Playing with Type II DDS and NANO


alan_r_cam@...
 

That's fine - if you only ever go above 35MHz.
I'd say it complements the AD9850 / 9851, rather than replaces it: put them together for increased spectrum coverage.
Personally, for a Network Analyser, I want coverage below 450kHz. That allows me to "tune" the IF stage of a conventional AM radio.
Others, working with LF and VLF equipment, may want even lower.


Asadullah Mir
 

I was thinking of how this chip could be used considering that the output is square wave and hence full of harmonics. Wondering if I could do with only a single generator ( vs using two, the second at an offset frequency. . If the test signal was amplitude modulated at a very low frequency say one khz and if the  If the signal at the "in" port of the mixed with a copy of the un-modulated original signal one could get to use a low pass filter to detect this the carrier would appear as DC in the output while the LF ( I khz ) could be measured for finding the response?  just thinking. i need to work out the details but was wondering what your response would be. AM of the exciting signal would be easy to arrange?
Azzy


Asadullah Mir
 

How about the ADF4351? It goes from 35MHz to 4.4 GHz. I got a board from Aliexpress and wrote some code to sweep it in any range of 256 steps of any step size. I could contribute that.

Azzy


N5IB
 

There's enough interest (see the Poll) to order at least a batch of 40 of the experimenter boards.
Looks in the Files for "DDS Type II and Arduino NANO Experimenter Board.pdf" for details
This is the "tentative, proposed, final" layout  :^))

Basically it's a Type II DDS to Arduino NANO lashup with lots of lines brought out to play with.
And you get an attenuator and low pass filter layout as lagniappe.

I can offer them for $5.00 postpaid to a CONUS address, about $7.00 to a DX address.

To get a firm count, send your "pre-orders"     off-list   to n5ib (at) juno (dot) com
Send no money at this time

It will be 3 to 4 weeks before I have them in hand to send out.

73,
Jim, N5IB

PS. I have two or three each of the DDS60/NANO PHSNA, Crystal Test Fixture, and Low Pass Filter boards remaining.



DuWayne Schmidlkofer
 

The Si5351 is a very nice little chip for many purposes, its main drawback for use in the PHSNA is that its output is a square wave instead of the sine wave from the AD985x.  Ashar Farhan used a si570 in his SWEEPERINO  http://hfsignals.blogspot.in/p/sweeperino.html  He explains a little about watching out for harmonics because of the square wave. 
I used the si5351 for several projects and really like it.   One of the first was a simple antenna analyzer, and it appeared that I was getting some responses that I think were related to the square wave from the 5351. I have a little about them on my blog KV4QB.blogspot.com  also a recent VFO  I added to a Frog Sounds CW transceiver.  That VFO board with its little OLED display makes a nice module to experiment with.
I recently found an antenna analyzer using the si5351 that takes care of the harmonic problem.  http://www.iw2ndh.com/  He uses two of the clock outputs of the 5351.  One at the test frequency, and the other with an IF offset that feeds a mixer going to a simple crystal filter before the log detector.  This should eliminate any harmonic response getting to the log detector.
One of my ongoing projects is to expand on that design with a beefed up crystal filter at a lower frequency.  I hope to be able to combine the functions of a Signal Generator, SNA, Antenna Analyzer and Measurement Receiver into one instrument
DuWayne KV4QB

On 9/5/2015 9:45 AM, jab3739@... [PHSNA] wrote:

 
Hi Jim,  What about using the Si5351.  Check out 

 


http://qrp-labs.com/synth.html

 

 would this work for the PHSNA?

john kg9dk










jab3739@...
 

Hi Jim,  What about using the Si5351.  Check out 

 


http://qrp-labs.com/synth.html

 

 would this work for the PHSNA?

john kg9dk









N5IB
 

A project that has been back-burnered for quite a while is heating up. I've been wanting to use what we've learned here with the PHSNA and apply it to some other projects. I've been planning to do a 60 meter transceiver, using the DDS modules and either a NANO or ProMini. Rather in the fashion of the Dave Benson design that was in the 2006 Handbook.

So today I made up a little carrier board to marry the NANO and the DDS in as small a footprint as possible. Turns out, with some tedious fiddling, they can be piggy backed. The clearances are tough to do with a home brew single sided board, but would be a piece of cake for a board house product.

I posted an Album in the Photos section showing what I did. This is NOT a new PHSNA, or even a finished device of any sort. It's just an experimental platform for play. The DDS control lines are tied to the NANO (had to change pin assignments in the software to accommodate the most straightforward layout), The two sinewave outputs are brought out  to a transformer and a load resistor, there is a 5 V regulator, pads for a reset switch,and a bunch of the unused lines are brought out to pads to play with.

The key is to use the little machined pins as the header on the NANO, then a conventional header strip on the DDS. To make a slightly taller socket to receive the DDS's pins I took a right-angled header socket and straightened the pins, then did not seat them flush against the board before soldering. If the DDS is not quite seated all the way into the socket, the bottom of the DDS module clears the USB connector housing on the NANO.  A regular header socket can probably be used if the machined pins can be inserted into the board with the body of the pin in the hole, rather than just tips. But that is too fine for home-brew work.

Anyway, the one I made is all I need for the time being, But it occurs to me that others might want to play in the same sandbox. I'm willing to get a few of these gadgets made if there is interest. I'd guess if I got a batch of 20 they'd cost $3 to $4 postpaid CONUS.

I'm trying out the "insert a poll question in the message" to try to get an informal gauge of interest.

73,
Jim, N5IB