Diamond SX-400
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| Frequency | 140-525 MHz (2 m, 70 cm, and the VHF/UHF range between) |
| Bands | 2m, 70cm, VHF/UHF 140-525 MHz |
| Power | An SWR/power meter, not a transmitter. It reads forward power, reflected power and SWR on three ranges (5, 20 and 200 watts), with a 200-watt maximum and about 4 watts as the minimum for a usable SWR reading. |
| Modes | SWR/power measurement (forward, reflected, VSWR) |
| Weight | 540 g (19 oz) |
| rf in | SO-239 (from the transceiver); the SX-400N variant uses N-type |
| antenna | SO-239 (to the antenna); the SX-400N variant uses N-type |
| dc in | 12 V DC input that powers only the scale illumination and LEDs (the meter measures without external power) |
| power req | No external power is needed for measurement; a 12 V DC input runs the scale illumination and LEDs only. |
A simple, dependable VHF/UHF SWR and power meter with a continuous 140-525 MHz range that covers 2 m, 70 cm, GMRS and commercial use in one box. It reads forward power, reflected power and SWR on 5, 20 and 200 watt ranges, switches between average and PEP, and works without external power (the 12 V input is only for the lamp). An N-type version is available, and it is inexpensive.
It is a single-needle meter, so reading SWR means calibrating on forward power and then switching, rather than the at-a-glance display of a cross-needle meter. The ceiling is 200 watts, accuracy is the usual plus or minus 10 percent of full scale rather than lab-grade, and the standard model uses SO-239 connectors, which some operators prefer to avoid at 70 cm (the SX-400N answers that with N-type).
The Diamond SX-400 is a standard, affordable VHF/UHF station meter: a continuous 140-525 MHz range, three power scales to 200 watts, forward, reflected and SWR readings, and average-or-PEP switching, in a solid metal box that stays in the feedline. It suits 2 m and 70 cm operators and GMRS users who want a reliable in-line meter; those who want at-a-glance reading prefer a cross-needle meter, and those who need N-type choose the SX-400N.
The Diamond SX-400 is an SWR and power meter for VHF and UHF. It covers a continuous 140 to 525 MHz, which spans the 2 meter and 70 centimeter amateur bands, GMRS, and the commercial VHF/UHF range in between, so one meter serves most stations operating above HF. It is a pass-through instrument that stays in the feedline between the radio and antenna.
It reads forward power, reflected power or SWR on three ranges (5, 20 and 200 watts), with a 200-watt ceiling and roughly a 4-watt minimum for a usable SWR reading, and it can show either average or peak (PEP) power. It is a single-needle meter, so checking SWR means calibrating on forward power and then switching, rather than the at-a-glance reading of a cross-needle meter. Stated accuracy is about ten percent of full scale, which is normal for this class. Importantly, the meter measures without any external power; the 12-volt DC input runs only the scale illumination and indicator LEDs.
Standard units use SO-239 connectors, and Diamond also offers an SX-400N variant with N-type connectors for operators who prefer them at 70 centimeters. The meter lives in a compact metal case of about 155 by 63 by 103 millimeters and weighs around 540 grams.
It is the VHF/UHF member of Diamond's SX meter family. The SX-200 is the HF-and-2 m version, the dual-sensor SX-600 combines HF and VHF/UHF in one box, and for at-a-glance reading a cross-needle meter such as the Daiwa CN-801 is the alternative.