Futaba PCM
10-21-2019 | 10:13 PM
#1
Thread Starter
Tech Rookie
Joined: Oct 2019
Posts: 1
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?
10-21-2019 | 11:55 PM
#3
Almost certainly there will be a crystal for the transmitter. Most likely the radio has a module unit that will house the crystal within it. There should be tabs on two sides of the module to remove it and get to the crystal. Like the previous poster said more info or picture will help.
10-23-2019 | 11:04 AM
#4
Tech Master
Joined: Aug 2001
Posts: 1,825
From: Miami, FL
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.
Chances are, if it’s a pre- 2.4GHz radio, it uses crystals.
10-23-2019 | 11:12 AM
#5
Tech Master
iTrader: (28)
Joined: Mar 2003
Posts: 1,568
From: Indy
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.
10-23-2019 | 12:19 PM
#6
Tech Lord
Joined: Aug 2007
Posts: 14,052
From: Holland
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 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
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