Varible Frequency Microwave Oven

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Discussion Overview

The discussion centers around the need for a variable frequency microwave oven that can selectively heat specific parts of a composite sample. Participants explore the limitations of standard microwave ovens, which operate at a fixed frequency, and the potential for adjustable frequency and amplitude settings to achieve targeted heating.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant expresses a need for a microwave oven that can operate at a specific wavelength to heat different parts of a composite sample more effectively.
  • Another participant challenges the claim that normal microwave ovens have a random frequency, asserting that they operate at a defined frequency of 2.45 GHz.
  • A third participant agrees with the defined frequency assertion and mentions that any frequency drift is likely minimal, around a couple of MHz.
  • A different participant notes that there is an initial chirp of about 100 MHz as a magnetron warms up and questions whether the heating is intended to differentiate materials based on their microwave absorption spectra.

Areas of Agreement / Disagreement

Participants disagree on the characterization of microwave oven frequencies, with some asserting that they are random while others maintain they are fixed at 2.45 GHz. The discussion remains unresolved regarding the feasibility of a variable frequency microwave oven for specific heating applications.

Contextual Notes

Participants have not fully defined the specific materials or their absorption spectra that would be relevant for the proposed heating application, leaving some assumptions unaddressed.

duordi134
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I have a need for a microwave oven which uses a specific wave length to heat a specific part of a composite sample more than another part of the sample.

Normal microwave ovens have a random frequency and amplitude and the frequency is not adjustable.

A radio like a short wave radio would work but it does not have an adjustable carrier wave.
I would have to have an adjustable carrier wave.

The frequency and the amplitude could remain constant while the signal was intermittent or the amplitude could be varied while the signal remained constant.

My hope is that something like this is exists already which can be purchased.

If not I will have to build one which brings up some safety concerns.

Any thoughts?

Thanks

Duordi
 
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Normal microwave ovens have a random frequency ...

i don't think that is so.

I think they operate at 2.45ghz.
 
jim hardy said:
Normal microwave ovens have a random frequency ...

i don't think that is so.

I think they operate at 2.45ghz.

agreed ... their freq is well defined and any freq drift is likely to be reasonably low
from what I have read, in days gone bye, around a couple of MHz

cheers
Dave
 
You can still expect an initial chirp of about 100MHz while a magnetron approaches operating temperature.

duordi134 said:
I have a need for a microwave oven which uses a specific wave length to heat a specific part of a composite sample more than another part of the sample.
Do you want to select which material is heated based on microwave absorption spectrum?

If so what materials are you trying to differentiate and what are their absorption spectra.
 

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