[Hammarlund] HQ-180 question

[Steve Dresser]

Hi all,

I'm new to this list, and new to a recently acquired HQ-180 for which I don't yet have a manual.  On the back of the receiver, between the speaker terminal and ground, there's a terminal labeled "AGC".  What is its purpose?

Also, I notice what looks like a 100-volt socket on the back of the receiver.  Is it really 100 volts, and when is it active?

Thanks in advance for your help.

Steve (WA1RTB)