HP 8644 (866x) internal modulation generator jitter, need firmware update?

[Juris]

Working with my repaired 8644A (options 002,004,007,010) I noticed quite jitter on generator modulation audio output.
If I choose square output there is 600 ns waveform jitter present.
When using sine output there isnt any.

Same internal modulation generator (NSM OSC) PCB is used in whole 8644/64/65 generators series, can you look at it ?
Is it known bug / limitation of internal LF generator ?

My suspect is old firmware - 2.10.0 on bay I seen 8644 advertised with 4.2 (?) firmware versions.
Can you look what FW version is in your 8644A/B (showing for couple of seconds at startup)?
Anybody have firmware files newer than 2.10? more information about firmware versions ? is firmware inter changeable between 8644 and 8664/5 ?

Juris
yl3cb

p.s.
If anybody want to upgrade 8644 to 2GHz option, on bay is available doubler module for 70$, also other modules from 8644...

[dthung]

Hi,

Do you know the std doubler on bay is compatible with 8644B or not? Thz.

[Juris]

There isnt any difference between 8644A and 8644B, what I can find, except default configuration - 8644B include option 004 (COAX DSC - low noise) and 007 (NSM OSC - modulation generator) by default.
Both use same STD DOUBLER (08644-61040) module for 2GHz range extension.

Juris

p.s.
what is your 8644 FW version ?

[dthung]

Thz for the information. My 8644B can't power up at this moment. I bought it cheap on bay when it was listed as not-working (didn't power up). Now I just need a good weekend to fix it so that it can power up, hopefully. 

Dick.