[BC] putting phone calls on the air

[Rudman, Richard A]

During my first year working summer relief as a tech for WBZ in 1966,  
I occasionally handled the engineering for a talk show with callers  
on the air called "Contact" hosted by Bob Kennedy. Don Parker was the  
CE of WBZ and developed a telephone hybrid circuit. It was not  
perfect, but it got calls on the air. I know "Contact!" aired on WBZ  
starting in 1961. If memory serves, shows based on the "Contact" talk  
show format of host with guests and callers on the phone aired on  
other Group W stations, KYW and KDKA, among them.

The show used a tape delay system with a Dump" button complete with  
substitute sound played from a cart machine that Don designed around  
two floor cabinet-mounted Ampex 350 reel-to-reel machines next to  
each other. The machine on the left recorded, the tape wended its way  
around on outboard tape rollers, and the machine on the right played  
the tape back. Aside from having to deal with the occasional tape  
break, it worked fine -- Ampex 350 broadcast quality playback.  
Starting it was an exercise in learned coordination.

Excuse the digression -- back to the hybrid. The hybrid Don developed  
was built around venerable Western Electric 111C coils. I was  
involved in some measurements after Don left to go to KFWB in LA in  
an attempt to improve rejection on it and seem to recall best case  
was on the order of 15-20 db. on some phone calls. Don's hybrid of  
course did not have dynamic balancing or other electronic bells and  
whistles introduced later, but it got the job done.

Richard Rudman
Remote Possibilities Tech Consulting
11054 Ventura Blvd., Ste. 700
Studio City, CA 91604
213-447-5392