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<DIV>Head switching was done on the back porch by AMPEX. This was done
because the AMTEC used the leading edge of sync to generate an error signal for
the delay line. If you did not do this, the first line of each head pass
would be pulled off to one side or the other. We have all seen tapes that
have this phenomenon. </DIV>
<DIV> </DIV>
<DIV>RCA did sync tip switching. I do not have a book on the ATC system to
see what was going on there. I have a TR 4 manual but it is the bare bones
and no TBC information.</DIV>
<DIV> </DIV>
<DIV>VR-1000 would show a wider H blanking on the switch line. It was
something that was cured in the later machines. </DIV>
<DIV> </DIV>
<DIV>The RCA machines through the TR 3, 4, and 22 would have the VARIBLE EQ
switch on the de mod that would allow the machine to playback an early TRT 1 A
special color format. This was to compensate for the 9.54 db pre emphasis
of the video. The deviation was close enough to LO BAND COLOR that the
levels would just be a little off.</DIV>
<DIV> </DIV>
<DIV>If the tape were a dub of a color signal that had used the early heterodyne
playback system, then the ATC had to be turned to NON PHASED COLOR. </DIV>
<DIV> </DIV>
<DIV>I hope that gives a little bit of information.</DIV>
<DIV> </DIV>
<DIV>Chris Hill</DIV></FONT><br/><font style="color:black;font:normal 10pt arial,san-serif;"> <hr style="margin-top:10px"/>Access 350+ FREE radio stations anytime from anywhere on the web. <a href="http://toolbar.aol.com/aolradio/download.html?ncid=emlcntusdown00000003">Get the Radio Toolbar</a>!</font></DIV></BODY></HTML>