On Fri, 15 Jul 2005 02:18:05 GMT, "Don" wrote:

First of all, "Thanks!" to everyone who has commented so far! Your insights
have been extremely helpful.

Some additional info for things that folks have had to make assumptions
about:

The signal is an RGB video signal with sync on green (i.e. there are only
three outputs - RGB - from the video card to the monitor.

The system is an old DEC Alpha VME system. I have not been able to dig up
any info on the video output. General consensus in the lab is that the
display is running at 1280x768, but since the system is currently down for
maintenance, no way of really checking.

That's an odd size, 1280x1024 or 1024x768 would be normal.

The monitor is a DEC 21" VRCX1-WA with RGB and high density DB15 inputs.
Obviously, we are using the RGB inputs. The monitor it self is spec'ed at
1600x1200 at a 75Hz update rate. This should give the upper end of the
video bandwidth, but I am not sure how to convert it into an equivalent
video bandwidth in MHz.

1600 x 1200 x 75 = 144e6

That's a maximum pixel clock of 144MHz.

Right now I have got my hands on some double shielded RG-59 and looking for
some 75ohm BNCs. Our lab has a boat load of 50 ohm stuff, but one poster's
comments about the connectors being the weak link have me real concerned and
I am going to try to minimize any impedance mismatch. Unfortunately, the
video card end is a basic DB-15 (not the normal high density type used for
PC video).

You'll be glad of that when you solder your RG59 to it, the
high-density DE-15s are a pig to solder conductors that thick to.


Dave.