The NEW Intermediate Licence

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A guide to the changes to the new Intermediate Licence examination syllabus

I will use the words Foundation, Intermediate and Advanced as shorthand to mean their syllabi throughout this piece. I discussed the Foundation changes last month and this month turn to Intermediate. Some 30 teaching points have come ‘down’ to Intermediate from the old Advanced. There is new material too − look for entries in bold.


Has the RSGB ‘raised the bar’? Not overall – the total amount of radio knowledge to be acquired over all three licence levels has not changed. But by re-levelling − putting a little more theory into Foundation, and rather more into Intermediate −- Advanced becomes less daunting and more amateurs, the plan is, will progress to a Full licence.


Changes to Intermediate were necessary for another reason. Ofcom have long been unhappy with this level. Theory-wise, Intermediate is barely a step up from Foundation. Students can too easily pass at Intermediate, gaining access to more bands, higher power and the right to build and use transmitters. 


So here we go. I have detailed all the changes (I hope; I may have missed some minor ones!)

 

Section 1: Licensing Conditions
Syllabus ref 1A4 gives the conditions whereby licences can be varied and revoked. The requirement to revalidate your details at least every five years has always been covered at Foundation, so students should know it.

Section 2: Technical Aspects
My commentary appears below and my specific comments, sub-section by sub-section, in Table 1 at the bottom of this article.


Section 2E introduces the concept of ‘phase’ in AC waveforms. This is new. A rondeau or ‘round’ in music might help in teaching this. Do you remember these from primary school? One group of singers starts, and a line or two later another group starts. Both groups proceed, at the same speed, singing different parts of the song.


Section 2F Digital Signals, which was introduced at new Foundation, is now built on.


Section 2F1 made me stop and think: Nyquist’s rule, based on Shannon’s work, says that a digital sampling rate must be at least twice the bandwidth of the analogue ‘data’ to be sampled. CD-quality sound has a frequency response of 20kHz and a sampling rate 44kb/s, for example.


Resonance is covered in Section 2H1. Students must understand that at resonance capacitive and inductive reactance are equal and ‘opposite’. I modelled a 20m resonance in Excel - see Fig. 1. Xc and Xl lines crossing and will be theory enough for most students. Xl’s direct proportionality to frequency versus Xc’s inverse relationship with it is required knowledge.

Fig1. Resonance modelled in Excel – note where the inductive and capacitive reactances cancel.


Q is introduced in section 2H4, as an indication of selectivity. It is defined as bandwidth divided by frequency.


Section 2H5 is about filters. Response curves and filter sharpness, including cut-off frequencies, are covered. Students learn about crystals, classified as ‘electro-mechanical resonators’. (See Sections 10B and 10C.)


Section 2I5 deals with biasing. Semiconductors must be provided with the correct voltages and currents to function.


Section 2I7 takes us beyond transistors and introduces Integrated circuits and their substrate design and construction. Applications students can be examined on are amplifiers, oscillators, voltage regulators and digital processing chips.


Section 2J introduces students to different battery technologies.

 

Section 3: Transmitters
Modulation depth and Deviation are new. Students may be familiar with modulation depth from HF SSB operating but beware! Many Foundation students don’t operate HF and their only SSB experience could be from their course.


Deviation settings should be well-known from programming memories into radios. Wide and narrow deviation can be demonstrated with a 2m handie. Peak deviation can be explained in terms of channel steps and avoiding co-channel interference.


Section 3A3 includes a new recall point – that digital signals may use less bandwidth than any of (in order, high to low), FM, AM, SSB or CW.


Digital Synthesis DDS is introduced in Section 3C3. Students should recall that RF and AF (analogue) waveforms can be created by computers using a look-up table. Anybody who uses Excel seriously will know look-up tables.


Amplifier efficiency – but not classes of amplifier – now features in Intermediate. Section 3F1 requires students to understand amplifier (RF or AF) efficiency based on input (DC) power consumed. This topic may expose student weaknesses in calculating percentages.


Chirp appears, in Section 3G5. Are students likely to have experienced this, given the Foundation licence’s power restrictions? I doubt it, but if an Intermediate student were to homebrew a 50W CW transmitter with insufficient DC isolation between the keying stage and the PA, Chirp could rear its ugly head.


Section 3H2 requires students to understand block diagrams for crystal and direct conversion receivers. 


Superhets are covered by Section 3I. Students will learn to ‘identify the tuned circuits in the circuit of an IF amplifier’.


Section 3M1 has more Digital Signals ‘recall’ points. Time and Frequency domains are central concepts to digital signalling. See Fig. 2, another Excel model, which shows amplitude against time for a10Hz waveform with the second and third harmonics added. This is a Time Domain plot. Because of the scale and easy numbers, the relative amplitudes are easy to pick out.

Fig 2: Digital signal in the time domain.


Now look at Fig. 3. This is a Frequency Domain display of the same waveform and shows the three component frequencies. This frequency resolving is what Fourier transformation does. Students are required to identify simple harmonic waves with one or two harmonics.

Fig 3: Digital signal in the frequency domain.


Automatic Gain Control (AGC) was already part of Intermediate. Section 3L1 now adds that AGC ‘can drive a signal meter’. How or why is not explained! Disabling AGC will prove this − the S-meter will simply stop working.

 

Section 4: Feeders and Antennas
Section 4G1 explains Dummy loads and the importance of resistors being as non-inductive as possible. Carbon resistors are good but the syllabus does not give examples.

 

Section 5: Propagation
The syllabus gives students a good picture of how propagation works.

 

Section 6: EMC
Section 6D2 requires students to understand common and differential mode currents. This is one of those things many of us nod sagely along to when it comes up without really understanding!


Consider an open feeder terminated by a resistive load and connected to an RF AC source. See Fig. 4. It’s a straightforward complete circuit and the instantaneous ‘up’ current (let’s say on the left) has to equal the ‘down’ current on the right. These are ‘differential’ currents.

Fig 4: Feeder, driven by AC source and terminated with a resistor.


Now make the load a dipole at resonance. The circuit, from the RF generator’s point of view, has not changed. This is the ultimate in balanced antenna systems.


Now let reality bite and add a bit of imbalance – perhaps the antenna slopes, say, Fig 5. This shows a new current flowing in the antenna system. This is quite unlike the differential current, because it flows in the same direction on both feeder wires.

Fig 5: As Fig. 4 but with some imbalance in the system.


Why both wires? Because they are so close together compared to the RF wavelength that the open feeder ‘looks like’ one wire. Say the instantaneous differential and common mode currents are 1000mA and 100mA respectively. The currents combine, so the up current will be 1100mA when the down current is 900mA.


The problem comes when amateurs talk of common mode currents in coax.


Open feeder looks like, and to RF is, two wires. Coax also looks like two conductors, but to RF it has three, Fig. 6. There is the inner conductor, the inside surface of the braid and the outside of the braid. The inner conductor and inside surface of the braid are so closely coupled that any currents in them are always equal and opposite.

Fig 6: Modelling coax (see text).


Even with a balanced antenna current can easily flow down the outside of the coax. But the coax inner offers no additional path for an imbalance-generated current to flow. The current on the outside of the coax consequently has nothing to be ‘common’ with. It’s a nuisance, for sure (hence the use of choke baluns) but it is not, strictly speaking, a ‘common mode’ current.


I hope that helps. By exploring that, at least I understand it now!

 

Section 7: Operating practices and procedures
Section 7B1 covers some important international conventions such as no SSB on 10MHz, no contests on 10, 18 and 24MHz and satellite frequencies to be avoided for terrestrial QSOs.


Band Plans for 2m and 20m are provided in the exam. These may not be ‘real’ so students should forget what they know from operating and check the band plans supplied for the exam. Such easy marks should not be squandered.


Section 7F2 has more about receiving and transmitting Digital signals. Students must recall that different types (modes) of transmissions can be received using a computer and ‘a suitable interface’. See Figs. 7 and 8 for block diagrams (not the ‘official’ ones) of a simple SDR receiver and transmitter. When transmitting, voice distortion can be minimised by adjusting the operation of the Digital Audio Controller (DAC).

Fig 7: Block diagram of a software defined receiver.

 

Fig 8: Block diagram of software defined transmitter.

Section 8: Safety
These still are the easiest marks in the exam. Starting at question 40, students should ignore radio and electronics per se and just consider safety.


There is no 8A3, 5 or 7.

 

Section 9: Measurement and Construction
At Intermediate level, EMC includes elements of design and construction. Section 9D1 requires students to recall that metal sheeting such as a radio’s case is effective in preventing unwanted RF from radiating and is used in design and construction to isolate RF stages.

 

Section 10: Practical assessments
Wiring mains plugs has gone from the syllabus. I say no more.


10B Construction. This section of the article differs from above in that it details all that is required. Considering all the theory changes, the practical exercises – which have not increased – might seem to be less important. I don’t think they are; hands-on radio skills are still central to the Intermediate licence. 


10B2 – Students may solder anything – no component types are specified! – to anything, even solder tags. Tutors (braver than me) could use this to introduce surface mount construction.


For Section 10B3 I offer the circuit in Fig. 9, which meets the literal requirement. The switch is not an on-off, so the LEDs will always be on if power is connected, and that makes me wonder if something less involved may have been intended.

Fig 9: A simple circuit meeting the requirements of Section 10B3


I strongly recommend LEDs over bulbs. LEDs need resistors, as does the exercise, and have a more modern feel.


10B4 does not say ‘build’, even if is under ‘Construction’. Pre-made transistor switch boards with meter connections already in place could be used. Students can touch prominent contacts to demonstrate the circuit in operation. After reading base and collector currents they can calculate the gain.


10C Instrumentation and Measurement: Nothing to add here above what I have included in the table.


Conclusion
I said in my Foundation article that it must have been an enormous task to update the syllabus, and that goes a thousand-fold for Intermediate. I think the RSGB has done an amazing job. I sincerely mean that.


Yes, Foundation is more difficult (but not much). 


Yes, Intermediate is (definitely) more difficult. 


Yes, clubs have planning to do and changes to make. Some clubs, I’ve heard, are giving up running courses. I hope that does not turn out to be true.


All this needs to be seen in the ‘big picture’. Starting with new Foundation, and really built on by new Intermediate, students will be much better prepared both for ‘doing’ amateur radio and progressing to a Full licence. 

 

This article has been taken from the March 2019 issue of Practical Wireless and has been written by Tony Jones. To read our article on the new Foundation Licence, click here.

 

 

Table 1:

Section

Syllabus requirements

Comments

2C2

Potential dividers with two and three resistors. Calculations of voltage splits

Follow-up to Kirchhoff’s Law covered in Foundation 2C

2C3

Difference between Potential Difference and Electro - Motive Force (EMF)

Important - Inductors now bigger part of essential knowledge

2D2

Capacitors adding in series and parallel

 

2D4

Inductance of coil dependant on turn count and dimensions

 

2D5

Inductances adding in series and parallel

 

2D6

Coils with high (magnetic) permeability cores, leading to ‘slug’ tuning’

 

2E2

Phase difference between AC waveforms (of same type and frequency) expressed in degrees

Square waves (recognise graphically)

 

2E3

Ohm’s law gives Resistance only when phase difference of current and voltage is zero degrees

Commonly expressed as current and voltage ‘in phase’

2E3

Ohm’s law gives Reactance when only Capacitance or Inductance in circuit

Phase difference is 90 degrees for both (but different directions)

2E3

In a capacitor the current leads the voltage

‘CIVil’ mnemonic - in a C(apacitor), I leads V[T1] 

2E3

In an inductor the voltage leads the current

‘ciVIL’ – V leads I in L[T2]  (inductor)

2E4

Capacitive reactance increases as capacitance decreases

‘Xc’ and formula not in syllabus

2E5

Inductive reactance increases as inductance increases

‘Xl’ and formula not in syllabus

2F1

Digital signals with more bits and faster sampling permit more accurate reproduction of analogue signals

Recall

2F1

Error introduced by sampling is a form of distortion

Recall

2F1

Increasing data rate increases bandwidth

Recall

2F1

Sampling rate must be at least twice the analogue frequency to adequately capture waveform detail

Ambiguous

2F1

Minimum sampling rate called the Nyquist rate

Recall

3M1

Fourier Transforms sift the composite signal into its constituent independent frequencies for processing

Recall

3M2

This process can create spectrum or waterfall displays

See Pic 2

3M2

Digital filters can be much more selective than analogue filters

Recall

3M2

Meaning of Time and Frequency domains

Understand

3M3

Block diagram of an SDR

 

4A1

Waveguides- must be at least half a wavelength long

See Pic 5

4B1

Choke Baluns

See Pic 6 – Coax should not be wound in a jumble!

4C2

Front to back ratio for Yagi antennas

Beam width

Radiation patterns exist in three dimensions

 

4C3

Isotropic radiator and dbd to dbi gain comparison

One of the most useful topics in my opinion

4C4

Radiation angle of antennas

Low angles give DX – this is not obvious and needs careful handling.

4C5

Theoretical and practical impedance of a dipole

 

4D2

Traps, used in multi-band and Yagi antennas

 

5A3

Low range ground-based propagation.

Loss increases with frequency

Rule of thumb 2000 wavelengths.

5B2

Maximum Useable Frequency – highest frequency refracted by ionosphere

RF higher in frequency than this goes out into space

5B3

Long and short path propagation

 

5B4

Lowest Useable Frequency – lowest frequency which passes through D layer

LUF can exceed MUF, making HF propagation impossible. Teaching this should be fun!

5B5

Sporadic E – not just for VHF

Can facilitate multiple hops for further dx

Affects 10m and 12m HF bands

Up to 2000 km

8A1

High-value capacitors are dangerous because they can store a lot of energy for a long time.

Use ‘bleed’ resistors to provide discharge path

Demo this. Charge up a hefty electrolytic and short it out!

Hundreds of kiloOhms usually

8A2

Chassis earthing - any exposed metal in a piece of equipment should be properly earthed

 

8A4

Special types of fuse eg slow- and quick-blow

See Pics 9a and 9b

8A6

Working on (mains) live equipment allowed ‘if it is not practical to do otherwise’ providing risks and procedures understood

Was ‘forbidden’ at Foundation – this reflects greater knowledge and trust at Intermediate

8A8

Dangers of vehicle batteries – possibility of large currents and hydrogen gas when charging

 

10B1

Review safety aspects in syllabus

 

10B2

Make five (minimum) ‘good’ soldered joints

Not used after this

10B3

Make simple circuit with power source, switch, two resistors (minimum) and two bulbs or LEDs. Joints need not be soldered.

Circuit must be ‘configurable’ for series or parallel use.

This isn’t a cut-down version of the transistor switch circuit from the old syllabus

See 10C1

10B4

Demonstrate a simple transistor switch circuit. Measure transistor gain.

See below

10B5

Build an RF project

No change

10C1

Measure voltage and current in series and parallel circuits

 

10C2

Measure the resistance of a number of resistors with a meter and compare against colour bands

My club uses a ‘toast rack’ of resistors. See Pic 11

10C3

Determine the resistance of two resistors by measuring voltage and current

Use easy values – it’s a test of applying Ohm’s law, not maths

10C4

Demonstrate that a crystal oscillator is stable when subjected to reasonable temperature changes and mechanical shock

Use a hairdryer for heat or a compressed air blower for cool. Tap lightly with a plastic pen

10C5

Demonstrate that a VFO (LC type) is ‘not very stable’ when subjected to temperature changes and mechanical shock

 

10C6

Find at least the 2nd and 3rd harmonics using a receiver or spectrum analyser

An excellent opportunity to introduce students to laboratory equipment.

10C7

Demonstrate that a Low Pass Filter or an AMU suppresses harmonics

Does anyone call an AMU an AMU in real life?

10C8

Calibrate a VFO using a receiver or spectrum analyser

Same as old syllabus


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