Re: LF: RE: Antenna wire

[KEN WRIGHT <ken.h.wright@btinternet.com>]

Hi Peter.
I did not think we used cad/copper for drop wire, 40lb  open wire yes ,  I was with  GPO/BT  1963  - 2002,  and the  early  drop wire  was  stranded, rubberised insulation, later we went to solid and i thought we had stoped using cadmium by then. currnt drop wire is now 2 pair .

Regards.
Ken 
M0KHW

IO91TV
 

Peter Dodd <g3ldo@ukonline.co.uk> wrote:
>  many thanks to those who replied to my email regarding telephone drop wire.
>
> The material I have is not copper coated steel wire - it looks like 
> copper material all through.
> The conductors are 1mm diameter and the black insulation is about 1.25mm 
> thick. The pair of wires are 2.5mm apart. I have used it as twin feeder 
> to an OCFD for the HF band to good effect.
> G3JMG, in an article
>  in RadCom March 1970 noted that BT had their own 
> recipe for the conductors of drop wire: an addition of one per cent 
> cadmium to the basic copper mix. This increased the tensile strength of 
> hard drawn copper by 50% from 30 tons psi to 30 tons psi. This also 
> increased the DC resistance by about 20%.
>
> regards
>
> Peter, G3LDO
> > On 16 May 2008 at 7:08, Laurence KL1X wrote:
> >
> >   
> >> ..........I never had to deal
> >>  with open wire spans by the time of my apprecticeship but I think
> >>  that was very similar physically.
> >>     
> >
> > There was some open wire around when I was a BT (Post Office) 
> > apprentice. It was solid copper wire. As I recall, dropwire (steel 
> > with a thin copper coating) had a limit to its usable length because 
> > it had a higher DC resistance than open wire. This resistance may not 
> > be high in relation to other losses on an LF Marconi, but it
>  would 
> > rule out its use in a transmitting loop antenna.
> >
> > Mike, G3XDV
> > ==========
> >
> >
> >
> >
> >