Date   
Experimenter Board build notes

N5IB
 

After playing around with a few different kinds of pins, headers, and socket strips I had in the junque boxe, I decided to revise my earlier recommendations on how to mount the header strip for the DDS. I posted an updated document in the Experimenter Board folder in the Files area. Not really anything radically different. Has to do with how much the socket strip needs to be elevated above the board. DRY FIT TEST is essential in any case.

Wouldn't hurt to read it over before beginning parts collection and building.

73
Jim, N5IB



Re: preset pot on AD9850

Terry VK5TM
 

Just a word of caution.

Certain settings of that pot can add garbage to the sine signal.
Best to remove the resistor coupling the sine output to the comparator if not using it.

Terry VK5TM

Re: preset pot on AD9850

Wayne Johnson
 

Cheers, thanks fellas, I guess we can ignore it for our application, construction is coming along fine with the generator section finished, now working on the power meter (Det.), my PHSNA is self contained with an analogue meter included in the PM.
73
Wayne
VK6EH

Re: preset pot on AD9850

N5IB
 

Look at either one of the square wave outputs on a scope while turning that pot. You'll see the duty cycle change. It has no effect on either sine wave output. On my Type II DDS (little blue pot) I could just barely get to 50%

Jim, N5IB


---In PHSNA@..., <vk6eh@...> wrote :

I'm sure it's written here but can anybody tell me what the preset on an AD9850 is for? Tried to tweak it while watching the output level but NG, mind you I only shifted it a few degrees either way


Regards

Wayne VK6EH

Re: preset pot on AD9850

Mvs Sarma
 

the sine wave output can be sent to a comparator to convert it to square wave.
 while so, the mark to space ratio can be adjusted by the said pot  as it sends a ref dc to the other input of comparator.
 Hope I could clarify it.

preset pot on AD9850

Wayne Johnson
 

I'm sure it's written here but can anybody tell me what the preset on an AD9850 is for? Tried to tweak it while watching the output level but NG, mind you I only shifted it a few degrees either way


Regards

Wayne VK6EH

Re: Arduino Library for AD9852

HAM-Radio
 

I belive you could program it in the same way as AD9851 on a serial programmer, looking at the

FUNCTIONAL BLOCK DIAGRAM - not much difference i pin-assignment.

de OZ6YM

Re: An SNA based on AD9851 AD8307 and any 8051 based u Controller in Assembly

Nick Kennedy
 



On Mon, Nov 23, 2015 at 11:05 AM, mirasad314@... [PHSNA] <PHSNA@...> wrote:
 



I don't ever make schematics of my projects. The reason,  I make PCBs for every thing I build (laser ptr and teflon ppr ) and the circuit can be seen in the PCB layout. For this one I will make an exception and make the schematics.  I presume that everyone has access to "Express PCB" so will make it in the same.

Lately I've been making schematics of things I'm doing boards for if it's for a new design I'm working on.  It seems to enforce another "design review" phase -- while I'm doing the schematic, problems and/or errors sometimes jump out at me.  Sometimes I've done the schematic twice: once in LTspice and again in ExpressSCH.  But not so much on already proven designs.

 

It appears to me, seeingthe display graphs  (PHSNA) that every measurement point is plotted as a single point. This makes the graphs a bit ragged when the amplitude response is changing rapidly.And that is what I have too, on mine.

I looked at some of my PHSNA plots and don't see any jaggies.  Maybe you're doing something different??

73

mirasad

(was AP2AM once now waiting for new CS)

AKA Azzythehillbilly


73-

Nick, WA5BDU

Arduino Library for AD9852

Alfredo Mendiola Loyola
 

Dear All:


Do you know if there is an Arduino Library o example code to program the AD9852?


I have seen that the AD9852 has better SFDR than the AD9851, but I can't find example code to program it with arduino.


73s.

Alfredo Mendiola Loyola

Lima, Peru

Re: An SNA based on AD9851 AD8307 and any 8051 based u Controller in Assembly

Asadullah Mir
 

Hi,
Thank you Dave for the PDF. Cleared up some misconceptions. Why do I never find them on my own on Google.

Considering that I want to upload my project, I have been looking at it a bit more carefully. Some laconic software was rewritten/re-commented. I have added a display of the transmitted and received signal levels on the static frequency mode display and a fast screen clear. Also altered the graphic display to range from +20dBm to -60dBm No need for -80dBm as the stray signals on my board make anything below -60dBm rather useless. With an 18.432 xtal sys clk and 6 clks per instruction cycle on AT89C51RE2,  I get one plot every 5 second. Other processors can do a whole lot faster.

I don't ever make schematics of my projects. The reason,  I make PCBs for every thing I build (laser ptr and teflon ppr ) and the circuit can be seen in the PCB layout. For this one I will make an exception and make the schematics.  I presume that everyone has access to "Express PCB" so will make it in the same.

It appears to me, seeingthe display graphs  (PHSNA) that every measurement point is plotted as a single point. This makes the graphs a bit ragged when the amplitude response is changing rapidly.And that is what I have too, on mine.

I was wondering if the graphs should be changed so that a continuous line is plotted between every two consecutive plot points. Do you think this is worth the trouble? The lines would be vertical half on one and the other half on the next column.  In my case all columns are plotted. so consecutive points are always on adjacent columns. 

73

mirasad

(was AP2AM once now waiting for new CS)

AKA Azzythehillbilly

Re: AD-9851 on a Type II DDS

Dennis Rogers
 

Thank you for the info as I ordered one.

On Fri, Nov 20, 2015 at 8:44 AM, n5ib@... [PHSNA] <PHSNA@...> wrote:
 

Hendy reports that he found eBay item # 381248883052  It's a Type II DDS with an installed AD-9851. He ordered and received the module and it was indeed a 9851 (at least, that's the way the chip is marked) I don't think he's tested it yet, but the price is not bad - about US $12.

The vendor name is "smooth-dealer" ..... gives one pause, eh ?  But I've risked more at an untried pizza joint  :^))

73,
Jim, N5IB






--
------------------------------------------------------
Dennis, N5VRP
n5vrp.satx@...

Near Hemphill, Texas

Re: Where to buy HCMos Crystal with Paypal

vasilyivanenko@...
 

The biggest problem with this product at higher frequencies  = worrisome, multiple spurious outputs.

As long as the phase noise of the reference oscillator is lower than the chip, you should ~ OK. On their web site with a related DDS, they mention the use of a 125 MHz Butler reference oscillator (with a good quality crystal) -- the Butler is pretty much what the VHF-microwave transverter builders apply due to it's low phase noise.

Phase noise is accumulative in the system. Dividing down helps by 20 log N. The reference frequency should be as high as possible. The reference oscillator phase noise, in conjunction with the residual phase noise of the DDS constitutes the total phase noise in the DDS output, so the reference oscillator phase noise ranks as important (along with your budget) if your seek lower phase noise.

AD9910 = much better choice for VHF if you're bent on the DDS route.
T

Re: Where to buy HCMos Crystal with Paypal

Alfredo Mendiola Loyola
 

I would like to get the same phase noise included in the AD9851 datasheet (SFDR charts) at 30 Mhz.  A SFDR > 70dB @ 30 Mhz would be ok.

I don't know if I have to use a low jitter oscillator or a "standard" oscillator with period jitter of 50 ps peak to peak.

What would be an acceptable oscillator with a period jitter peak to peak to use it with a DDS like the AD9851 with the x6 multiplier enabled.
 
73
Alfredo Mendiola Loyola
OA4AJP

Re: PC Boards - remaining inventory

N5IB
 

They went pretty quickly, so I was able to mail out most new requests before the holiday duties interfere.

Very little remains (see below), except for Experimenter Boards that I'd decided to keep a small inventory of.


New PCBs:
    35 --- Experimenter Boards  $4.00 ea
    1 - Type I / Type II DDS adapter boards $2.00 ea

Old PCBs:
     0 --  Measurement Receiver 2-board sets $8.00

     5 --  PHSNA for Type I DDS and UNO  $4.50 ea

     1 -  PHSNA for Type II DDS and UNO  $4.50 ea

     3 -- PHSNA for DDS-60 and NANO   $4.00 ea

     0 -- Crystal Test Fixtures $4.00 ea

     0 -- AD-8307 Power Meters  $3.50 ea

     0 - Return loss Bridges with 1% resistors  $2.00 ea

     0 - Low Pass Filters   $1.00 ea

All of the above - plus postage


If you want any of these contact me --off list please --


n5ib (at) juno (dot) com


I won't be able to mail any more of them until after the Thanksgiving holidays.


73,

Jim, N5IB

Re: Where to buy HCMos Crystal with Paypal

vasilyivanenko@...
 

Hi Alfredo

It sounds like you need a 180 MHz reference source?  Multiplying a DDS chip from 30 MHz will increase the already fairly rotten phase noise by 20 log N or 15.6 dB.  I'm not sure what you phase noise requirements are?

At any rate, a simple. older chip often sold on eBay will give 180 MHz with a 30 MHz fundamental crystal
Integrated Circuit Systems - datasheet pdfBest regards
Todd

 

Re: WA5BDU on "QSO Today"

Gary Winblad
 

Thanks Lee for the heads-up.

And thanks Nick, great interview!
Wow, we have a lot in common...
Novice at 13, led to BSEE, always kept our original call signs, etc.!!

AND, you guys have a 100ft tower  (probably on high ground), now that's really cool!

73,
Gary
WB6OGD

AD-9851 on a Type II DDS

N5IB
 

Hendy reports that he found eBay item # 381248883052  It's a Type II DDS with an installed AD-9851. He ordered and received the module and it was indeed a 9851 (at least, that's the way the chip is marked) I don't think he's tested it yet, but the price is not bad - about US $12.

The vendor name is "smooth-dealer" ..... gives one pause, eh ?  But I've risked more at an untried pizza joint  :^))

73,
Jim, N5IB



PC Boards - remaining inventory

N5IB
 

Most  of the boards I mailed out have arrived safely. Only a handful have yet to be mailed, so it's probably safe to offer up what remains.


Here's what's left...


New PCBs:
    40 --- Experimenter Boards  $4.00 ea
    5 - Type I / Type II DDS adapter boards $2.00 ea

Old PCBs:
     2 --  Measurement Receiver 2-board sets $8.00

     5 --  PHSNA for Type I DDS and UNO  $4.50 ea

     1 -  PHSNA for Type II DDS and UNO  $4.50 ea

     4 -- PHSNA for DDS-60 and NANO   $4.00 ea

     2 -- Crystal Test Fixtures $4.00 ea

    13 -- AD-8307 Power Meters  $3.50 ea

     5 - Return loss Bridges with 1% resistors  $2.00 ea

    12 - Low Pass Filters   $1.00 ea

All of the above - plus postage


If you want any of these contact me --off list please --


n5ib (at) juno (dot) com


I won't be able to mail any of them until after the Thanksgiving holidays.


73,

Jim, N5IB

WA5BDU on "QSO Today"

Lee Hiers
 

Cheers to Nick for his appearance on the most recent QSO Today podcast - http://www.qsotoday.com/podcasts/wa5bdu

And he gets extra points for signing in on CW! ;-)

73 de Lee
--
Lee Hiers, AA4GA

Submit your QRP DXCC totals to www.qrpdx.com!

Re: Where to buy HCMos Crystal with Paypal

Alfredo Mendiola Loyola
 

Dear All:

Do I have to use a 30 Mhz oscillator with the 6x multiplier to get 180Mhz with the AD9851, or do I have to use 180 Mhz crystall oscillator to get the better phase noise?

73
Alfredo Mendiola Loyola
OA4AJP