No, the design is such that one actually requires a well matched pair
for the cascode or the gain ratio between the collector that drives the
output and that which drives the agc detector to have the desired value
of 1x.
The amplifier design isnt a good one as the high differential dc gain
from the cascode output transistor bases to the output severely degrades
the flicker phase noise.
However one should be able to substitute arrays like the CA3054 for
which Mouser has a substitute or just use a CA3083 which appears to
still be available, however some rea arrangement of the connections
would be required.
Alternatively if one has to use discrete transistors using separate
cascode buffers to drive the agc detector and the output emitter
followers would be advisable to eliminate the requirement for transistor
matching.
Bruce
paul swed wrote:
Bert that is helpful. I can see that pretty much the 10544 output is that
ic.
Bruce there is a cap feeding it if the signal is clean there and the voltage
is fine feeding the chip it would tend to be the ca3045. That could be
replaced by many modern amplifiers if the chip could not be obtained.
On Fri, Jan 15, 2010 at 7:39 PM, Bruce Griffiths<[email protected]
wrote:
[email protected] wrote:
Attached is a scan of the schematic of the 10544 vintage 1976 given to me
by HP as part of TI's work on the first GPS receiver. Maybe it will help.
Bert Kehren
That circuit appears to be for the early, higher phase noise version.
The later version extracts the oscillator output signal through the crystal
rather than from the emitter of the oscillator transistor..
Bruce
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