[QuadList] RCA air guide photos

[Don Norwood]

The air film guides were one of the selling points that RCA pitched beginning with the TRT-1.  I'm sure it seemed like a great idea at the time. 

Ampex also used air guides in instrumentation recorders, but the clever thing about the guides on those machines was that in addition to providing the air film for the tape, they were also used to sense the tape tension for the reel servo system.  A transducer monitored the pressure at the guide.  High tape tension allowed less air to escape causing the pressure to rise while low tension allowed more air to escape and lowered the pressure.  The variable outputs from the transducers provided the tension feedback to the reel servo system.  The servo system worked well, but I don't know if the air holes caused problems on the instrumentation tapes as it did on the quads.

Don Norwood
Digitrak Communications, Inc.
www.digitrakcom.com
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