Date   

Re: AD9850/51 module pc boards

Terry VK5TM
 

Iain, private message sent to your bigpond address.

Terry VK5TM


Re: Type 2 Build QRV

William Heller
 

If you can afford it digikey probably has a kit of the resettable fuses try
littlefuse on there search box.

On Wed, Oct 3, 2018, 6:44 PM Curt via Groups.Io <wb8yyy=yahoo.com@groups.io>
wrote:

okay first the boring status: supply chain (me) has ordered a Uno, some
headers and a type 2 AD9850 board from the far east - so it should land
here someday and likely soon enough. I mounted the SMT passives to the
detector board - wow this is fun in spite of not having good eyesight. I
have the ICs in hand and/or on order.

I did figure out which side was ground for the board and that tantalum.

I noticed the AD820 I have are surface mount. I am so tempted to place
one on one of the pads and gently wire the few other connections needed (I
have done this before. If this isn't sane - tell me - I have PDIPs for two
alternate parts with LT in the number on route).

Looks like I have most everything else on hand -- well except for those
resettable fuses that I am not familiar with. Those things do look cool -
time to see if I can get an assortment maybe with those two values.

Good to be started - that was the hardest part thus far. Thanks to the
designers (yes I have fond memories of dialog with Jerry and I have two of
his paddles in use here). Glad a few folk are still on list when I have
issues.

73 Curt






Type 2 Build QRV

Curt
 

okay first the boring status: supply chain (me) has ordered a Uno, some headers and a type 2 AD9850 board from the far east - so it should land here someday and likely soon enough. I mounted the SMT passives to the detector board - wow this is fun in spite of not having good eyesight. I have the ICs in hand and/or on order.

I did figure out which side was ground for the board and that tantalum.

I noticed the AD820 I have are surface mount. I am so tempted to place one on one of the pads and gently wire the few other connections needed (I have done this before. If this isn't sane - tell me - I have PDIPs for two alternate parts with LT in the number on route).

Looks like I have most everything else on hand -- well except for those resettable fuses that I am not familiar with. Those things do look cool - time to see if I can get an assortment maybe with those two values.

Good to be started - that was the hardest part thus far. Thanks to the designers (yes I have fond memories of dialog with Jerry and I have two of his paddles in use here). Glad a few folk are still on list when I have issues.

73 Curt


Re: AD9850/51 module pc boards

VK5ZIF
 

Hi Terry,

How many shekels do you need and how do you prefer it sent?

I'll take one please.

73

Iain VK5ZIF

On 3/10/2018 2:35 PM, Terry VK5TM wrote:
When the Pocket Money Fairy deigns to leave a few shekels under the pillow, I will do a run of 10 pcb's to check that there are no errors.

Probably take in the region of 4 weeks by the time the pcb's arrive (I don't do DHL -> rip-off merchants if you live outside a major city).


Re: AD9850/51 module pc boards

William R Maxwell
 

Had that experience too, Terry. Actually, DHL agents in China seem to be particularly adept at deeming parts of Australia as remote, with absolutely no local knowledge, I suspect. I'm almost exactly 8 nautical miles from Launceston Airport, where most incoming airfreight arrives in Tassie but no, I'm remote too in some Chinese DHL assessments!

Thanks for the private email. I'll take a look at it now.

Bill VK7MX

On 3/10/2018 4:51 PM, Terry VK5TM wrote:
Hi Bill.

My problem is, because I am supposedly in the most remote of locations according to them (lets see them deliver to Birdsville), they doubled the shipping cost then added a remote fee on top of that.

Used them once, $68 shipping fee on a $30 order - not doing that again.

PS, I sent a private email to your bigpond address.



Re: AD9850/51 module pc boards

Terry VK5TM
 

Hi Bill.

My problem is, because I am supposedly in the most remote of locations according to them (lets see them deliver to Birdsville), they doubled the shipping cost then added a remote fee on top of that.

Used them once, $68 shipping fee on a $30 order - not doing that again.

PS, I sent a private email to your bigpond address.


Re: AD9850/51 module pc boards

William R Maxwell
 

I guess at our age, a gift from the Pocket Money Fairy is more likely than the Tooth Fairy, Terry.

Know what you mean about DHL  when you live outside the metropolis. I'm 30 kms south of Launcesaton, on the main north-south highway. I'm sometimes lucky and a local courier delivers when driving past the door but more likely than not, its a trip into the depot.

Still, at the size of these boards there are currently some incredible offers from Chinee fab houses. I had some made by JLCPCB.om last week, just before they shut for a 3 day holiday. Mine were slightly too big to qualify but the claasic 100x100mm size is again on offer at $2 USD for 10, plus shipping. At that price even DHL shipping seems almost bearable, although they offer cheaper alternatives too.

Bill VK7MX

On 3/10/2018 3:05 PM, Terry VK5TM wrote:
When the Pocket Money Fairy deigns to leave a few shekels under the pillow, I will do a run of 10 pcb's to check that there are no errors.

Probably take in the region of 4 weeks by the time the pcb's arrive (I don't do DHL -> rip-off merchants if you live outside a major city).



Re: AD9850/51 module pc boards

Terry VK5TM
 

When the Pocket Money Fairy deigns to leave a few shekels under the pillow, I will do a run of 10 pcb's to check that there are no errors.

Probably take in the region of 4 weeks by the time the pcb's arrive (I don't do DHL -> rip-off merchants if you live outside a major city).


Re: AD9850/51 module pc boards

Glenn
 

Hi all, as it happens I had been working on a replacement pcb for the "type 2" board.

I made one some months back and had some produced by a Chinese supply house, but it had an error in the serial port section. I have reworked it though to fix that error and also to add the 3v3 regulator for the oscillator. Its 41.5 x 30mm in size, pretty close to the originals. It also was reworked for 5o ohm output and the LPF changed accordingly with a cut-off of about 44MHz. The LPF can be built using smd inductors or you can wind your own on toroids. The output of the AD9850 itself uses a trifilar wound transformer on a BN43-2402 core. (I did not footprint a commercial transformer as Terry has done)

I have not though had this board pro made. (I fixed the small error on the 1st version, running a couple of wires & track cuts.) Currently the Gerbers result in 6 boards on a panel with V-grooving between boards. Sch and Gerber pic of the panel attached.

glenn
vk3pe


Re: AD9850/51 module pc boards

William R Maxwell
 

Same here, Clifford

On 1/10/2018 5:31 PM, Clifford Heath wrote:
On 1 Oct 2018, at 4:42 pm, Don Vosper via Groups.Io <donald.vosper=btinternet.com@groups.io> wrote:
I see on the Farnell site in the UK that one off 9851, 9850 and the useful AD8037 are £25.00, £23.00 and £10.00 each respectively.
My last 80 or so purchases have been through AliExpress.
Typically you get parts for under the 10,000 unit price.
I think I've twice had a situation where a completely
wrong thing was shipped, and I didn't pay for those after
disputing them.

All other parts have been up to normal spec, and were
shipped free of charge. Most of the world's electronics is
made in China. There are a lot of "partial reels" of perfectly
good parts being sold off through the thousands of vendors
on AliExpress. I'm really struggling to see any downside.

Clifford Heath.



Re: AD9850/51 module pc boards

Clifford Heath
 

On 1 Oct 2018, at 4:42 pm, Don Vosper via Groups.Io <donald.vosper=btinternet.com@groups.io> wrote:
I see on the Farnell site in the UK that one off 9851, 9850 and the useful AD8037 are £25.00, £23.00 and £10.00 each respectively.
My last 80 or so purchases have been through AliExpress.
Typically you get parts for under the 10,000 unit price.
I think I've twice had a situation where a completely
wrong thing was shipped, and I didn't pay for those after
disputing them.

All other parts have been up to normal spec, and were
shipped free of charge. Most of the world's electronics is
made in China. There are a lot of "partial reels" of perfectly
good parts being sold off through the thousands of vendors
on AliExpress. I'm really struggling to see any downside.

Clifford Heath.


Re: AD9850/51 module pc boards

Don Vosper
 

Some years ago  I got a free sample out of AMD but with subsequent requests the reply came via Germany that they did not supply free samples to individuals with my type of email address. I guess that meant that they would only supply trade or perhaps education.

I see on the Farnell site in the UK that one off 9851, 9850 and the useful AD8037 are £25.00, £23.00 and £10.00 each respectively.

All "supplied until stocks are exhausted"

Don m5aky


Re: AD9850/51 module pc boards

Terry VK5TM
 

Hi Bill.
Same experience here, I got samples once from the Australian agent after jumping through multiple hoops. That was for a commercial project that ended up crashing anyway.
Would be nice if it had changed, but I doubt it. Hopefully the guys in the US will have better luck.

Ok, the attached pdf is a preliminary set of notes to go with the pcb, so additions, corrections or updates if anybody can think of any please.

You will notice I have been fiddling again and added a couple of pads so that the Rset resistor can be isolated for those that want to experiment with either level setting or AM modulation.

Now is the time to make suggestions to add or change something (providing it can be fitted on the pcb).


Re: AD9850/51 module pc boards

William R Maxwell
 

I have not found the Analog sample program to be of any practical use in Australia for many years, Terry.

Back in the 1990s, sample requests to Analog were handled on line from Analog itself and they were happy to forward samples to Australian requesters. Some time in the 2000s, that policy changed, with Australian requests being forwarded to the Australian agents, Arrow from memory, who then insisted on project details, likely production numbers, likely monthly purchases etc. My explanation that I was prototyping, essentially for private, hobby use did not seem to cut the ice with them.

I never once succeeded in obtaining samples from the agents, despite Analog's ongoing sample policy. I did once get samples direct from Analog, after contacting them to enquire whether the Analog policy still applied and to ask whether the Australian agent had been made aware of it. Thereafter though, subsequent requests to them were again forwarded to the Australian agent.

I haven't tried again in recent years but I would be delighted to hear that things had changed and samples were again readily available to Australian users.

Bill, VK7MX

On 1/10/2018 10:22 AM, Terry VK5TM wrote:
Depending on how many you need, you may be able to get free samples out of Analog themselves (I haven't had any samples out of Analog for some time, so not sure of their current policy on samples).

No experience of the Ebay sellers, I base whether to buy on their ratings, reviews and comments in forums such as this.



Re: AD9850/51 module pc boards

Terry VK5TM
 

Depending on how many you need, you may be able to get free samples out of Analog themselves (I haven't had any samples out of Analog for some time, so not sure of their current policy on samples).

No experience of the Ebay sellers, I base whether to buy on their ratings, reviews and comments in forums such as this.


Re: AD9850/51 module pc boards

K5ESS
 

Does anyone have a reliable Ebay (or otherwise) source of AD9850 and/or AD9851 chips? Ebay has some advertised as low as $9.50 for 9850 chips but I have no experience with any of the suppliers listed. New chips from Mouser are almost expensive as the complete modules from China.
Mike
K5ESS

-----Original Message-----
From: PHSNA@groups.io [mailto:PHSNA@groups.io] On Behalf Of Terry VK5TM
Sent: Friday, September 28, 2018 9:10 PM
To: PHSNA@groups.io
Subject: Re: [PHSNA] AD9850/51 module pc boards

Here is a preliminary 3 pics of the pcb, combined top and bottom layers, top only and bottom only.
Nothing is set in concrete, so changes can be made. The other style module version could also be done.

Couple of points to note:
Obvious one is there is no on-board filter.
The output is through a 1:1 transformer (Coilcraft), this can be changed, but the transformer gives a better output signal both level wise and harmonic suppression wise.
There are some either/or components depending on whether the square wave output is required, these will be explained fully if this goes any further than just an idea.
Most smd components are 0805 sized rather than the smaller size on the current modules.


Re: AD9850/51 module pc boards

Steven Dick
 

LP2985 is an excellent part. go for it.
-Steve K1RF

-----Original Message-----
From: Terry VK5TM
Sent: Sunday, September 30, 2018 8:58 AM
To: PHSNA@groups.io
Subject: Re: [PHSNA] AD9850/51 module pc boards

Henning,

There are two decoupling caps right at the chip on the underside of the pcb,
I can't get them any closer without cutting the top off and mounting them on
the die :) <-smiley face
Another one next to the V+ pin on the underside and the 10µF next to the
other V+ pin.
Looking at the evaluation board, which has much longer supply lines, it only
has one more than this around the DDS chip, the others are associated with
the interface chips.

Re the supply to the xtal osc, the LP2985 is listed as a low noise regulator
and I believe should be more than adequate.
It is well decoupled and again is on the underside of the pcb.

I did some digging through Analog's forums and engineering notes today and
one thing that I noticed was that, in their own words, some of their
recommendations for decoupling, seperate ground planes etc was somewhat over
the top and simpler schemes made no noticeable difference.

Re oscillator phase noise, well you're already hindered by the limitations
of the AD9850 to begin with, so I can't see using ultra pure regulators and
massive amounts of decoupling are going to do anything useful. I could be
wrong, which wouldn't be anything unusual, but I don't think so in this
case. The obvious proviso is of course to use a good quality Xtal Osc
module.

The test will be to build a couple and compare them against the standard
module and rework it if necessary.


Re: AD9850/51 module pc boards

Terry VK5TM
 

Steve,

Same package and pinout as the LP2985, so a straight drop-in.

Quick look at the datasheet shows not much difference between the two other than 1A verses 150mA


Re: AD9850/51 module pc boards

Terry VK5TM
 

Henning,

There are two decoupling caps right at the chip on the underside of the pcb, I can't get them any closer without cutting the top off and mounting them on the die :) <-smiley face
Another one next to the V+ pin on the underside and the 10µF next to the other V+ pin.
Looking at the evaluation board, which has much longer supply lines, it only has one more than this around the DDS chip, the others are associated with the interface chips.

Re the supply to the xtal osc, the LP2985 is listed as a low noise regulator and I believe should be more than adequate.
It is well decoupled and again is on the underside of the pcb.

I did some digging through Analog's forums and engineering notes today and one thing that I noticed was that, in their own words, some of their recommendations for decoupling, seperate ground planes etc was somewhat over the top and simpler schemes made no noticeable difference.

Re oscillator phase noise, well you're already hindered by the limitations of the AD9850 to begin with, so I can't see using ultra pure regulators and massive amounts of decoupling are going to do anything useful. I could be wrong, which wouldn't be anything unusual, but I don't think so in this case. The obvious proviso is of course to use a good quality Xtal Osc module.

The test will be to build a couple and compare them against the standard module and rework it if necessary.


Re: AD9850/51 module pc boards

Steven Dick
 

I would recommend the TI TLV75733PDBVR for a 5V to 3.3V regulator. It uses an SOT23-5 package, is relatively low noise, and inexpensive (.86 at Mouser.) I have used the 5V version with excellent results. The "super cap" is a good circuit but doesn't help high frequency performance. It is best used in low frequency power supply applications. simple regulator will more than do the job in a compact and low cost solution. Here's a link to the Mouser part:
https://www.mouser.com/ProductDetail/Texas-Instruments/TLV75733PDBVR?qs=sGAEpiMZZMsGz1a6aV8DcD1rpA6FsR3JV0%2fewXLxMYU%3d
-Steve K1RF

-----Original Message-----
From: Henning Weddig via Groups.Io
Sent: Sunday, September 30, 2018 7:37 AM
To: PHSNA@groups.io
Subject: Re: [PHSNA] AD9850/51 module pc boards

Terry,

anohter idea: i just read in an Analog Devices app note that the jitter
of the reference clock has a large influence of the overlall jitter
performance of the DDS. From my own experience a well regulated and low
noise supply to the xtal osc and also TCXO will improve the phase nosie
performance of the reference clock and therefore minimize the jitter.

The best known low noise regualtor is the LT3045-- unfortunately not
cheap and sometimes hard to get due its large demand. Another idiea ist
o use a "super cap" i.e. an emitter follower with a large cap from the
the base to ground. This cap will be multipleid wth the hfe of the
transistor.

I had the idea for a piggy back pcb on the chinese units, but never
tried. See the attached schematic file.

Henning


Am 30.09.2018 um 05:34 schrieb Terry VK5TM:
Updated pics with the 3.3v reg underneath the Xtal osc.

I have moved some things around to shorten the length of tracks between IC output, transformer and pin at the edge of the pcb.

Will leave this alone for a day or two, firstly so any comments can be added/updated and secondly, I find getting away from a design sometimes suggests improvements that can be made or something shows that has been missed (like a power track missing in the first set of pics).