Wouf Hong

At the March 2012 meeting, Joe/W4UEB brought in a medium-sized box carefully held in a green cloth bag. Joe tenderly opened the box, revealing a white Styrofoam packing container. He slowly opened the container and there it was. But what was it? The mystery mechanism was passed around and examined in excruciating detail and the consensus held that it was some sort of video head module from a tape recorder.

Bingo! It's a Mark IV video recording head made by the Ampex Corporation and was used in their VR-1000, the original Quadruplex VTR, and also the first VTR ever sold, video tape recorder. The Ampex Mark IV 2" Quadruplex" recorder was unveiled to a select group of CBS network people and affiliates during a private showing at the National Association of Broadcasters convention in Chicago in April of 1956. It was state of the art then. Those of us who have worked with the Ampex audio tape recorders remember their quality of sound and absolute reliability. Their video machines were built like battleships, using cast-metal and precision-machined parts where necessary instead of stamped components. The Ampex VR-1000 is the original quadruplex VTR, and also the first VTR ever sold.

Here's a shot of the complete video tape recorder. The cover over the head assembly would be closed during operation.

The two-bay rack in the background held the vacuum-tube electronics for sync, speed control, and such, one module for each head in the rotating assembly. This is not exactly a portable system as it weighed it weighed in at about a ton.

The two-inch tape can be seen here in this closeup. The "shoe", seen just to the left of the light gray triangle in this photo, was pulled out of the way and the tape fed through past the head assembly seen just below the end of what looks like PVC plumbing above (the plumbing brought air through the head-assembly drive motor for cooling). The shoe was then closed and locked into position.

The tape is now in a U-shaped configuration between the shoe, shown closed here, and head assembly. During operation the four-head assembly rotates at 14,400 rpm, (240 rps), as tape is pulled from reel to reel. A vacuum in the shoe holds the tape cupped to the shape of the shoe and in alignment with the heads. A servo motor under the baseplate moves the shoe in and out as required to maintain the tape's position during operation You can see two of the four heads (hence Quadruplex) in the assembly. As the heads rotate, they lay down magnetic tracks at a slight angle across the tape. The heads in this unit withstood only about 400 hours of normal operation.

If you'd like to learn more about these beasts, Google ampex vr-1000. A particularly good site is http://www.lionlamb.us/quad/ampex.html by Tim/NS9E a retired broadcast engineer in Reno, NV. Thanks, Tim, for all the good details you shared with me.