PUBLIC REVIEW DRAFT, OCTOBER 2008KENYA STANDARD KS 1884-3:2008 
ICS 33.120.40; 33.160.10 
© KEBS 2008 First Edition 2008  
 
 
  
 
  
 
Specification — Accessories for use in 
antenna installations —  
 
Part 3: TV channel amplifiers, band amplifiers and 
broadband amplifiers 
 
 
   
 
  
 
 
 
PUBLIC REVIEW DRAFT, OCTOBER 2008 
 
 
 
 
 
 PUBLIC REVIEW DRAFT, OCTOBER 2008KS 1884-3:2008  
ii © KEBS 2008 — All rights reserved TECHNICAL COMMITTEE REPRESENTATION 
 
The following organizations were r epresented on the Technical Committee: 
 
Widestream Communications Limited Kenya Broadcasting Corporation 
Meteorological Department 
Kenya Power & Lighting Company  
Telea (K) Limited 
SR Kenya Limited 
Department of Defence 
Kenya Police Force 
Communications Commission of Kenya Kenya Bureau of Standards — Secretariat 
 
  
 
   
REVISION OF KENYA STANDARDS 
 
In order to keep abreast of progress in industry, Ke nya standards shall be regularly reviewed. Suggestions 
for improvement to published standards, addressed to  the Managing Director, Kenya Bureau of Standards, 
are welcome. 
 
  
 
   
 
  
© Kenya Bureau of Standards, 2008 
 
Copyright. Users are reminded that by virtue of Section 25 of the C opyright Act, Cap. 12 of 2001  of  the Laws of Kenya, copyrig ht 
subsists in all Kenya Standards and except as provided under Section 26 of this Act,  no Kenya Standard produced by Kenya Bureau  of 
Standards may be reproduced, stored in a retrieval system in any form or transmitted by any means without prior permission in w riting 
from the Managing Director. 
 
   
 
  
 
   
 
  
 
 
 
 
  
 PUBLIC REVIEW DRAFT, OCTOBER 2008KENYA STANDARD KS 1884-3:2008 
ICS 33.120.40; 33.160.10 
© KEBS 2008 — All rights reserved  iii  
 
 
  
 
 
 
Specification — Accessories for use in antenna installations —  
 
Part 3: TV channel amplifiers, band amplifiers and 
broadband amplifiers  
 
            
   
 
KENYA BUREAU OF STANDARDS (KEBS) 
 
Head  Office:  P.O. Box 54974, Nairobi-00200, Tel.: (+254  020) 605490, 69028000, 602350, Mobile: 0722202137/8, 0734600471/2; 
Fax: (+254 020)  604031 
E-Mail: info@kebs.org,  Web:http://www.kebs.org  
 
KEBS Coast Region 
P.O. Box 99376, Mombasa 80100 
Tel: (+254 041) 229563, 230939/40 
Fax: (+254 041) 229448 E-mail: kebs-msa@swiftmombasa.com KEBS Lake Region 
P.O. Box 2949, Kisumu 40100 
Tel: (+254 057) 23549,22396 
Fax: (+254 057) 21814 
E-mail: kebs-ksm@swiftkisumu.com KEBS North Rift Region 
P.O. Box 2138, Nakuru 20100 
Tel: (+254 051) 210553, 210555PUBLIC REVIEW DRAFT, OCTOBER 2008KS 1884-3:2008  
iv © KEBS 2008 — All rights reserved FOREWORD 
 
This Kenya standard wa s prepared by the Communication Equipment  under the mandate of the Electrical 
Industry Standards Committee in accordance with the procedures of the Bureau and is in compliance with 
Annex 3 of the WTO/TB Agreement. 
 
  
 
Normative and informative annexes  
 
A 'normative' annex is an integral part of a standard, whereas an 'inf ormative' annex is only for information 
and guidance.  
  
 
  
 
  
 
Summary of development  
 
This Kenya Standard, 
having been prepared 
by the Communication Equipment Technical 
Committee was first 
approved by the 
National Standards 
Council in December 2008  
 Amendments issued since publication 
Amd. No. Date Text affected 
   
   
   
   
   
 PUBLIC REVIEW DRAFT, OCTOBER 2008PD/09/01/2005 
© KEBS 2006 — All rights reserved  v  
Contents 
 
1 Scope ....................................................................................................................... ............................. 1 
2 Normative re ferences ........................................................................................................ ................... 1 
3 Defini tions ................................................................................................................. ............................ 1 
4 General r equireme nts ........................................................................................................ ................... 2 
4.1 Mate rial .................................................................................................................. ............................... 2 
4.2 Corrosion protection ...................................................................................................... ....................... 2 
5 Mechanical r equirements ..................................................................................................... ................. 2 
5.1 Terminal robustness ....................................................................................................... ...................... 2 
5.2 Sealing ................................................................................................................... ............................... 2 
5.3 Continuity between input and out put terminals of the outer cable ........................................................ 2 
6 Electrical requirements ..................................................................................................... .................... 2 
6.1 Amplitude frequency re sponse of output(s) ................................................................................. ......... 2 
6.2 Cross-m odulation .......................................................................................................... ........................ 3 
6.3 Intermodulation-lim ited output voltage .................................................................................... .............. 3 
6.4 Carrier-to- noise ratio .................................................................................................... ......................... 3 
6.5 Return  loss ............................................................................................................... ............................. 3 
6.6 Component radiati on characteristics ....................................................................................... ............. 3 
7 Test methods ................................................................................................................ ........................ 3 
7.1 Corrosion pr otection test ................................................................................................. ...................... 3 
7.2 Test for term inal robustness .............................................................................................. ................... 4 
7.3 Seali ng test .............................................................................................................. ............................. 4 
7.4 Test for continuity between input and output terminals of the outer cable ........................................... 4 
7.5 Test for amplitude frequen cy response of  output(s) ........................................................................ ..... 5 
7.6 Test for cro ss-modulation ................................................................................................. .................... 5 
7.7 Test for intermodulatio n-limited output  voltage ........................................................................... .......... 7 
7.8 Test for television carrier-to-noise ratio ................................................................................ ................ 8 
7.9 Test for return loss ...................................................................................................... ........................ 10 
7.10 Test for component ra diation charac terist ics ............................................................................. ......... 10 
8 Packing and marking ......................................................................................................... ................. 14 
8.1 Packing ................................................................................................................... ............................ 14 
8.2 Marking ................................................................................................................... ............................ 14 
8.3 Instructi on leaflet ....................................................................................................... .......................... 14 
Annex A (normative)  Equipment required — Additi onal items .................................................................... ... 23 
Annex B (normative)  Preliminary checks on the me asuring equipment for carri er-to-noise ratio .................. 24 
Annex C (normative)  The absorbing clamp and its applic ation for the measurement of interference power 25 
Annex D (informative)  Adaptors for conn ecting the cables to the component ............................................... 28 
Annex E (informative)  The stop filter ........................................................................................ ...................... 30 
Annex F (informative)  Correction factors ..................................................................................... ................... 31 
Annex G (informative)  Calibrati on of the select ive voltmeter ................................................................. ........ 32 
 
 PUBLIC REVIEW DRAFT, OCTOBER 2008PUBLIC REVIEW DRAFT, OCTOBER 2008 
KENYA STANDARD KS 1884-3:2008  
© KEBS 2008 — All rights reserved  1   Specification — Accessories for use in antenna installations — Part 3: 
TV channel amplifiers, band amp lifiers and broadband amplifiers 
 
 
1 Scope 
 This part of KS 1884 specifies the mechanical and elec trical requirements for TV channel amplifiers, band 
amplifiers and broadband amplifiers, for use in antenna installations both indoors and outdoors, that cover 
the following frequency bands: 
 
⎯ FM sound 88 MHz to    108 MHz 
 
⎯ VHP television band III 174 MHz to   254 MHz 
 
⎯ S-band 254 MHz to   438 MHz 
 
⎯ UHF television bands IV and V 470 MHz to   860 MHz 
 
⎯ Ku band (satellite) 950 MHz to 2 050 MHz 
 
2 Normative references 
 
The following referenced documents are indispensable fo r the application of this Kenya Standard. For dated 
references, only the edition cited applies. For undated references, the latest edition of the referenced 
document (including any amendments) applies.  
EC 68-2-11, Basic environmental testing procedures — Part  2: Tests — Chapter 11: Test Ka: Salt mist  
 
IEC 68-2-18, Basic environmental testing procedures — Part  2: Tests — Chapter 18: Test R and guidance: 
Water  
 IEC 68-2-21, Basic environmental testing procedures — Part 2:  Tests — Chapter 21: Test U: Robustness of 
terminations and integral mounting devices  
 IEC 60934, Moulded-case circuit-breakers
 
 
3 Definitions 
 
For the purposes of this part of KS 1884, the following definitions apply:  
3.1 
Acceptable 
acceptable to the parties concluding the purchase contract 
 
3.2 
Amplifier 
A term that includes channel amplifiers, band amplifiers  and broadband amplifiers, unless specifically stated 
otherwise.  
3.3 
cross-modulation 
The modulation of the ca rrier of a wanted signal F
w by the modulation of another, unwanted signal Fuw, and 
expressed quantitatively as follows: 
 PUBLIC REVIEW DRAFT, OCTOBER 2008KS 1884-3:2008  
2 © KEBS 2008 — All rights reserved carrier wanted theon  modulation d transferre of ge peak volta - peak carrier wanted theon  modulation wanted of  ge peak volta peaklog−20  
 
3.4 
return loss The difference between the forward voltage (or current) an d the reflected voltage (or current) at the amplifier 
input terminals, expressed in decibels.  
4 General requirements 
 
4.1 Material 
 
Amplifiers and their mounting facilitie s shall be fabricated from a material that is suitable for use in the 
environment in which the amplifiers and mounting fac ilities are intended to be used. Non-metallic materials 
used shall be stabilized to  ultraviolet (UV) light. 
 
4.2 Corrosion protection 
 The requirement given below applies only to amp lifiers intended for use outdoors or where high 
temperatures and high humidity are experienced. 
 
When an amplifier and its mounting facilities are tested in accordance with 7.1, they shall show no sign of 
corrosion. (See also 6.1.) 
 
5 Mechanical requirements 
 
5.1 Terminal robustness 
 
The requirement given below applies only to amplifie rs where screw type terminal cable connections are 
incorporated. It does not apply where su itable terminal sockets are fitted. 
 
The input and output terminals shall be so designed that they will accommodate a 75 Ω coaxial cable (of 
dimensions specified by the amplifier manufacturer) in such a way that the characteristic impedance of the 
cable is not affected. 
 
When the amplifier is tested in accordance with 7.2, there shall be no sign of damage or deformation of the 
cable or terminals and the cable shall not have become dislodged.  
 
5.2 Sealing 
 
When an amplifier that is intended for use outdoors is  tested in accordance with 7.3, no water shall have 
entered the housing. 
 
5.3 Continuity between input and output terminals of the outer cable 
 When tested in accordance with 7.4, the circuit- breaker shall have tripped on each performance of the 
procedure in 7.4.2.2. When the track between termi nals is being inspected, there shall be no sign of 
deterioration owing to generation of heat.  
6 Electrical requirements 
 
6.1 Amplitude frequency response of output(s) 
 
The manufacturer shall state the frequency response of  the output(s), giving the maximum gain, in decibels. 
The line joining the gain at the lower and upper frequenc ies of the band under consideration is the "nominal 
line". 
 
When determined in accordance with 7.5, the deviati on in gain from the nominal line shall not exceed the 
values given in Table 1.  
 PUBLIC REVIEW DRAFT, OCTOBER 2008KS 1884-3:2008 
© KEBS 2006 — All rights reserved  3 Table 1 — Limits for amplitude frequency response of output(s) 
 
Values in decibels 
1 2 3 
Frequency band Band and broadband amplifiers Channelized amplifiers 
FM 2 — 
III 2 0.5 
S (14-40) 2 0.5 
IV & V 5 0.5 
Satellite — 5.0 
 
If an amplifier is intended for outdoor use, the test sha ll be performed both before and after the test specified 
in 7.1. The results of the two tests shall not differ. 
 
6.2 Cross-modulation 
 
When determined in accordance with 7.6, the cros s-modulation ratio shall be not less than 40 dB. 
 
6.3 Intermodulation-limited output voltage 
 
When determined in accordance with 7.7, the lowest  value of intermodulation-limited output voltage ( U3), 
taken from the curve, is the "maximum intermodulat ion-limited output voltage" and at no point on the curve 
shall the "intermodulation ratio" fall below the appropriate relative value given in Table 2. 
 
Table 2 — Limits for maximum intermodulated-limited output voltage 
 
1 2 3 
Frequency band Channel amplifiers, a1 
dB Band and broadband amplifiers a1
dB 
VHP (FM) — 50 
TV bands  
(III, IV, V) 54 With 2 TV channels 60 
 
6.4 Carrier-to-noise ratio 
 When determined in accordance with 7.8, the televi sion carrier-to-noise ratio shall be not less than 40 dB. 
 
6.5 Return loss 
 When determined in accordance with 7.9, the return  loss within the frequency range stated by the 
manufacturer, shall, at a frequency of 80 MHz but reduced by 1.5 dB per octave, be a minimum of 40 dB. 
 
6.6 Component radiation characteristics 
 
When determined in accordance with 7.10, the minimu m value for the component radiation characteristic 
shall be: 
 
⎯ 75 dB in the frequency range 0.01 MHz to 470 MHz; 
 
⎯ 65 dB in the frequency range 470 MHz to 960 MHz; and 
 
⎯ 55 dB in the frequency range 960 MHz to 2 050 MHz. 
 
7 Test methods 
 
7.1 Corrosion protection test 
 
NOTE This test is applicable only to thos e amplifiers and associated mounting facili ties that are intended for outdoor use or f or use in 
situations where high humidity and high temperatures are expe rienced, and is carried out both before and after the test given i n 7.5. 
 
 PUBLIC REVIEW DRAFT, OCTOBER 2008KS 1884-3:2008  
4 © KEBS 2008 — All rights reserved 7.1.1 Apparatus 
 Chamber and solution , for producing the salt mist as described in IEC 60068-2-11. 
 
7.1.2 Procedure 
 
7.1.2.1 Suspend the component under test, together with its mounting facilities (where supplied), as 
centrally as possible in the chamber. 
 
7.1.2.2 Subject the component to the procedure described in  test Ka of IEC 60068-2-11, for a period of 24h. 
 
7.1.2.3 Repeat 7.1.2.2 a further three times. 
 7.1.2.4 Examine the component and its mounting facilities (where supplied) for signs of corrosion. 
 
7.1.2.5 Check for compliance with 4.2.
 
 
7.2 Test for terminal robustness 
 
7.2.1 Apparatus 
 7.2.1.1 Clamp , that is suitable for mounting the component under  test (as given in 7.2.2) and that is capable 
of withstanding the forces given in 7.2.3.  
7.2.1.2 Apparatus , as specified in tests Ua and Ub of IEC 60068-2-21. 
 
7.2.2 Mounting of the components 
 
Mount the component in the clamp and connect the coaxial cable recommended by the manufacturer to 
each outlet in turn, in accordance with the manufacturer's instructions.  
7.2.3 Procedure 
 
Follow the procedures specified in test U
a, and test Ub of IEC 60068-2-21, once for each test, applying forces 
of 40 N and 20 N respectively to the coaxial cable. Ex amine the cable and terminals for compliance with 5.1. 
 
7.3 Sealing test 
 
7.3.1 Apparatus  
Apparatus, as specified in test Rb 2.2 of IEC 60068-2-18. 
 
7.3.2 Test conditions 
 The test conditions shall be as specif ied in test Rb 2.2 of IEC 60068-2-18. 
 
7.3.3 Procedure 
 
Mount the component in the apparatus in a way that simulates, as far as possible, the way in which the component would be mounted for use outdoors. Subject t he component to a spray for 15 min, without the 
shield.  
7.3.4 Check for compliance with 5.2. 
 
7.4 Test for continuity between input and output terminals of the outer cable 
 
7.4.1 Apparatus  
7.4.1.1 20 A moulded-case circuit-breaker, that comp lies with the relevant clauses of IEC 60934. 
 
7.4.1.2 Load resistor, with a resistance of approximately 7 Ω and that is capable of carrying 20 A for a period 
equal to the time taken for the circuit-breaker to trip. PUBLIC REVIEW DRAFT, OCTOBER 2008KS 1884-3:2008 
© KEBS 2006 — All rights reserved  5  
7.4.1.3 Mains switch, capable of carrying a minimum of 30 A.  
 7.4.2 Procedure 
 
7.4.2.1 Connect the apparatus as shown in Figure 15. 
 
7.4.2.2 Switch the apparatus on and ensure that the circ uit-breaker has tripped, then switch the apparatus 
off and restore the circuit-brea ker to its operational state. 
 
7.4.2.3 Repeat the procedure specified in 7.4.2.2 a further nine times consec utively and without interruption. 
 7.4.2.4 Check for compliance with 5.3.
 
 
7.5 Test for amplitude frequency response of output(s) 
 
NOTE In the case of an amplifier that is intended for outdoor us e, this test is carried out both before and after the test give n in 7.1. 
 
If an amplifier employs automatic gain control (AGC), the manufacturer shall state, for test purposes, how the 
AGC can be switched off and provided with a const ant control voltage, or he may indicate how the 
measurement can be made within t he control range of the amplifier. 
 
7.5.1 Apparatus 
 
7.5.1.1 Signal generator , with appropriate frequency coverage. 
 
7.5.1.2 Measuring receiver , with appropriate frequency coverage. 
 
7.5.1.3 Two suitable calibrated attenuators , of appropriate impedance, adjustable in steps of not more 
than 1 dB. These may be incorporated in the signal generator and receiver. 
 7.5.1.4 Suitable coaxial changeover switch.  
 
7.5.2 Procedure 
 
7.5.2.1 Connect the apparatus as shown in Figure 1. 
 
7.5.2.2 With the switch in position A and the signal generator set to the lowest frequency of the frequency 
range under consideration, so adjust the output from t he signal generator and att enuator 1 that the input to 
the component under test is at a level com parable to that encountered in actual use. 
 
7.5.2.3 With the switch in position A, adjust attenuator  2 to obtain a convenient reading on the measuring 
receiver and record the attenuation in attenuator 2 as U
a dB. 
 
7.5.2.4 With the switch in position B, increase the att enuation in attenuator 2 to  restore the reading on the 
receiver that was obtained in 7.5.2.3 and record the attenuation in attenuator 2 as Ub dB. 
 7.5.2.5 Record the gain U
b - Ua. 
 
7.5.2.6 Measure and record the gain at the end freque ncies of the frequency range claimed by the 
manufacturer and at a sufficient number of frequencies wi thin this range to enable a curve of gain against 
frequency to be plotted.  7.5.2.7 Check for compliance with 6.1.  
 
7.6 Test for cross-modulation 
 
7.6.1 General  
The method described is applicable to the measurement of the cross-modulation ra tio between two television 
signals by the transfer of modulation from an interfer ing unwanted signal to an unmodulated wanted signal 
between two points in a cabled dist ribution system or component. 
 PUBLIC REVIEW DRAFT, OCTOBER 2008KS 1884-3:2008  
6 © KEBS 2008 — All rights reserved It uses an interfering test signal modulated symmetrica lly about a level such that the voltage at the peak of 
the modulation envelope is equal to the reference level L,  which is also the level of the unmodulated wanted 
signal. (For signals with unequal levels, see 7.6.4.4.) 
 A correction factor is also included to allow for t he use of modulation depths of less than 100 % (see Table 
3). 
 
Table 3 — Modulation depth correction factors 
 
1 2 
Modulation (a.c. coupled) Correction (add to measured ratio) 
% dB 
100 
90 
80 0 
0.4 0.9 
70 
60 
50 1.4 
1.9 
2.5 
40 
30 3.1 3.7 
 
The relationship between cross-modulation ratios obta ined at different signal levels might not follow the 
theoretical level variation for third-order products. 
 
7.6.2 Apparatus 
 7.6.2.1 Radio-frequency (r.f.) selective voltmeter , that covers the frequency range under consideration. If 
the selectivity and linearity of the vo ltmeter are not adequate to prevent th e internal generation of spurious 
signals, the bandpass filter shown in figure 5 shall be used. The voltmete r shall indicate the r.m.s. value of its 
input signal at the peaks of  the modulation envelope. 
 
7.6.2.2 Two signal generators , that cover the frequencies of the test signals and one of which has the 
required modulation facilities, linear at the depth of modulation to be used. The modulation frequency shall 
approximate to the line scan frequency of TV signals, in order to include the effects that might be caused by 
low-frequency (l.f.) circuits (for example, decoupling) in the equipment to be tested. 
 
Any symmetrical modulation waveform (excluding pulse modulation) may be used, provided that the same 
signal generator is used for both calibration and m easurement and that the modulation depth and waveform 
remain the same.  
7.6.2.3 Audiofrequency (AF) selective voltmeter , that covers the modulation frequency to be used and 
has a calibrated input level range that exce eds the expected cross-modulation ratio. 
 7.6.2.4 Combiner, matching devices, attenuators and filters, etc. , to obtain the correct signal level, 
matching and reduction of spurious signals. 
 7.6.3 Conditions of measurement 
 
7.6.3.1 Television signals employ d.c. coupled modulation, ei ther decreasing from (negative) or increasing to 
(positive) a maximum level L. The cross-modulation ratio is expressed in terms of a 100 % d.c. coupled 
modulated signal. This can be simulat ed by the use of other r.f. carrier levels and depths of modulation, 
corrected by the appropriate factor given in Table 3. 
 The sensitivity of the measurement is  increased with the depth of modulatio n used, but it should be restricted 
to a depth at which the linearity of the modul ation and demodulation processes are beyond doubt. 
 7.6.3.2 Measurements should be carried out wi th the test signals widely and closely spaced over each band 
of interest, in order to determine the least favourable environmental conditions.
 
 
7.6.3.3 Measurements should be performed at the reference level L. Except where otherwise specified, the 
reference level L used in the measurements is the normal operating signal level or levels specified for the 
amplifier. Where the tests are to be carried out with  unequal levels for the two signals, L is the specified PUBLIC REVIEW DRAFT, OCTOBER 2008KS 1884-3:2008 
© KEBS 2006 — All rights reserved  7 output level for the signal at the wanted carrier frequency Fw. The level of the unwanted carrier frequency Fuw 
is changed to equal that of Fw for calibration only (see 7.6.4.2 and 7. 6.4.3). The levels used should be quoted 
together with the results and together with the modulation frequency used. 
 
7.6.3.4 Where the system or equipment to be measured includes: 
 a) automatic gain control (AGC), te sts should include the designed maximum and minimum levels for the 
input signals; and 
 
b) automatic level control (A LC), standard pilot signals or other cont rol stimuli should be provided to ensure 
normal operation. 
 7.6.3.5 If instruments other than those specified are used, the test procedure should be modified only to the 
minimum extent necessary. The resu lts obtained should be checked for agreement with this test method. 
Great care should be taken in extrapolating results fr om measurements using this method to other system 
arrangements, for example, additional signals or repeater amplifiers. 
 7.6.3.6 All levels shall be expressed in r.m.s. values.  
 7.6.4 Procedure 
 
7.6.4.1 Connect the equipment as shown in Figure 5. 
 7.6.4.2 With SG
w turned off, tune SG uw to Fuw, set the modulation depth and adjust the output to give the 
desired r.f. peak level L at the output of the amplifie r to be tested, using the r.f. selective voltmeter. 
 
7.6.4.3 Adjust the AF selective voltmeter for a convenient reading A of the demodulated signal. Note this 
reading. 
 
7.6.4.4 Where the two signals have unequal levels, reset SG uw to give the specified value for Fuw at the 
output of the amplifier to be tested. 
 
7.6.4.5 Switch off SG uw and switch on SG w. Tune SG w to Fw and set its unmodulated output to give the 
desired r.f. level L at the output of the amplifier to be tested, using the r.f. selective voltmeter. 
 7.6.4.6 Switch on SG
uw and, with the r.f. selective voltmeter tuned to Fw, note the level C of the demodulated 
cross-modulation signal on the AF selective voltmeter.  7.6.4.7 The difference, in decibels, between level A and level C (A - C), corrected as in table 3, is the cross-
modulation ratio referred to 100 % d.c. coupled modulation.  7.6.4.8 Check for compliance with 6.2. 
 
7.7 Test for intermodulation-limited output voltage 
 
7.7.1 General 
 
The following test gives the maximum intermodulation-limited output voltage for a specific intermodulation 
ratio. 
 If an amplifier employs automatic gain control, the manuf acturer shall state, for test purposes, how the AGC 
can be switched off and provided with a constant cont rol voltage, or he may indicate how the measurement 
can be made within the control range of the amplifier. 
 
7.7.2 Apparatus 
 
7.7.2.1 Three signal generators , that cover the appropriate frequency range. 
 
7.7.2.2 Combiner , for the three generators. 
 
7.7.2.3 Two attenuators , variable in steps not exceeding 1 dB. 
 
7.7.2.4 Measuring receiver .  PUBLIC REVIEW DRAFT, OCTOBER 2008KS 1884-3:2008  
8 © KEBS 2008 — All rights reserved  
7.7.3 Procedure 
 
7.7.3.1 Connect the apparatus as shown in Figure 2. 
 
7.7.3.2 In the case of channel amplifiers, set the three unmodulated signal generators to the frequencies f1 
(vision carrier), f2 (colour carrier) and f3 (sound carrier) and with the relative amplitudes shown in Figure 3 at 
the output of the component under test. 
 
In the case of band and broadband amplifiers, set the frequencies to f1, f2 and f3, which are arbitrary within 
the frequency range to be covered and with the frequenc y spacings and relative amplitudes shown in Figure 
4.  
7.7.3.3 Adjust the level of the signal spectrum, by means of  attenuator 1, until the am plitude of the larger of 
the intermodulation products U
1 and U’1 in the output signal is less than the output voltage U3 by 40 dB. At 
this point, the value of U3 is the "intermodulation-limited output voltage for the specified intermodulation 
ratio". 
 7.7.3.4 Check for compliance with 6.3. 
 7.7.3.5 In the case of band and broadband amplifiers, take measurements at the band ends and at a 
sufficient number of approximately equally spaced poi nts in between, to enable curves to be drawn of 
"intermodulation-limited output voltage" and "intermodulation ratio" against frequency. 
 If the amplifier has a manual gain control after the input  stage, perform measurements at the positions of 
minimum and maximum gain.  7.7.3.6 Check for compliance with 6.3.  
 
7.8 Test for television carrier-to-noise ratio 
 
7.8.1 General  
The method described is applicable to the measuremen t of the carrier-to-random-noise ratio within a 
television channel. The method actually determines the carrier-(plus noise)-to-noise ratio; however, the difference between this and the carrier-to-noise-rat io is very small if the value exceeds 20 dB. 
 
The method assumes that the random noise is evenly distributed within the channel. 
 
7.8.2 Apparatus 
 
7.8.2.1 Selective voltmeter , with a known noise bandwidth that is less than that of the television channel to 
be measured.  7.8.2.2 Signal generator (continuous wave) , that covers the frequencies at which the tests are to be 
carried out (see Figure 14). 
 
7.8.2.3 Variable attenuator , with a range that exceeds the expected carrier-to-noise ratio, variable in steps 
not exceeding 1 dB. 
 
7.8.2.4 Shielded terminating resistor . 
 
NOTE Additional items might be necessary, for example, to ens ure correct calibration and operation of the test equipment (see 
Annex A). 
 
7.8.3 Procedure 
 
7.8.3.1 General 
 Ensure that the set-up is well matched  and that the sensitivity of the me asuring equipment is known over the 
frequency range to be measured (see Annex B). 
 PUBLIC REVIEW DRAFT, OCTOBER 2008KS 1884-3:2008 
© KEBS 2006 — All rights reserved  9 Where the amplifier to be measured includes automati c gain control (AGC), carry out tests at minimum and 
maximum levels of signal input.  
 
Where the amplifier to be measured includes automati c level control (ALC), maintain pilot signals of the 
correct type, frequency and level throughout the tests. 
 
7.8.3.2 Calibration 
 For the calibration of equipment, ensure that the following variables are controllable: 
 
a) level correction, average/r.m.s.  or peak/r.m.s. (see Annex F); and 
 b) noise bandwidth (see Annex G). 
 
7.8.3.3 Other checks 
 Perform the following checks: 
 a) sensitivity (see Annex A); 
 
b) noise (see Annex B);  
c) intermodulation (see Annex B); and 
 d) overload (see Annex B).  
 
7.8.4 Measurement 
 7.8.4.1 Connect the equipment as shown in Figure 14. 
 
7.8.4.2 Set the signal generator to the vision carrier freq uency of the channel to be tested and adjust its 
output to obtain the specified input level to the amplifier being tested. 
 
7.8.4.3 Tune the selective voltmeter to the vision carrier frequency and note the attenuator value A
1 required 
to obtain a convenient voltmeter reading R. 
 
The attenuator value A1 should be slightly greater than t he carrier-to-noise value expected. 
 
7.8.4.4 Disconnect the generator and replace it by the shielded resistor, or, if a vision carrier signal is used 
for AGC, so retune the voltmeter within the channel that  it is influenced only by random noise. Reduce the 
attenuator setting to the value A2 that is required to restore the voltmeter reading R. 
 
7.8.4.5 Where a band or broadband amplifier is being tested , perform the test specified in 7.8.4 at the band 
ends and at the centre frequency of the amplifier. 
 7.8.4.6 The carrier-to-noise ratio (C/N), in decibels, is given by: 
 
C/N = A
1 × A2 × Cm × Cb  
 where 
 
A
1   is the attenuator value for the reference signal; 
 
A2   is the attenuator value for the noise measurement; 
 
Cm  is the voltmeter level corr ection factor (see Annex A); and 
 
Cb   is the bandwidth correction factor (see Annex A). 
 
7.8.4.7 Check for compliance with 6.4.  
 
 PUBLIC REVIEW DRAFT, OCTOBER 2008KS 1884-3:2008  
10 © KEBS 2008 — All rights reserved 7.9 Test for return loss 
 
7.9.1 Apparatus 
 
7.9.1.1 Signal generator , with appropriate frequency coverage. 
 7.9.1.2 Measuring receiver , with appropriate frequency coverage. 
 
7.9.1.3 Terminating impedance , for every output port of the item under test. 
 
7.9.1.4 Standing wave ratio (SWR) measuring bridge .  
 
7.9.2 Procedure 
 7.9.2.1 Connect the apparatus as shown in Figure 16. 
 
7.9.2.2 Using an unmodulated signal that is within the manu facturer's stated frequency  range and at a level 
comparable to normal use, calibrate the SWR measur ing bridge in accordance with the manufacturer's 
manual, and record the reference level A
1. 
 
7.9.2.3 Connect the component under test to the test port of  the bridge and, without altering the level of the 
signal generator, note the reading A2 on the measuring receiver. The return loss is given by (A 1 × A2) dB. 
 
7.9.2.4 Measure and record the return loss at the end fr equencies of the frequency range stated by the 
manufacturer and at a sufficient number of frequencies  within this range, to enable a curve of return loss 
against frequency to be plotted.  
7.9.2.5 Check for compliance with 6.5. 
 
7.10 Test for component radiation characteristics 
 
In the frequency range 30 MHz to 300 MHz, most of t he radiation is from input and output cables, therefore 
the absorbing clamp method is specified. In the frequ ency range 300 MHz to 1 GHz, the splitter itself could 
radiate; hence a "substitute radiati on method" of measurement, with and without a connected output cable, is 
specified. 
 
7.10.1 Apparatus 
 
7.10.1.1 Signal generator , that covers the appropriate frequency range and has sufficient output power. 
 
7.10.1.2 Absorbing clamp,  conforming to the description in Annex C (for the absorbing clamp method only). 
 
7.10.1.3 Stop filter , as described in Annex E (for the radiation method only). 
 
7.10.1.4 Transmitting dipole antenna , of known radiation characteristics and suitable for the required 
frequency range (for the radiation method only).  7.10.1.5 Receiving antenna , of known radiation characteristics and suitable for the required frequency 
range (for the radiation method only).  7.10.1.6 Measuring set , of appropriate impedance and that co vers the required frequency range. 
 
7.10.1.7 Measurement cable , at least 0.5 λ in length (at the lowest frequency of interest) plus 2 m, and of 
appropriate impedance. 
 
7.10.1.8 Shielded terminating loads , of appropriate impedance and design. 
 
7.10.1.9 All necessary coupling devices,  of appropriate design. 
 7.10.1.10 Absorbing devices , such as ferrite rings, that are suffi cient to suppress signals from the 
equipment under test on its input. 
 PUBLIC REVIEW DRAFT, OCTOBER 2008KS 1884-3:2008 
© KEBS 2006 — All rights reserved  11 7.10.1.11 Suitable calibrated attenuator , of appropriate impedance. 
 
7.10.1.12 Suitable coaxial changeover switch . 
 
7.10.2 General measurement requirements 
 
The test cables, coupling devices and terminations  shall all be well matched and well screened. Test 
equipment should normally be 75 Ω impedance. 
 
An indoor or an outdoor test site may be used. When an  indoor site is selected, the room shall be of 
sufficient size. Any reflecting and absorbing objects sh ould be so positioned or suffi ciently moved away from 
the measurement set-up that they  do not influence the results. 
 
7.10.3 Equipment layout and connections 
 Figures 6, 7, 8 and 9 show the measurement set-up and equipment layout for the absorbing clamp method 
(frequency range 30 MHz to 300 MHz), which is outlined in 7.10.5. 
 
Figures 10, 11 and 12 show the measurement set-up and equipment layout for the radiation method 
(frequency range 300 MHz to 1 GHz), which is outlined in 7.10.6. 
 
The component under test shall be placed at a heigh t of approximately 1 m above the ground, on a non-
metallic support on which the absorbing clamp or stop filter can be accommodated and moved.  
The output of the component under test shall be connected to a measurement cable of the same 
characteristic impedance and the cable shall be termi nated with the nominal impedance of the output via the 
attenuator and coaxial switch.  Well-screened cables shall be connected to the terminal s of the component under test, as specified by the 
manufacturer. When a direct connection cannot be m ade owing to the dimensions of the well-screened 
cable, an adaptor shall be used (see Annex D). 
 
The unused outputs, if any, of the component under test shall be te rminated with their nominal impedance by 
means of non-radiating loads connected dire ct, without any cabling (see Figure 13). 
 
The signal generator coaxial cable shall be provided with  suitable absorbing devices (for example, ferrite 
rings), placed close to the component under  test, to avoid measurement errors. 
 
7.10.4 Operating conditions 
 
The component under test shall be operated in accordance with the manufacturer's recommendations and shall be tested with a signal input that is equal to the maximum input specified by the manufacturer. 
 Measurements shall be performed on all output ports in  turn, and at the highest and lowest frequencies in 
the range specified by the manufacture r, and at a selection of intermediat e frequencies so chosen as to give 
a realistic representation of the radiation patte rn throughout the operating frequency range. 
 7.10.5 Procedure (absorbing clamp method — frequency range 30 MHz to 300 MHz) 
 
For sensibly consistent results, the disposition of th e signal generator cable preceding the absorbing clamp, 
the signal generator mains lead and the meas urement cable beyond the absorbing clamp, and their 
proximity to other items, shall not influence the read ings on the measuring set by more than ± 1 dB. This 
shall be checked by moving the cables and by ru nning a hand along their length, after the equipment has 
been set up in accordance with Figures 6, 7, 8 and 9.  7.10.5.1 With the equipment set up as shown in Figures 7 and 8 and the measurement cable coupled to an 
output port of the component under test, position the absorbing clamp at the component end of the 
measurement cable and place the coaxial switch in the "check level" mode. Adjust the signal generator to the 
test frequency and to an input level that equates to t he maximum rated output level of the component under 
test. Record this input level V, (in microvolts) from the signal generator. 
 
7.10.5.2 Tune the measuring set. Turn the coaxial switch to  the "measure radiation" mode. Set the calibrated 
attenuator to 0 dB. Move the absorbing clamp along t he cable, away from the component, until a maximum PUBLIC REVIEW DRAFT, OCTOBER 2008KS 1884-3:2008  
12 © KEBS 2008 — All rights reserved reading is obtained on the measuring set (at a spacing of ± 0.5 λ). Record the level of the reading Vm 
obtained. 
 
7.10.5.3 Repeat the procedure in 7.10.5.1 and 7.10.5.2 for each output port and at the frequencies specified 
in 7.10.4. 
 
7.10.5.4 From the preceding tests, the highest reading of Vm obtained for each frequency then has to be 
converted to the "substituted radiation power" pm, using the calibration chart of the absorbing clamp. Convert 
into power form pi the values of Vi, recorded. Calculate the component radi ation characteristic, in decibels, 
from the following formula: 
 Cfx = 10log p
i/pm  
 where  
Cfx is the component radiation characteristic at frequency x; 
 
p
i is the maximum input power (as used for the measurement); 
 p
m is the maximum value of substituted radiated power obtained at frequency fx; and 
 
fx is one of the frequencies of measurement.  
 
7.10.5.5 Check for compliance with 6.6. 
 
7.10.6 Procedure (radiation method — frequency range 300 MHz to 1 GHz) 
 For sensibly consistent results, the combined residual  radiation and pick-up of the test set shall at all 
frequencies be at least 20 dB lower than the expected measurement value. 
 
This shall be checked after the first component radiat ion measurement and before the result is recorded, by 
removing the component under test and, with the i nput and output leads correctly terminated and the 
position of these connecting leads and other test e quipment otherwise unchanged, measuring the residual 
radiation. The residual radiation shall be at leas t 20 dB lower than that measured, or expected to be 
measured, with the component connected. If this cannot  be achieved, repositioning of the test equipment 
might be helpful. 
 
The positioning of the transmitting and receiving ant ennae shall be carefully adjusted to ensure sensibly 
consistent results over the required frequency range. 
 
This shall be checked with a transmitting antenna conn ected horizontally in place of, and in the same 
position as, the component under test, and parallel with the receiving antenna not less than 1.3 m away. A 
test shall then be carried out to ensure that, when the tr ansmitting antenna is moved vertically or laterally by 
± 10 cm, the measuring set readings do not vary by more  than ± 1.5 dB. This test  shall be repeated at each 
test frequency and the distance d and the height h adjusted until this requirement is met (see Figure 12). 
 
The antennae positions, supports, etc., shall then be rotated in the horizontal plane by 90°, keeping the 
same precise spacing distance between the antennae. The new reading obtained shall be noted. If the readings vary by more than 3 dB, the following might be required:  
a) change the size of the room; 
 b) add metallic layers or plates to improve the reflection properties of the ground; 
 
c) use a corner reflector antenna; and  
d) add absorbing material to the walls. 
 
7.10.6.1 Measurement procedure without meas urement cable (all output ports terminated) 
 
7.10.6.1.1 With the equipment connected as in Figures 10 a nd 12 and the coaxial switch in the "measure 
radiation" mode, adjust the signal generator to the te st frequency and to an input level that will give the 
maximum rated output level from the component under test. Record this input level V
i from the signal PUBLIC REVIEW DRAFT, OCTOBER 2008KS 1884-3:2008 
© KEBS 2006 — All rights reserved  13 generator. Tune the measuring set and adjust the controls  to give a convenient reading. Then rotate the 
component under test in all planes, until the maximum reading Vr is obtained and record this reading.  
 
7.10.6.1.2 Substitute the transmitting antenna for the component  under test, and so place the antenna that it 
is parallel with the receiving antenna and that its ce ntre corresponds to that of  the component under test 
(when the component is in position). Adjust the output level of the signal generator to give the same reading 
V, on the measuring set. The available power from the generator to the transmitting antenna is the 
substituted radiated power ps from the component under test. Record this value. 
 
7.10.6.1.3 Repeat this procedure for each of the test frequencies specified in 7.10.4. 
 
7.10.6.1.4 The highest reading of ps obtained at each frequency in the preceding tests indicates the radiation 
characteristic of the component, expres sed as the substituted radiated power. 
 
7.10.6.1.5 Calculate the component radiation characterist ic, in decibels, from the following formula: 
 
Cfx = 10log pi/ps  
 
where  
Cfx is the component radiation characteristic at frequency x; 
 
p
i is the maximum input power (as used for the measurement); 
 p
s is the maximum value of substituted radiated power obtained at frequency fx; and 
 
fx is one of the frequencies of measurement.  
 
7.10.6.1.6 Check for compliance with 6.6.  
 
7.10.6.2 Measurement procedure with measurement cable connected to one port 
 
7.10.6.2.1 With the equipment connected as in Figures 11 a nd 12 and the coaxial switch in the "measure 
radiation" mode, connect the measurement cable to the port to be tested. So position the measurement 
cable, with stop filter in position at the component end,  that it is parallel with the receiving antenna. Adjust 
the signal generator to the test frequency and to an i nput level that will give the maximum rated output level 
from the component under test. 
 
Record this input level V, from the signal generator. Tune the measuring set and adjust the controls to give a convenient reading. Tune the stop filter  to the calibration mark for the test frequency in use (as determined in 
Annex E). Move the stop filter along the cable, away from the component, until a maximum reading is 
obtained on the measuring set (at a spacing of ± 0.5 λ). Check that the stop filter is correctly tuned by 
observing the meter reading whilst making fine adjustment s to the filter tuning. Then rotate the component 
under test in all planes, to determine whether a higher readi ng can be obtained. If it can, readjust the position 
of the stop filter, etc., and note the final maximum reading V
m. 
 
7.10.6.2.2  Substitute the transmitting antenna for the compone nt under test, and so place the antenna that it 
is parallel with the receiving antenna and that its ce ntre corresponds to that of  the component under test 
(when the component is in position). Adjust the output level of the signal generator to give the same reading 
Vm on the measuring set. The available power from the signal generator to the transmitting antenna is the 
substituted radiation power ps from the component under test. Record this value. 
 7.10.6.2.3  Repeat this procedure for each of the test frequencies specified in 7.10.4. 
 
7.10.6.2.4  Repeat the above procedure for each of the measurement ports specified in 7.10.4. 
 
7.10.6.2.5  The highest reading of p
s obtained at each frequency in the preceding tests and in the test given 
in 7.10.6.1 indicates the radiation characteristic of the component, expressed as the substituted radiated 
power. Using the above ps figure and the Vi values recorded, but converted into power form pi, calculate the 
resultant component radiation characteristic, in deci bels, at each frequency from the following formula: 
 
Cfx = 10 log pi/ps  
 PUBLIC REVIEW DRAFT, OCTOBER 2008KS 1884-3:2008  
14 © KEBS 2008 — All rights reserved where 
 
Cfx is the component radiation characteristic at frequency x; 
 
pi is the maximum input power (as used for the measurement); 
 
ps is the maximum value of substituted radiated power obtained at frequency fx; and 
 
fx is one of the frequencies of measurement. 
 
7.10.6.2.6 Check for compliance with 6.6. 
 
8 Packing and marking 
 
8.1 Packing 
 
Each amplifier shall be so acceptably packed as to  protect it from damage during normal handling, 
transportation and storage. 
 
8.2 Marking 
 
The amplifier shall bear the following information: 
 
a) the manufacturer's/distributor's brand name or trade mark or both;  
b) the frequency range or channel for which the amplifier has been designed; 
 
c) the gain of the amplifier; 
 
d) identification marks for t he input(s) and output(s); and 
 
e) whether or not the amplifier is suitable for use ou tdoors or in situations where high humidity and high 
temperatures are experienced. 
 
With the exception of (d) above, the above info rmation shall also be printed on the packaging. 
 
8.3 Instruction leaflet 
 
In addition to the information in 8.2, the following inform ation shall be printed in an instruction leaflet provided 
with the amplifier: 
 
a) the noise figure of the amplifier; 
 
b) channel derating; and  
c) complete instructions for the mount ing and connection of suitable cable. 
 
  
 
  PUBLIC REVIEW DRAFT, OCTOBER 2008KS 1884-3:2008 
© KEBS 2006 — All rights reserved  15 
 
 
 
  
Figure 1 — Apparatus for test for amplitude frequency response of output(s)  
 
 
 
   
 
 
 
 
Figure 2 — Measuring set-up for determining the maximum intermodulation-limited output voltage  
 
 PUBLIC REVIEW DRAFT, OCTOBER 2008KS 1884-3:2008  
16 © KEBS 2008 — All rights reserved Dimensions in millimetres 
 
 
 
 
Figure 3 — Test for maximum intermodulation-limited output voltage: relative values of frequencies 
for channel amplifiers 
 
 
  
Dimensions in millimetres 
 
 
 
Figure 4 — Test for maximum intermodulation-limited output: relative values of frequencies for band 
and broadband amplifiers  
 PUBLIC REVIEW DRAFT, OCTOBER 2008KS 1884-3:2008 
© KEBS 2006 — All rights reserved  17 
 
 
 
 
Figure 5 — Measurement of two-signal cross-modulation  
 
 
 
 
 
 
Figure 6 — Measurement set-up for absorbing clamp method  
 
 
 PUBLIC REVIEW DRAFT, OCTOBER 2008KS 1884-3:2008  
18 © KEBS 2008 — All rights reserved 
 
 
 
 
Figure 7 — Absorbing clamp method (frequency range 30 MHz to 300 MHz)  
 
 
 
1 = component under test 
2 = absorbing clamp 3 = measuring set 
4 = signal generator 
5 = absorbing device 
6 = terminating resistor 
7 = mains filter 
8 = coaxial switch 
9 = attenuator 
10 = measurement cable
 Coaxial switch 
Measure radiation 3 – 2, 6 – 9  
Check level 3 – 9, 6 – 2  
 
 
 
 
 
 
Figure 8 — Example of general measurement set-up for absorbing clamp method over the frequency 
range 30 MHz to 300 MHz  PUBLIC REVIEW DRAFT, OCTOBER 2008KS 1884-3:2008 
© KEBS 2006 — All rights reserved  19  
1 = component under test 
2 = absorbing clamp 3 = measuring set 
4 = signal generator 
5 = absorbing device 
6 = terminating resistor 
7 = mains filter 
8 = coaxial switch 
9 = attenuator 
10 = measurement cable  
11= input signal cable
 Coaxial switch 
Measure radiation 3 – 2, 10 – 9  
Check level 3 – 9, 10 – 2  
 
 
 
 
Figure 9 — Example of measurement set-up for absorbing clamp method over the frequency range 
30 MHz to 300 MHz for measurements on the input port of an active component  
  
 
 
  
Figure 10 — Radiation method (frequency range 300 MHz to 1 GHz) without measurement cable  
 PUBLIC REVIEW DRAFT, OCTOBER 2008KS 1884-3:2008  
20 © KEBS 2008 — All rights reserved 
 
 
 
 
Figure 11 — Radiation method (frequency range 300 MHz to 1 GHz) with measurement cable  
 
1 = component under test 
2 = stop filter 3 = measuring set 
4 = signal generator 
5 = absorbing device 
6 = terminating resistor 
7 = mains filter 
8 = coaxial switch 
9 = attenuator 
10 = measurement cable 
11 = receiving antennaCoaxial switch 
Measure radiation 3 – 11, 6 – 9  
Check level 3 – 9, 6 – 11  
 
  
 
 
 
Figure 12 — Example of measurement set-up for frequency range 300 MHz to 1 GHz  
 PUBLIC REVIEW DRAFT, OCTOBER 2008KS 1884-3:2008 
© KEBS 2006 — All rights reserved  21 
 
 
 
 
Figure 13 — Termination of components with several outputs  
 
 
 
 
  
 
Figure 14 — Arrangement of test equipmen t for carrier-to-noise ratio measurement  
 
 PUBLIC REVIEW DRAFT, OCTOBER 2008KS 1884-3:2008  
22 © KEBS 2008 — All rights reserved  
 
 
where 
A     is the unit under test;  CB   is the 20 A circuit-breaker;  
R     is the load resistor; and  
S     is the main switch 
 
 
 
Figure 15 — Circuit arrangement for test for conti nuity between input and output terminals of the 
outer cable
 
 
 
 
 
 
 
Figure 16 — Apparatus for test for return loss  
 PUBLIC REVIEW DRAFT, OCTOBER 2008KS 1884-3:2008 
© KEBS 2006 — All rights reserved  23  
Annex A 
(normative) 
 
Equipment required — Additional items 
 
A.1 Voltmeter pre-amplifier 
 
If the sensitivity of the selective vo ltmeter is not adequate for the levels of noise expected at the point of 
measurement, a suitable pre-amplifier of the correct input impedance and sensibly flat response over the 
channel to be measured will be necessary. This pre-amplifier should be included as part of the measuring equipment when the checks described in Annex B are being made. 
 
A.2 Voltmeter input filter 
 If the selectivity of the selective vo ltmeter is not adequate to reduce to an insignificant level the effects of 
"out-of-channel" signals on the measur ement of the noise voltage, a suitabl e filter that has a sensibly flat 
response over the channel to be measured w ill be necessary, as shown in Figure 14. 
 
In this case, it is important that the matching between the filter and the preceding equipment be such that it 
results in a return loss ratio of at least 20 dB with in the frequency range of the channel to be measured, and 
that the entire measuring equipment sati sfy all the requirements of Annex B. 
 Where this is in doubt, an attenuator of sufficient value to satisfy this requirement should be included as 
shown in Figure 14. 
 PUBLIC REVIEW DRAFT, OCTOBER 2008KS 1884-3:2008  
24 © KEBS 2008 — All rights reserved  
Annex B 
(normative) 
 
Preliminary checks on the measuring equipment for carrier-to-noise ratio 
 
B.1 Noise 
 
With the input to the measuring equipment terminated and the variable attenuator set to zero, tune the voltmeter over the frequency range of interest and check that the reading remains negligible relative to that 
expected when the system noise is being measured.  
B.2 Intermodulation 
 
B.2.1 Via a matched directional coupler, connect signals to the measuring equipment that correspond to 
those that will be present at the point of measurement. Tune the meter to any significant intermodulation 
products and note the lowest value of the signal/inter modulation ratio within the channel being considered. 
 
This ratio should exceed the minimum carrier-to-noise ratio expected at the point of measurement by an 
amount relevant to the accuracy desired. For example,  20 dB would result in an error of less than 1 dB. 
 B.2.2 If this requirement is not met, include an appropriate  channel pass-band filter to attenuate one of the 
signals as indicated in Figure 14, and re peat the checks of cl ause B.1 and B.2.1. 
 
NOTE This check relating to intermodulation is necessary only if automatic level control (ALC) pilot signals or other signals a re 
present during the carrier-to-noise ratio tests. 
 
B.3 Overload 
 
B.3.1 Connect signals as in B.2.1 and attenuate one of them  to a level comparable with that of the noise 
voltage expected at the point of measurement. Tune t he meter to the low level signal. Tune the low level 
signal and the meter in step over the frequency ran ge of the channel to be measured and check that the 
meter reading does not change when the high-level signals are switched off and on. 
 
B.3.2 If this requirement is not met, include a filter to attenuate one or more of the signals as indicated in 
Figure 14 and repeat all t he checks of clause B.2. 
 PUBLIC REVIEW DRAFT, OCTOBER 2008KS 1884-3:2008 
© KEBS 2006 — All rights reserved  25  
Annex C 
(normative) 
 
The absorbing clamp and its application fo r the measurement of  interference power 
 
 C.1 General 
 
The general method is shown in Figure C.1. The test l ead B is connected direct from the appropriate port of 
the component under test, A. C is a current transformer or current probe that is placed around the test lead 
that provides an output voltage proportio nal to the resultant current in the lead. D and E are ferrite tubes or 
series of ferrite rings that surround, respectively, the test lead and the screened lead to the measuring 
instrument. A satisfactory device that covers the fr equency range 30 MHz to 300 MHz has been constructed, 
using 56 rings of ferrite for D and 60 similar rings for E, as shown in figure C.2. The current transformer C is 
made of three such rings encircled by a single turn of  screened wire. C and D are mounted in fixed relative 
positions as close together as practicable, in such a way that the distance d can be varied. Both D and E 
serve to load their respective cables and to attenuate currents flowing along them. 
 
C.2 Mains lead testing 
 When the lead being tested forms the mains supply and the high-frequency isolation between mains supply 
and the input of the measuring device on the side of the appliance appears to be insufficient, a fixed ferrite 
absorber F should be placed along the mains lead at a di stance of about 4 m from the appliance. This 
improves the stability of the loading impedance a nd reduces extraneous noise coming from the mains 
supply.  C.3 Position of measuring device 
 
When the connector of the measured appliance makes it impossible to pos ition the measuring device at the 
first maximum, the second maximum may be used, the lead being extended via connector G. In this case, the reading should be increased by about 1 dB (see curve B in Figure C.4). 
 
C.4 Test lead length 
 
The straight portion of the test lead should be about ( λ
maxl2) + 60 cm, in order to allow at any time the 
positioning of the measuring devices. ( λmax is the wavelength that corresponds to the lowest frequency at 
which measurements are to be made.) 
 
C.5 Calibration of measuring device 
 
When the measuring device is being calibrated, it is assemb led as in Figure C.1, except  that the test lead is 
replaced by an insulated wire of e ffective cross-sectio n approximately 1 mm2 to 2 mm2 and that the end that 
is normally connected to the appliance,  is connected instead to the centre pin of a connector arranged to 
feed through the wall of a screened enclosure. 
 
NOTE A generator with 75 Ω output impedance is connected to the other end of the connector through a 75 Ω attenuator that has an 
attenuation of at least 10 dB (see Figure C.3). 
 
The measuring device is then positioned for maximum indication. From the generator output indication and attenuator setting, a calibration curve can be drawn in terms of the available power at the output of the 
attenuator. 
 
C.6 Method used to establish the calibration curve shown in Figure C.4 
 The calibration described in clause C.5 can be assumed to be a measurement of the insertion loss of a 
quadripole. The input of the two-port is effectively at  the coaxial terminal in the wall of the screened room 
and the output is at the input of the measuring receiver.  As a precaution, to avoid possible spur ious effects of mismatch in the c able, a 10 dB attenuator is inserted 
before the coaxial connector. When the switch S is in t he position shown in Figure C.3, a signal is injected 
and the receiver indication is noted. When the absorb ing device is adjusted for maximum response, the PUBLIC REVIEW DRAFT, OCTOBER 2008KS 1884-3:2008  
26 © KEBS 2008 — All rights reserved attenuation A1 of the generator is noted. The generator is th en connected to the receiver direct and the 
attenuator is adjusted to A2 to give the same reference reading. 
 
The insertion loss shown in Figure C.4 is given by:   
(A
1 - A 2 - 10) dB (curve A, first maximum). 
 
It can be shown that, if the generator and receiv er each has an internal resistance of 75 Ω, and if the 
insertion loss of the measuring device (after the 10 dB attenuator) is 18.75 dB, the indication on the receiver, 
expressed in decibels (microvolts), has the same numer ical value as the available power, expressed in 
decibels (picowatts), at the output of the signal genera tor. This is the reason for the correction scale shown 
in Figure C.4. The correction scale gives the factor in decibels, to be added to the indication of the receiver in 
decibels (microvolts) to convert the reading to power in decibels (picowatts).  
 
  
 
 
 
 
Figure C.1 — Schematic diagram — Measurement of interference power between 30 MHz and 300 
MHz 
 
 
 
 
 
 
 
 
Figure C.2 — Detail of absorbing clamp  
 PUBLIC REVIEW DRAFT, OCTOBER 2008KS 1884-3:2008 
© KEBS 2006 — All rights reserved  27 
 
 
 
  
Figure C.3 — Schematic diagram — Calibration of the absorbing clamp between 30 MHz and 300 MHz  
 
 
 
   
 
 
Available power-reading on the receiver + correction 
 
 
Figure C.4 — Calibration of the absorbing clamp  
 PUBLIC REVIEW DRAFT, OCTOBER 2008KS 1884-3:2008  
28 © KEBS 2008 — All rights reserved  
Annex D 
(informative) 
 
Adaptors for connecting the cables to the component 
 
 
When the diameter of the well-screened cables used for measurement differs from that for which the 
component is made, and the cables ca n therefore not be connected direct to the terminals of the component, 
one of the following types of adaptor should be used, as relevant: 
 
⎯ Components with "screwed clamp" terminals 
 
In this case, the adaptor is made using a piece of suit able cable that is as short as possible, is connected 
at one end to the terminals of the component and is pr ovided at the other end with a coaxial connector 
for connection to the well-screened cable, as indicated in Figure D.1. 
 
⎯ Components with coaxial connectors 
 
In this case, the adaptor is made using two coaxial co nnectors that are soldered together direct or are 
joined with a piece of cable that is as short as possible. The first connector should be suitable for 
connection to the component; the second should be suitable for connection to the well-screened cable 
(see Figure D.2).  
 
   
 
 
 
 
Figure D.1 — Adaptor for components with "screwed clamp" terminals  
 
 
 PUBLIC REVIEW DRAFT, OCTOBER 2008KS 1884-3:2008 
© KEBS 2006 — All rights reserved  29 
 
 
 
Figure D.2 — Adaptor for components with coaxial terminals  PUBLIC REVIEW DRAFT, OCTOBER 2008KS 1884-3:2008  
30 © KEBS 2008 — All rights reserved  
Annex E 
(informative) 
 
The stop filter 
 
E.1 Function 
 
The stop filter has to give an effect ive blocking of either the radio-freque ncy current that flows on the outside 
of a screened cable or the asymmetrical radio-frequency currents that flow in a mains lead. It is tuned to a 
specific frequency, which should be  variable over a certain range. 
 
The layout of a stop filter is shown in Figure E.1. The stop filter works as a quarter-wave stub. It is made from 
two concentric metal tubes at some distance from each other. The coaxial cable or the mains lead passes 
through the inner tube without making any metallic contact with the filter. A short-circuiting plunger is inserted 
between the two tubes. This short-circuit is transformed to a very high impedance at the open end of the filter 
a quarter wave-length away. Therefore a current in the f ilter of a frequency that corresponds to the quarter 
wave-length will be zero at the open end. As the diameter of the stop filter is much less than a wave-length, 
the currents at the same frequency that flows on the outside of the screened cabl e, or the asymmetrical 
currents in the conductors of the mains lead, have to be zero at the point where the cable, or mains lead, 
enters the stop filter.  
E.2 Construction 
 
The inner one of the two metal tubes of the stop filter could be mounted in side the outer one by means of a 
metallic support at the far end of the filter. This suppor t should be so strong that  no support other than the 
short-circuiting plunger is needed for a stop filter used  at UHF. For lower frequencies, the corresponding long 
length of the filter will necessitate a support at t he end towards the component under test. This support 
should be made of insulating material that has a low power factor. 
 
Means should be provided to adjust the position of the plunger, for instance by one or more rods that are 
connected to the plunger and that penetrate through the sh ort-circuit support at the far end of the filter, or by 
handles that are connected to the plunger and that penet rate through longitudinal slots in the outer tube of 
the filter. 
 
E.3 Frequency calibration 
 Owing to the "edge effect" at the input end of the two t ubes, the frequency calibration of the stop filter is not 
given direct by the geometrical dist ance from the input end to the short-circuit. Instead, the calibration is 
made by inserting a single insulated conductor through the filter; at the input end of t he filter, the conductor is 
connected to a signal generator and at the far end, it is connected to a receiver. No connections should be 
made between the earth of the signal generator, or receiv er, and the stop filter. For each frequency of tuning 
of the signal generator, the stop filter should be t uned by so moving the short-circuiting plunger that a 
minimum indication is observed at the receiver. A calibration curve can thus be made. Because a single 
conductor is used and the earth is not defined, parasitic resonances can occur in the calibrating set-up, which can give rise to calibration errors. For this re ason, the calibration should be carried out carefully by 
checking that the calibration curve is smooth. 
 
 
 
 
Figure E.1 — Stop filter  PUBLIC REVIEW DRAFT, OCTOBER 2008KS 1884-3:2008 
© KEBS 2006 — All rights reserved  31  
Annex F 
(informative) 
 
Correction factors 
 
F.1 Level correction factor Cm 
 
If a selective voltmeter that responds to the average value of the applied voltage but that is calibrated in 
r.m.s. values (assuming a sinusoidal input signal) is employed, it will indicate a level approximately 1 dB 
below the r.m.s. value of the applied noise voltage in its noise bandwidth. In this instance, Cm may be taken 
as 1 dB. 
 
If a selective voltmeter of the peak reading type is used, a correction appropr iate to the particular instrument 
should be employed as Cm. 
 
F.2 Bandwidth correction factor Cb 
 
This correction factor takes into account the di fference, in decibels, between the noise bandwidth Bm of the 
selective voltmeter and that of the appropriate television system BTV. It is calculated from the formula: 
 
mTV
b logBBC 10=  PUBLIC REVIEW DRAFT, OCTOBER 2008KS 1884-3:2008  
32 © KEBS 2008 — All rights reserved  
Annex G 
(informative) 
 
Calibration of the selective voltmeter  
 
 Noise bandwidth B
m 
 
A well-matched noise generator is required, that has a known bandwidth Bg (see Note 1), and an output 
voltage of known r.m.s. value Vg sufficient to give a convenient reading on the voltmeter. 
 
Connect the voltmeter to the noise ge nerator (see Note 2) and tune it to a test frequency. Measure the true 
r.m.s. voltage Vm (see Annex F). Repeat this pr ocedure at each test frequency. 
 The noise bandwidth B
m of the voltmeter is given by: 
 
2)/(g m g m VVBB=  
 
where Bm and Bg are in the same units, for example megahertz, and Vm and Vg are in the same units, for 
example microvolts. 
 
NOTE 1 Bg will usually be taken as 1 MHz and Vg is calculated for this bandwidth from info rmation provided by the manufacturer of the 
noise generator. 
 
NOTE 2 The noise generator may consist of a noise diode source followed by an appropriate amplifier.