| ADVANCED LESSON 10 | |
| LEARNING OBJECTIVES and NOTES |
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| 2i Apparatus, Inspection Closedown and renewal. |
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| 2i.1 7(1) 7(1)The Licensee shall ensure that: (a) the emitted frequency of the apparatus comprised in the Radio Equipment is as stable and as free from Unwanted Emissions as the state of technical development for amateur radio apparatus reasonably permits. To check for frequency stability of a receiver, tune in to one of the standard transmissions (e.g. 5MHz, 10MHz, 20MHz). Zero beat and check for any shift over time. To check your transmit frequency stability, use a frequency counter with a suitable attenuator . You can also listen to your signal on another receiver for signs of short term instability such as chirp.Tune the receiver to look for spurious transmissions and harmonics above and below the operating frequency. Feed the transmitter into a dummy load and listen on a nearby receiver for any drift in frequency. b) Whatever class of emission is in use, the bandwidth occupied by the emission is such that not more than 1% of the mean power of the transmission falls outside the nominal modulated carrier bandwidth. Not easy to measure! If you have a spectrum analyser or an SDR receiver you can monitor the amount of signal falling outside the bandwidth. This should be minimal. |
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7(2) Where this Licence is a Foundation Licence, the Licensee shall
only use commercially available Radio Equipment which satisfies IR
2028. Foundation Licence holders may also use Radio Equipment
constructed using commercially available kits which satisfy IR 2028. |
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| 7(3)
Not withstanding any other terms of this Licence, the Licensee shall ensure that the Radio Equipment is designed, constructed, maintained and used so that its use does not cause any Undue Interference to any wireless telegraphy. This would include filtering of key clicks not overdriving the PA or driver stages and the use of low pass filters to remove harmonics. |
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| 7(4) If any Undue Interference to wireless telegraphy is caused by the radiation of Unwanted Emissions from the Radio Equipment, then the Licensee shall suppress the Unwanted Emissions to the degree satisfactory to Ofcom. Ofcom could measure the interference and make suitable suggestions as to how to reduce the interference to an acceptable level. |
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| 7(5) The Licensee shall conduct tests from time to time to ensure that the requirements set out in this Clause 7 are met. Please refer to note (a) to this Licence. |
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| 7(6) Equipment In order to reduce the likelihood of causing Undue Interference, the Licensee shall ensure that the Radio Equipment is capable of receiving Messages on the same frequencies and with the same classes of emission in use for the transmission of Messages by the Radio Equipment. NB The how to achieve this part of the licence is also covered in the technical section of the exam. |