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Re: [TCML] 1 Mhz ,1 kw

In the days where hams were using spark transmitters the LOWEST frequency they were supposed to use was 1500 kHz and guys worked really hard to try to get 1 kW input to theirpower transformers. A typical hot station used 25 kV for charging and ran an 0.01 ufd mica capacitor, rotary spark gap, and single-turn inductor of wide copper strap which was less than 12" in diameter. Spark rates were of the order of a couple of hundred Hz. There are plenty of pictures of these transmitters' which were built into a box with leads between parts kept to an absolute minimum. You're going to have to do something like this [high voltage, small tank inductor, biggest capacitor you can charge] to get the results you're asking for. Input power is proportional to the spark rate so if you are able to use high rates you can increase the input power for a given capacitor - assuming the transformer will charge it fast enough - but may or may not get longer streamers. One way to find out is to try! 

Ed

jimlux wrote:


Dex Dexter wrote:
I'm considering making a very high frequency (spark gap type) coil with decent power level. 
Resonant frequency at least 1 Mhz and power input about 1000 W.
Can someone give me advice and recommend design parameters for this?
Thanks.
Tough at that power level with a spark gap. Run some numbers with the spreadsheet or JavaTC and see what kinds of primary L&C. You'll need small L and small C to get to 1 MHz fres. But, you also need high energy per bang to get your kilowatt. That means high voltage on the C (1/2 C V^2) which makes all kinds of design trouble with insulation and corona.
Losses will also be higher (both in dielectric and IR losses, because skin depth is small).
There's a reason why folks use big tubes for kW power levels at MHz frequencies. 



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