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AD9851 Type II DDS module questions

Steven Dick
 

Hi All. I am finishing up a Type II PHSNA and have a AD9851 Type II DDS module. They are not that common, but there are a few ebay sellers that offer it such as this one: AD9851 DDS Signal Generator Module 0-70MHz 2 Sine Wave and 2 Square Wave

 


I have several questions:

1. Does anyone know where I can get the schematic for a type II DDS module of this type? or even for the AD9850 type?

2. Can someone point me to what the required filter values are for the LPF-components on the PHSNA for the AD9851?  I plan to use this up to about 50 MHz as I need to test some 45 MHz filters.

3. I know all the DDS module filter components should be removed in order to be able to use the two outputs with transformer coupling.  What is the minimum number of components that need to be removed and where is a jumper required?  The info is probably in the files section somewhere but I haven't found it.

4. Can the "Hotrod phsna software" by WB6OGD be used on an Arduino Uno instead of the Nano?  Has anyone modified the code for use on an Uno?


Thanks,

"Digital Steve", K1RF

William Kimber
 

Hi,

As you say most of info is in files some where. Try the AD9850  directory for the Type II AD9850.  I believe AF9851 is the same just that the oscillator is multiplied by 6 internally.

The only difference between Nano and Uno is pinout.  You would need to change the defines at the start.

Cheers,
Will

On 24/12/15 12:54, sbdick@... [PHSNA] wrote:
 

Hi All. I am finishing up a Type II PHSNA and have a AD9851 Type II DDS module. They are not that common, but there are a few ebay sellers that offer it such as this one: AD9851 DDS Signal Generator Module 0-70MHz 2 Sine Wave and 2 Square Wave

 


I have several questions:

1. Does anyone know where I can get the schematic for a type II DDS module of this type? or even for the AD9850 type?

2. Can someone point me to what the required filter values are for the LPF-components on the PHSNA for the AD9851?  I plan to use this up to about 50 MHz as I need to test some 45 MHz filters.

3. I know all the DDS module filter components should be removed in order to be able to use the two outputs with transformer coupling.  What is the minimum number of components that need to be removed and where is a jumper required?  The info is probably in the files section somewhere but I haven't found it.

4. Can the "Hotrod phsna software" by WB6OGD be used on an Arduino Uno instead of the Nano?  Has anyone modified the code for use on an Uno?


Thanks,

"Digital Steve", K1RF


gtennys54@...
 


Steve,

I just built up a PHSNA using a Type II 9851 module.  I can answer three of your questions. 

Question 1 and 3 -- In the files section of the PHSNA group on Yahoo, there is a folder entitled 'Type II PHSNA - version using Type 2 DDS module.' In that folder is a file entitled 'PHSNA Type II DDS info.pdf.'  This file has the schematic of the module, the filter elements to remove, and where to connect a jumper once the elements are removed.  The file deals with a 9850 module, but everything is the same.

Question 2 -- Also in the files section of the PHSNA group on Yahoo, there is a folder entitled 'Type I PHSNA - version using Type 1 DDS module.'  In that folder there is a file entitled 'PHSNA ERA-3+ Type 1 DDS rev6r10.pdf.'  In that file is a schematic.  The schematic has the filter components for both a 9850 and a 9851.

I can't answer your question #4. 

Good luck,

Gary
KO4CY

Steven Dick
 

Glen and Will thanks for the info. I'm on my way!!  It's a shame the on-board filter can't be used (not sure how bad the performance is with an AD9851 but you can't use it with the two outputs for the transformer anyway)

"Digital Steve", K1RF

Steven Dick
 

For new builders, on the PHSNA board, R7, the dropping resistor to the ERA-3+ amp, is a 1/2 watt resistor called out in the parts list (660-MF1/4DCT52R2700F). This is same part on Type 1 or 2 boards.  This has inadequate de-rating . There is a comment in the notes in the BOM that 1 watt might be better.  A good choice might be the dropping resistor used on the xtal test fixture, a 2W resistor, Moouser P/N 660-MO2CT631R271J whose size should fit and cost 14 cents.  The resistor really wants to be at least 1 watt.

"Digital Steve", K1RF

N5IB
 

I've updated the schematics and BOMs for the Type I and Type II PHSNA to reflect use of a 1 W or 2 W resistor for the ERA-3+ bias. Now available in the Files area.

Also added the LPF filter component data to the Type II schematic for use with these newly found AD-9851 Type II modules.

Jim, N5IB

---In PHSNA@..., <n5ib@...> wrote :
Thanks for catching that, Steve.
The nominal current is 35 mA, for around 300 mW, but there surely ought to be a 4x or so de-rating.
I need to update the BOMs and make sure the schematics call out a 1 or 2 W part.
I've been using the 2 W metal oxide resistors that are about the size of the old 1 W carbon comps.
I like to mount them with a little air gap between the body and the PCB
The first one I made used a pair of 560 ohm 1/2W in parallel.
Jim, N5IB


---In PHSNA@..., <sbdick@...> wrote :
For new builders, on the PHSNA board, R7, the dropping resistor to the ERA-3+ amp, is a 1/2 watt resistor called out in the parts list (660-MF1/4DCT52R2700F). This is same part on Type 1 or 2 boards.  This has inadequate de-rating . There is a comment in the notes in the BOM that 1 watt might be better.  A good choice might be the dropping resistor used on the xtal test fixture, a 2W resistor, Mouser P/N 660-MO2CT631R271J whose size should fit and cost 14 cents.  The resistor really wants to be at least 1 watt.
"Digital Steve", K1RF