I give it FIVE Soldering Irons! 

I found it on Amazon Prime.  The workshop scenes remind me of ham workshops.  The movie character Harry Caul was based on real-life Marty Kaiser.  Was Marty a ham? 

POSTSCRIPT (August 23, 2024):  Yes, he is a ham!   W3VCG!   FB.  Here is his web site: 

http://www.martykaiser.com/fbi1~1.htm

https://en.wikipedia.org/wiki/The_Conversation

http://www.martykaiser.com/odyssey2.htm

Thanks to Roy WN3F for reminding me to watch this film.  Roy found a clip that is reminiscent of hamfests: https://www.youtube.com/watch?v=joM5VDCIQg8