Question about how to read this schematic

  • Thread starter Charle2kx
  • Start date
  • #1
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I'm using this link to help me understand how this circuit works. However, I don't exactly know what the T & R test points surrounding the ground mean. There are 3-- two near the 27 MHz xtal and one near the speaker transformer. How should I be interpreting this? Does the ground just mean attach it to ground? Or do the surrounding T & R have to be connected somehow?

I've looked around everywhere, but I still haven't found an answer...

http://www.talkingelectronics.com/projects/200TrCcts/200TrCcts.html#59

Thanks in advance!
 

Answers and Replies

  • #2
1,762
59
T & R in the schematic refer to the transmit and receive positions of the push to talk switch. There actually is a fourth T/R switch located close to the antenna. That means the push to talk switch must be a 4 pole double throw momentary switch wired so that the normal position is wired for receive.

I don't see a ground. To what are you referring? A walkie talkie would not have to be connected to ground.
 

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