"Internal PA" feature on a Spectra Conventional?

[SpectraBob]

I have a couple of conventional Spectra VHF radios, into which I can program the "Internal PA" feature, and a button to access the feature. However, I am not sure just what the feature is actually used for. It's my understanding that it uses the internal audio amplifier to provide a low-power (5-watts?) audio-output, using the standard microphone and allowing you to talk on an external speaker? IF so, to where would you connect the external speaker? Would it be on a pair of particular pin-outs, on the A7 or A9 (9000-series) Control Heads?

Thanks in advance for any help on this.

[Victor Xray]

I think it was only available in certain Spectras. Here's a related thread (but ignore cowthief's posts):
http://batboard.batlabs.com/viewtopic.php?t=46705

[SpectraBob]

THANK YOU for the link to the threads on this topic! I appreciate it...

Regards,

Bob