Product Review: Xiegu G90 HF Transceiver
Reviewed by Phil Salas, AD5X
ad5x@arrl.net
The Xiegu G90 HF transceiver bridges the gap between QRP (typically 5 W output) and 100 W radios. This review examines an interesting product distributed and supported in the US by MFJ Enterprises.
Overview
The Xiegu G90 is built on a downconverting software-defined radio (SDR) platform, utilizing a 24-bit 48 kb/s sampling analog-to-digital/digital-to-analog converter. It operates as a direct conversion transceiver, mixing signals directly to baseband for processing. The G90 transmits on the 160- through 10-meter ham bands and features a general-coverage receiver tuning from 500 kHz to 30 MHz. Transmit power is adjustable from 1 to 20 W, supporting SSB, CW, and AM modes, as well as digital modes via an external computer.
The transceiver incorporates features common to desktop units, including split-frequency operation, a built-in SWR bridge, an automatic antenna tuner, receiver preamp and attenuator, a digital noise blanker, a CW decoder, and variable band-pass audio filters. It also includes a built-in CW keyer and a speech processor for SSB. A 1.8-inch color TFT LCD screen displays operational information, a 48 kHz wide spectrum display, and a waterfall display. It is equipped with a top-mounted speaker.
Bottom Line
With 20 W of output power and a wide-range internal auto tuner, the Xiegu G90 is a capable transceiver in a well-thought-out, compact package, making it ideal for portable operation.
Interfaces and Controls
The G90 resembles a miniature version of the Icom IC-706MKIIG 100 W transceiver. The front panel can be remotely mounted using an included 1-meter-long DB9 extension cable. Despite its numerous controls and interface connectors, everything is easily accessible.
Rear Panel Connectors: The rear panel features a standard SO-239 antenna connector, 3.5 mm stereo jacks for KEY (manual, paddle, or external keyer) and COM (for firmware updates), an I/Q output for external processing or display, an eight-pin mini-DIN ACC jack for amplifier interfacing and external audio, a mini-Tamiya power connector, and a ground connection.
Front Panel Connectors: On the left side of the front panel are two 3.5 mm stereo jacks for headphones and front-panel firmware updates. The microphone connects via an RJ45 jack on the right side. Up/down buttons for band and mode selection are located on the top of the radio.
Front Panel Controls: The front panel includes 13 pushbuttons, a volume knob, a multifunction knob, and a tuning knob. The knobs offer multiple functions. Buttons are clearly marked with good tactile feel, and many provide secondary functions accessed via the FUNC button.
Indicators: A yellow LED flashes in sync with incoming CW when the signal is tuned. A yellow LED illuminates when the FUNC button is pressed. A green LED indicates receive status, and a red LED indicates transmit status. The multifunction keypad on the included microphone provides access to all radio features.
Figure 1: The Xiegu G90 rear panel.
Figure 2: Connectors on the sides of the G90, near the front panel.
Power Requirements
The G90 requires an external power source between 10.5 and 16.5 V dc. While specifications state a maximum current of 8 A, measurements indicate less than 5 A is needed at maximum power. For portable use, lithium polymer (LiPo) batteries are recommended for their cost and energy density. A 4S LiPo battery, with a fully charged voltage of 16.8 V dc, is suitable as the G90 operates fine up to 17 V dc.
A 10 A fused #16 AWG cable with a mini-Tamiya power connector is included. An Anderson PowerPole connector was added for the reviewer's standard DC interface. Note that airsoft gun LiPo batteries use the same mini-Tamiya connector, but power cables may have reversed polarity.
Firmware Updates and Documentation
A 3.5 mm-to-USB cable is provided for firmware updates and computer interfacing. Both the main unit and front-panel firmware must be updated separately, a process detailed in the G90 User Manual.
Xiegu is responsive to user feedback for bug fixes and feature updates, meaning supplied documentation may be outdated. MFJ maintains the latest firmware and documentation on their website. An active G90 user group at groups.io/g/XieguG90 also provides the latest firmware and documentation in its FILES section, serving as a resource for tips and questions.
Additional Testing
Testing in the ARRL Lab, detailed in Table 1, covered various performance aspects. The G90's power setting is accurate, typically within 1/2 W. Current draw at 13.8 V dc input ranges from about 2 A at 1 W output to 4-4.5 A at full output, significantly less than the 8 A maximum specification.
The internal automatic antenna tuner (ATU) was tested for its resistive matching range and loss. The ATU showed reasonably low internal losses and did not match open or short circuits, indicating good performance.
An issue with unstable transmit power variation on 17 meters when tuning reactive loads to 1:1 was noted. Xiegu has reportedly resolved this in units shipped after June 2019, a fix verified by MFJ.
Figure 3: The G90 display.
Figure 4: CW keying waveform for the Xiegu G90 showing the first two dits using external keying. Equivalent keying speed is 60 WPM.
Figure 5: Spectral display of the Xiegu G90 transmitter during keying sideband testing. Equivalent keying speed is 60 WPM.
Figure 6: Spectral display of the Xiegu G90 transmitter output during phase-noise testing.
Table 1: Xiegu G90 Specifications and ARRL Lab Measurements
| Manufacturer’s Specifications | Measured in the ARRL Lab | |
|---|---|---|
| Frequency coverage: 0.5 – 30 MHz; transmit, 160 – 10 meter amateur bands. | As specified. On 60 meters, transmit is 5.3305 – 5.405 MHz. | |
| Power requirement: transmit, 8 A maximum; receive, 500 mA maximum, at 10.5 – 16.5 V dc. | At 13.8 V dc: Transmit, 4.4 A typical at maximum RF output, 2.1 A at minimum RF output. Receive, no signal, maximum volume and lights, 558 mA; minimum lights, 540 mA. Power off, 0 mA. | |
| Modes of operation: CW, AM, SSB. | As specified. | |
| Receiver SSB/CW sensitivity: 1.8 – 2 MHz, 0.35 µV; 2 – 30 MHz, 0.25 µV. | Noise floor (MDS), 500 Hz bandwidth: Preamp off / Preamp on: 1.0 MHz –128 dBm / –136 dBm; 3.5 MHz –131 dBm / –138 dBm; 14 MHz –132 dBm / –138 dBm; 28 MHz –134 dBm / –139 dBm. Preamp off/on: 14 MHz, 17/8 dB. | |
| Noise figure: Not specified. | 10 dB (S+N)/N, 1 kHz tone, 30% modulation, 6 kHz bandwidth: Preamp off / Preamp on: 1.0 MHz 4.73 µV / 2.04 µV; 3.8 MHz 2.82 µV / 1.49 µV; 29 MHz 2.40 µV / 1.66 µV. | |
| AM sensitivity: 0.5 – 2 MHz, 10 µV; 2 – 30 MHz, 2 µV. | Preamp off/on: –8/–17 dBm. | |
| ADC overload level: Not specified. | Blocking gain compression dynamic range, 500 Hz bandwidth: 20 kHz offset: Preamp off/on 3.5 MHz 123/121 dB; 14 MHz 121/118 dB. 5/2 kHz offset: Preamp off 3.5 MHz 123/120 dB; 14 MHz 121/108 dB. | |
| Blocking gain compression dynamic range: Not specified. | 14 MHz, 20/5/2 kHz offset (500 Hz BW): 100/84/84 dB. | |
| Reciprocal mixing dynamic range: Not specified. | Preamp off/on, 14 MHz, +39/+47 dBm; 21 MHz, +29/+27 dBm. | |
| ARRL Lab Two-Tone IMD Testing (500 Hz bandwidth) | Measured IMD Level / Input Level / IMD DR | |
| 3.5 MHz/off, 20 kHz | –131 dBm / –46 dBm; –97 dBm / –23 dBm | 97 dB |
| 14 MHz/off, 20 kHz | –132 dBm / –37 dBm; –97 dBm / –25 dBm | 95 dB |
| 14 MHz/on, 20 kHz | –138 dBm / –47 dBm; –97 dBm / –14 dBm | 91 dB |
| 14 MHz/off, 5 kHz | –132 dBm / –41 dBm; –97 dBm / –29 dBm | 91 dB |
| 14 MHz/off, 2 kHz | –132 dBm / –42 dBm; –97 dBm / –29 dBm | 90 dB |
| Transmitter RF power output: 20 W (CW/SSB); 5 W (AM carrier), at 13.8 V dc. | Transmitter Dynamic Testing: CW/SSB, typically 1.4 – 19 W; AM, 1.4 – 19 W at 13.8 V dc. | |
| RF power output at minimum specified operating voltage: Not specified. | At 10.5 V dc: 1.4 – 15.2 W typical. | |
| Spurious-signal and harmonic suppression: 45 dB. | HF, typically 68 dB; 55 dB (worst case, 160 meters); 50 MHz, 68 dB. | |
| Third-order intermodulation distortion (IMD) products: Not specified. | 3rd/5th/7th/9th order, 19 W PEP: –32/–46/–50/–58 dB (HF typical); –29/–43/–44/–48 dB (worst case, 20 m). At 10 W RF output: –34/–39/–45/–56 dB (14 MHz). | |
| CW keyer speed range: Not specified. | 5.3 to 57 WPM; iambic mode A and B. | |
| CW keying characteristics: Not specified. | See Figures 4 and 5. | |
| Transmit-receive turnaround time (PTT release to 50% audio output): Not specified. | S-9 signal, SSB, 400 ms; CW, 132 ms. | |
| Receive-transmit turnaround time (TX delay): Not specified. | SSB, 60 ms. | |
| Receive processing delay time: Not specified. | 8 ms. | |
| Transmit phase noise: Not specified. | See Figure 6. | |
| Size (height, width, depth): 2.0 × 5.5 × 9.8 inches (including protrusions). Weight, 3.6 pounds. | Second-order intercept points were determined using S-5 reference. *Default values; bandwidth is adjustable. |
Operating the G90
The display is noted as amazing, providing clear information including signal level in dBm on the spectrum display. Signal level readings were accurate when compared to an Elecraft XG3 signal generator. S-meter readings are accurate at reasonable signal levels, dropping 6 dB per S-unit from –73 dBm to –107 dBm. At very high signal levels (–33 dBm), the S-meter reads approximately 20 dB high.
Controls are generally intuitive. The volume control, when tapped, redirects audio to the headphone jack and reduces the level. The G90 does not directly drive an external speaker; a powered external speaker is required. An AlexMic G90 with a built-in amplified speaker is available (see www.alexloop.com).
The multifunction knob, below the power button, defaults to 100 kHz tuning steps. A long press accesses other functions like squelch level, power output, keying speed, and FFT scale. The main tuning knob's tap function cycles tuning steps between 10, 100, and 1,000 Hz. The five buttons below the display have clearly marked secondary functions accessible via the FUNC button.
The internal auto tuner is engaged by tapping the TUNE button once, and held to start tuning. It reverts to receive mode upon completion. Tuning typically takes less than 1 second, and the last tuning solution is remembered per band.
Tapping the POW button allows adjustment of transmit power with the main tuning knob. A second tap sets the SWR level for power foldback. A long press initiates an SWR sweep (default 150 kHz, adjustable ranges available). Pressing FUNC then POW allows adjustment of microphone gain or audio input selection.
Tapping the LOCK button adjusts display brightness. A long press locks/unlocks the radio. Pressing FUNC then LOCK adjusts the spectrum display gain (FFT level).
CW Operation
The internal keyer speed range is approximately 5 to 55 WPM. The reviewer set the multifunction knob default to keying speed. CW or CWR (reverse) can be selected based on interference. The default CW filter bandwidth is 500 Hz, adjustable down to 50 Hz using FUNC F-L and FUNC F-H buttons.
Break-in delay can be set from 0 to 1 second in 100 ms increments. However, due to SDR processing latency, full break-in (QSK) operation is not supported. There are no CW memories. No key clicks were observed, and the waveform shaping is adequate.
Transmit/receive relay clicking is audible but not objectionable. The lack of rubber feet on the G90's case can transfer mechanical coupling sounds to a tabletop surface; adding rubber feet is recommended.
SSB Operation
SSB contacts are easier at 20 W compared to 5 W QRP levels. The G90 includes a speech compressor, enabled via a button below the display, with a fixed setting that works well. The default SSB receive filter bandwidth is 2.4 kHz, adjustable using FUNC F-L and F-H keys. The receive audio passband response is pleasant. Transmit audio is reported as excellent.
Digital Modes
The G90 supports digital modes like FT8, RTTY, and PSK with a computer and sound card. An eight-pin mini-DIN radio-to-computer sound card interface cable or the Xiegu CE-19 Expansion Interface is required. Interface connections are detailed in the G90 User Manual.
Final Thoughts
The Xiegu G90 is described as an enjoyable transceiver to operate, with the 20 W transmitter power making a significant difference, especially for SSB. The SDR architecture suggests potential for future feature enhancements. Desired improvements include a built-in tilt stand and an option to substitute 6 meters for 160 meters.
The Xiegu G90 comes with a 2-year warranty when purchased through MFJ Enterprises.
Manufacturer: Xiegu Technology Co. Ltd.
Distributed and supported in the US by: MFJ Enterprises, 300 Industrial Park Rd., Starkville, MS 39759, www.mfjenterprises.com.
Price: $449.95. CE-19 Expansion Interface, $29.95.
