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Forums | Crystal Radio Think Tank ** Advanced Forum | Double slider question. Post Reply Send Topic To a Friend
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Garry NicholsPosted - 8 March 2013 8:9  Show Profile  Email Poster  Edit Message
golf ' ;

" Video at Time = 2:25.....2:40 clearly shows . . . "

OK, I see that now. Missed it first time through - I was studying the cam.

TNX,

Garry

Electronic TechnicianPosted - 26 May 2013 22:20  Show Profile  Email Poster  Edit Message
A contra-winding used with slug tuning might solve a few slug tuning problems. You effectively get two bands so you have more band spread at the high end of the band. You also get much higher Q at the high end of the band where high Q is important. You may have to wind the two windings so they occupy the same space. I have not tested this configuration for Q. Alternately use two separate coils and two separate ferrites to tune the two coils together. They can then both be switched either series for the low end or parallel for the high end.
I wonder why not just use capacitors for tuning? Capacitors with HDPE insulators can have VERY high Q levels. It might be really hard to make a fixed capacitor with a higher Q then the HDPE insulated capacitor.
homebrewPosted - 27 May 2013 11:57  Show Profile  Email Poster  Edit Message  
What tuning problems?
I used a sliding core coil (hand sliding, no gearing) with the windings spaced farther apart on the high side as a ATU for a while. A silver plated trimmer cap in series worked great for fine tuning anywhere in the band.
A sliding core contrawound coil sounds like a good one to try. Maybe large jumps in adjustment as the core approaches the second coil? I'm thinking maybe a second core from the opposite side?
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