[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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