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Q & A: How far you can turn the dial when transmitting in SSB voice mode?
· HF, Spectrum · admin

Time and again the question arises as to how far you can turn the tuning knob when transmitting in SSB voice mode. Up to the edge of the band range? Using the 60 m band as an example, we will discuss the question here.

According to WRC-15, the range from 5351.5 to 5366.5 kHz, also called the “5 MHz band”, is allocated to the amateur radio service on a secondary basis. So, for example, are radio amateurs allowed to transmit on 5366.0 kHz within the WRC-15 60 m band in USB? [1]

The so-called “dial frequency” indicates only the frequency of the carrier suppressed in SSB. However, the modulation range for USB extends up to 3.0 kHz higher. That means 5366.0 kHz + 3 kHz = up to 5369.0 kHz. This means that a large part of the signal is outside the range assigned to the amateur radio service (see diagram, right signal, in red)! And: parts of the modulation spectrum cover the section intended for “narrow band weak signal modes”, such as WSPR. And thus leads to interference.

Therefore, the band plan indicates in the “notes”, that in the case of the 60 m band in USB, the highest “dial frequency” to be set is 5363 kHz (diagram, left signal, in green). Here the whole range of the modulation spectrum is below 5366.0 kHz. And thus both within the band and outside the “weak signal narrow band mode” range.

The same applies to the 20 m band: The highest frequency to be set in USB would be 14,347.0 kHz — i.e. 3 kHz below the upper band limit.

[1] Note: Individual countries have allocated a larger frequency range to the amateur radio service due to Radio Regulations Article 4.

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The IARU has agreed the first preliminary IARU positions for WRC-23
· SpectrumTagged , · Barry, G4SJH

The preparatory work for WRC-23 has started across all regions in both the ITU‑R and the Regional Telecommunications Organisations (RTO’s). The IARU has representatives in these RTO’s and the ITU‑R contributing to the studies and helping to develop the regional positions on all the WRC agenda items. It is vital that the amateur community presents its views in a consolidated and consistent manner on each WRC agenda item across all the regions.

To this end the IARU Administrative Council (AC) has agreed the first preliminary positions covering the six most important agenda items for the amateur and amateur satellite services.

The IARU SRLC asks that the regional representatives and the member societies take careful note of these positions and follow them when discussing WRC related matters with their national regulators.

The IARU WRC-23 preliminary positions can be found here.

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5 MHz Band in South Africa
· HF, News · admin

South Africa’s SARL has asked the communications regulator ICASA to allow radio amateurs a 100 kHz wide allocation in the 5 MHz (60m) band with 400 watts output. In terms of the outcome of the WRC-15, ICASA published on 25 May 2018 in the National Radio Frequency Plan an allocation of 100 kHz of spectrum to South African Radio Amateurs. There are two separate footnotes in the plan, splitting access to the 60m band into three segments.

In footnote 5.133B there is an allocation of 5351.5 to 5366.5 kHz with a power limit of only 15 W EIRP. This is the most common allocation in countries where 60 metres is permitted. In footnote NP 0, ICASA has allocated a full 100 kHz: “The 5350 — 5450 kHz segment and the channel 5 290 kHz are allocated on a secondary basis to radio amateurs under Article 4.4 of the ITU regulations.” ICASA has however not yet updated Annexure I of the Frequency Spectrum Regulations which stipulates power limits and modulation types. However, in the SARL’s motivation to have 100 kHz of 5 MHz spectrum allocated, the SARL requested a power limit of 26 dBW (400 Watts PEP) for ZS and ZR licence holders and 20 dBW (100 watt PEP) for ZU licence holders. These power limits are common in South Africa for all bands that are allocated on a secondary basis. On bands where amateur radio has a primary allocation, the power limit for ZS and ZR licensees is 30 dBW. The current situation is that these power limits for secondary allocations apply on 5 MHz except for the segment 5351.5 to 5366.5 kHz where only 15 Watt EIRP is permitted.

Source: SARL/SARN

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