[GreenKeys] Open lines?

[Sheldon Daitch]

Check out:

http://www.strombergcarlsontelephone.com/kellogg/PDF/1917_BLTN_98_REPEATING_COILS_PHANTOM_CIRCUITS.pdf

Sheldon

Sam Hallas wrote:
> amourdutigre wrote:
>   
>>  I have been perusing my copies of the greenbooks, (I have the last
>>  two, and am shopping for the first two), and was fascinated by the
>>  fact that the longlines engineers would phantom a third call upon two
>>  pairs of open lines. I have several questions about this.
>>     
>
>   
>>  First, are there anymore open line circuits still in operation?
>>     
>
> I can't speak for the US but there are open line circuits on rural 
> railways in the UK.
>
>   
>>  Second, if there are say four pairs of wires, ("sides"), could you at
>>  least theoretically phantom up to six other calls on those four
>>  wires? One phantom circuit between each possible pairing of pairs so
>>  to speak.
>>     
>
> If you think about it Joe, the answer must be no. It would be like 
> saying you could make six circuits with four wires - 1&2, 1&3, 1&4, 2&3, 
> 2&4, 3&4. The circuits that share a wire interfere with each other, 
> which ends up being all of them.
>
> However, it was practice to generate a phantom on a pair of phantom 
> circuits. So your four pairs could generate two straight phantoms and 
> single double phantom. So your four pairs could generate seven circuits. 
> I recall that making phantom circuits work properly over long distance 
> required great attention to wire transpositions along the pole route.
>
> Cheers,
> Sam
>
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