[time-nuts] fast switching quiet synthesizer

Alan Melia alan.melia at btinternet.com
Tue Oct 7 13:47:37 EDT 2014

Jim I am not sure if this will meet your requirement for "hygene" but google 
Trinity Power Inc (Bob Yarbrough) he has a unit that was featured in EDN 
some time around a year ago. I doesnt switch fast enough at present but that 
could be altered..... the problem might be that I think it is a PLL Rather 
than a DDS..... But might be worth a look ....I know the PTS I have a couple 
of earlier Wavetek- Rockland units ...one TTL and one GPIB also an Adret 201 
which uses the same technique.


----- Original Message ----- 
From: "Jim Lux" <jimlux at earthlink.net>
To: "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com>
Sent: Tuesday, October 07, 2014 6:02 PM
Subject: [time-nuts] fast switching quiet synthesizer

> 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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