[time-nuts] fast switching quiet synthesizer

Alan Melia alan.melia at btinternet.com
Tue Oct 7 19:11:40 EDT 2014


Hi Don, Jim, that is the one I was refering to, It has a VCO as the source 
(all part of the AD4351) but I think your description of the unit is more 
accurate that mine. Contact him directly he is keen to contact new areas and 
hobbyists. There are two units one is a source with 4 output levels, I 
believe he sells that on eBay at $280 but direct contact may get you a 
better deal. There is a version with a calibrated attenuator but this has FM 
capability which adds to the VCO control and may not be good for PN. I think 
this sells for $340.
Robert Yarbrough  robert at rf-consultant.com  (blame me for airing his ID 
:-))  )

Alan
G3NYK




----- Original Message ----- 
From: "Don Latham" <djl at montana.com>
To: "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com>
Sent: Tuesday, October 07, 2014 9:19 PM
Subject: Re: [time-nuts] fast switching quiet synthesizer


>I have two "versions" of the ADF4351 dds. One is the AD eval board, and the
> other the TPI synthesizer
> (http://www.rf-consultant.com/calibrated-signal-generator/) at $280 that 
> might
> do the job. The latter device performs well. It will be as good as the 
> 4351, I
> think. It has a programmable attenuator. A good price.  Requires a 
> Healthy!
> USB port.
> Don
>
>
> Magnus Danielson
>> 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.
>>
>> 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.
>>
>> Cheers,
>> Magnus
>>
>> On 10/07/2014 07:02 PM, Jim Lux wrote:
>>>
>>> At work, I'm putting together a multichannel stepped frequency CW radar
>>> breadboard, and I'm looking for something to serve as a source that I
>>> can step quickly.
>>> I'm looking at stepping every millisecond or so.  Right now, I use a
>>> Ardunino type microcontroller driving a serial DAC driving a VCO, but
>>> that's a bit wonky and noisy, although it's easy to get the step timing
>>> right on.  The spectral purity is, shall we say, downright ugly.
>>>
>>> Since I'm going to be doing precision ranging with this, the spectral
>>> purity has to be reasonably good (not 1E-15 at 1000 seconds good,
>>> fortunately)..
>>>
>>> I was thinking about a PTS synthesizers  (beloved of time-nuts for all
>>> kinds of reason), and they're nice because they are quiet, and switch
>>> really fast (microseconds).  However, they all seem to have BCD or GPIB
>>> interfaces (only).  Sure, I can code up something on an Arduino or other
>>> microcontroller to drive the BCD on the PTS, but maybe there's something
>>> else out there that might work as well?  And is already off the shelf.
>>>
>>>
>>> I could hook a Prologix on the back of a PTS with GPIB, and hit it over
>>> the ethernet, but I'm not sure I'd be able to get the steps to occur
>>> when I want them (ethernet and determinism do not go well together).
>>>
>>> Maybe some DDS in a box product?  That will take my nice clean 10 MHz
>>> reference?
>>>
>>> Ultimately, I'm looking at output frequencies in single digit GHz, but
>>> something that can be mixed/multiplied up will work just fine.
>>>
>>> I'm looking for something that is off the shelf-ey as much as possible.
>>> Using surplus gear is ok, because I really only need 3 or 4 channels and
>>> that might be scroungeable, but spending hours wiring up weird adapters
>>> or locating connectors that haven't been made since 1943 is something
>>> I'd like to avoid.
>>>
>>>
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>
>
> -- 
> "The power of accurate observation is commonly called cynicism by those 
> who
> have not got it."
> -George Bernard Shaw
>
> Dr. Don Latham AJ7LL
> Six Mile Systems LLC
> 17850 Six Mile Road
> Huson, MT, 59846
> mail:  POBox 404
> Frenchtown MT 59834-0404
> VOX 406-626-4304
> Skype: buffler2
> www.lightningforensics.com
> www.sixmilesystems.com
>
>
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