Radtel RT-490 Compliance Test

Compliance testing to ascertain if this radio meets ITU guidelines for spurious emissions.

Radtel RT-490 Final Grade: Fail

The Radtel RT-490 amateur radio sample we tested generated multiple spurious emissions above the 2m (144 MHz) band fundamental that were not in compliance with ITU guidelines for such emissions. Performance in the 70 cm (440 MHz) band was fully compliant.

Use of this radio primarily for 2m VHF transmission is dubious. Use of this radio primarily for 70 cm UHF transmission is more credible.

It is important to note that this was a single-sample test and that it is possible other samples could vary in performance.

Tests performed in Surrey, BC, Canada on July 6, 2024 by Reg Natarajan.
Discuss this radio on our forums. https://forums.advancedamateur.ca/t/radtel-rt-490

Power Output Testing

Power output was measured using a Surecom SW-33 Plus into a dummy load. The radio was set to maximum power. The ITU guidelines for spurious emissions require measurements of "the power (W) supplied to the antenna transmission line". That requirement makes this separate power measurement necessary, as it is incorrect to measure relative to the fundamental (f0). All numbers have been rounded.

2M

146.520 Mhz

6.0 watts

Using the ITU formula of 43+10log(P) dB, spurious emissions for a signal of 6.0 watts must be at least 51 dB below the power supplied to the antenna transmission line. 6.0 watts is approximately 38 dBm, which means no spurious signal may exceed -13 dBm, or approximately 50 microwatts.

70cm

446.000 Mhz

5.2 watts

Using the ITU formula of 43+10log(P) dB, spurious emissions for a signal of 5.2 watts must be at least 50 dB below the power supplied to the antenna transmission line. 5.2 watts is approximately 37 dBm, which means no spurious signal may exceed -13 dBm, or approximately 50 microwatts.

Spurious Emissions Testing

Spurious emissions were measured using a Tiny SA Ultra. The radio was set to maximum power and was connected to the TinySA through an attenuator. It is important to understand that the graphs below are using a decibel scale, not a linear scale. If a spurious emission spike appears to be almost as tall as the fundamental, that does not mean it is emitting almost as much power. Refer to the raw data shown.

VHF 2m Band Test Results: Fail

Raw Data 2m

All numbers have been rounded

Power at Antenna: 38 dBm (6.0 watts)

Fundamental (f0): 34.6 dBm (2.9 watts)

2nd Harmonic (2f0): 22.9 dBm (194 milliwatts)

Should be less than -13 dBm (50 microwatts)

3rd Harmonic (3f0): 0.3 dBm (1.1 milliwatts)

Should be less than -13 dBm (50 microwatts)

4th Harmonic (4f0): -19.5 dBm (11.2 microwatts)

Should be less than -13 dBm (50 microwatts)

The Radtel RT-490 sample that we tested displayed three harmonic emissions above the 2m band fundamental, two of which were out of compliance with ITU guidelines. Any spurious emissions should be at least 51 dB below the power measured at the antenna transmission line. The Radtel's second harmonic was just 15.1 dB below, which is well out of specification.

UHF 70cm Band Test Results: PASS

Raw Data 70cm

All numbers have been rounded

Power at Antenna: 37.1 dBm (5.2 watts)

Fundamental (f0): 35.8 dBm (3.8 watts)

The Radtel RT-490 sample that we tested displayed no significant spurious emissions above the 70 cm band fundamental in our testing.

Comments

Many thanks to Dmitry VA7DVO for the use of his radio for testing.

~Reg Natarajan VA7ZEB / HJ1ZEB, July 6, 2024

Discuss this radio on our forums. https://forums.advancedamateur.ca/t/radtel-rt-490

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