Problem to use 32 mhz xtal osc in dds ckt by VU3CNS

[vu3suy]

Dear Sir,
32 mhz crystal is available in Kolkata market,now price is Rs
75 each.I am using that oscillator.But during calibration if I select
x1 option and input System clock 31.999HZ then out put frequency is
exactly 10 MHZ and DDS is working well,but max freq is not high.So to
get max freq high if I use x6 option then I have to change the System clock
frequency 191.994 to get the 10 mhz output but the software is allowing
maximum 190 mhz. So now I cannot using x6 option.

I think if I use 20 or 25mhz oscillator if available Then the problem will be solved.But my
question is----Is there any solution to input the system clock frequency
above 190 mhz,If so we can then use 32mhz oscillator.

[vu3cns]

But my
question is----Is there any solution to input the system clock frequency
above 190 mhz,If so we can then use 32mhz oscillator.

Please note that the max value of system clock for AD9851 is 180MHz.

[vu3suy]

Thanks for the information.It was beyond my knowledge.Actually I have nothing to do for the microcontroler projects due to lack of knowledge about that field .I can do only copy and paste the projects.hi hi hi.

[vu3suy]

Dear Sir ,
Now I am assembling DDS VFO by respectable VU3CNS.
Some years ago I assembled DDS VFO by respectable VU3WIJ.
During calibration using 32 MHz crystal if I input system clock frequency
192 MHz then the out put frequency is 10 MHz and then Max DDS freq is
increasing up to 86.4mhz which is 45% of the system clock frequency and the DDS is working well.

Now if I enter system clock frequency 200 MHz then the DDS output frequency is
below 10 MHz and Max DDS frequency showing 90 MHz.Now the output frequency
must not be 90 MHz because this is the wrong calibration.But it is able to
accept system clock frequency up to 200 MHz.

I don't know why and how it is accepting system clock frequency
above 180 MHz and working well.

[vu3cns]

Now I am assembling DDS VFO by respectable VU3CNS.
Some years ago I assembled DDS VFO by respectable VU3WIJ.
During calibration using 32 MHz crystal if I input system clock frequency
192 MHz then the out put frequency is 10 MHz and then Max DDS freq is
increasing up to 86.4mhz which is 45% of the system clock frequency and the DDS is working well.

These are two different designs/softwares, and please see the data sheet of AD9851, and find the specification for system clock. Above 180MHz, you are overclocking the chip.
73's
CNS

[vu3suy]

OK sir,
Now I have to collect 30 mhz or below this freq osc to use x6 option and not to overclocking the AD9851.Many many tnx to you for this advice.My best regards to you.
Thanking you ,
VU3SUY (Subhas)

[mvs sarma]

Subhas jee, you can very well get an oscillator module of 30MHz. if you cant procure one, perhaps i can send one from my spare stock at Hyderabad. forget engineering it at 32MHz.

[vu3suy]

Dear sarma jee,
I am very very glad to know the 30 mhz crystal is available at your end.If It is not available in Kolkata market I must collect from you. What may be the cost of each?

[mvs sarma]

it is oscillator and not crystal. it is costly at around Rs.90. Actual value can be intimated later. but it is better toi try at kolkatta asa modlue it would be locally cheaper to avoid courier charges.

[vu3suy]

TNX

[mvs sarma]

TNX

now i do have the KDS brand 30MHz crystals also, and can send them at by post. i bought them at 15 each.