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Products => Test Equipment => Topic started by: marcopolo on March 17, 2021, 04:37:56 pm

Title: HP8657A Not working - Looking for help and a good quality service manual
Post by: marcopolo on March 17, 2021, 04:37:56 pm
Hi,

One of my friends has a not working HP8657A RF generator.

The problem is similar to the one described here:
https://www.antiqueradios.com/forums/viewtopic.php?f=8&t=254016 (https://www.antiqueradios.com/forums/viewtopic.php?f=8&t=254016)

1/ Is this kind of problem known?

2/ Does anyone have a good quality Service Manual? The one available on the internet is horrible.

Thanks,
Marc
Title: Re: HP8657A Not working - Looking for help and a good quality service manual
Post by: marcopolo on March 18, 2021, 03:20:53 pm
Anyone?

Surprising that this Service Manual is so difficult to find
Title: Re: HP8657A Not working - Looking for help and a good quality service manual
Post by: bdunham7 on March 18, 2021, 03:46:36 pm
https://www.keysight.com/zz/en/assets/9018-05479/service-manuals/9018-05479.pdf?success=true (https://www.keysight.com/zz/en/assets/9018-05479/service-manuals/9018-05479.pdf?success=true)

https://www.keysight.com/zz/en/assets/9018-05378/user-manuals/9018-05378.pdf?success=true (https://www.keysight.com/zz/en/assets/9018-05378/user-manuals/9018-05378.pdf?success=true)

You need both manuals together.

How are you setting up the oscilloscope to see that pattern? 

Can you connect the scope to the clock out BNC and see what is there?

Title: Re: HP8657A Not working - Looking for help and a good quality service manual
Post by: marcopolo on March 18, 2021, 05:51:12 pm
As said before, the service manual is of poor quality.

It isn't my setup but the setup from one guy who had the same problem 12 years ago.

The 10Mhz reference output (Opt. 001) is a clean sinus.

On Saturday, with the owner of the generator, we're going to do some measurements to try to understand what's going on.
Title: Re: HP8657A Not working - Looking for help and a good quality service manual
Post by: bdunham7 on March 18, 2021, 06:05:09 pm
Quote from: marcopolo on March 18, 2021, 05:51:12 pm
As said before, the service manual is of poor quality.

OK, I've worked with worse.  I don't know of any free ones that are better.  If you are willing to pay a nominal sum, these guys have a version that may be clearer.  You need both volumes for $12.50 USD.

http://artekmanuals.com/manuals/hp-manuals/ (http://artekmanuals.com/manuals/hp-manuals/)
Title: Re: HP8657A Not working - Looking for help and a good quality service manual
Post by: marcopolo on March 20, 2021, 09:22:08 pm
We did some measurements: 800 Mhz on TP3 is missing
Why?
Because the generator was used with option 022 (GMSK modulator), so we have to make a bridge between the 800Mhz output and input

(http://azurelectronics.com/WEFiles/Image/WEImage/HP%208657B%20022%20r2-32441f04.jpg)

And now it works fine :)

HP8657 with Opt. 022
(http://azurelectronics.com/WEFiles/Image/WEImage/HP%208657B%20022%20r3-a5db4f24.jpg)