Surge Arrestors

Discussion in 'Technical Discussions' started by Jerry SKINNER, Jan 14, 2008.

  1. Recently we installed a site for Cingular in which they where using TMA's surge arrestors and Bias T's. We installed the co-located tested all the lines and all passed w/ very good sweeps. About a month later we received a call stating that there was no power getting to the TMA's. We troubleshot, replaced, and reswept. To find that the issue was not resolved. After speaking to others w/ more RF knowledge than I have they all seemed to think there was problem w/ our line or a jumper although all the sweeps indicated that it was all good. After not being able to sleep that night, I laid there and thought what could it be. And then it hit me, a couple of months prior we had received a set of ( surge arrestors which had visible defects from they manufacturer. The next Monday we went out w/ new ones and replaced them. It worked. The surge arrestors where letting signal go out but but when the TMA tried to respond back to the PDU it was giving it an error message do to the surge arrestor. Lesson Learned. Start @ the bottom and work up. I hope anyone who has this problem or is currently sitting there and wondering what else can I do will see this post and it helps them.
  2. Brian Leary

    Brian Leary Friend of the Community

    Jerry. We ran across this in many cases this past year in Georgia. When AT&T went with the 3G project a few years ago they installed MHA's on various sites. Some sites they chose not to and as a result they also installed surge arrestors that wont pass DC. (they were cheaper) So when you sweep the site it looks good but when you power up the Bias T the site will fail.
  3. To prevent this in the future, i.e. manufacture defects, test your TMAs and or your BIAS Ts with a volt meter. However, your readings will differ with the different type of TMA/BIAS T. This is info you can get from your site contact or better yet a tech that you have a good relationship with. Also, they will appreciate this help, especially the documentation you can add to the on site log book. TMAs are measured in mA with your BIAS T in VDC. Email me if you have any problems....

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