In alt.engineering.electrical Brian Cryer wrote:
| "Foxtrot" wrote in message
| ...
|I am in the UK and want to make several phone extensions.
|
| QUESTION: I would like to know I this will increase the level of hum.
|
| ISTR UK phones have a transformer and some other components to
| neutralise hum but would that be good enough to prevent hum from a messy
| setup like mine? Some details are below.
|
| -------------------------
|
| In my situation the phone extension wires and the mains wires will run
| close to one other.
|
| There will be about four or five additional extension phone sockets.
|
| Can't comment on the hum ... but it looks like others have.
|
| One contribution I would make is that you are aware that your phone service
| will support 4 REN and that each phone is normally 1 REN, meaning that you
| can have a maximum of 4 phones. My parents had more of this and whilst from
| their perspective it seemed to work (they could call out), it stopped people
| from calling in because their phones stopped ringing.
I used to see phones rated in terms of their "ringer equivalence" here in
the USA. These numbers were, for some phones, as low as 0.2. I do not
recall ever seeing one about 0.9. That would suggest to me that you could
readily have more than 4 phones on such a phone circuit. I never had any
reason to actually do a scientific test of this.
| So be aware that if you are adding four or five additional phone sockets
| that you won't be able to use all of them (at the same time).
Or check your phone specs for an REN or ringer equivalence number.
If you want to put DSL on your phone line, I also suggest a splitter at
the entrance of the phone line and a separate NON-branching higher grade
(e.g. twisted pair) wire for the run from the DSL side of the splitter
to the intended connection.
--
|---------------------------------------/----------------------------------|
| Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address below |
| first name lower case at ipal.net /
|
|------------------------------------/-------------------------------------|