A while back, a discussion on a radio forum came about on how would someone get a COR signal out of a UV-5R for the possibility of using it as a portable repeater receiver. Now I will not debate that the UV-5R is not the best receiver to use for this as it has a wide open front end and subject to overload and desense. But ignoring that issue and trying to solve the answer to question lead me to split one open and look inside. With the help of a schematic and a DMM , an easy point to get COR can be achieved.
Looking at the schematic diagram, the TDA2822 opamp that is used for the speaker, only gets power when the PL/DCS is unlocked. Otherwise, the TDA has no power. Therefore, its a great place to use to get a COR signal. I've tested this and I'm using this currently attached to a high impedance input on an Arduino I'm using as a controller.
You can see the NPN transistor (Q19) that is providing the power to the op amp. This only comes on when the PL/DCS code opens.
One other note, the surface mount op amp is very,very sensitive to heat. So if you do solder on that pin 2, be very careful you don't overheat it otherwise you'll destroy that chip.
Here is the quick video on where you can get a COR signal if you really wanted to use a UV-5R for this purpose.
https://youtu.be/ejhxLleNXHw
No comments:
Post a Comment