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[Russell Ault]

Hi all!

I'm working a show that's using a new Sennheiser ASA 214 to distribute a pair of antennas between a couple of ASA 3000s. When we started turning things on we noticed that the ASA 3000s powered up when the ASA 214 was turned on, even if the ASA 3000 wasn't plugged into wall power. We're assuming this is because the 214 is feeding 12V DC into its outputs to power G3/G4 RXs and the 3000 is receiving it because it normally tries to back-feed 12V DC on its inputs to feed inline amplifiers. We decided to plug the 3000s into wall power to be on the safe side, and so far the system has been running for 48 straight hours without any problems.

The question I have is whether I should be worried about the DC coupling between the 214 and the 3000s? My (fairly rudimentary) understanding of electronics suggests that 12V DC is 12V DC, and that the only real concern is that the 3000s (if not plugged into wall power) might draw more current than the 214 is capable of of happily supplying, a problem that is totally resolved by making sure the 3000s have their own power supplies plugged in.

Am I missing something? Thoughts?

Thanks!

-Russ

[Henry Cohen]

I'm working a show that's using a new Sennheiser ASA 214 to distribute a pair of antennas between a couple of ASA 3000s. When we started turning things on we noticed that the ASA 3000s powered up when the ASA 214 was turned on, even if the ASA 3000 wasn't plugged into wall power. We're assuming this is because the 214 is feeding 12V DC into its outputs to power G3/G4 RXs and the 3000 is receiving it because it normally tries to back-feed 12V DC on its inputs to feed inline amplifiers. We decided to plug the 3000s into wall power to be on the safe side, and so far the system has been running for 48 straight hours without any problems.

The question I have is whether I should be worried about the DC coupling between the 214 and the 3000s? My (fairly rudimentary) understanding of electronics suggests that 12V DC is 12V DC, and that the only real concern is that the 3000s (if not plugged into wall power) might draw more current than the 214 is capable of of happily supplying, a problem that is totally resolved by making sure the 3000s have their own power supplies plugged in.

Am I missing something? Thoughts?

I suspect the DC powering of the ASA3000 via its inputs from the 214 is an unintentional back feed. I agree that it's likely too much current for the 214, and powering from the wall is the correct way to go. Pull the two input modules and set the "DC FEED" antenna power switches to the off position as a precaution.

[Russell Ault]

[...] Pull the two input modules and set the "DC FEED" antenna power switches to the off position as a precaution.

I will do when I get a chance. Thanks, Henry!

-Russ

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