RCA 1861, NTSC and a DEC VR-201

The VR201 is not tolerent of the wider timing that monitors allow and also of sloppy levels. It was designed to be the tube for a host of systems and designed to a narrower spec. the reason for that is it runs on Pro3xx, DECmate and a few other things without adjustment so it's one part and no adjustments for centering external. Feed it gook and it does bad things. On the other hand the 1861 is sloppy as well get out and relies on consumer TVs that will generally synce or can be adjusted (back then Hhold and Vhold were common knobs!). Also some of the comac 1861 implmentations were rather poor about output levels and impedences. I've seen one that would not drive a tube unless it presented a ~75ohm resistive load due to a lack of a DC path to ground at the drive end (crummy circuit!). I've used Barco and other mono monitors with DECmates and the like and they output NTSC. Unlike common monitors the VR201 is rather strict about getting good stuff to give good stuff. It was made that way so that it could be plugged into any dec system with no adjustment other than brightness and be in sync and centered. Your right but still worng in the sense I applied it. It also does not have a Hhold external, Vhold external or access externally to toher than brightness or contrast. It was factory adjusted to expect a strict timing for a properly centered image. It can be re adjusted to accept different but it will look poor on a DECMATE until adjusted back. Hence the comment that a Vr201 is not a generic monitor, though it's _possible_ to use it as one assuming the drive source does not take to many liberties. Allison