[time-nuts] 4 KV Power Supply Recommendations

[Didier Juges]

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
>