[time-nuts] 4 KV Power Supply Recommendations

Brooke Clarke brooke at pacific.net
Mon Jan 18 23:09:39 UTC 2010


Hi Didier:

You may want to see about a recall.

The US Food and Drug Administration (FDA) 
<http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?CFRPart=1030&showFR=1> 
has a regulation on microwave oven leakage. In Title 21 it states that 
the power density limit from an operating microwave oven "shall not 
exceed 1 milliwatt per square centimeter at any point 5 centimeters or 
more from the external surface of the oven, measured prior to 
acquisition by a purchaser, and, thereafter, 5 milliwatts per square 
centimeter at any such point."

http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?CFRPart=1030&showFR=1

Have Fun,

Brooke Clarke
http://www.PRC68.com


Didier Juges wrote:
> I could not resist, so I checked my relatively expensive Sears/Kenmore
> microwave oven.
> The results are there:
> http://www.ko4bb.com/Test_Equipment/Microwave_oven_leakage/
>
> In one word, dismal. Almost 1W peak power leakage at 1 foot, and almost
> 100MHz occupied bandwidth.
>
> I looked with a crystal detector driving a scope, and it is obvious the unit
> is driven from a 60Hz transformer with half wave rectification, and has no
> filtering whatsoever, like the first Microwave oven I have ever opened (a 20
> years old model long dead).
>
> Didier KO4BB
>
>
>    
>> -----Original Message-----
>> From: time-nuts-bounces at febo.com
>> [mailto:time-nuts-bounces at febo.com] On Behalf Of Chuck Harris
>> Sent: Monday, January 18, 2010 8:28 AM
>> To: Discussion of precise time and frequency measurement
>> Subject: Re: [time-nuts] 4 KV Power Supply Recommendations
>>
>> As I understand it, the supplies are 100KHz, and have no
>> significant filtering at HV.  They modulate the magnetron
>> with the 100KHz PWM mess.  As long as the signal doesn't
>> leave the rather wide ISM band, they are under no obligation
>> to filter anything.... routers, etc. are squatters on the IMS
>> band, after all.
>>
>> I am sure that some brands are better than others, but then
>> some brands are only $50.
>>
>> I don't have any of the new ovens as yet... My old beaters
>> from the early '90s are still running strong.  I have no
>> neighbors, so their choices are not an issue.
>>
>> -Chuck Harris
>>
>>      
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>
>    




More information about the time-nuts mailing list