[time-nuts] fast switching quiet synthesizer

Alan Melia alan.melia at btinternet.com
Tue Oct 7 19:54:52 EDT 2014

Bob Yarbrough's built units do 50 to 4400MHz, +10dBm and input for external 
10MHz ref signals, though has an internal 10MHz TCXO. It sounds worth a try 
if it can be programmed to step fast enough, min step size is 1kHz (from 

----- Original Message ----- 
From: "Jim Lux" <jimlux at earthlink.net>
To: <time-nuts at febo.com>
Sent: Wednesday, October 08, 2014 12:36 AM
Subject: Re: [time-nuts] fast switching quiet synthesizer

> 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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