Rap 'n Tap
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From: Gordon
Date: 8/23/00
Time: 12:23:48 AM
Remote Name: 24.93.21.190
This reply is for John Davidson, thanks for the info. You were right about the inductance of a variometer being greater than the sum of the stator and rotor. I measured 145uH min and 350uH max,100uHs more than the sum of my stator and rotor. That is interesting. Also, the reason I used a varicap was that I was experimenting(fun)just to see what I could get this thing to do. Used as a variocoupler, I got results, so I think I will focus on that for now. As you suggested, I added 200 uH to the stator using a coil that was collecting dust on my workbench. Now it tunes right down to 540khz, this is great stuff isnt it? What I need to do now is build another variocoupler with more windings on the stator, I will call it "plan B". I plan on winding the stator with 72 turns of #22 enamel close wound on the 3" core. If my calculation is right, that should be around 340uH, the same amount I measured when the stator and that dusty ol' coil were connected in series. Should I change the number of windings and/or wire size on the rotor? Is there some sort of rule of thumb for antenna/ground coupling like x amount of primary windings per secondary? Thanx!