[QuadList] Patch cables/bays (Was ...some useful info fromBAVC...)

[Don Norwood]

----- Original Message ----- 
From: Ted Langdell

>>SNIP<<

So, you need to know whether your panel has:

WECO or RCA
75 ohm or 50 ohm (You need 75 for video)
Terminating or non-terminating
Normaled or single jack "straight-through"
--------------------------------------

Ted and Ed........

It is true that no matter what the application, WECO and RCA patch 
connectors should never be intermixed due to the physical differences.

But.......if what Ed is dealing with is composite video, then the 75 ohm 
situation needs some clarification.  The two connector styles each have a 
characteristic impedance (which is what gives them the slightly different 
dimensions).  WECO is 75 ohms and RCA is 50 ohms.  However, at baseband 
video frequencies, that's not really an issue.  There were many thousands of 
RCA patch panels used with 75 ohm video systems.  If you examine the part 
numbers, you'll see that the 50 ohm RCA normalling jacks are available with 
either 50 or 75 ohm internal terminating resistors.  That's the important 
part as you do not want to use normalling jacks (in either style) with 50 
ohm internal terminations.  This situation is similar to the use of BNC 
connectors, virtually all of which were 50 ohms for many years.  At baseband 
video frequencies (<10MHz), it doesn't matter electrically, only physically.

Now....if we're talking about digital patching, that's a different ball 
game, but I don't think that's what Ed is doing.

Don