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com over CAT5... update

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Keith Broughton:

--- Quote from: Mac Kerr on September 10, 2015, 11:57:42 PM ---You could also put dry out boxes at each end of the run, but you would have to power each end separately.

Here's a LINK to Pete Erskine's download page of a dry out box. Connect the balanced sides together with a Cat5 cable, making sure pins 2&3 are on the same pair, and you're good to go. As I said, this does require power at both ends.

Mac

--- End quote ---
I had considered this option but wasn't sure if the call light would still function.
Thanks for the link.

Pete Erskine:

--- Quote from: Keith Broughton on September 11, 2015, 06:42:11 AM ---I had considered this option but wasn't sure if the call light would still function.
Thanks for the link.

--- End quote ---

CC Call light is done with DC so it won't work.

Mac Kerr:

--- Quote from: Keith Broughton on September 11, 2015, 06:42:11 AM ---I had considered this option but wasn't sure if the call light would still function.
Thanks for the link.

--- End quote ---

The call light will not work with Clear Com for sure, they use a DC voltage for signaling. RTS might work, they use a 20k tone for signaling.

Mac

Pete Erskine:

--- Quote from: Keith Broughton on September 10, 2015, 03:15:56 PM ---Replaced the CAT with mic cables and com was quiet so I can only associate the noise with the lack of shield on the CAT.

--- End quote ---

I have used twisted pair successfully.  The gig was handed to me after the venue (a river in Tennessee) had already been wired with 25 pair telco cable up one side and down the other with punch blocks at each gate on both sides of the river, all paralleled.  I was using RTS so was saddled with unbalanced comm.

At each Gate on each side of the river of the White water rafting event the judges needed to talk to each other and to the main judge.  There were 10 Gates spanning 200 yards at least.

I started by assigning to each twisted pair a ground and a comm channel.  A second pair was the Ground only so each RTS beltpack got the common ground pair on pin 1, the hot of the ch 1 twisted pair on pin 3 and the hot of the ch 2 twisted pair on pin 2.  Pin 2 was unique to each gate and pin 3 was common among all the beltpacks.

I was hoping that the unbalanced comm would be shielded by the twist with a ground wire.  These ground wires were only grounded at the base.

Worked OK but still had a medium level of buzz, OK for communication but not ideal.  I had used 12 Pairs so far, 1 for each gate private, 1 for global channel 1 and 1 for common ground.  On a lark I grounded the remaining 13 pairs and all the buzz went away. 

With Plain Cat5 you don't have the advantage of all those unused pairs as a ground/shield.  Shielded Cat6 might have a chance but if you need to run a cable anyway run shielded twisted pair like Belden 8451 at least.

David Buckley:
I'd give pro intercom a call.  They have a couple of boxes, the AD903 being the one I'm familiar with, that converts party line to four wire audio, and also the AD920 that convert party line unbalanced to four wire intercom.  The AD920 can convert signalling as well to match four wire comms, but what I don't know is if you can just use a pair of AD920s back to back.

Not a cheap solution, but an off-the-shelf solution.
Its a pity the designers and manufacturers  of the AD903 did not include a call signal passthrough using audio signalling.

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