I am designing a simple radio beacon for 28mhz.

What is the simplest oscillator? I look for an ic, i think a vco (pll?) would work, easy to adjust with trim pot. The problem is when the battery runs down the frequency will shift so it needs a zener regulator, complicated.

How much voltage swing do i need on the antenna to get 5w output. 12v/50ohms=240ma*12volts = 2.9W (no good). I have never understood this.

 

I am designing a simple radio beacon for 28mhz.

What is the simplest oscillator? I look for an ic, i think a vco (pll?) would work, easy to adjust with trim pot. The problem is when the battery runs down the frequency will shift so it needs a zener regulator, complicated.

How much voltage swing do i need on the antenna to get 5w output. 12v/50ohms=240ma*12volts = 2.9W (no good). I have never understood this.

I think you'd be better off with a crystal oscillator like a Pierce. If the voltage drops below a certain level, it will just quit.\

Why do you need any more than 2.9 watts for a beacon. Especially for 10 meters. (I trust you have a license for this)

eric

 

Go through old CB circuits, they are nothing but simple 27Mhz oscillators, 1 transistor and a crystal.