[arm-allstar] Radio-less node part question

Doug Crompton wa3dsp at gmail.com
Wed Jan 31 16:42:04 EST 2018


 The purpose of the bat43 Schottky diode is to prevent outside voltages
greater than +5V from getting to the FOB chip. Most radios we interface
with today do not even need the diode because the level driving COS is a
TTL level +5 max. Some older radios would have high levels far exceeding 5V
and the diode was there for protection. For a radio-less node - one where
you use the mic PTT to ground the COS line you do not need the diode at
all. Just connect the COS line to the PTT switch in the microphone.

*73 Doug*


*http://www.crompton.com/hamradio <http://www.crompton.com/hamradio>*

On Wed, Jan 31, 2018 at 3:37 PM, "Terry Bethlehem via arm-allstar" <
arm-allstar at hamvoip.org> wrote:

> Can the BAT43 diode be substituted with something else? I don't have much
> of a parts bin and I'm asking friends for help.
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