- August 3, 2010 at 11:29 pm #7506Ken NorrisParticipant
Total posts : 137
As some of you know, my first successful loading coil is based upon the Manteca Magnum design. The main difference is that mine is wound on a 4″ PVC sewer pipe whose wall is 1/8″ (1/2 that of a Schedule 40 pipe), and its O.D. is 1/4″ less. It’s used with an SStran/AntennaGuy-type 3/4″ copper pipe antenna with a slotted 1″ copper bottom slotted tuning mount.
These coils have no taps. I made the frequency decision over a period of several weeks of intensive listening tests, and wound it accordingly. It’s covered with 8 coats of General class PVC cement for weather proofing, which has worked well. I’m still going to put a custom top cover made from a plastic CD cannister on it at some point.
Remember, the coil winds are 18 gauge insulated stranded wire (note:stranded). I think these work so well because the combination of stranded wire and insulation work together to solve the problem of disruption from the ‘regular’ eddies set up in the induction field … Ermi’s caution about close winding is apparently at least partially solved by the spacing of two insulation thicknesses between the otherwise close-wound turns, and the stranding apparently diffuses the eddies without loss. I’m sure the ‘no tap’ situation helps with efficiency as well.
All I can say is that apparent induction in this type of coil is quite powerful. This new one, with no tuning, i.e., however the antenna sat in its slotted adjustment tube at the time I tested, with the coil and hookup at the lower level on top of 6′ 3″ PVC pipe, and no 8′ mast (pulled out of the assembly to make the antenna reachable for tuning), and with only the power supply and cabinet ground, the difference is this:
At 1630kHz it went from about 150 ft with the 10′ internally tuned wire antenna, to about 1500 ft. No doubt, tuning it to resonance and raising it on the mast should get it out quite a bit further.
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