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Hi Leo,

Which synthesizer board do you have?

There is a service note (E4436B-01F) that says: "Serial Numbers:
[0000A00000 / 9999Z99999]" "The ESG-B AP/DP Family of Signal Generators
has been experiencing failures in the Frac-N board assemblies. This is
due to a failure in the divide-by-eight circuit of the Divider chip A24
U313 which causes the ESG to display Error 511 "Output unleveled". All
ESG-B AP/DP units with the serial numbers mentioned above may experience
Error 511 along with UNSTABLE or NO OUPUT below 1GHz. If this occurs,
the A24 Frac-N/Divider Assembly (E4423- 60019) needs to be replaced.
This assembly should be ordered using part number E4423-69019 and should
be treated as a warranty repair. The defective assembly should then be
returned with documentation referencing this service note as "Error 511"."

Tom Bryan



On 11/11/2018 4:39 AM, Leo Bodnar wrote:
> I have E4435B signal gen from ESG series that loses output in certain
> parts of its output range 250..350MHz, 500..700MHz, etc.
> The problem seems to be in the VCO or its PLL loop.
> Its output is supposed to be 500..1000MHz before further
> multiplication/division but lower part of the range is unstable. As
> you go down in frequency from 1000MHz to 500MHz, somewhere around
> 690MHz it becomes noisy and at 680MHz it loses signal altogether.
> These siggens sometimes have prescaler U313 1GC1-4210 failure, but
> here it does not seem the case as it is further down the signal path -
> after YIG multiplier that converts 0.5-1GHz VCO output into 4-8GHz signal.
>
>