Read JBL ON TOUR XT (serv.man5) EMC - CB Certificate online
12/05/2006
Report Number: 3109671ATL-005
Issued:
Intertek
Measurement of immunity to induced voltages (EN 55020 - Sec. 5.7)
6.0
Method:
Figure 8 of EN 55020 shows the measuring circuit and set-up for receivers, video tape and audio equipment.
The wanted test signal is supplied via the respective connections A or V or S or T (see table 21 of EN 55020 ) by generators G1, G2, G3 and G4 (see table
22 of EN 55020). The unwanted signal is supplied by generator G5. Network RCi matches the RF disturbance source to the input impedance of the relevant
audio terminal and a similar network RCo is used to match the output terminals. A mains stopfilter MSF is used to inject the unwanted signal at the mains
terminal and acts as a stopfilter for unwanted signals from the mains network.
22 of EN 55020). The unwanted signal is supplied by generator G5. Network RCi matches the RF disturbance source to the input impedance of the relevant
audio terminal and a similar network RCo is used to match the output terminals. A mains stopfilter MSF is used to inject the unwanted signal at the mains
terminal and acts as a stopfilter for unwanted signals from the mains network.
The equipment under test is placed 0.1 m above the centre of a metal ground plane of dimensions 2 m by 1 m. The mains lead shall be bundled to a length
less than 0.3 m and connected in the shortest possible way to the mains stop filter MSF.
less than 0.3 m and connected in the shortest possible way to the mains stop filter MSF.
The cable supplying the RF voltage to the audio input and output terminals of the equipment under test shall be of a coaxial type with a transfer impedance of
50 m /m at a maximum at 30 MHz.
50 m /m at a maximum at 30 MHz.
In case the terminals of the equipment under test are non-shielded (e.g. loudspeaker terminals) the connection from the coaxial cable to the terminals shall
be kept as short as possible. The shield of the coaxial cable shall be connected to the metal plate, as close as possible to the terminals of the coupling unit
and by a connection as short as possible.
be kept as short as possible. The shield of the coaxial cable shall be connected to the metal plate, as close as possible to the terminals of the coupling unit
and by a connection as short as possible.
To avoid ground loop problems (e.g. hum, RF coupling) it is recommended that measuring instruments such as audio power meter and signal generators are
of the ungrounded type.
of the ungrounded type.
Alternatively the instruments may each be powered via individual mains isolation transformers.
For connection to the phono or tape input, care shall be taken to ensure an efficient shielding against mains pick-up. The earth conductors of the cable at the
signal generator output and of the networks RCo, RCi and MSF are connected to the metal plate.
signal generator output and of the networks RCo, RCi and MSF are connected to the metal plate.
As a rule the connecting cables shall be of the 50 coaxial type, up to the terminal under test (e.g. also for loudspeaker and headphone ports).
The unused input terminals and the loudspeaker and/or headphone or any other audio output terminals are terminated with appropriate load resistors as
specified by the manufacturer or in the relevant standard.
specified by the manufacturer or in the relevant standard.
For stereo or two channel sound television equipment respectively the unwanted signal is simultaneously fed to the two audio input channels. The output
terminals of the channels are fed as well as measured separately.
terminals of the channels are fed as well as measured separately.
Prior to measurements a check shall be carried out to see that no interference signal penetrates directly into the measuring equipment.
The audio output power levels are measured according to 5.2.2 of EN 55020.
The audio output power levels are measured according to 5.2.2 of EN 55020.
In table 22 of EN 55020 the conditions for the measurement are given for receivers, video tape and audio equipment. The wanted signals are specified
according to the operating mode of the equipment under test and provided by generators G3 and G1, or G4 and G2 and G1 or G1 or G2.
according to the operating mode of the equipment under test and provided by generators G3 and G1, or G4 and G2 and G1 or G1 or G2.
The unwanted signal shall be amplitude modulated with 1 kHz at 80 % depth, supplied by generator G5.
Measurement procedure
For adjusting, the wanted signals are set, dependent on the type of equipment under test and its operating mode, by making the connections of figure 8 as
follows:
A for audio terminals,
V for video terminals (simultaneously audio signal at audio terminals),
S for antenna terminals (sound broadcast signal) and
T for antenna terminals (television broadcast signal).
For adjusting, the wanted signals are set, dependent on the type of equipment under test and its operating mode, by making the connections of figure 8 as
follows:
A for audio terminals,
V for video terminals (simultaneously audio signal at audio terminals),
S for antenna terminals (sound broadcast signal) and
T for antenna terminals (television broadcast signal).
The audio controls of the equipment under test, other than the volume control, are set at normal position. The volume control is adjusted to obtain an audio
output power of 50 mW (or 500 mW) (see 5.2.2 for audio power measuring arrangements).
output power of 50 mW (or 500 mW) (see 5.2.2 for audio power measuring arrangements).
For stereo equipment the balance control shall be adjusted to obtain 50 mW (or 500 mW) from both channels. The video controls of the equipment under
test are set to obtain a picture as described in 5.2.3.
test are set to obtain a picture as described in 5.2.3.
For the measurement the unwanted signal is applied to the terminal under test by making the connections of figure 8 as follows:
Ai for audio input terminals,
M for the mains lead and
Ao for audio output terminals.
The connections L, R, respectively Lo, Ro, are for adjusting and/or measurement of the adequate output channels.
Ai for audio input terminals,
M for the mains lead and
Ao for audio output terminals.
The connections L, R, respectively Lo, Ro, are for adjusting and/or measurement of the adequate output channels.
For television receivers and video tape equipment in the RF recording mode, measurements are carried out with the wanted signal at the frequency of the
middle channel of the lowest band available in the equipment under test (or the lowest of the available channels 04, 08, 25 or 55 for system L).
middle channel of the lowest band available in the equipment under test (or the lowest of the available channels 04, 08, 25 or 55 for system L).
Description:
Manufacturer:
Model:
Asset Number:
Cal Date:
Cal Due:
Test Equipment Used:
AC Millivoltmeter / Measuring Amplifier
B&K
2610
213203
10/26/2006
10/26/2007
Amplifier, Wideband RF Power
Kalmus
747LC-CE
213031
11/03/2003
VBU
Page 10 of 27
EMC Report for Harman Consumer Group on the JBL On Tour II
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