LF loading coils
Thu, 24 Jun 1999 16:55:04 -0400
M. Bruno wrote:
> I had very good results with my loading coil. The construction
> is probably rudimental, but works and may be seen on the web
> site of G3YXM (look at pictures).
> The coil has about 3,5 mH, and tunes a 13 m vertical wire with
> 3 top wires, spanning about 23m, spaced 1 m (2 m total width).
> The coil is wound on a garbage bag holder (no idea how it is
> called in English ...) made of PE (poliethylene). The wire is a 2 mm
> solid Cu insulated with silicon plastics, for an outer diameter of 3
> mm. Total wire lenght is abt 120 m, and my coil has 100 turns.
> The Q at 137 is in the order of 1200 (calculated by G4FGQ sw) or
> over 1000 (extimated from real losses). The coil handles 20 kV on
> the high side (1 kW, about 6A RF x 3.3 kOhm reactance).
> The variometer is made of 10 turns on diameter 30 cm on the
> high side of the coil. The total excursion of the vario is more than
> enough to tune across the band and to compensate wet/dry soil
> If anyone is interested I may send detailed pictures. All calculations
> were done with G4FGQ SOLENOID.EXE. Initial extimations were from
> Bill Bowers' article in the LF Experimenter's Source Book (a very
> suggested reading). He tested various coil configurations, and the
> conclusions are valid.
> 73 - Marco IK1ODO