[QuadList] Fwd: Early Helical Scan concept at AMPEX

[C. Park Seward]

Some interesting background from Jim Wheeler.

Best,
Park

C. Park Seward
Visit us: http://www.videopark.com


Begin forwarded message:

> Subject: Re: Early Helical Scan concept at AMPEX
>
> Around 1953, Charlie Ginsberg hired Charlie Anderson and Alex Maxey  
> to be on the team to develop a videotape recorder.  Charlie A and  
> Maxey rented an apartment in Redwood City.  One evening, they were  
> sitting in their living room discussing possible methods for  
> recording video on mag tape.  Several people had tried linear  
> recording at high tape speeds and they all failed.  Maxey had a  
> cardboard core of a roll of toilet paper and he wrapped a long and  
> narrow strip of paper around it in various ways.  He liked the idea  
> of a 360 degree wrap and made a sketch of a tilted scanner with in  
> and out guides.  It did not have to be a full 360 degrees because of  
> the vertical interval.  I believe that he used an audio deck as the  
> base.
>
> After Maxey played with various ideas, Charlie G believed that  
> helical had too many potential problems so Maxey tried another one  
> of his "crazy" ideas.  He used four inch wide mag tape and cupped it  
> around a small diameter electric motor.  This was the beginning of  
> the quad format.  They had calculated that they needed a 2,000 ips  
> head-tape speed.  Maxey found a motor that met his requirements  
> using two inch wide tape.He first tried a male guide that cupped the  
> tape properly.  He could not get the head-tape contact he needed so  
> he developed a female guide.  This worked and made reasonably good  
> video using a special tape that 3M had made for Ampex.
>
> Actually, Maxey did not initiate the idea of cupping the tape.  That  
> was Alan Camas in Chicago.
>
> Meantime, Charlie A had accidentally discovered a way of recording a  
> wide bandwidth of video using a vestigial sideband FM.  This meant  
> that 2,000 ips was no longer required and made it easier for Maxey.
>
> Maxey was a mechanical genius and later developed both the Type A  
> and the Type B formats.  I was one of the engineers who developed  
> the Type C format.  Quad never got a SMPTE letter designation.   
> Maxey is credited with inventing the word "glitch" when he was  
> working on the NASA Atlas project in the late fifties.
>
> Charlie A lives in the Reno area.  Both Maxey and Charlie G died  
> several years ago.
>
> Jim Wheeler
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