max2870 cable connections and frequency changing

[mervexx6]

sir how can we connect the max2870 to arduino and we use 25kHz instead of 10 KHz. How can we change it ?

[brycecherry75]

The MAX2870 interface is connected to the hardware SPI pins on the microcontroller.
For step frequency, SetStepFreq(StepFrequency) is the function in question and usage is included in the demo sketch.

[mervexx6]

thanks for your interest. I have also a question. When we enter the SWEEP command on the serial monitor, it gives us a harmonic wave. For example we write "SWEEP 1000000000 5000000000 1000 1 1 FUNDAMENTAL" and we get 5 peak at 1,2,3,4,5 GHz. But we want to peak only at 1 GHz. How can we do it ? Do we need to use a filter maybe ?

[brycecherry75]

As per the datasheet, the MAX2870 has a second/third harmonic of about 20 dBc with 3 GHz RF output, VCO frequency of 6 GHz, VCO output divider of 2 and a PFD frequency of 25 MHz.
The harmonic content can depend on the RF output components; one thing you can try is changing the Frac-N Noise Mode with (where vfo is the library member and x is the mode being 0 for Low Noise, 2 for Low Spur Mode 1 and 3 for Low Spur Mode 2) BitFieldManipulation.WriteBF_dword(29, 2, vfo.MAX2870_R[0x02], x);