Re: Kramer VDAs

"William Meyer" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]
> oN 12-Nov-03, Rick Hammang said:
>
> > Bill, very nice way to put it. I have used some, gain only, GV
> > multi-card VDA's to adjust levels of various cable runs, by loop
> > through. Example, source to transmitter, 400 feet, convidence monitor,
> > 10 feet, house distribution 50', and beyond etc., But I'm always
> > getting some subcarrier loss at the ends of those longer runs. I
> > resorted to equalizing VDA's to bump up the sub carrier, a touch, to
> > keep readings preserved. There is plenty more (EQ) gain available for
> > the longer runs, like the 1000' that you mention, and I understand
> > about the type of precision cable to keep that extra EQ from causing
> > problems. In a large facility, several hundred feet could add up
> > quickly. Say PCR to router, to MC, on to transmitter etc. Regardless
> > of what high quality cable I use, runs exceeding 50'to 80' show a
> > slight loss in sub-carrier, longer runs a bit more. Any tips on
> > preserving the sub carrier losses, without EQ?
>
> Some years ago, I worked in a sports facility that was badly limited by
> building architecture. Cable runs were aggravated by a rigid
> requirement to preserve the aesthetics of the structural design. Net
> result: to get the feed from a camera in the press box two doors down
> from the control room required a link down to the patch room and from
> there, up to the press box. Those architectural issues made this two
> 1,000 foot runs, each of which required an equalizing DA running flat
> out to compensate. The reference feed to the camera could tolerate some
> loss, so only a single EQ DA was used on that run.
>
> The best way to minimize equalization losses is to use good cable (an
> 8281 equivalent), and make sure that cables are never kinked, scraped,
> or otherwise abused. Take care with installation of BNC connectors, as
> well.
>
> BTW, I've demonstrated to doubters in the past that introducing even a
> short length (one foot) of RG-59 into a video run produces a measurable
> loss. Also note that the characteristic of RG-59 is different than that
> of 8281, and that EQ DAs are designed to compensate the 8281
> characteristic, *not* the RG-59 characteristic.

What kind of measurements are you making to demonstrate this?

Leonard Caillouet