Date   
Re: The "OTHER" AD9850 module

W0PWE
 

I bought one of the "other" DDS boards intentionally so that I could build this Steve Weber project:

http://kd1jv.qrpradio.com/XMEGA/XMEGA.htm


I guess the one we use in PHSNA would have worked for that too since you make your own connections. I'm going to buy a few more of one or both versions just to have around for backup and future projects.


By the way the Weber project is pretty cool too. The software he wrote for it is loaded with features and it makes a great backbone for a multiband transceiver. As soon as I squeeze all the fun out of this PHSNA project I hope to move on to the xcvr project. The PHSNA will sure be handy to have around when that project starts.

73

Jerry - W0PWE



Re: The "OTHER" AD9850 module

Lee Hiers
 

I don't see much reason for the adapter board if it's five bucks when you can get an entire DDS module for what, 6 bucks?  I had a couple of the "wrong" ones on hand and when I started following this project, got a couple of the the "right" ones...now I've got at least one spare of each left for whatever comes along...and will probably buy a couple more of each while they're still available.

It just seems like a lot of effort to go through to save a dollar...unless I'm missing something...

73 de Lee

Re: The "OTHER" AD9850 module

Kirk Kleinschmidt <sohosources@...>
 

No worries. I bought mine before this project was even announced. :)

It just surprised me that there were multiple versions, as I'd read somewhere that all of the eBay modules came about because of a massive manufacturing run of modules that had a design flaw, etc.

But, please keep us informed if you go ahead with a board, even if it's just a board layout for us DIYers.

73,

--Kirk, NT0Z
 
My book, "Stealth Amateur Radio," is now available from
www.stealthamateur.com and on the Amazon Kindle (soon)


On Tuesday, November 12, 2013 7:20 PM, Jerry Haigwood wrote:
 
Hi Kirk,
 If you look at the Bill of Materials in the files section of this yahoo group, you will see a picture of the DDS we chose.   I did most of the BOM and I thought a picture of what it looked like would prevent people from purchasing the wrong one.   I am sorry you have 5 of the wrong ones.  Maybe you can sell them to some other unsuspecting soul.   ;-0
Jerry W5JH
"building something without experimenting is just solder practice"
 
----- Original Message -----
Sent: Tuesday, November 12, 2013 4:56 PM
Subject: Re: [PHSNA] The "OTHER" AD9850 module

 
That's the "other" DDS board?

I didn't know there were multiple versions. Too bad I bought 5 of them!  :)

Darn.

I guess an adapter board would be helpful, especially if it might be usable with other "$5 DDS" projects!

73,

--Kirk, NT0Z

 
My book, "Stealth Amateur Radio," is now available from
www.stealthamateur.com and on the Amazon Kindle (soon)


On Tuesday, November 12, 2013 4:33 PM, "n5ib@..." wrote:
 
I have a couple of the "other" AD9850 DDS modules... the ones with the cute little square blue trimpot and the pins along the long edges. I'm sure many of y'all have some as well.

I really have no inclination to redo the SSNA to match that DDS. But if anyone in the group wants to have a go let me know I'll help with some starting point files.

But it occurred to me that it would be pretty quick and easy to do an adapter board. The adapter would plug into either SSNA in place of the original DDS, and it would accept the "other" DDS as a plug-in. The stack would bit a bit taller.

So I put a poll question out to gauge interest.  Go ping the poll if you're interrested.
I'd suspect even a relatively small run could be done and they'd come in around the $5 level postpaid CONUS.

Jim, N5IB




Re: The "OTHER" AD9850 module

Jerry Haigwood
 

Hi Kirk,

 If you look at the Bill of Materials in the files section of this yahoo group, you will see a picture of the DDS we chose.   I did most of the BOM and I thought a picture of what it looked like would prevent people from purchasing the wrong one.   I am sorry you have 5 of the wrong ones.  Maybe you can sell them to some other unsuspecting soul.   ;-0

Jerry W5JH

"building something without experimenting is just solder practice"

 

----- Original Message -----
Sent: Tuesday, November 12, 2013 4:56 PM
Subject: Re: [PHSNA] The "OTHER" AD9850 module

 

That's the "other" DDS board?

I didn't know there were multiple versions. Too bad I bought 5 of them!  :)

Darn.

I guess an adapter board would be helpful, especially if it might be usable with other "$5 DDS" projects!

73,

--Kirk, NT0Z

 
My book, "Stealth Amateur Radio," is now available from
www.stealthamateur.com and on the Amazon Kindle (soon)


On Tuesday, November 12, 2013 4:33 PM, "n5ib@..."
 
I have a couple of the "other" AD9850 DDS modules... the ones with the cute little square blue trimpot and the pins along the long edges. I'm sure many of y'all have some as well.

I really have no inclination to redo the SSNA to match that DDS. But if anyone in the group wants to have a go let me know I'll help with some starting point files.

But it occurred to me that it would be pretty quick and easy to do an adapter board. The adapter would plug into either SSNA in place of the original DDS, and it would accept the "other" DDS as a plug-in. The stack would bit a bit taller.

So I put a poll question out to gauge interest.  Go ping the poll if you're interrested.
I'd suspect even a relatively small run could be done and they'd come in around the $5 level postpaid CONUS.

Jim, N5IB


Re: The "OTHER" AD9850 module

Kirk Kleinschmidt <sohosources@...>
 

That's the "other" DDS board?

I didn't know there were multiple versions. Too bad I bought 5 of them!  :)

Darn.

I guess an adapter board would be helpful, especially if it might be usable with other "$5 DDS" projects!

73,

--Kirk, NT0Z

 
My book, "Stealth Amateur Radio," is now available from
www.stealthamateur.com and on the Amazon Kindle (soon)


On Tuesday, November 12, 2013 4:33 PM, "n5ib@..." wrote:
 
I have a couple of the "other" AD9850 DDS modules... the ones with the cute little square blue trimpot and the pins along the long edges. I'm sure many of y'all have some as well.

I really have no inclination to redo the SSNA to match that DDS. But if anyone in the group wants to have a go let me know I'll help with some starting point files.

But it occurred to me that it would be pretty quick and easy to do an adapter board. The adapter would plug into either SSNA in place of the original DDS, and it would accept the "other" DDS as a plug-in. The stack would bit a bit taller.

So I put a poll question out to gauge interest.  Go ping the poll if you're interrested.
I'd suspect even a relatively small run could be done and they'd come in around the $5 level postpaid CONUS.

Jim, N5IB


The "OTHER" AD9850 module

N5IB
 

I have a couple of the "other" AD9850 DDS modules... the ones with the cute little square blue trimpot and the pins along the long edges. I'm sure many of y'all have some as well.

I really have no inclination to redo the SSNA to match that DDS. But if anyone in the group wants to have a go let me know I'll help with some starting point files.

But it occurred to me that it would be pretty quick and easy to do an adapter board. The adapter would plug into either SSNA in place of the original DDS, and it would accept the "other" DDS as a plug-in. The stack would bit a bit taller.

So I put a poll question out to gauge interest.  Go ping the poll if you're interrested.
I'd suspect even a relatively small run could be done and they'd come in around the $5 level postpaid CONUS.

Jim, N5IB

New Poll for PHSNA

PHSNA@...
 

Enter your vote today! A new poll has been created for the
PHSNA group:

Would you be interested in purchasing a small adapter PCB that would allow use of the &quot;other&quot; kind of AD9850 module? Estimated cost around $5 postpaid CONUS.

- Yes, I&#39;d want one
- Yes, I&#39;d want two
- Yes, I&#39;d want more than two
- No, have no need for it


To vote, please visit the following web page:
http://groups.yahoo.com/group/PHSNA/surveys?id=2484219

Note: Please do not reply to this message. Poll votes are
not collected via email. To vote, you must go to the Yahoo! Groups
web site listed above.

Thanks!

Re: LTSpice of Lowpass Filter

N5IB
 

 

If instead of plotting just V(out) you plot V(out)/V(n003), you'll see the output vs input response of the filter. It has a couple more artifacts near the cutoff. And the pass band loss can now be easily seen, since 0 dB now represents the lossless case.

If you wanted to see the input impedance of the filter, plot V(n003)/I(L1)
You'll see some wiggling going on above 10 MHz, but staying pretty much between 45 and 65 ohms.

Jim, N5IB

Re: 70 MHz version of the SSNA

N5IB
 

The AD9851 modules that you can get for about $20 use a different clock oscillator. The 9851 has a X6 clock multiplier on the chip, so the on-board clock is run at 30 MHz. That yields a 180 MHz master clock.


The first spurious response of the DDS is at Fspur =  Fclock - Fout

So at 70 MHz output there's a spur at 110 MHz. At 80 MHz out the spur is at 100 MHz, etc. So if you can make a decent filter with a steep enough cutoff you can use the 9851 up past 70 MHz or so, as Jerry has done.

Given the cost of the chip, cost of a new clock, and the pain in various body parts of tiny SMT chip swapping, I'll pay the 20 bucks  any day  :^))

Jim, N5IB

Re: 70 MHz version of the SSNA

Jim Pruitt <wa7duy@...>
 

Jerry,
 
Someone speculated that the batch of AD9850 boards we are getting so cheap were supposed to contain 9851's.  Is that true?  If so,  can we replace the 9850 on the bargain board with a 9851?  What other changes would be needed?  Would it be worth the trouble if we already had the 9851 on hand?
Thank you.
 
Jim Pruitt
 

----- Original Message -----
Sent: Monday, November 11, 2013 7:24 PM
Subject: [PHSNA] 70 MHz version of the SSNA

 

Hi Folks,

    I recently built a 70 MHz version of the SSNA.  Jim and I originally tried to hold the cost to under $50 USD.  I think we did a pretty good job of doing that.  In order to hold costs down we used a low cost AD9850 DDS module.  Most of you probably know that there is an AD9851 module that looks just like the AD9850 module.  It will plug into the same pins on the combo board as the AD9850 board.  There are some changes that are needed if you want to use the higher frequency AD9851 module.  Here is what is needed.

1.       You have to use the ERA-3 board.  There will be too much roll off on the 2N5109 board.

2.       The low pass filterL1, L2, L3, C3, and C4 will have to be changed.

3.       The final attenuator (R12, R13, and R14) may need to be changed based upon how much output you want.  I chose to use a -7 db attenuator and I have 0 dbm output.

4.       You will need to use different software.  I have already modified the software to support the AD9851 DDS.

If you are interested in building the 70 MHz version, order yourself an AD9851 module.  Modify it by removing the on board filter per Jim’s instructions.  They cost about $21-22 USD.  Change L1 and L3 to 0.13 uHy (7t #30 on a T30-10 core).  Change L2 to 0.22 uHy (9t on T30-10 core).  Change C3 and C4 to a 22 pF NP0 in parallel with a 39 pF NP0 for a total of 61 pF.  For the final attenuator I used 130 ohms 1% resistors for R12 and R14 and a 44.2 ohm 1% resistor for R13.  Remember that 0 dbm is probably to high of a level for measuring crystal filters.  You will probably want to use an external -10 db attenuator.  If you are interested in making this change, email me for a copy of the software.

Jerry W5JH

"building something without experimenting is just solder practice"

70 MHz version of the SSNA

Jerry Haigwood
 

Hi Folks,

    I recently built a 70 MHz version of the SSNA.  Jim and I originally tried to hold the cost to under $50 USD.  I think we did a pretty good job of doing that.  In order to hold costs down we used a low cost AD9850 DDS module.  Most of you probably know that there is an AD9851 module that looks just like the AD9850 module.  It will plug into the same pins on the combo board as the AD9850 board.  There are some changes that are needed if you want to use the higher frequency AD9851 module.  Here is what is needed.

 

1.       You have to use the ERA-3 board.  There will be too much roll off on the 2N5109 board.

2.       The low pass filterL1, L2, L3, C3, and C4 will have to be changed.

3.       The final attenuator (R12, R13, and R14) may need to be changed based upon how much output you want.  I chose to use a -7 db attenuator and I have 0 dbm output.

4.       You will need to use different software.  I have already modified the software to support the AD9851 DDS.

 

If you are interested in building the 70 MHz version, order yourself an AD9851 module.  Modify it by removing the on board filter per Jim’s instructions.  They cost about $21-22 USD.  Change L1 and L3 to 0.13 uHy (7t #30 on a T30-10 core).  Change L2 to 0.22 uHy (9t on T30-10 core).  Change C3 and C4 to a 22 pF NP0 in parallel with a 39 pF NP0 for a total of 61 pF.  For the final attenuator I used 130 ohms 1% resistors for R12 and R14 and a 44.2 ohm 1% resistor for R13.  Remember that 0 dbm is probably to high of a level for measuring crystal filters.  You will probably want to use an external -10 db attenuator.  If you are interested in making this change, email me for a copy of the software.

Jerry W5JH

"building something without experimenting is just solder practice"

 

Calibrating the AD8307 Power Meter

N5IB
 

Look in the "Links" section for a link to an article from Analog Devices.

Key point is that if the AD8307 is driven with a DC source, it will read 3.01 dBm too high, compared to a sine wave. This gives you a way to calibrate your power meter using a battery, trimpot, and a DC voltmeter.

Of course the regular input to the 8307 is capacitively coupled, so to do this you have to connect the DC source directly to pins 1 and 8, and the source has to float.

I have done this with a previous build of a power meter and it appears to work, but I'd like to hear from others who try it, especially if you have a good  independent means to verify the result.

Jim, N5IB

LTSpice of Lowpass Filter

Nick Kennedy
 

I uploaded an LTSpice file of the LPF we're building (not the one that came on the DDS board.)  Gives you a nice look at the response.


I thought I might make the inductors a little bit "real" by adding some resistance, but you really can't simulate Q over a wide frequency range unless you were able to write a loss statement that's a function of frequency. (That's beyond me.)

One thing you can do is experiment with non-ideal (not 50 ohms) terminations and note the effect.  Also if you are concerned with whether your inductors will wind up "on the money", you can see what variations will do to the response curve.

I made the source have 50 ohms internal resistance, which results in maximum output being plotted as -6 dB.  So -6 equals zero in this case.

Continuing the discussion of how the attenuator isolates the filter from the amplifier's input resistance somewhat, I calculated that for the 10 dB filter as designed, if the termination is 0 ohms the input is 41 ohms and if the termination is infinity (open), the input is 61 ohms.  So that oughta keep the filter happy.

73-

Nick, WA5BDU

Re: Boards arrived in ZL

Ross Smith
 

Mine arrived yesterday. Very nice boards.

Ross vk3ucr



---In phsna@..., <ijdownie@...> wrote:

And mine arrived in VK3 last Friday, even with the noted errors, still a great pair of PCB’s.

Ian VK3LA

Re: Boards arrived in ZL

Ian
 

And mine arrived in VK3 last Friday, even with the noted errors, still a great pair of PCB’s.

Ian VK3LA

Boards arrived to LU-LW zone

nestor fernando casari
 

The two boards arrive today to Bs.As Argentina

What can I said exellent quality and thanks for the effort to get a very useful instrument a cost near everyone can afford.

Thanks again and the best for all.

Fernando LW5DNC

Power Meter BOM ?

 

The part numbers for the pots are for 12 turn trimmers.  Is it ok to use 1 turn ones, 652-3306K-1-202, similar to what is in the pictures?

Also, the part number for the shell of the connector is the same as 0.22 cap, so I ordered, 50-57-9402, the $0.49 ones that look like they should work.

SRI is I missed any posts about this subject.

73
John
K3YJP

Re: ERA-3+ Version passes the smoke test

N5IB
 

Thanks to you folks finding all my screw-ups, my SSNA/ERA3 is up and running.


I'm powering the UNO from the USB port, and using a 5V regulator for the DDS.
Output rolls off not more than 4 dBm from 1 to 30 MHz.
R7 is a 1/2 W part and doesn't seem too warm after 15 minutes of use.
AD9850 is warm, but only cozy, not toasty.

My power meter reads -3dBm at 1 MHz and between -6 & -7 dBm at 30 MHz. I think the relative change is nearly correct but I'm not real confident yet of the absolute magnitude. My old scope's calibration is probably suspect.

I did notice the previously reported "balky startup" issue. I'm suspecting it has to do with the USB port being recognized as a COM. Plugging and unplugging the USB (which in my case powers down the UNO) would resolve it. I never had any problem with the bare Arduino or Funduino when operating from the laptop on AC power, but this morning I was on battery. I wonder if the USB-Serial is on the cusp when on battery power. If you had this problem, please report back whether it was on shore power or battery. And how are you powering your UNO?

Jim, N5IB

Re: SPICE modelling

W0PWE
 

I played around with the amp model by increasing R11 to 11 ohms and then bypassing it with a capacitor. When the capacitor is around 550 pf it peaks at the upper end of the frequency range. 330pf looked pretty good in terms of frequency response and the input Z went from 67 ohms at 1 MHz to around 40 ohms at 30 MHz. Per Nick's comments about the attenuator dominating the Z seen by the filter, this should be OK.


Then I put those components on the circuit board and got the following output (measured with my 60MHz scope):

MHz    dBm

1         -8.5

5         -8.5

10       -8.7

15       -9.0

20       -9.4

25      -10.0

30      -10.0


There are probably some practical reasons why this is not a good idea but I sure have had a ton of a lot of fun tonight playing with LTSpice and the soldering iron......

73,

Jerry - W0PWE



---In phsna@..., <j.b.hall@...> wrote:

Thank you Jim and Jerry! I was going to build a model of that amp in LT Spice so you saved me some work there. Sounds like a pretty versatile amp and I want to learn more about how it behaves. 

My SSNA is now flat to within 3 or 4dB across the band and I see that you guys have built in a compensation scheme that should take care of that.  

My filter was the problem. When I wound the toroids I tuned them as close to the desired inductance as possible using my AADE meter. As a result they each ended up a turn or two short. Re-winding them with the correct number of turns made a big difference. Not sure what is wrong with my AADE meter but that is another project. 
73 - Jerry-W0PWE

Re: ERA-3+ Version passes the smoke test

Michael McShan <n5jky@...>
 

Jerry,

Thanks for info.  I've done a bit of surface mount work, so it is not a real problem.  On the other hand, I don't mess with these tiny components just for grins. :-)


73,
Mike W5RST, ex-N5JKY

On Nov 10, 2013, at 2:46 PM, Jerry Haigwood <w5jh@...> wrote:


Hi Mike,

     The DDS board has a lot of loss in the on board filter.  I am guessing the Q of the components is not good.  By eliminating the on board low pass filter and using the one on the ERA-3 board, you get a flatter amplitude output.  It will still have a small roll off at the upper frequencies but not nearly as bad as if you leave the DDS on board low pass filter.

Jerry W5JH

"building something without experimenting is just solder practice"

 

From: PHSNA@... [mailto:PHSNA@...] On Behalf Of Michael McShan
Sent: Sunday, November 10, 2013 11:16 AM
To: PHSNA@...
Subject: Re: [PHSNA] ERA-3+ Version passes the smoke test

 

 

Jerry,

 

Yesterday we were getting ready to throw a birthday party for a friend at our house last night, so there wasn't any time for playing with the SSNA.  Before I hack the board, what are the advantages of doing so versus leaving it stock?

 

73,

Mike W5RST, ex-N5JKY

 

 

On Nov 8, 2013, at 10:28 PM, Jerry Haigwood <w5jh@...> wrote:


Mike,

    Once you check out the DDS fix, you will need to put your power meter calibration into the program at line 125.  Also, you will need to run a sweep from 1-30 MHz with the generator output connected to the power meter and the power meter feeding back into the SSNA.  You will need to record the data using a step size of 100000 Hz (TERM232 allows you to capture a file).  You can send this file to Jim and he will do a curve fit for you (to flatten the response of the DDS).  He will send you 6 coefficients that you will enter into the program at lines 29-34 (C0 through C5).  Then you should be all set to go!

Jerry W5JH