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Arduino-Transmod.php    8945 Bytes    09-06-2024 12:44:32


Arduino/Genuino Project Transmod


A low noise Downconverter ... 6.8 ± 1 GHz >> 1.0 ± 1 GHz





ARDUINO/Genuino Transmod

The final Design in a KOH-4 case.





✈ The Block Diagram / Function Description






At the Input, we use an N-connector. This is to make sure, that a High Power Attenuator (e.g. BW-N20W50+) can be used.

The design is based around a HMC416LP4E VCO running at 2.9 GHz. The Frequency is stabilized by a ADF4153 PLL. The PLL uses a 100 MHz VCXO, locked to an external 10 MHz signal. (And if no 10 MHz is present, the VCXO is some ppm below 100 MHz).

The LO-signal is doubled by a KC2-36+ (from Mini Circuits) and then passes a Bandpassfilter (VBFZ-6260+).

As the signal level after the doubler was near -20 dBm, we used twice the ZX60-V63+ (each delivering 15.4 dB Gain @ 6GHz).

The now (calculated approx. +10 dBm) is fed to a mixer (ZX05-153LH-S+) @ LO-Port.

At the IF output, a broadband matched Lowpassfilter (VXLF-172H+) is used.



As the Block Diagram suggests ... not much inside :-)

The bright green led indicates that the VCXO is locked to the external 10 MHz. The arrangement of the Mini-Circuits components only deems uncorrelated at first sight :-)




✈ Is the band inverted ?




NO. As we use an LO below the desired RF-Spectrum, we make use of the Difference. In that case, the RF Spectrum is not inverted.




✈ Downloads








✈ Local Oscillator






The LO-level (measured with the SA124B — 12.4 GHz Spectrum Analyzer) is +9.3 dBm, very close to the +10 dBm desired by the ZX05-153LH-S+ Mixer.




✈ Output Spectrum






The IF (= Output) Spectrum shows an unwanted spur at 10 MHz. This must be some stray coupling of the external 10 MHz, as the Phase Comparator Frequency of the PLL is 25 MHz. Nothing else observed up to the 2 GHz. The Input (= RF Port) was terminated with 50 Ω.




✈ Conversion Loss




For this measurement, we used a R&S SMB100A running at - 20 dBm. The IF-Level was recorded with an R&S FSP3 Spectrum Analyzer. We recorded the following Levels :


It can be seen, that at those high frequencies, every connector causes losses. All those summed up give an average Insertion Loss of 16.3 dB.




✈ 1-dB Compression Level




For this measurement, we used a R&S SMB100A running at 6.8 GHz at various levels. The IF-Level was recorded with an R&S FSP3 Spectrum Analyzer.


From this measurement, we can define a safe operating level ob 0 dBm RF / CW at the input.




✈ Remote Control




The Remote Control Functionality of the Transmod is very limited. The Arduino Nano Every outputs just the Lock-Status of the PLL. Every second it will output the Logic Level of the MUX-Pin of the PLL by Serial.println(StatusMux, DEC) - which is just zero or one.




✈ Share your thoughts



The webmaster does not read these comments regularely. Urgent questions should be send via email. Ads or links to completely uncorrelated things will be removed.


Your Browser says that you allow tracking. Mayst we suggest that you check that DNT thing ?

 
t1 = 6585 d

t2 = 200 ms

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