[Asterisk-Users] Adtran TA750 Noise

[Rich Adamson]

> I have an (actually 2) Adtran TA750s with 8 FXO ports. I get a terrible buzz on every FXO 
port. If I unplug the Adtran and put an analog phone
> on each incoming line, I have no buzz.
> 
> I also have 2 Carrier Access Access Bank Is with 12 FXO ports. When I plug the same analog 
lines into either one of those, no noise or buzz
> whatsoever.
> 
>  
> 
> I went so far as to move the TA750 to within 5 feet of the demark and ran a short CAT5 cable 
from the demark to the TA705 and still lots of buzz.
> 
>  
> 
> I have duplicates of every part for the TA750s and swapped every component and cannot get rid 
of the hum on either unit. I have the power
> supply of the Adtran grounded. I am out of ideas L.
> 
> Any assistance would be greatly appreciated.

Well, you're the second one in a rather short period of time that
has complained about the exact same hum/buzz when the Adtran 750
is used with FXO interfaces and with X100P cards.

There was another posting earlier today in which the individual made
a comment the 750 FXO interface does not support impedence matching.
I thought the statement was rather strange, but since I don't own one
of these units, I went to the Adtran site in search of a technical
description of the FXO card. I couldn't find one, and for that matter,
it appears Adtran has little reference to the 750 being used with any
FXO interface. (Its almost like they know there is a problem and
removed the 750 FXO options. Selling as FXS only now.)