Andre' Kesteloot akestelo@bellatlantic.net
Sun, 29 Nov 1998 01:23:19 -0500

vernall 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.  Trying tapped turns was hopeless as the "overwinding" seemed
> to dominate the tuning and Q was always low.  I found that for around
> 180 kHz (here in ZL we have access to 165-190 kHz) it only needed about
> 12 turns to tune, using a BB212 varicap with both diodes in parallel.
> This was tried using 50 wire ribbon, with 4 wires in parallel for each
> "turn", and 6 wires for the final turn, but it still did not perform
> with high Q or to my satisfaction for weak signal use.
> 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 ....
> 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 have yet to build a frame loop that does what I want in the way of
> performance.  Other ZL experimenters have good performing LF frame loops
> using wire with spacing of a diameter or so between turns, and siting
> them in a back shed (away from QRM), with remote tuning.  I dont have a
> back shed, and my best receiving antenna is an active whip (a 10 metre
> whip, with integral low pass filter).
> But no Europeans on 136 kHz heard on it yet ....
> Cheers,
> Bob ZL2CA
> >
> > Dear Friends OM,
> > I would like  to have some INFO to build a portable LOOP
> > in order to receive the new 136 kHz band (max 1 meter side).
> > My indoor LOOP is not sensitive (square 1,25 mt side, 50
> > core cable computer).
> > Tnx for the answer, I hope to listen you on 136 kHz !!!
> > Ciao.
> >
> > Alessandro.
> > (sry for my English)
> >
> > SWL IV3-2161/TS - IW3SGT
> > P. O. Box 238 - 34100 TRIESTE TS -ITALY
> > e-mail: alessandro.kosoveu@iol.it
> > http://users.iol.it/alessandro.kosoveu/index.html
> > http://www.geocities.com/CapeCanaveral/Hall/7588/index.html