fm-pll-pic16f870.jpg

12 volt besleme ile 500mw güçü var devre PIC16F870 ve LMX2306 üzerine kurulu basit bir devre birtek bobinler biraz uğraştırır :)

88 108MHz arası yayın yapılabiliyor frekanslar birer kademe her birim için ayrı hex kodu var devrede kullanılan direnç ve kondansatörleri tam değerinde olmalı özellikle bobinlere dikkat edin Proje detaylarına ve Dosyalara Buradan ulaşabilirsiniz Alternatif

Buffer stage
Here you find another HF transistor and it is working in class C.
The resistor R1 and the resistor Re2 set the DC current. In this case I found that 9.1k will give good output power and so the same with 150. If you wish to increase the power Re2 should be lower. You can add another 150 ohm resistor parallel.
In the table below I show you the output power with different voltages and values of resistor Re2.
I advice you not to run this transmitter with to high output power. The transistor I use is a small one and tends to get hot.
I advice you to run the unit from 0 - to 200mW. At 500mW the transistor will be in pain…*smiling*
At the output you will find a T network. This “filter” will match the antenna impedance to the transmitter output stage.
You have two variable capacitors 60pF to tune the transmitter for best performances.
The antenna I used I a 1/4 wave whip antenna (wire) about 75cm long.
This type of antenna is smaller but not so good performance as a dipole.
With a dipole you will be able to transmitter much longer distance.
How long can I transmit?
That is a very difficult question because the environment affect the transmitting distance very much.
In a city environment with concrete buildings the transmitter will send maybe 200m.
I an open filed it will transmit 2000m.
I did a filed test and with 70mW output power into the “bad” whip antenna placed indoors I could transmit 200-300m out into a park with no problem