Sherwood Engineering HF Test Results
Model: Xiegu G90
Serial #: X0420170780
Test Date: 03/11/2021
Front End Selectivity
| Front End Selectivity (A – F) | Not known |
| First IF rejection +/- kHz, does not apply | Direct conversion |
Dynamic Range (No Preamp)
| Dynamic Range 20 kHz | 78 dB |
| Dynamic Range 10 kHz | 78 dB |
| Dynamic Range 5 kHz | 77# dB |
| Dynamic Range 2 kHz | 76* dB |
# Combination of phase noise and 3rd order product
* Consisted of phase noise only
Blocking Above Noise Floor (1uV signal, AGC On)
| 100 kHz, phase noise limited at all test spacings | 116 dB |
| 50 kHz | 107 dB |
| 20 kHz | 97 dB |
| 5 kHz | 85 dB |
Phase noise increases the audio output before the radio starts to block in a 500-Hz CW bandwidth.
Reciprocal Mixing Dynamic Range (RMDR)
| Spacing kHz | dB |
|---|---|
| 2.5 | 81 dB |
| 5 | 81 dB |
| 10 | 86 dB |
| 15 | 91 dB |
| 20 | 95 dB |
| 25 | 98 dB |
| 30 | 100 dB |
| 40 | 104 dB |
| 50 | 107 dB |
| 75 | 113 dB |
| 100 | 114 dB |
| 200 | 114 dB |
| 300 | 122 dB |
| 400 | 124 dB |
| 500 | 124 dB |
Phase Noise (Normalized)
| Spacing | Value |
|---|---|
| 2.5 kHz spacing | -105 dBc/Hz |
| 5 kHz spacing | -105 dBc/Hz |
| 10 kHz spacing | -113 dBc/Hz |
| 20 kHz spacing | -122 dBc/Hz |
| 50 kHz spacing | -134 dBc/Hz |
| 100 kHz spacing | -141 dBc/Hz |
Noise Floor and Sensitivity (SSB, 14 MHz)
| Measurement | Value (No Preamp) | Value (Preamp On) | Value (Attenuator On) |
|---|---|---|---|
| Noise floor, SSB bandwidth 14 MHz | -113 dBm | -129 dBm | -98 dBm |
| Sensitivity SSB at 14 MHz | 1.9 uV | 1.0 uV | 11.5 uV |
Noise Floor (500 Hz, 14.2 MHz)
| Measurement | Value (No Preamp) | Value (Preamp On) | Value (Attenuator On) |
|---|---|---|---|
| Noise floor, 500 Hz | -120 dBm | -136 dBm | -105 dBm |
Signal for S9
| Condition | Value | Equivalent uV |
|---|---|---|
| Signal for S9, no preamp | -57 dBm | 317 uV |
| Signal for S9, preamp | -66 dBm | 112 uV |
| Signal for S9, attenuator | -51 dBm | 633 uV |
Gain and AGC Threshold
| Measurement | Value |
|---|---|
| Gain of preamp | 18 dB |
| Attenuator | 15 dB |
| AGC threshold at 3 dB, no preamp | -100 dBm (2.1 uV) |
| AGC threshold at 3 dB, preamp | -118 dBm (0.27 uV) |
| AGC threshold at 3 dB, attenuator | -85 dBm (12.7 uV) |
Notes
- The CW noise floor values are quite reasonable in respect to the 18 dB of preamp gain.
- The 2400-Hz SSB noise floor is proportional to the 500-Hz CW noise floor.
- The receiver phase noise in dBc/Hz is similar to the Icom IC-703+. The Lab599 TX-500 and Icom IC-705 are better in this respect, as are the KX3 and KX2.
- Blocking is phase noise limited, though for SOTA and POTA this is not likely an issue.
- The digital dBm signal level tracks from -120 to -10 dBm, but reads 9 dB low.
- The AGC threshold is excellent with either no preamp or with the preamp on.
Transmit Composite Noise (dBc/Hz)
| Offset kHz | 20 watts | 5 watts |
|---|---|---|
| 2 | -106 | -100 |
| 5 | -109 | -106 |
| 10 | -115 | -113 |
| 20 | -113 | -119 |
| 50 | -131 | -124 |
| 100 | -127 | -118 |
| 200 | -135 | -126 |
| 300 | -135 | -126 |
Current Drain
- 20 watts output: 3.5 amps
- 5 watts output: 2.2 amps
Local Oscillator Leakage
Local oscillator leakage out the antenna jack.
Spectrum Analyzer Screenshot Description:
The display shows a spectrum analyzer output with the following settings:
- Center Frequency: 14,200,000.0 Hz (14.2 MHz)
- Span: 50,000.0 Hz (50 kHz)
- Reference Level: -25.0 dBm
- Vertical Scale: 10 dB/DIV
- Resolution Bandwidth (RBW): 300 Hz
- Video Bandwidth (VBW): 30 Hz
- Sweep Time (ST): 17.4 SEC
A single, narrow signal peak is visible, slightly offset from the center frequency. A marker is placed at 14,199,150.0 Hz, indicating a signal level of -85.1 dBm. This represents the local oscillator leakage detected at the antenna jack.
LO Leakage Details
As with any direct conversion transceiver, such as with the Elecraft KX3, the LO radiates out the antenna jack. The above screen shot is through a 30 dB pad, thus when connected to an antenna, the level is -55 dBm with the preamp OFF and the attenuator OFF. The preamp's reverse isolation reduces the LO level 22 dB. The attenuator reduces the LO level 15 dB.
Operational Observations
- The G90 UI could be better, but with a 1.8 inch display, that is difficult to accomplish. The display is very sharp and easy to read.
- The SSB AGC decay speed on Slow is too fast for my liking. A way to adjust the decay speed was not found.
- Making a change to DSP filter bandwidth requires more than a single adjustment.
- The AGC/Split button when held in affects the RF gain, which does not appear to be documented. The default is 50% and this setting was not changed. At that setting, the 500-Hz noise floor with and without preamp is very reasonable. There is no documentation as to where that gain stage is located in the signal chain.
- Earphones are pretty much required as the internal speaker is very tinny, and headphone output can barely drive a speaker. An amplified computer speaker would be desirable for fixed operation.
- The band scope works OK, but the waterfall is way too fast to be useful. No way was found to slow down the waterfall.
- The auto scale of the scope gain works well if an absolute value isn't desired.
- The tuner finds a match faster than the FTdx10.
- There is some internal spurious likely from a DC to DC converter.
- The manual states it needs a 10 amp supply, but the current draw isn't anywhere near the 8 amps listed in the manual.
- The switchable tuning rate by display digit is convenient to adjust by pushing the tuning knob.
- There is no schematic or block diagram in the manual. State-side service options are unknown.
Rev E
