Jeff Liebermann wrote:

On Sun, 18 Mar 2012 22:15:43 +0100, "Antonio I0JX"
wrote:


The frequency stability of my HP3312A function generator is poor, very
annoying for any practical use. I am trying to determine whether that
behavior is fairly normal for function generators, or my particular unit has
got a problem.

What is your experience on function generators frequency stability?


How good stability were you expecting?
Are you asking about temperature stability, or just drift?

The HP3312A was not intended to be the ultimate stable frequency
standard. Just because it goes up to RF frequencies doesn't mean it
can substitute for a proper RF generator. If you look at the
specifications:
http://www.testbuyer.com/pdf/specs.cfm?pdf_id=55055909FB
you'll see that the frequency stability is not specified. That should
be a clue. Dial accuracy is only 5%, whatever that means.

If you want accuracy and stability, I suggest a synthesized function
generator.

If you want to do it yourself with a PLL, build an external phase
comparitor, with the output going to the FM sweep input, and the
inputs from the sync output, and a suitable frequency reference. A
1KHz reference frequency, will give a frequency output locked at 1KHz
intervals.


or. get one of those DDS AF from Rigol like I did.

http://www.tequipment.net/RigolDG1022.html

Now there's a thing of beauty for the price. I got it when it was on
sale and paid less.

Jamie