Re: AD9850/51 module pc boards

Steven Dick
 

Looks good. I like the coilcraft transformer on-board as I have used one myself (Coilcraft WB1-6TSLB)
and it allows good wideband performance and adequate output power for me with a lowpass filter and no output power amp which adds harmonics. Some of those amps are marginal, some can oscillate if the layout is not adequate. There is a problem with the xtal oscillator on EBAY AD9851 type II boards. For the ebay modules. the AD9851 was running off 5 volts but its crystal oscillator also ran on 5 volts but was only rated for 3.3v. Make sure the xtal oscillator is really compatible with 5V input voltage.

for AD9850, 125 MHz oscillator labelled MCO 1510A 125 MHz TQG-9h is a 5 volt oscillator made by Shenzhen Great Electronics. Data sheet:

http://www.szgreat.com/UploadFiles/2010322153029.pdf

For AD9851, 30 MHz oscillator Type II AD9851 boards are labelled CETDCJ 30 032. They are made by Taiten Electronics. It is a 3.3V oscillator, much to my dismay. One of them already failed. See part numbering guide:

http://www.taitien.com.tw/db/download/Model%20Numbering%20Guide_XO.pdf

I ordered a CTS CB3-3C-30M0000 which is rated for 5V. Mouser sells them: https://www.mouser.com/ProductDetail/CTS-Electronic-Components/CB3-3C-30M0000?qs=HL%252bYNjdyZ0s2KrBi4NmH2g%3D%3D

See file https://groups.io/g/PHSNA/files/K1RF/Bandpass%20Filter%20measurement%20anomalies%20R2.pdf discussing output amplifier
and file https://groups.io/g/PHSNA/files/K1RF/Expected%20power%20output%20from%20Type%20II%20PHSNA.pdf
-Steve K1RF

-----Original Message-----
From: Terry VK5TM
Sent: Friday, September 28, 2018 10:10 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.

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