Increase Analog Line voltage

[Dphone]

How do you increase the on and off hook voltage for analog phones on 81C? What is the on and off volage and loop current range? Mine analog phone are 39 to 40VDC on hook and 6.5VDC off hook.

 

[acewarlock]

Why do you want to change the voltages?
Are the phones not working?




This is a Signature and not part of the answer, it appears on every reply.

This is an Analogy so don't take it personally as some have.

Why change the engine if all you need is to change the spark plugs.

 

[Dphone]

I would like to use some Emergency phones that the spec. call for 10-12 Volts off hook and 50 -52 Volts on hook. and 30 Ma loop current. My spec are lower than this.

 

[PERRYPJ]

Have you tried to see if they work

OLD ROLMEN WORKING ON NORTELS

 

[Dphone]

They work most of the times but, not all the time. Being emergency phones they need to work all the time. The vendor tells me the volage is to low.
I was wondering what voltage other have?

 

[ArchTelecom]

The sets that you are measuring the voltage for...are they far away from the switch? If so, maybe a larger guage cable would provide you less loss.

 

[steve64]

You might also look in to using a NT1R20 OPX Analog line card. It is only an 8 port card but I've used it very successfully on some pretty long external loops from the switch. The other possibility is using an external 2W loop extender module. They are designed to fit in a standard 400 series card shelf.

 

[Dphone]

I'm getting the Voltage right off the feeder pairs in the PBX room(about 20 feet from the PBX).

 

[trvlr1]

Its been about 15 years, but I seem to remember an AC powered transformer to plug in to such a phone as this. The line coming in triggers a switch so the power is "transformed up" to the required voltage. Sorry don't remember manufacturer but I would suspect Graybar or the like would be a good place to start if they are still made.

 

[Dphone]

Is 39 to 40VDC on hook and 6.5VDC off hook considered low?

 

[acewarlock]

Quote:
Is 39 to 40VDC on hook and 6.5VDC off hook considered low?

Yes I think that is to low.



I think you may have a bad Power Supply in that shelf, have you tried a card in a different shelf?






This is a Signature and not part of the answer, it appears on every reply.

This is an Analogy so don't take it personally as some have.

Why change the engine if all you need is to change the spark plugs.

 

[aswipay]

Here is a thought. Why not explain to the "vendor" that You only support industry standard analog devices. Provide a device that fits this requirement and you will support it.
I had an alarm system "technician" tell me that the line voltages that we were providing him were bad. I gained this knowledge while standing at the foot of his ladder after asking him why in the h3ll he was cutting into my cable plant and installing a 31x in the ceiling. I proceeded to take Mr. Bell System to the fiber remote of the bldg. I then asked for his meter and proceeded to measure across tip and ring of every port on the remote. I then looked at him and said "looks like every port out here is bad, guess I better replace all of these cards". He frowned and mumbled that I had made my point. He replaced the dialer in the alarm panel and the problem was solved.
My point is that it is bad policy to allow vendors to show up with any kind of stray cat device then put the burden onyou to support it.

 

[Dphone]

Well today the on hook voltage, on all the shelfs is running around 41.5V +or- 0.2V. Would you consider this still low? I randomly checked on hook voltage on each shelf. I'm surprised it changed almost 2 voltage since last Friday.

 

[hawks]

From the book:
"–48 (can be as low as –42 for DC-powered systems)"

Checked a couple of mine and they read -45 & -46 on hook, and -6 off hook.


so it looks like you might be on the Low side.

 

[acewarlock]

What phone system do you have and does it have a seperate Power system?




This is a Signature and not part of the answer, it appears on every reply.

This is an Analogy so don't take it personally as some have.

Why change the engine if all you need is to change the spark plugs.

 

[Dphone]

81C DC- Powered
The power feeding the system is -52VDC