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Futaba PCM
Hello everybody; I have one question about a vintage FUTABA RC SYSTEM. It says PCM but I really do not know if it does use crystals. I see a crystal in the receiver but can not find a crystal in the transmitter. How does it work?
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What is the model? PCM radios would normally have a crystal, Futaba did do a radio with a synthesized transmitter module (3GR) but I don't think that was PCM.
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Originally Posted by alexhahner
(Post 15532063)
Hello everybody; I have one question about a vintage FUTABA RC SYSTEM. It says PCM but I really do not know if it does use crystals. I see a crystal in the receiver but can not find a crystal in the transmitter. How does it work?
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I still have my old Futaba 3PJS Radio, which uses FM crystals. You have to be specific, because I believe that the radios that came before PCM was introduced used AM crystals. I know for a fact that I couldn’t use my old Magnum Jr. crystals because of it. Chances are, if it’s a pre- 2.4GHz radio, it uses crystals. |
If it is 3PJ PCM, there is a module in the back of the radio that you can pull out. The receiver will be on the bottom of it. There is a groove where the module meets the radio were you can also see where the crystal goes. You do not have to remove the module to remove the crystal.
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As mentioned, it is in the TX module
PCM is a digital version of PPM. The pulse width of each channel is converted into an 10 bit number and that number is as a serial bitstream transmitted to the receiver which translates the serial bit stream into sepperate PWM signals |
pcm stands for pulse code modulation...a line of computer code is sent out with the fm signal
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