10-500 MHz inductive heating

[chrss]

I am materials person wanting to heat ferrite powders in the low MHz range. A US patent 5208443 (

http://freepatentsonline.com/5208443.pdf,

column 11 of text) has some equipment description for making a small coil (for <40MHz) that would work (although the freq range is limited). The description appears to be just connect a power supply to a transmatch to a coil - is it that simple? It seems that there should be a signal source as well? Any advice about parts to make this kind of system or a broadband version would be greatly appreciated. Of course low power and/or shielding will be needed...

 

[electricuwe]

Using induction heating within that frequency range seems strange to me.

The common frequencies for induction heating are in the range of line frequency to several MHz, but I never came across an installation operating at more than 10 MHz.

You always need some king of matching ciruit, in the lower frequency range switched capacitors, for the higher frequencies a matchbox consiting of variable capacitors or inductors.

I will check the patent later and provide additional hints if necessary.

 

[biff44]

13.56 MHz is a common frequency for such machines.

 

[BrianR]

The power supply is a multi-kW radio transmitter. The matching circuit needs to be low-Q to tolerate large changes in load Z. I have worked on a 10KW 40MHz device used for welding plastic.

 

[biff44]

I worked on one (multi KW RF gen) back in school on a Tokomak reactor. We would tune it manually while watching a loose flourescent bulb lying across the cables. ie "Tune for maximum smoke".