by 5B4AIY » 01 Nov 2022 13:33
Yes, that is correct, the tip of the 3.5mm TIP/RING/SLEEVE plug has to be pulled to ground to put the linear amplifier into transmit. Note that you MUST use a standard stereo plug, that is TIP/RING/SLEEVE, because the sleeve connection repeats the PTT signal, and a mono plug would short this to ground.
The PTT line is pulled up to +12V via a 10K resistor in series with a 1K resistor. (I am attaching the schematic if you do not already have it.) Make sure that your PTT line does not have more than +12V on it when in the RX mode. An open-collector or dry relay contact is ideal.
Adrian, 5B4AIY
- Attachments
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PA100-Main-Board Schematic-1 T-R Attenuator & Current Sense.pdf
- PA Main Schematic
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