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Hi,
To save $100, I'm not going to copy *anybody's* circuits. An unfortunate choice of words on my part perhaps; possibly 'copy his technique' would have been better. A technique, I should add, that has been in the public domain for a very long time. The basic idea being - 1. Take an oscillator tank circuit with fixed C1 or L1. 2. Measure frequency F1. 3. Connect unknown Cx across C1 or Lx in series with L1. 4. Measure new frequency F2. 5. Calculate Cx (Lx) using a scientific calculator, remembering that F2/F1 = sqrt(C1 + Cx) or sqrt(L1 + Lx) then we have, Cx = C1([F1/F2]^2 - 1) or Lx = L1([F2/F1]^2 - 1). For best accuracy you would need to know the value of the strays which may easily be worked out using the same technique in reverse, or swamped, as the fancy takes you. On the subject of copying, I would guess that 95% of homebrew projects rely on pre-published information; there must have been hundreds of 'chinese copies' of commercial rigs produced by hams over the years. And it goes without saying that homebrewing not buying is what we are supposed to be talking about in this group. Cheers - Joe |
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