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Electronics => Repair => Topic started by: AndersJ on February 17, 2016, 09:14:56 am

Title: HP8657A Signalgenerator - Output distorted at > 15 dBm
Post by: AndersJ on February 17, 2016, 09:14:56 am
At higher output levels,
approximately 15 dBm and higher the output sine wave is distorted.
The distorsion happens for all frequencies.
The output is terminated with 50 Ohms.

I would like to believe this is NOT normal but have nothing to compare with.
Can anyone do a comparison and let me know.
If my generator has a problem,
all repair suggestions are more than welcome.

Thanks,
Anders J

Title: Re: HP8657A Signalgenerator - Output distorted at > 15 dBm
Post by: Kilrah on February 17, 2016, 09:56:33 am
From what I can find with a quick search:

Quote
Output Range (dBm)
8657A
+13 dBm to –143.5 dBm into 50 ?
+10 dBm to –143.5 dBm for frequencies from 100 kHz to 1 MHz

So you shouldn't be exceeding +10dBm at that frequency, and you likely found out why.
Title: Re: HP8657A Signalgenerator - Output distorted at > 15 dBm
Post by: KJDS on February 17, 2016, 11:29:22 am
In the words of so many car salesmen,

"they all do that sir"

Title: Re: HP8657A Signalgenerator - Output distorted at > 15 dBm
Post by: AndersJ on February 17, 2016, 12:14:50 pm
It never ocurred to me that the user interface would allow me to exceed the specifications.
Next time I will read the manual first, then ask.

Thank you for pointing out my mistake.
Title: Re: HP8657A Signalgenerator - Output distorted at > 15 dBm
Post by: Richard Head on February 18, 2016, 11:49:25 am
Also, if you enable the internal amplitude modulation the peak of the amplitude envelope cannot exceed the max level (+13dBm I think). I have a 56, a 57A and a 57B. Brutes, but nice.
Title: Re: HP8657A Signalgenerator - Output distorted at > 15 dBm
Post by: mmagin on February 18, 2016, 08:41:35 pm
A quick glance at http://literature.cdn.keysight.com/litweb/pdf/5968-2704E.pdf?id=1000030211:epsg:dow (http://literature.cdn.keysight.com/litweb/pdf/5968-2704E.pdf?id=1000030211:epsg:dow):
"Output power to drive high-level inputs For applications requiring high output power, the 8657A and B can overrange beyond the +13 dBm specified output level to >+16 dBm for most frequencies. "

I assume the manual has more to say, but it sounds like that might be normal.