[time-nuts] another Ebay mixup, 5370

[Didier Juges]

One of my 5370A's had a severely distorted sine out, which Bruce helped me
trace to a bad solder joint on one of the cap that is part of the output
filter. After reflowing the solder joint, it all came to life with a pretty
good sinewave output.

Some of the caps on the amplifier board look different than most others. I
suspect they were maybe higher grade, but the leads must have been a
different alloy.

Didier 

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Dr Bruce Griffiths
Sent: Saturday, June 09, 2007 4:55 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] another Ebay mixup, 5370

SAIDJACK at aol.com wrote:
> Hi Tom,
>  
> this was the recommended setup (by HP) for checking the internal  
> noise. Feed the 10MHz output back to the input using a short cable, 
> and set the  unit for "COMMON" input, setting 50 Ohm impedance etc.
>  
> In the meantime I did some more tests, and found the following:
>  
>    1) The sine-wave output is crappy. The sine wave has some sort  of 
> "Class-B" cross-over distortion, and it measures a whooping 200ps RMS 
> jitter  on my Wavecrest jitter analyzer (>400ps pk-pk). Compare that 
> to 2.7ps RMS  jitter I measure on our Fury 10MHz output. Definitely 
> the crystal got damaged,  or something else.
>  
> The unit has about 2x better jitter performance (around 50ps RMS) if I 
> feed a clean Fury 10MHz into it. I think the 10811 OCXO or the 
> internal driver circuit may have gotten damaged.
>  
>  
> thanks,
> bye,
> Said
>   
Said

Can you send an image of the rear panel sinewave output waveform?

Bruce

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