I was looking for a powerful RF transmitter lately but I didn't find many. They are low power (< 0.5W) or expensive.

I have a little understanding of a regular 433MHz transmitter's schematics. It is so simple, I want know can I build an RF transmitter with that circuit with more transmitting power (for example 2W power). Or if it is not possible with that circuit, I want to know what makes it impossible?

Edit : I know about legal terms on radio transmitters, and I only want to know about technical limitations.

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    \$\begingroup\$ Nothing makes it impossible. As you said - just more expensive. \$\endgroup\$ – Eugene Sh. Jan 22 at 17:17
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    \$\begingroup\$ What makes it hard is paying the fine for breach of licencing regulations. Tip: MHz for megahertz. 'm' is for milli. \$\endgroup\$ – Transistor Jan 22 at 17:24
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    \$\begingroup\$ In general, the FCC (or other country regulatory body) limits power to ~1mW together with strong restrictions on duty-cycle for unlicensed transmission on 433MHz. \$\endgroup\$ – Kevin White Jan 22 at 17:26
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    \$\begingroup\$ Forget legal terms I understand them , I only want to know about technical development of it. \$\endgroup\$ – MohamadAli Zeraatkar Jan 22 at 17:44
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    \$\begingroup\$ @MohamadAliZeraatkar The legal terms are a key part of the cost though, as more heavily regulated = smaller market = lower economys of scale = more expensive. \$\endgroup\$ – user1937198 Jan 22 at 17:55

Such devices are available but in almost all cases you must be licensed by the appropriate authority, such as the FCC in the USA, to operate such equipment. The requirements for unlicensed operation almost always has an upper limit on the radiated power so that interference with licensed service does not happen.

The 433 MHz band is shared by a number of services, both licensed and unlicensed and so devices like you are using fall into the unlicensed category and should not be used with an RF amplifier.

For example there are any number of Amateur Radio 433 MHz amplifiers on the market since the 70 cm band is popular among HAM Radio operators. But these are relatively expensive compared to the low-power amplifiers used by unlicensed services. Building a high-powered 433 MHz amplifier takes careful design as well as high-quality components which makes them cost more than "junk" does.


I have a little understanding of a regular 433mhz transmitter schematics. It is so simple , I want know can I build an rf transmitter with that circuit with more transmitting power (for example 2W power) ?

It's not that you can't but that you aren't allowed to. There are regulations set by telecommunication bodies such as the FCC and ITU. You are permitted to operate only within permissible power levels. You might be interfering with adjacent (and other) channels when you operate at power levels higher than recommended. Our handheld mobile equipments typically operate in mWs of power. There is a standard for each application.

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    \$\begingroup\$ Not only power is restricted but also duty cycle. The band is intended for uses such as car remote locking, remote controls or wireless remote temperature sensors. Activity is general limited to ~1%. \$\endgroup\$ – Kevin White Jan 22 at 18:18

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