[Fwd: LF: LF LOOP INFO]
Mon, 30 Nov 1998 16:08:42 -0500
Peter Dodd wrote:
> > I can pass on some experience from New Zealand. Computer ribbon is an
> > attractive way to make a "coil" by connecting wire1 end2 to wire2 end1,
> > and so on ... and there could even be tapped turns. However, actual
> > testing has shown that computer ribbon has quite high capacitance per
> > unit length, and if nothing else this limits tuning range, but it also
> > lowers Q.
> I have made an LF receiving loop with a square configuration, one
> metre per side. I used 14 wires of a section of ribbon cable and used
> one separate turn for coupling to the receiver.
> The main loop is tuned with a 1000pf air-space capacitor.
> > The basic test of a frame receiving loop for LF DXing is that it can
> > distinguish QRN as the main component of background noise. If it can't
> > then you are probably missing some weak signals ....
> Very true. I used a MAR amplifier as described by John, G4GVC, in
> 'The LF Experimenter's Source Book' to improve the sensitivity.
> > So the computer ribbon is expedient, but unlikely to be a high
> > performer. I was hoping to stuff the ribbon inside plastic conduit
> > pipe, and have a weatherproof frame loop for mounting outside, but it
> > has not worked out that way.
> I used the plastic conduit construction and it kept the wires dry
> even in this very wet year we have had in the UK. The tuning
> capacitor is mounted outside the conduit and wrapped in polythene.
> Regards, Peter, G3LDO