[QuadList] TBC

[Don Norwood]

Hi Chris:

Merlin did do some conversions of VR-1100's, but they also did conversions of 1200's which is what Park has.  Merlin did this for years, starting with the TBC-800 from Ampex, and progressing thru other models as the technology improved so that when you get to the version that Park has, the TBC design is relatively "modern", ie 10-bit.  My impression (which may not be accurate!) is that most of their work went into 1200's.  Perhaps Ken can addess this for us.

Don
  ----- Original Message ----- 
  From: Chill315 at aol.com 
  To: quadlist at quadvideotapegroup.com 
  Sent: Tuesday, December 08, 2009 9:52 AM
  Subject: Re: [QuadList] TBC


  The RCA machine did use the servo to keep the video in the center of the TBC window.  Ampex did it a different way.  Thus I always found the Ampex method easier to keep running.  The feed back loops in the RCA had you scratching your head every now and then.

  The reason that I would put the TBC after the AMTEC is that it does a flywheel type of correction when the machine is not H locked.  This is the first step in the correction process.  To go later would be a potential issue.  The Colortec would be shut down in this mode.  The Proc Amp would replace the sync.  Thus this is then the only spot that is easy to grab with any certainty of working.  

  The Merlin machine was based upon the upgrading of a VR-1100.  This originally came with a simple servo that could only do Vertical lock.  Thus the need for a one line window TBC.  Thus you could High Band the machine and not have to get an Intersync or Colortec.  

  The playback in the side by side shows the quality of both.  If this is the original, you can see the difference.  The aliasing will tell you which is the Merlin machine.  The lack of a good drop out compensator will tell you which is the Ampex original.  The Ampex machine used the built in one that was included with the AFC modules.

  Chris Hill
  WA8IGN


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