[time-nuts] homebrew 13 dBm distribution amplifier based on NIST design 5 to 100 MHz

hasweb at has.org.nz hasweb at has.org.nz
Mon Oct 13 19:35:55 UTC 2008


   Gerhard
     One trick that has been used for fixed frequency isolation amplifiers =20
     is to use a low Q
     series tuned LC circuit to short out the resistor in series with the =20
     base at the
     frequency of interest.
     Using a suitable ferrite bead instead of the resistor may allow a =20
     lower base to ground
     impedance at the signal frequency whilst ensuring transistor stability.
     Such instabilities are perhaps one reason why Spectracom and NIST use =20
     much lower ft
     transistors in their low noise 1-20MHz distribution amplifiers.

     Bruce




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