14 iulie 2021

Xiegu G90 output power versus supply voltage

Someone pointed to me that the Xiegu G90 has inconsistency in Tx power at various power supply voltages.

So, because I am a brave curious ham, I setup a quick test bench with some pieces of hardware laying around at my home lab.

The setup is pretty simple:

The radio is connected to a Proxel 832 NFAR power supply (slightly modified for 16V output) and to the R&S NRP-Z11 power sensor (through a JFW 30db/50WJFW 30db/50W attenuator).

The radio firmware is:
-Main unit: 1.77
-Front Panel: 1.76

The PC software was:  R&S Power Viewer

Note: The power sensor is working from 10 MHz so i measured the power from 10 MHz to 30 MHz. Below 10MHz, the results are pretty consistent at various voltages but I cannot hold them as being accurate therefore I removed them from datasheet.

The RF output power was measured from 9V to 16.5V and when i was playing around 9V i noticed a faint sound from inside the radio. The origin was determined to be the relays in the ATU path. Rising the voltage, they will switch around 9.3 V and will keep the contacts untill under 8.7V. Therefore, even the radio is able to work under 9.3V, there are reason not to do that because the voltage drop in SSB or CW will affect the proper function of various relays.

I choose 4 power levels to measure: 1W, 5 W, 10W and 20W. The results are in dbm. You can transform those values into W by using an online dbm to W conversion tool.

The radio was set in CW mode and a straight key was used to put the radio in Tx for the time reading was made.

I also made crude measurements for the Rx current and the Tx current (the last one, just the maximum values).

The voltage was tested against a VC-960 DMM which was then used to measure the current draw.

Here are the results in images. You can download the full test in pdf from the link at the bottom of the post:







And here are the values in W, courtesy of EA5IYL:

Some conclusions:
-At minimum power set in menu, the radio puts around 1.3W.
-Between 10 and 16.5V, setting the radio to 10W will put very close to 10W.
-When settings are for full power, the radio will put between 10W (10m@10V) to 20W (10m@16.5V) being pretty consistent to 20W from 12.8V to 16.5V.
-There are slight variations at max power when using in normal voltage range (12-14V) between 16-20W but in real life this is neglictible, in my opinion.

Much interesting is how the Rx current is evolving on various bands!

Power attenuator:

Power sensor unit:

You can download the test results in pdf format HERE.

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