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Old 07-13-2016, 06:16 PM
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LeeBob84 LeeBob84 is offline
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Join Date: Feb 2016
Location: Marmora, Ontario Canada
Posts: 18
Originally Posted by Jeff Pearson View Post
CRI coil for 1340Khz Kvot

Corrected 1/4 wavelength= 142.25 ft.
using .7752 correction factor. 102% velocity factor X 76% burden factor.
I avoided all rounding till the end
Length per turn= 85.35 inches
At this point I figured for an octagon instead of a circle since my coil form is an octagon and I'm trying to be as accurate as possible so I calculated 10.67 inches per facet of octagon
Diameter of circle would be 27.18 inches
Height= 5.44 inches

The tuning seems to be right on. With topload and ground connected I can hear the radio station clearly through a regular crystal detector consisting of a germanium diode, demodulation capacitor, load resistor and crystal earpiece. It makes noise but unintelligable with no ground or top load.
At the moment the detector is connected across the secondary. I put together a simple amplifier using a LM386 IC driving a piezo element.
With the amplifier 1340Khz comes in clear with the secondary connected to nothing. When I add the top load the signal gets a little bit stronger and when I connect the ground the signal gets a lot stronger. I have tuned it up to 1510Khz by tapping the top load at the 16th or 17th turn. And I have accidentally tuned it down to 950Khz by adding a long ground wire one day when I didn't want to carry it out to the ground rod.
That's what I have done for testing so far. Oh and I did put a temporary primary on it with variable capacitor. There is a sweet spot where it raises the power of the secondary. Getting ready to rewind the whole thing. I am happy with the frame. More appropriate wire for the secondary and some 4 inch wide copper flashing for the primary coming soon.

Great Looking coil Leebob.
Thanks Jeff

Your coil sounds like its coming along nicely. How far are u from the station u are tuning for. And as for the rift it shouldn't effect your signal to badly as it is still connected down there somewhere. I am about 25 miles from the radio station which i am trying to recieve and have a hard time to get the station on my Iphone doc with the antenna at exactly 90 degreesIMG_0721.jpg to the station signal. The interesting thing i accidently discovered after messing around with the coil yesterday is that with it plugged into just the house ground and the extra coil and topload in the circuit i was able to lay the antenna coil from the iphone doc flat on the tableIMG_0722.jpg and the station would come in clearly. I thought at first that maybe it was just the weather at the time or something but as soon as i unplugged it from ground the station would cut out.
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