[GreenKeys] question about TTY signals and Telephone Signals

[Don Robert House]

Paul,

You and I would have no trouble with installation and repair of  
telegraph signals, however if scores or hundreds of folks started  
putting 130 vdc 62.5 milliamp circuits in their home wiring I would  
not want to be a modern telephone technician trouble shooting  
problems in those homes or noise trouble on the neighbors phones.   
Especially when you add DSL to the equation.

Having worked in the Chicago area many of our cables were 19AWG and  
dedicated to telegraph to keep the noise segregated from the rest of  
the telephone cables. Even so we still had problems with some analog  
digital data customers.

Frequencies work much better over telephone wiring than DC square  
waves which is why modems were invented.... and we are not beginning  
to talk safety issues.

Don


On 2 Jan 2006, at 8:06 PM, Paul Wills wrote:


----- Original Message ----- From: "Eugene Hertz" <ehertz at tcaf.org>
To: "GreenKeys" <greenkeys at mailman.qth.net>
Sent: Monday, January 02, 2006 6:06 PM
Subject: [GreenKeys] question about TTY signals and Telephone Signals


Hello all.

> I recently purchased a house and in it there is fairly extensive  
> telephone wiring. Each room has 6 pair >and in the basement there  
> are punchdown blocks and a multi-line telephone system. I believe  
> it is an >analog system as the phones that are used use RJ-11 not  
> RJ-45 (although that might not tell the whole >story). Only 2 pair  
> are used for each phone

> My ham shack/workshop is in a spare bedroom on the 2nd floor. My  
> office is on the first floor. I was >thinking of using the existing  
> wiring to create a loop from the shack down to the office. Does  
> anyone >know if the proximity of 60ma current loop signals might  
> cause interference to the telephone signals >running adjacent to  
> them on the same cable? Please note that I might also want to run  
> 60ma polar for a >teletype ticker model (401?) if that makes  
> matters better or worse.

> Please give me your opinions of whether you think this is a bad  
> idea to run them together.

I've done it for years here.  Everything shares a common MDF in the  
basement.  It worked that way on the railroad too.  Just be sure to  
keep the "outbound" and "inbound" wires of a loop in one twisted pair.

PDW
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