[R-390] SWL antenna

[Transmaster]

You know something that is a excellent idea.  I happen to be
rebuilding my transmission HF dipole antenna and am looking through
all of the possible designs and I found Fair Radio sales has twinax
cable. here is the catalog description; .

Twisted Twin Axial RF cable with braided silver shield Both conductors
are 24 gauge with 19 strands per conductor. Cable rated at 77 ohm
impedance. Light blue jacket. #WT-24, $25.00/100ft; $95.00/500ft.

The search term I used was to find this item is "antenna wire"

Now I have a question;  Has anyone out there used field telephone wire
for antenna wire?
I am looking at this stuff it is cheap. the conductors are some kind
of steel.  It isn't the easiest stuff work with but I have seen this
stuff in the field that has been in use for decades. You can get this
wire in mile long spools for a really cheap price.



On 11/8/06, Tim  Shoppa <tshoppa at wmata.com> wrote:
> John Kolb wrote:
> >At 04:37 PM 11/6/2006, Dan Merz wrote:
>
> >>  But I've been
> >>wondering about the transmission line across and inside the attic
> house
> >>about 40 feet across and down about 16 feet into the basement.  My
> first
> >>idea was to use one of the better .240 diam coax types either 50 or
> 75 ohms
> >>but then I starting reading about losses when mismatch exists and
> thought
> >>maybe RG8 might be worthwhile.  Or will I be just as well off using
> the
> >>cheap 300 ohm foam twin lead that I now use.
>
> >The RG-8 won't work any better than the smaller coax and will be
> >a lot stiffer and harder to handle
>
> >>  I don't expect much noise from
> >>things in the house but do know the current washer is a problem when
> it's on
> >>- probably has more electronic controls than the older one that I had
> for
> >>years with mechanical switching.  My current system picks that up
> because
> >>the lead-in wire drapes over toward the laundry room.  But I can hear
> it on
> >>a portable am radio operating on its internal antenna as well.  I
> usually
> >>lose interest in listening when the washing machine is running.
>
> >Coax instead of twin lead should help with pickup from local QRM such
> as
> >washing machines.  Noise of your current washer probably comes from
> >the motor, not the controls.
>
> To build on top of what John and Roy have said:
>
> Even better than coax is twinax or whatever they call shielded
> balanced line today. I got a bunch and it works wonders on
> MW and LW along with a magnetically shielded loop antenna.
> Loops have a very real advantage in that they have a deep
> null that is useful for eliminating a single point source of
> interference. For the higher SW bands I have a dipole in
> the air connected via the twinax. In all cases the reduction
> in local RFI is profound compared to coax (worst) or coax
> and a balun (slightly better than just coax but still not wonderful).
>
> And the twinax is wonderful for use with the 390A, with
> it's balanced antenna jack. You're using it exactly as it was
> designed. Remember that the 390A was often used with noisy
> mobile generators and in environments with lots of noise.
>
> Twinax is often found surplus (meaning you should dumpster-dive!)
> from IBM mainframe deinstallations, or you can buy it in quantity
> and new on E-bay or other places.
>
> Tim.
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