I'm trying to understand the function and behaviour of the "PA" button in EESDR2 and EESDR3.

Am I right in assuming that when this is selected, pin X8 of the EXT CTRL connector is asserted during TX and if it is not selected, that will not be asserted? If so, it should match the regular PTT when selected and lie dormant when no selected. Am I correct in this understanding?

danielwee wrote:
Why are you overthinking the function

The PA option is Simply to turn on the connection for enabling pins 14/14 on the back DB15 connector to control an external Amplifier PTT line or another device which needs a KEY line signal,

Yes, when enabled the PA button functions alongside the PTT switch
Yes if selected in the options (enable PA in Tune Mode) then Yes the External Key Line of the DB15 connector will operate/ send signal to close Key line while in Tune mode

Having the ability to choose if enabled or disabled is great for use with an external amplifier so you can close to have options to NOT enable an external amp or to enable it over various functions such as PTT or TUNE

or how about in this scenario
using the BM in V3 you can select which bands to enable the PA function- so in my case with a manual amp which I must manually select Band and manually tune this is great
because now since I don't have a resonate antenna for say 160- I simply do not select the PA function for 160 which means I can't send my amp driven into a no resonate loaded antenna

also note in V3 option of always enable and using the function in BM its one or the other, I prefer setting in BM because that means as above it will not send a Key signal to my ACOM if I happen to goto 160 and TX on accident.

it is nothing more than a software switch to turn on or off the ability to send a signal for Key Line close out of the DB15 connector

Thanks for the clarification. It wasn't completely clear from the manual what being enabled meant but it is essentially as described. I was looking for a way to know when the PA button has been activated in order that I can get an external controlled to automatically limit the power output. So, say I want to output 100W when the amplifier is bypassed and not in use (PA button not selected) but I only want 5W output when the amplifier is in use. I don't see a way to do this internally to EESDR2 or 3 hence my trying to come up with a separate automated solution.