RE: Xfinity X1 CATV box DC umbilical project

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Posted by Duster (M) on September 17, 2016 at 09:50:03

In Reply to: RE: Xfinity X1 CATV box DC umbilical project posted by Uncle Mike on September 17, 2016 at 02:48:37:

The stock switch-mode power supply is rated at 3A, of which one might assume is intended for peak current capability. I would never implement an aftermarket power supply with a lower current rating than a stock power supply. The modern Xfinity X1 DVR CATV box is essentially a computer with current hungry processors, and with a 3A rated power supply, it actually involves less current demand than a typical laptop computer with say a 15.6 volt 8A rated power supply.

As for a short-length 2 foot cable with 23 AWG pure silver conductors (with higher conductivity than a copper conductor), I simply did the math to find out if it might be acceptable in terms voltage drop, which is the only important factor I considered in order to choose the cable as a DIY DC umbilical. Since the Newmar 115-12-6E 3.5A regulated linear power supply output measures 13.3 volts without a load, a minimal amount of voltage drop will be insignificant. Another factor I found when evaluating a 16 AWG vs. 18 AWG DC umbilical is that the smaller 18 AWG conductor sounds better than the larger 16 AWG version for the Xfinity X1 application. Bigger is not always better when it comes to various DIY experiments.

In regards to the foil shield, I've had good success with shielded DC umbilicals, so this project is no exception. I'm expecting the twist ratio of the Connex BL-Ag cable to be fairly lazy, so the foil shield should be an effective factor against RFI, and to a lesser extent EMI which can be further mitigated by keeping the DC umbilical away from AC power cords.

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Follow Ups Full Thread

Topic - Xfinity X1 CATV box DC umbilical project - Duster 20:40:53 09/16/16 (14)

RE: Xfinity X1 CATV box DC umbilical project - Old SteveA 22:47:12 09/18/16 (3)

RE: Xfinity X1 CATV box DC umbilical project - Duster 05:09:23 09/19/16 (2)

RE: Xfinity X1 CATV box DC umbilical project - Old SteveA 06:18:47 09/19/16 (1)

RE: Xfinity X1 CATV box DC umbilical project - Duster 08:12:27 09/19/16 (0)

RE: Xfinity X1 CATV box DC umbilical project - tweakmenow 14:23:33 09/17/16 (1)

RE: Xfinity X1 CATV box DC umbilical project - Duster 17:53:28 09/17/16 (0)

RE: Xfinity X1 CATV box DC umbilical project - Uncle Mike 02:48:37 09/17/16 (1)

RE: Xfinity X1 CATV box DC umbilical project - Duster 09:50:03 09/17/16 (0)

RE: Xfinity X1 CATV box DC umbilical project - Sondek 22:47:38 09/16/16 (5)

RE: Xfinity X1 CATV box DC umbilical project - Duster 14:56:25 09/18/16 (4)

RE: Xfinity X1 CATV box DC umbilical project - Sondek 12:57:35 09/19/16 (3)

RE: Xfinity X1 CATV box DC umbilical project - Duster 14:15:54 09/20/16 (2)

RE: Xfinity X1 CATV box DC umbilical project - Sondek 14:31:02 09/20/16 (1)

RE: Xfinity X1 CATV box DC umbilical project - Duster 16:40:01 09/20/16 (0)

Follow Ups

RE: Xfinity X1 CATV box DC umbilical project - Duster 09:50:03 09/17/16 (0)

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