Re: [time-nuts] sysclock source for AD9912 DDS?

2013-12-31 Thread Anders Wallin
Some more testing today. It turns out that AD's schematic for the evaluation board doesn't match with reality - and so I had not connected the PLL filter components at all previously! Now they are 'in the loop' and I get reasonable results without the 2x reference clock setting. With 2x activated

Re: [time-nuts] sysclock source for AD9912 DDS?

2013-12-31 Thread Jim Lux
On 12/31/13 8:07 AM, Anders Wallin wrote: Could the remaining -60 dBc spurs at +/- 50 kHz be due to my 10MHz clock source, an Agilent 33120A? Yes the spurs could be from your source. that's a function generator/ARB and spectral purity isn't one of the big design criteria for that kind of

Re: [time-nuts] sysclock source for AD9912 DDS?

2013-12-31 Thread Magnus Danielson
Hej Anders, On 31/12/13 08:31, Anders Wallin wrote: Thanks for all replies so far! It looks like I will play around with the evaluation board some more, and see if I can get the on-chip PLL to behave better. The settings with 2x edge-detector and 60x PLL were the only ones I could find where

Re: [time-nuts] sysclock source for AD9912 DDS?

2013-12-31 Thread Richard (Rick) Karlquist
On 12/30/2013 9:37 AM, Gerhard Hoffmann wrote: Driving the DDS system clock from an expensive RF generator (e.g. HP 8648A) would be possible but I'd prefer a PLL from 10MHz if it's doable simply/cheaply. Although expensive from a hobbyist viewpoint, the HP8648A is far from HP/Agilent's best,

Re: [time-nuts] sysclock source for AD9912 DDS?

2013-12-31 Thread Tom Knox
-hochfrequenz.de; time-nuts@febo.com Subject: Re: [time-nuts] sysclock source for AD9912 DDS? On 12/30/2013 9:37 AM, Gerhard Hoffmann wrote: Driving the DDS system clock from an expensive RF generator (e.g. HP 8648A) would be possible but I'd prefer a PLL from 10MHz if it's doable simply

Re: [time-nuts] sysclock source for AD9912 DDS?

2013-12-30 Thread Jim Lux
On 12/30/13 7:56 AM, Anders Wallin wrote: I've tested the AD9912 evaluation board: http://www.anderswallin.net/wp-content/uploads/2013/12/dds_test_2013-12-30.png I want to use it with a 10MHz external input clock, but it looks like the on-board PLL that generates a 1200MHz sample clock from my

Re: [time-nuts] sysclock source for AD9912 DDS?

2013-12-30 Thread ben bloom
My lab has had good luck with the ADF4350 eval boards as clock generators. The snippet description on the analog devices website of them is incorrect though, they can accept a 10 MHz clock ref. The datasheet is definitely more accurate than the description. -Ben On Mon, Dec 30, 2013 at 9:36

Re: [time-nuts] sysclock source for AD9912 DDS?

2013-12-30 Thread Said Jackson
Anders, I used an AD9858 years ago in our FireFox synthesizer product clocked at 1GHz locked to the on-board 10MHz GPSDO. I used an ADF4002 or 4000 (can't remember) pll with integer division driving a UMC (now Sirenza) VCO. It worked very well and there where no 10MHz spurs measurable. Its

Re: [time-nuts] sysclock source for AD9912 DDS?

2013-12-30 Thread Gerhard Hoffmann
Am 30.12.2013 16:56, schrieb Anders Wallin: I've tested the AD9912 evaluation board: http://www.anderswallin.net/wp-content/uploads/2013/12/dds_test_2013-12-30.png I want to use it with a 10MHz external input clock, but it looks like the on-board PLL that generates a 1200MHz sample clock from

Re: [time-nuts] sysclock source for AD9912 DDS?

2013-12-30 Thread Michael Jensen
Try to look on these designs made by me http://rudius.net/oz2m/ngnb/vcopll.htm Michael -Oprindelig meddelelse- Fra: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] På vegne af Anders Wallin Sendt: 30. december 2013 16:56 Til: Discussion of precise time and frequency

Re: [time-nuts] sysclock source for AD9912 DDS?

2013-12-30 Thread Grant Hodgson
Anders I've used the AD9912 Eval board with great success - spurs with the on-chip clock multiplier were -60dBc, IIRC, maybe better. My guess is that you are pushing the on-chip VCO too high - do you really need a 1200MHz system clock? The AD9912 is only specified for a sys. clock of

Re: [time-nuts] sysclock source for AD9912 DDS?

2013-12-30 Thread Mike M
From: Said Jackson Today I would not use a simple (cheap) 1GHz VCO anymore because of the relatively high phase noise, and some if them require up to 20V drive voltage. I would use a Crystal based product such as our ULN-1G 1GHz crystal oscillator. That part may be overkill since

Re: [time-nuts] sysclock source for AD9912 DDS?

2013-12-30 Thread Graeme Zimmer
Hi Anders, Have a look at my AD9910 quadrature DDS http://members.wideband.net.au/gzimmer/QuadDDS/default.html I used a Crystek 1GHz SAW oscillator regards Zim ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to

Re: [time-nuts] sysclock source for AD9912 DDS?

2013-12-30 Thread Anders Wallin
Thanks for all replies so far! It looks like I will play around with the evaluation board some more, and see if I can get the on-chip PLL to behave better. The settings with 2x edge-detector and 60x PLL were the only ones I could find where the output frequency setting in the software