dave wrote:

On 03/12/2014 10:20 PM, Michael A. Terrell wrote:

dave wrote:


These are pretty darn close to what you need, as long as they are true
balanced. This will put a face on it, any way.

http://www.markertek.com/CATV-Headen...ver-CAT5.xhtml


75 Ohm unbalanced to 110 Ohm, balanced, twisted pair? The fact that he
is using unbalanced audio implies 5K ohm or higher impedance.


Baseband Video is always 75 Ohms unbalanced 1VAC p/p.

Yawn. Actually, it's 1.4 volts, because the sync is .4 volts below
the video.

110 Ohms is a
standard for digital audio. The fact the device is a BalUn means the
unbalanced audio (and video) is transformed for the balanced
transmission line (and back again after). The video will be a couple
10ths low but the first DA it hits will fix that, otherwise most devices
will AGC it to where it needs to be. As long as the group delay isn't
hideous it'll work for SDTV. There are audio only devices that is the
application we need here.

PS I'm surprised Ma Bell didn't try to sell you a bunch of 111C coils
and active official interface devices.


'Ma Bell' didn't own the telephone hardware on that Army base. In
fact, they didn't own the White Alice' microwave network that provided
the long distance phone service for a large part of Alaska.


Test some of those cheap video baluns with audio, then tell us the -3
dB points. You keep forgetting that I built Telemetry & video equipment
that you'll never see, and to standards that you can't come close to.
Long before digital TV, my video hardware was flat to 40 MHz. That
included diversity reception, and video combiners that would provide a
solid video signal from multiple fading signals.


--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.