[time-nuts] AM vs PM noise of signal sources

Charles Steinmetz csteinmetz at yandex.com
Mon Jan 8 08:49:42 EST 2018

Don wrote:

> I`m looking at the circuit of an HP10544 oscillator - can anybody confirm,
> please, if the HP transistor types 53-20, and 54-215 have commercial
> equivalents?

54-215 (full HP part number 1854-0215) is the ubiquitous 2N3904.

53-20 (full HP part number 1853-0020) is 2N3702.  2N4403 is an 
equivalent if 3702 is hard to find.

Also, note that the HP schematics of the 10544 have some errors that 
were (as far as I can tell) never corrected by HP.  I posted a corrected 
and annotated schematic to Didier's site (ko4bb.com).  Here's a link:


Best regards,


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