[time-nuts] fast switching quiet synthesizer

Bob Camp kb8tq at n1k.org
Tue Oct 7 19:43:15 EDT 2014


The output spectrum of some DDS’s is pretty rich. You may find that a 1 GHz DDS can be filtered to operate directly over the 3.1 to 3.4 GHz. 


On Oct 7, 2014, at 7:36 PM, Jim Lux <jimlux at earthlink.net> wrote:

> On 10/7/14, 10:32 AM, Magnus Danielson wrote:
>> You should be able to use DDS test-boards and by timing your last write,
>> you should be able to time the frequency jump.
>> The STEL-1173 takes 6 bytes, but writing the last one latches all 6
>> bytes over to a single 48 bit word. I expect that other DDSes have the
>> same distinct transfer-phase if you only look in the datasheet for the
>> details.
> Yes, virtually all of them have a "load" input of some form (I'm familiar with the AD98xx and AD99xx ones, and they certainly do).
> What I'd really like, though is something at a slightly higher level of integration (for which I am willing to pay.. it's a time vs money thing).  Does someone sell a DDS in a box with connectors, etc.
> I need a tuning range, for now, of around 3.1 to 3.4 GHz, so any of the "1 GHz" DDSes can generate something that I could mix up with a 2.8-3 GHz LO (which I have), although I'd have to be careful about images.
> Or I can run the few hundred MHz out of the DDS into a doubler/tripler, then mix up.
>> Some of the modern DDSes can take 10 MHz directly and step it up
>> internally before hitting the DDS core, but it may be that you need to
>> synthesize a higher clock from the 10 MHz first.
> Not a problem, I think I have a 10 in to 100 MHz out set of bricks from Wenzel (x5 and x2) from a previous project
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