[time-nuts] HP 10544

Bruce Griffiths bruce.griffiths at xtra.co.nz
Sat Jan 16 03:35:17 UTC 2010


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<bruce.griffiths at xtra.co.nz
>    
>> wrote:
>>      
>    
>> ewkehren at aol.com 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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