measuring REN

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niknak
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Location: Staten Island, NY

Re: measuring REN

Post by niknak » Thu Aug 20, 2009 8:49 am

I agree with your hypothesis, however what would happen if you then introduce the "Itchy and Scratchy" phenomenon?
Last edited by niknak on Thu Aug 20, 2009 8:51 am, edited 2 times in total.

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StevenJohn
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Location: East Tennessee

Re: measuring REN

Post by StevenJohn » Thu Aug 20, 2009 8:50 am

OK, great discussion going on here. I really don't feel worthy to join in, and forgive me if I'm not, but I say what Wayne said. Look on the bottom of the darned phone! :-o

lohertz
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Joined: Fri Mar 06, 2009 8:42 pm
Location: Far West Burbs, Chicago

Re: measuring REN

Post by lohertz » Thu Aug 20, 2009 9:07 am

Forgive me and my ignorance, but why does it matter in a home installation or SOHO?

I understand the importance in a POTS application as to how many phones you can connect, but, how advanced are you taking this and isn't there better alternatives?

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southsound
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Re: measuring REN

Post by southsound » Thu Aug 20, 2009 9:58 am

jm9496 wrote:How do I measure REN for all phones on a line? Do I call the phone line and measure voltage and current when it rings to find the impedance? I suppose that would give me |Z|.

(in the US, 6930Ω resistor in series with an 8 µF is 1 REN)
Possibly a more serious answer than the one I offererd before. I found this article on how to measure REN using a standard 2500 set as a known value. Scroll down a bit on the page and you will see the details under "Measuring the REN of all the phones on the line". The article also talks about some of the problems with VOIP devices delivering out of standard ring voltages. http://www.sandman.com/ringvoltbul.html

I holpe this helps you determine what you were looking for.
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VoIP hardware: 2 Telo w/3 handsets & Linx / ooma core
Total Lines: 8 / Numbers: 11 / Handsets: 20
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jm9496
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Re: measuring REN

Post by jm9496 » Sat Aug 22, 2009 9:57 am

So I used my method to calculate approximate REN load on my phone line:


I measured 57 V AC, 30mA AC, and 20Hz when the line is ringing.

(57 volts) / ((6930 ohm) + (i / (2 * pi * (20 hz) * (8e-6 F)))) = 0.008059066 - 0.00115678228 i amperes)
|0.008059066 - 0.00115678228 i amperes| = 8.14mA

30mA/8.14mA = 3.7 REN

I know this implies REN is untiless. It is not. REN is a haphazard unit of impedance.

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