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Eric's "Crystal Radio Initiative" Challenge

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  • LeeBob84
    replied
    Originally posted by Aaron View Post
    Hi Lee,

    If you don't mind, can you post a summary of your questions and Eric's answers from the skype call? Will probably help everyone out.
    Sure thats no problem. I will post it as soon as I can.

    Leave a comment:


  • Aaron
    replied
    Live call in 1 hour

    Originally posted by Aaron View Post
    TOMORROW NOON PACIFIC DAYLIGHT SAVINGS TIME - LIVE CALL WITH ERIC DOLLARD - have questions? Call in and ask him yourself - Conference Call Dial-in: 1-857-232-0155
    Conference Code: 582590
    Live call in 1 hour.

    Leave a comment:


  • Aaron
    replied
    Tomorrow Live call with Eric Dollard

    TOMORROW NOON PACIFIC DAYLIGHT SAVINGS TIME - LIVE CALL WITH ERIC DOLLARD - have questions? Call in and ask him yourself - Conference Call Dial-in: 1-857-232-0155
    Conference Code: 582590

    Leave a comment:


  • Aaron
    replied
    Q & a

    Originally posted by LeeBob84 View Post
    Perfect thanks Aaron I will Email U the info.
    Hi Lee,

    If you don't mind, can you post a summary of your questions and Eric's answers from the skype call? Will probably help everyone out.

    Leave a comment:


  • Jeff Pearson
    replied
    I do have enough of the pictured wire whatever it is. It has 3 twisted pairs and a copper? foil sheath. The foil sheath is a little large but the entire wire with the insulation is about right to tight wind the thing. I have also thought about using the twisted pairs inside as some makeshift litz wire. I want to wind it with copper tubing but not for any really good reason other than it would look really good with a copper flashing primary. I am kinda leaning towards using the twisted pairs at the moment. If anyone has pros and cons of each choice it would much appreciated
    Attached Files

    Leave a comment:


  • LeeBob84
    replied
    Originally posted by Aaron View Post
    I'll ask him. Are you on skype as well? Email me your skype id and I'll see if I can get you on a skype call with Eric before he leaves.
    Perfect thanks Aaron I will Email U the info.

    Leave a comment:


  • LeeBob84
    replied
    Originally posted by Jeff Pearson View Post
    Looking into what to purchase to wind the secondary with and am really getting confused. I am looking for a 6 AWG size conductor. 1/8th inch copper tubing and 6 AWG welding wire cost about the same. The welding wire is made of many small conductors so should be good for skin effect. I saw some 6 AWG Litz wire on Ebay made of magnet wire but that guy didnt have a long enough length. Might look into a spool of that. A cheap solution is 1/8th inch wide copper tape. Lots of surface area low mass???. And the there is the suggested teflon insulated coax. What would i be looking for in coax that has an outer conductor the right size??? Any suggestions and or pros and cons of each choice would be much appreciated. Today I got an antenna 29 feet into the air and am messing with a standard crystal radio.


    oh and I am 15.87 miles away from my thousand watt station with the rift a little closer to me as per attachment on post #38..........and yes have done the PVC pipe trick for trees out here in the desert I will do that for my ground rods when I get them.

    Hey Jeff

    Sounds like u have some good ideas for conductors, Only thing I would suggest is to stay away from buying anything for now. The trick I used was to scrounge at the dump and local guys with junk in their yard will sometimes sell u bits and pieces for pennies, also an option that I almost took was to use many strands of magnet wire scrounged out of a few old CRT tv's, U can get about two layers of full length turns from one tv depending on the size,I calculated that I was going to need 8 turns of magnet wire to make up the conductor diameter, so I would have needed about 4 tv's about 27" or bigger ... Now that said u may not be able to find the exact conductor diameter for your project. I found that it was easiest for me to do all the math for my frequency following Aaron and Eric's video presentation and the e-book. Then once I knew my conductor length i was able to find something of that length that I had laying around luckly, which was actually quite a bit larger then I wanted diameter wise but its what I had. So I took my conductor diameter and started to work the math backwards till I came up with a form size built for the conductor diameter. That is why my coil is so large. I looked up buying conductors of around the same diameter and it is very pricey for experimentation purposes. I found it much cheaper to buy material to build the form a different diameter. As for skin effect, I am no expert thats for sure. I have read a few papers on it but it was about three years ago now and my knowledge retention is dwindling with the more kids I have lol. I will have to look up those papers again and get back to u. Pretty sure I just googled conductor skin effect at high frequencies. And as for the coax cable. I looked into it as well but I wasn't sure about stray capacitance between the outer conductor lining and the inner wire. It may have an effect on tuning. Hope this helps

    Leave a comment:


  • Aaron
    replied
    Talk to T-Rex

    Originally posted by LeeBob84 View Post
    I would like T-Rex to join the conversation if he has any suggestions?
    I'll ask him. Are you on skype as well? Email me your skype id and I'll see if I can get you on a skype call with Eric before he leaves.

    Leave a comment:


  • Jeff Pearson
    replied
    Looking into what to purchase to wind the secondary with and am really getting confused. I am looking for a 6 AWG size conductor. 1/8th inch copper tubing and 6 AWG welding wire cost about the same. The welding wire is made of many small conductors so should be good for skin effect. I saw some 6 AWG Litz wire on Ebay made of magnet wire but that guy didnt have a long enough length. Might look into a spool of that. A cheap solution is 1/8th inch wide copper tape. Lots of surface area low mass???. And the there is the suggested teflon insulated coax. What would i be looking for in coax that has an outer conductor the right size??? Any suggestions and or pros and cons of each choice would be much appreciated. Today I got an antenna 29 feet into the air and am messing with a standard crystal radio.


    oh and I am 15.87 miles away from my thousand watt station with the rift a little closer to me as per attachment on post #38..........and yes have done the PVC pipe trick for trees out here in the desert I will do that for my ground rods when I get them.
    Last edited by Jeff Pearson; 07-15-2016, 12:36 AM. Reason: addition

    Leave a comment:


  • LeeBob84
    replied
    Originally posted by Jeff Pearson View Post
    CKLW is a 50,000 watt, Class B, AM radio station . Is this the station your trying to pick up and have you done any receiving yet LeeBob. The local station I built for only puts out a thousand watts. I think maybe I could do pretty good by taking it to town and connecting to a fire hydrant for ground.
    No this is the station I am trying to tune too is CJBQ 800 in belleville ontario. 800 am cjbq - Google Maps.pdf it is a 10,000 watt station.

    Leave a comment:


  • Jeff Pearson
    replied
    Sounds like the Iphone picks up the resonance from your CRI coil. NICE!!

    Leave a comment:


  • LeeBob84
    replied
    I would like T-Rex to join the conversation if he has any suggestions?

    Leave a comment:


  • LeeBob84
    replied
    Originally posted by Jeff Pearson View Post
    ground here is dry sandy clay. I pounded a 4ft piece of rebar for a ground to start with. Then I tried my roof. I am building a concrete dome on top of rammed earth walls. There is a 3ft piece of rebar every 30 inches driven into the rammed earth walls to connect the bond beam to the metal skeleton of the roof. The CRI coil and the crystal radio both work better using this for ground than a standard ground rod. I have not made an actual ground plane yet but I do have the room to do so. the rammed earth walls are a 20ft diameter on the inside circle and the walls are about 30inches thick so the connection to earth is good as far as surface area goes
    Just as a suggestion for when u put in your ground network, maybe run some pvc pipe beside ur ground rods and wires with holes drilled so u can flush an electrolitic solution down to the conductors to help them. I have done this before with gardens for feeding the plants. It will saturate the soil and the conductor giving u a larger conductive surface area. I was going to do this with my system but my water table here is less than 4' from the surface so it is kinda pointless here.

    Leave a comment:


  • LeeBob84
    replied
    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.

    Leave a comment:


  • Jeff Pearson
    replied
    ground here is dry sandy clay. I pounded a 4ft piece of rebar for a ground to start with. Then I tried my roof. I am building a concrete dome on top of rammed earth walls. There is a 3ft piece of rebar every 30 inches driven into the rammed earth walls to connect the bond beam to the metal skeleton of the roof. The CRI coil and the crystal radio both work better using this for ground than a standard ground rod. I have not made an actual ground plane yet but I do have the room to do so. the rammed earth walls are a 20ft diameter on the inside circle and the walls are about 30inches thick so the connection to earth is good as far as surface area goes

    Leave a comment:

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