4.5Kv 4Mhz square wave

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JOCSTAA

Joined Jun 16, 2020
4
What would be the best way to obtain a 4.5kv square wave between 2 points which fluctuates at 4Mhz? I have a 4.5kv power supply(10ma) and a few 5kv rated MOSFETS. I am very new at this so I dont even know if such output can be obtained using those simple components, any solution would be appreciated.
 

Papabravo

Joined Feb 24, 2006
13,922
The output is an open circuit sort of like an arc gap, I need it for a project
This is not a responsive answer. It suggests that you have something to hide. In order to dispel the notion that you are engaged in some activity that would violate the TOS for this site you need to be more forthcoming.
 

ronsimpson

Joined Oct 7, 2019
705
If you said sine wave ….. maybe.
A triangle wave at 4mhz: 4500v/100nS (about) so 45V/nS. I found some 4500V MOSFETs what will turn off in 500nS at 4000V. (fall time) The only 4700V MOSFET I know of is slower yet.
Square wave by definition is much faster than triangle wave or sine wave.
I think you should look at SiC or GaN MOSFETs. In the 1000 to 1500 volt range. The speed is there but the voltage is not.
4Mhz? I have a 4.5kv power supply(10ma)
To switch fast will require power. Way beyond 10mA. Not ever 100mA. There is too much capacitance inside the MOSFETs. While they are turning on or off the current will be many amps. Because of the speed you want they will be switching all the time.
 

Thread Starter

JOCSTAA

Joined Jun 16, 2020
4
If you said sine wave ….. maybe.
A triangle wave at 4mhz: 4500v/100nS (about) so 45V/nS. I found some 4500V MOSFETs what will turn off in 500nS at 4000V. (fall time) The only 4700V MOSFET I know of is slower yet.
Square wave by definition is much faster than triangle wave or sine wave.
I think you should look at SiC or GaN MOSFETs. In the 1000 to 1500 volt range. The speed is there but the voltage is not.

To switch fast will require power. Way beyond 10mA. Not ever 100mA. There is too much capacitance inside the MOSFETs. While they are turning on or off the current will be many amps. Because of the speed you want they will be switching all the time.
Okay thank you. This is what I needed to know. I'll have to do more research on the other waveforms and possibly reduce voltage
 

ronsimpson

Joined Oct 7, 2019
705
A sign wave will only transmit RF at 4mhz and not do harmonics all over the RF band. You can use a resonant transformer to step up the voltage. Maybe have 4500 volts sign wave on the output of the transformer but only 1kv on the primary so you can use faster parts. You might look at what radio traffic you are going to interfere with. I think there is a band at 455khz no one transmits at. There are also some spots for wireless power.
 

Thread Starter

JOCSTAA

Joined Jun 16, 2020
4
I did a bit of research on transformers. I couldnt find any that is rated for that frequency range. I'm assuming 4Mhz is to high for transformers
 

RPLaJeunesse

Joined Jul 29, 2018
104
I did a bit of research on transformers. I couldnt find any that is rated for that frequency range. I'm assuming 4Mhz is to high for transformers
Uh, no. IF transformers at 10.7MHz are common. RF output stages could be designed with a transformer, but typically not. Easier to capacitively couple and use a Pi network to match the load. You might want to look at amateur radio handbooks for transmitter design.
 

kubeek

Joined Sep 20, 2005
5,724
I did a bit of research on transformers. I couldnt find any that is rated for that frequency range. I'm assuming 4Mhz is to high for transformers
Can you please say what is your goal? This whole debate looks like talking about your arbitrary goals which suddenly are not so firm once you are told they are not achievable.
 

ronsimpson

Joined Oct 7, 2019
705
I built transformers for FM transmitters. 100mhz 100,000 watts. It is not a problem. It is just not a 60hz transformer.
80 meter armature radio band is 3.5hz. I might start out looking at 100 to 1000 watt 80 meter transmitter. Look at the output stage. The transformer is "air coil" or on a "rf core".

Sorry I don't have a good picture. Here the inside of a home made transmitter. The transformer is at the bottom. It resonates with the capacitor on the left side.
1592344254326.png
 

ronsimpson

Joined Oct 7, 2019
705
Here is another picture of 80 meter transmitter. Transformer on left side. In this case they are trying to reduce the voltage with the transformer but it could be used to increase the voltage.
1592344484499.png
 
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