycle wasn't as long as my daughter's current microwave -- the
marshmallow would surely have EXPLODED!  What a mess that would have been!


I like the Panasonic for re-heating food.  I usually use 50% power for twice
as long and the benefit is that it rarely spatters food all over the inside
of the microwave.  I usually don't even bother to cover the food as a
result.  Handy!


The Panasonic very likely has a switch-mode PS (What consumer product
doesn't these days) and the oven is rather light weight.  Regardless, I
haven't noticed any RFI from my oven.


Gene K6TTM



-----Original Message-----
From: rfi-bounces@contesting.com [mailto:rfi-bounces@contesting.com] On
Behalf Of Don Nelson
Sent: Friday, December 17, 2010 4:29 AM
To: rfi@contesting.com
Subject: Re: [RFI] "Inverter Technology" microwave ovens


On 12/16/2010 10:40 PM, Dave Hachadorian wrote:

> I need to buy a new microwave oven.  I see many of the new ones

> advertise "inverter technology."  From an RFI standpoint, I am

> leery of anything that says "inverter."  Does anyone have any

> experience with these things as far as RFI goes? The particular

> one that I am considering buying is a Panasonic 778.


> I think what this feature does is , when you heat something at

> 50% power, the magnetron runs at 50% power for 100% of the

> cooking time.  The ones without this feature run at 100% power

> for 50% of the time.  Supposedly the cooking is more even in the

> inverter ones.



> Dave Hachadorian, K6LL

> Yuma, AZ



> _______________________________________________

> RFI mailing list

> RFI@contesting.com

> http://lists.contesting.com/mailman/listinfo/rfi




I am not familiar with any microwave oven that has an inverter instead 

of a standard transformer based power supply. However that technology 

makes for lighter less expensive power supplies and I do have a light 

weight microwave oven of several years. It may very well have an 

inverter power supply. Inverter power supplies have a very high power 

oscillator that takes DC and generates AC at maybe 50 KHz. How this 

oscillator and surrounding circuit are designed will determine the RFI 

generated. (You probably knew this.)


Bottom line - you may have to CONDITIONALLY buy the unit and test it for 

noise. Yup we are forced to do incoming inspection on goods we buy.


As an aside. A friend does county hunting from a Honda hybrid. I asked 

about the RFI from the motor control. He said it is manageable. He does 

operate his HF rig while in motion.  I have yet to talk to a HAM who 

owns a Toyota hybrid or all electric who can operate an HF radio in 

their vehicle. It demonstrates that some car companies do better RFI 

mitigation than other companies do.


Don, N0YE


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