Jim,
When/why did HP move the signal generators from Stanford Park to Spokane? ?I knew they had SA¡¯s at Santa Rosa but not Sig Gens¡¯s too.
Interesting aside about the Santa Rosa site. One of my friends has his company in one of the old buildings. The country and some ¡°other¡± folks have taken what used to be ¡°Mahogany Row¡±(div mgt) and turned it into an incubator with 10 or 15 small business in the old exec offices with communal support in the old support area, great re-use of the old building.?
Regards,
?
Stephen Hanselman
Datagate Systems, LLC
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On Dec 30, 2019, at 12:55, Jim Summers <kd7f@...> wrote:
?
Actually, the 8642A was the "replacement" for the 8640. ?It's code name internally was Shetland since its Spurs were low :). The 42 was a multi-loop synthesizer, fairly complex, and had low AM noise in addition to low phase noise as design goals. ?
The original PSG family included the 8644, 8645 and 8665 generators. ?The 8664 was basically an 8665 without the output section covering frequencies above 3GHz. ?The 8643 was an 8644 with the transformer power supply replaced by a switch mode supply, didn't allow the 140ns frequency discriminator option and its front panel was modified to delete the synthesis mode buttons. ?The PSG family utilized a single fractional N PLL and used frequency discriminators to improve VCO or YTO phase noise. ?AM noise was a bit higher than that of the 8642.
As I recall (my long term memory may be fading a bit) the 8642 AM floor was around -160dBc/Hz, the PSG generators were around -150dBc/Hz and the generators that followed using log leveling loops were around -130dBc/Hz.
Agilent/Keysight developed another family of generators referred to as PSG after the signal generator charter moved from Spokane Division to Santa Rosa.
As an interesting piece of history, before the PSG family was named the Performance Signal Generator family, one of the ideas for the name was New Family of Generators. ?Luckily someone noticed the initials...
Jim
On Dec 30, 2019, at 11:47 AM, alwyn.seeds1 <
a.seeds@...> wrote:
Dear All,
it rather depends what frequency range you need to cover and the offset from carrier at which you need the phase noise to be low.
Also, remember that signal generators have amplitude noise as well as phase noise and this is of particular concern at large offsets (> 50 kHz) from carrier.
The HP8643A and its higher frequency derivatives formed the replacement for the HP8640 cavity tuned signal generator and are particularly good on non-harmonic spurii.
Many DDS based generators have non-harmonic spurii at -70 dBc levels, which are a considerable nuisance when measuring off channel performance of receivers.
The 8643A is a big, heavy and complex beast with many special parts.
This series was replaced with the PSG series, which are still made.
Regards,
Alwyn
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