adf4351 oscilator board

Discussion about this major DATV Project. See https://wiki.batc.org.uk/The_Portsdown_Transmitter
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pa2mrx
Posts: 15
Joined: Thu Dec 28, 2017 6:00 pm

adf4351 oscilator board

Post by pa2mrx » Mon Oct 15, 2018 4:00 pm

hello folks,

I`ve just got a question using the adf5351 oscillator board.

I use this board for a time now as a signal source for everything.
But i`ve changed the crystal on it into a same size 10Mhz unit, so i can connect my 10Mhz GPSO directly to it. The software on the pc can
change this setting so the board can be programmed (working as long program is running on PC).

Is this option also availabe in the software on the SD card.

Don`t ask me to change something in the software,..I`m (almost) a neanderthal when it comes to software writing/changing.

73
Frank

G8GKQ
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Re: adf4351 oscilator board

Post by G8GKQ » Mon Oct 15, 2018 9:29 pm

Hi Frank

You can set the ADF4351 Reference Frequency from the touchscreen.

Go to Menu 2, then Menu 3, then select "Set ADF Ref Freq". If you select "Use Ref 2 10000000", it will go green. Then select "Exit". Done!

Dave

pa2mrx
Posts: 15
Joined: Thu Dec 28, 2017 6:00 pm

Re: adf4351 oscilator board

Post by pa2mrx » Tue Oct 16, 2018 4:03 pm

Hi Dave,

Thank you for the answer. I`ll check that.
I almost completed the build of the circuit boards.

more projects running, so need some time.

thanks
Frank

Roberto48
Posts: 19
Joined: Fri Jul 06, 2018 2:04 pm

Re: adf4351 oscilator board

Post by Roberto48 » Tue Oct 30, 2018 11:06 am

Hi All,

I found something strange in the output of my ADF5351 board...
When I control the board by the Portsdown software, the output is about -9 dBm. I found that very low.
To be sure that my board is not broken I controlled the board by an Arduino and then the output is -1 dBm (which is normal for the output settings in the sketch). The output frequency in both cases is correct.

What could be the problem?

73's
Rob PA0RWE

G8GKQ
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Re: adf4351 oscilator board

Post by G8GKQ » Tue Oct 30, 2018 12:18 pm

Hi Rob

I like the easy questions!

There are 4 output level settings on the ADF4351 modules. On the eBay modules (which do not meet the Analog Devices spec) these equate to about -8.5 dBm, -5.5 dBm, -2.5 dBm and +0.5 dBm at 437 and 1255 MHz.

During development of the Portsdown, I found that the filter-modulator board is perfectly happy with -8.5 dBm at its input, and as the QPSK modulator is non-linear in the RF path, increasing input to +0.5 dBm does not increase the output level. In fact, it can decrease the MER because of leakage of the higher level LO to the output. So, the Portsdown sets the output level of the ADF4351 to -8.5dBm.

You can check the predicted output level of the ADF4351 in the 4 modes by using the Portsdown signal generator in ADF4351 mode - it has a calibration file that is generally accurate within a dB or so. https://wiki.batc.org.uk/Portsdown_Signal_Generator

Hope that helps

Dave

g0mjw
Posts: 2330
Joined: Sat Sep 20, 2014 9:15 am

Re: adf4351 oscilator board

Post by g0mjw » Tue Oct 30, 2018 1:06 pm

G8GKQ wrote:
Tue Oct 30, 2018 12:18 pm
Hi Rob

I like the easy questions!

There are 4 output level settings on the ADF4351 modules. On the eBay modules (which do not meet the Analog Devices spec) these equate to about -8.5 dBm, -5.5 dBm, -2.5 dBm and +0.5 dBm at 437 and 1255 MHz.

During development of the Portsdown, I found that the filter-modulator board is perfectly happy with -8.5 dBm at its input, and as the QPSK modulator is non-linear in the RF path, increasing input to +0.5 dBm does not increase the output level. In fact, it can decrease the MER because of leakage of the higher level LO to the output. So, the Portsdown sets the output level of the ADF4351 to -8.5dBm.

You can check the predicted output level of the ADF4351 in the 4 modes by using the Portsdown signal generator in ADF4351 mode - it has a calibration file that is generally accurate within a dB or so. https://wiki.batc.org.uk/Portsdown_Signal_Generator

Hope that helps

Dave
It also explains my earlier uncertainty and to why the level coming out of the LO filter board is not too high following its 20 dB amplifier.

Mike

Roberto48
Posts: 19
Joined: Fri Jul 06, 2018 2:04 pm

Re: adf4351 oscilator board

Post by Roberto48 » Tue Oct 30, 2018 6:34 pm

Hi Dave,

Thanks for your answer!
OK now I understand that the Portsdown sets the output to -8.5 dBm.
Still something strange is that I'm not using an e-bay module and even the output = -8.5 dBm....

But I will check the output with the Portsdown signal generator (now I know that there is one...).
What a great project the Portsdown is!

Thanks for explanation!

73's
Rob PA0RWE

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