T/S 2068 Color Monitor Difficulties

Some hams have difficulty using some color monitors with the T/S 2068. There are very good reasons for these difficulties. If the usual standards are not followed, less than perfect quality results. The trouble is deciding what are the usual standards when you are trying to build a computer which can be used any place in the world.

Timex had to work hard to adapt the TV output of the spectrum to the US broadcast standards for use on our TV sets. The adaptation was not perfect.

The following table shows the angles at which the color vectors are produced by the T/S 2068 and the angles which are desired by the usual US TV set.

COMPOSITE VIDEO VECTOR ANGLES

Phase	TS 2068 degrees	NTSC Standard degrees
Blue	350	350
Magenta	64	62
Red	116	112
Green	242	240
Cyan	284	284
Yellow	170	170
Reference	224	180

There are also three other difficulties which cause some monitors to give less than perfect performance.

1. Color bust synchronization. The color burst is not synchronous with the waveform because it is generated from the 3.579545 MHz crystal and the waveform is derived from the 14.112 MHZ crystal. The result is observed as ripples at color boundaries such as green to magenta.
2. Color burst duration. The color burst duration on the T/S 2068 is 8 cycles while standard ТV broadcast stations provide 9 cycles. This short burst is a problem for some monitors.
3. Color burst timing. The color burst starts 6.4 microseconds from the leading edge of the sync pulse. Many monitors are designed to expect this start as early as 5.3 microseconds, thus these monitors may not produce color when attached to the T/S 2068.

I hope this helpful to those information is who аге having monitor problems with the T/S 2068.