Radtel RT-900 Demo Source Keil Project

When questions by the average person with probably no understanding of electronics, programming etc. , that does not call for sarcastic answers instead of answers based on knowledge and solutions by self appointed moderators with no real solution to offer. I am a retired electronics engineer and software developer. I took one of my RT-900s apart on the bench. The BK4819 chip uses a PLL (Phased Locked loop) chip to compare input to output characteristics to avoid for one thing transmitting off frequency. When the settings are incorrect the PLL does not lock as desired. This in turn prevents the PLL from locking and leads to no output and drift. That is why you are seeing power levels (all over the place) free rolling and/or none at all. Read the BK4819 chip specs and ask yourself why the y have the PLL right before the power amp section. See page 4 of 22. If the PLL doesn’t see the correct values from the MUX (multiplexer) the output will be erroneous. An easier explanation was when the LM1800N (PLL stereo demultiplexer) chip was used in FM stereo receivers to detect a stereo signal. It used a 19KHz pilot signal and internally compared the input signal to the pilot, if it matched a left and right stereo signal would appear on pins 4 and 5. Back to the 900, basically the PLL isn’t seeing what it needs to provide The desired output to the power output circuit. I was able to modify (temporarily) the circuit to provide an output and what I saw on the scope was not what the input was set for. Marcus did a great job with the H3 but I have to agree with him about hardware issues. The implementation of the chip in this design leaves something to be desired. I won’t get into hardware mods here. I also looked at the stock code written in chinglish OMG!

Ken