Shure T2 User manual

Shure Incorporated
222 Hartrey Avenue
Evanston IL 60202-3696 U.S.A.
T Wireless System
E1999, Shure Incorporated Printed in U.S.A.
25–1018–1 (CC)
SERVICE MANUAL CHANGE NOTICE
T2 WIRELESS HANDHELD TRANSMITTER
Changes and corrections have been made to the Service Manual for the T2 handheld Transmitter. To update
your Service Manual, remove the pages identified in the tables below and replace them with the pages at-
tached to this Change Notice. Note that there are no changes to pages not specifically identified in the tables
below.
T2 HANDHELD TRANSMITTER SERVICE MANUAL REVISION HISTORY
Release Part Number Date Code Color
Original 25A1018 QH White
Revision 1 25B1018 SB Pink
Revision 2 25C1018 SI White
Revision 3 25C1018 TF White
Revision 4 25C1018 TL White
Revision 5 25C1018 AF White
Revision 6 25C1018 BA White
Revision 7 25C1018 CC Red
CHANGES EFFECTIVE MARCH 17, 2003
REMOVE
these pages from Revision the
T2 Service Manual
INSERT
these new Revision pages into the
T2 Service Manual
31 & 32 31 & 32

1Characteristics
25C1018 (CC)

T2 Vocal Artist Microphone-Transmitter
Service Manual
25C1018 (CC)
Characteristics
General This section tells how to service and align the Shure Vocal Artist T2
Microphone-Transmitter (Figure 1). The single-channel, crystal-con-
trolled transmitter operates in the 169 MHz to 216 MHz (FCC-approved
models) or 173–240 MHz (ETSI-approved models) VHF band. (The differ-
ences between the two versions of this product are explained on the next
page.)
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Figure 1.
Service Note: Shure recommends that all service procedures be
performed by a factory-authorized service center or that the product
be returned directly to Shure Brothers Inc.
Licensing: Operation may require a user license. Frequency or
power-output modifications may violate this product’s approvals.
Contact your country’s communications authorities.
E1999, Shure, Inc.
Printed in U.S.A.

Shure T2 Vocal Artist Microphone Transmitter
2
Characteristics 25C1018 (CC)
Circuit Description
This unit contains two interconnected circuit boards that comprise
the audio and RF sections, respectively. It is intended for use with the
matching T3 and T4 receivers.
FCC-Approved vs. ETSI-Approved Models: Models approved by
the Federal Communications Commission (assembly number 90–8690,
with boards marked 34A8494) have different sections from those ap-
proved by the European Telecommunications Standards Institute (as-
sembly number 90–8705, with boards marked 34A8538). The FCC-ap-
proved version, sold in North America and many other places, uses only
the frequencies listed in Table 3 on page 12. The ETSI-approved version,
sold in Europe and many other places, uses only the frequencies listed
in Table 4 on page 13. Hence, the following circuit descriptions have sep-
arate sections for the two RF boards. The audio sections are the same
for all T2 models.
Audio Section Input: The microphone element converts the sound source into an
electrical signal, which then enters the audio board through the center
contact of the head board (Figure 5, page 16).
Preamplifier Stage: This is centered in one section of operational
amplifier U102C. Externally accessible potentiometer R175 adjusts the
voltage gain of this stage over a 25 dB range.
Passive Pre-emphasis Network and Compandor: The network
(R145, C110, C111, C112, and R115) has a pole at 63 microseconds and
a zero at 12 microseconds. The NE571Dintegrated circuit compander
(U101A) provides 2:1 logarithmic compression of the audio signal.
Noise, Distortion, and Limiting: U102A lowers the noise floor, and
internal potentiometer R130 nulls the system audio distortion. Opera-
tional amplifier U102B, operating as a two-pole, active low-pass filter,
restricts the bandwidth of the system to the audio frequencies. PNP tran-
sistors Q103 and Q104 limit the level of the audio signal leaving the
audio section via U102B.
5 Vdc Bias and LED Drive Circuits: The NE571D’s identical second
channel (U101B) supplies regulated, low-noise 5 Vdc bias to various
audio and RF circuit points. Transistor Q105 provides “reverse battery
protection”to the circuit. Q106 drives LED D101 (“Power 0n”), and Q107
drives LED D102 (“Low Battery”).
RF Section: FCC-Approved Models
Audio Input: Processed audio enters R217, an internal potentiom-
eter that is adjusted for 15 kHz deviation (100% modulation) when the
audio section provides a –2.2 dBV, 1 kHz tone.
Oscillation: The audio then goes to varactor diode D201, which is
part of the modulated oscillator-tripler stage (Q201). The latter’s base-
emitter circuit operates as a crystal-controlled Colpitts oscillator in the

Shure T2 Vocal Artist Microphone Transmitter
3Characteristics
25C1018 (CC)
20 MHz region. Fundamental-mode crystal Y201 is tuned 10 kHz below
series resonance by the series combination of frequency-netting coil
L209, diode D201, capacitor C214, and capacitor divider C224 and
C230.
Frequency and Temperature Stability: To ensure frequency sta-
bility despite changes in the battery voltage, regulated 5 Vdc bias is ap-
plied to the varactor diode and to the base of Q201. C224, C230, and
C214 provide temperature compensation.
Tuned Circuits (FCC-Approved Models)
Stage 1: The collector circuit of Q201 is tuned to the third harmonic
of the oscillator frequency (approximately 60 MHz) by L205, C225, C234,
L202, C217, C237, and C233. (The latter components also form a ca-
pacitively tapped voltage divider for matching into the base of Q203.)
The output is double-tuned to provide high spectral purity. Regulated dc
bias is again employed to minimize changes in loading on the oscillator
stage and to stabilize the drive levels.
Stage 2: Q203 operates as a frequency tripler, with the collector cir-
cuit tuned to the output frequency (for example, 180 MHz). In this case,
L204, C216, C238, C236, L210, C235, and C222 perform tuning and
impedance-matching functions. As in the preceding stage, regulated dc
bias is applied to the base circuit to stabilize the drive level, and the
output is double-tuned to provide spectral purity.
Stage 3: Q204 operates as a tuned amplifier. Resistive loading on
the input provides stability. The output circuit consists of a resonant tank
circuit (L203 and C213) capacitively coupled to a low-pass filter (C219,
L206, and C218). C213 and C219 provide a capacitively tapped voltage
divider for matching into the low-pass filter.
Final Output (FCC-Approved Models)
Transmitter: This can deliver up to +17 dBm (50 milliwatts) to the
antenna. No user adjustments permit this value to be exceeded. Test-
point I110 provides a termination point for the 50 Ωoutput. C211 and
L207 act as a series resonating network for the battery, which acts as the
antenna. The unit should be powered exclusively by a 9 Vdc dry battery
(an alkaline type like the Duracell MN1604 is recommended).
Voltage Measurements: With 9 Vdc applied to the unit, the fol-
lowing voltages should appear at the terminals of the output transistor:
SVc = 8.88 Vdc
SVb = .450 Vdc
SVe = .473 Vdc
SBase current = 0.29 mAdc
SEmitter current = 21.5 mAdc
SCollector current = 21.8 mAdc
SPower input = 183 mW

Shure T2 Vocal Artist Microphone Transmitter
4
Characteristics 25C1018 (CC)
The output power is +16.5 dBm (44.7 mW) into a 50 Ω load, at a fre-
quency of 169.4445 MHz. At the lowest acceptable battery voltage of
6 Vdc, the final collector current drops to 15 mAdc and the output power
to +13.9 dBm (24.4 mW).
Spurious Emissions: To minimize the production and radiation of
spurious emissions and harmonic energy, and to promote stable opera-
tion, the collector of each RF stage is separately decoupled from the 9 V
supply by ferrite chokes, resistors, and bypass capacitors. The base cir-
cuits are similarly decoupled except they use resistor-capacitor (R-C)
networks, whose higher-impedance levels are more appropriate.
RF Section: ETSI-Approved Models
Audio Input: Processed audio enters R201, an internal potentiom-
eter that is adjusted for 15 kHz deviation (100% modulation) when the
audio section provides a –2.2 dBV, 1 kHz tone.
Oscillation: The audio then goes to varactor diode D201, which is
part of the modulated oscillator-tripler stage (Q201). The latter’s base-
emitter circuit operates as a crystal-controlled Colpitts oscillator in the
20 MHz region. Fundamental-mode crystal Y201 is tuned 10 kHz below
series resonance by the series combination of frequency-netting coil
L201, diode D201, capacitor C203, and capacitor divider C206 and
C207.
Frequency and Temperature Stability: To ensure frequency sta-
bility despite changes in the battery voltage, regulated 5 Vdc bias is ap-
plied to the varactor diode and to the base of Q201. C203, C206, and
C207 provide temperature compensation.
Tuned Circuits (ETSI-Approved Models)
Stage 1: The collector circuit of Q201 is tuned to the third harmonic
of the oscillator frequency (approximately 60 MHz) by L202, C208, C244,
C210, L203, C214, C213, and C215. (The latter components also form a
capacitively tapped voltage divider for matching into the base of Q202.)
The output is double-tuned to provide high spectral purity. Regulated dc
bias is again employed to minimize changes in loading on the oscillator
stage and to stabilize the drive levels.
Stage 2: Q202 operates as a buffer, with the collector circuit tuned to
the output frequency (for example, 60 MHz). In this case, L204, C216,
C245, C218, L205, C222, C221, and C224 perform tuning and imped-
ance-matching functions. As in the preceding stage, regulated dc bias is
applied to the base circuit to stabilize the drive level, and the output is
double-tuned to provide spectral purity.
Stage 3: Q203 operates as a frequency tripler, with the collector cir-
cuit tuned to the output frequency (for example, 180 MHz). In this case,
L206, C226, C227, C229, L207, C230, and C232 perform tuning and
impedance-matching.
Stage 4: Q204 operates as a tuned amplifier. Resistive loading on
the input provides stability. The output circuit consists of a resonant tank

Shure T2 Vocal Artist Microphone Transmitter
5Characteristics
25C1018 (CC)
circuit (L203 and C213) capacitively coupled to a low-pass filter (C219,
L206, and C218). C213 and C219 provide a capacitively tapped voltage
divider for matching into the low-pass filter.
Final Output (ETSI-Approved Models)
Transmitter: This can deliver up to +11.5 dBm (14 milliwatts) to the
antenna. No user adjustments permit this value to be exceeded. Test-
point TP6 provides a termination point for the 50 Ωoutput. C243 and
L211 act as a series resonating network for the battery, which acts as the
antenna. The unit should be powered exclusively by a 9 Vdc dry battery
(an alkaline type like the Duracell MN1604 is recommended).
Voltage Measurements: With 9 Vdc applied to the unit, the fol-
lowing voltages should appear at the terminals of the output transistor:
SVc = 8.83 Vdc
SVb = .097 Vdc
SVe = .32 Vdc
SBase current = 0.27 µAdc
SEmitter current =9.67 mAdc
SCollector current = 9.67 mAdc
SPower input = 87 mW
The output power is +9.5 dBm (8.9 mW) into a 50 Ω load, at a fre-
quency of 169.4445 MHz. At the lowest acceptable battery voltage of
6 Vdc, the final collector current drops to 8.84 mAdc and the output
power to +7.3 dBm (5.4 mW).
Spurious Emissions: To minimize the production and radiation of
spurious emissions and harmonic energy, and to promote stable opera-
tion, the collector of each RF stage is separately decoupled from the 9 V
supply by ferrite chokes, resistors, and bypass capacitors. The base cir-
cuits are similarly decoupled except they use resistor-capacitor (R-C)
networks, whose higher-impedance levels are more appropriate.

Shure T2 Vocal Artist Microphone Transmitter
6
Notes 25C1018 (CC)
Notes

Shure T2 Vocal Artist Microphone Transmitter
7Preliminary Tests
25C1018 (CC)
Preliminary Tests
Listening Tests Before disassembling the unit, operate it to determine whether it is
functioning normally.
Focused Testing: First and most important: Review any customer
complaint or request and focus your tests on any reported problem for
both listening and functional tests. For example, many complaints are for
“short range”and “drop-outs.”In such cases, perform only the RF tests in
this section to verify the problem. If the unit passes these, there is a
strong indication that the customer is using the product incorrectly (e.g.,
not keeping the transmitter in the receiver’s line of sight, not avoiding
metal enclosures or TV interference). Return the unit to the customer
together with an explanation of the proper set-up procedures.
Functional Test For complaints of distortion or other audio problems, try a “standard”
microphone cartridge (you should have one of each cartridge on-hand
for testing) and perform the audio tests in this section.
Note: Most of the following tests can be performed without disas-
sembling the unit.
RF Tests 1. Install a fresh 9 V battery in the T2, mute its audio, and turn it on.
2. Measure current drain: it should not exceed 35 mA.
3. Maximize the signal received on the spectrum analyzer by at-
taching a telescoping whip antenna to it. Then measure the
near-field output power: it should be 7 dBm (FCC-approved
model) or 3 dBm (ETSI-approved model).
(If you are unsure of the results you obtained here, measure the
output power conductively by soldering a 50 Ωcable to the out-
put of the transmitter. Verify that the output power is 15 dBm,
2 dBm [FCC-approved model] or 10 dBm, 2 dBm [ETSI-ap-
proved model].)
4. Verify that the carrier frequency of the transmitter varies from its
nominal value by no more than "6 kHz.
5. Check for an intermittent problem by shaking the transmitter and
tapping on it. As you do so, try to keep it at a constant distance
from the spectrum analyzer. Verify that the output power on the
spectrum analyzer shows no large and sudden drops in power
level (it will, however, vary a few dB with hand position).
6. Turn off the T2.
If the transmitter passes the above tests, its RF circuits are
working as designed.

Shure T2 Vocal Artist Microphone Transmitter
8
Preliminary Tests 25C1018 (CC)
Audio Tests
A: Verify the Matching Receiver
1. Make sure that the receiver is turned off. Connect the signal
generator to the receiver through a 50 Ωcable. Tack-solder the
center conductor to the antenna input and ground the shield of
the cable to pcb ground. Turn on the receiver.
2. Set the RF signal generator as follows:
Amplitude: –50 dBm
Modulation: 1 kHz
Deviation: 15 kHz
Frequency: T2 operating frequency
3. Connect the audio from the unbalanced output to the audio ana-
lyzer with a 3.3 kΩload. Turn the Volume control all the way up.
4. Engage the 400 Hz and 30 kHz filters on the audio analyzer.
Verify the following:
SFor the T3 and T4 the audio level is 400 mVrms ("90 mV)
SFor the T4N the audio level is 626 mVrms ("120 mV)
Sthd = <0.75%
B: Check the Transmitter
1. Disconnect the signal generator from the receiver. Monitor the
receiver’s unbalanced audio output with a 3.3 kΩload and the
audio analyzer. Make sure the receiver’s Volume control is at its
maximum setting.
2. Replace the microphone cartridge on the T2 with the test head.
Set the unit’s Gain control to minimum and unmute the audio.
3. Inject a 775 mV, 1 kHz signal from the audio analyzer into the
adapter cable and verify the following:
Sthe amplitude from receiver’s unbalanced output equals
400 mVrms ("90 mV)
Sthd = <0.75%
4. Change the frequency of the audio generator to 100 Hz and dis-
engage the 400 Hz high-pass filter from the audio analyzer.
Verify that the audio level is –1.0 dB ("0.7 dB) relative to the
level measured in step 3.
5. Change the frequency of the audio generator to 10 kHz and re-
engage the 400 Hz high-pass filter. Verify that the audio level,
relative to that measured in step 3, is –3.5 dB, "2 dB.
Units That Pass If the system components pass these tests and the microphone is
good, then the system is functioning as expected and shouldn’t require
tuning and alignment. Inform the customer that the product has retested
within specifications.

Shure T2 Vocal Artist Microphone Transmitter
9Disassembly and Assembly
25C1018 (CC)
Disassembly and Assembly
To access the printed circuit (pc) boards, disassemble the transmitter
(refer to Figures 2 and 3 on pages 9 and 10).
CAUTION
Observe precautions when handling this static-sensitive device.
Disassembly 1. Turn off the Power switch.
2. Unscrew the transmitter battery cup and remove the battery.
3. Unscrew the microphone cartridge.
4. If necessary, remove the microphone-transmitter subassembly:
(a) Use snap ring pliers to remove the retaining ring from in-
side the microphone handle.
(b) Remove the bezel by carefully inserting a small screwdriver
into the microphone handle, pressing the blade against the
plastic bezel tab, and prying it up (Figure 2). Remove the
label plate and switch actuators (Figure 3, page 10).
Note: Newer bezels have the labeling printed directly on
their faces; there are no separate label plates.
(c) As you slide out the transmitter subassembly (audio, RF,
and head circuit boards) from the handle, note how it was
positioned in the internal guides.
bezel
tab
handle
tab circuit-board
subassembly
(Right-side view)
Figure 2. Removing the Bezel

Shure T2 Vocal Artist Microphone Transmitter
10
Disassembly and Assembly 25C1018 (CC)
Reassembly 1. Insert the transmitter subassembly (audio, RF, and head circuit
boards) into the internal guides of the handle (Figure 3).
2. Orient the retaining ring so its gap will fit over the flat edge of the
head board (to avoid shorting the board). Use snap-ring pliers to
insert the retaining ring into the groove inside the handle.
3. Drop in the switch actuators and position the label plate (older
bezels only) over them. Position the bezel over the switches
then press until it snaps into place.
4. Screw on the microphone cartridge and ball screen. Install a bat-
tery (if desired) and screw on the battery cup.
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A
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AA
ball screen
microphone
cartridge
SM 58
retaining
ring
bezel
label plate
(older bezels only)
switch
actuators
9 V alkaline
battery
battery
cup
ball screen
microphone
cartridge
BG 3.1
circuit-
board
guides
head
board switches audio
circuit-
board gain
control
RF
circuit-
board
handle
access
to gain
control
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ÁÁ
(older, BG 3.0
cartridge)
Figure 3.

Shure T2 Vocal Artist Microphone Transmitter
11 Service Procedures
25C1018 (CC)
Service Procedures
Reference Material
The Shure Wireless System T Series User’s Guide describes the
product, tells how to operate it, and provides troubleshooting and techni-
cal data.
Special Equipment and Tools
In addition to the standard items described in the Wireless Service
Equipment manual, you will need:
Sto verify that the system is working properly, obtain the receiver
with which the transmitter is used (usually a T3 or T4); other-
wise, use the modified SC4 receiver described in the equipment
manual
Sa small flat-blade screwdriver to remove the bezel
Ssnap-ring pliers to remove and re-insert the retaining ring
Shand-made high-impedance probe (see the Service Equipment
manual)
System Operating Frequencies
Each transmitter circuit board is marked with a group letter that iden-
tifies the range of frequencies on which the transmitter can operate. Note
that Table 1 applies only to T2 transmitters that are FCC-approved, and
Table 2 applies only to T2 transmitters that are ETSI-approved.
Frequency Coverage: Earlier models used the same family of RF
boards (with Groups A, B, and C) for all the frequencies offered world-
wide at that time. Now there are separate board assemblies for units ap-
proved by the ETSI. If you have a frequency from Table 4, you have an
ETSI-approved model; if you have a frequency from Table 3, you have an
FCC-approved model.
Table 1
Pc Board Groups for
FCC-Approved Models
Group Frequency Range
A 169.000–183.975 MHz
B 184.000–198.975 MHz
C 199.000–215.975 MHz
Used with pcb assembly 90_8690
(pcb marking 34A8494).

Shure T2 Vocal Artist Microphone Transmitter
12
Service Procedures 25C1018 (CC)
Table 2
Pc Board Groups for
ETSI-Approved Models
Group Frequency Range
A 169.000–173.975 MHz
B174.000–180.975 MHz
C181.000–187.975 MHz
D188.000–194.975 MHz
E195.000–201.975 MHz
F202.000–208.975 MHz
G209.000–215.975 MHz
H216.000–222.975 MHz
K 216.000–239.975
Used with pcb assembly 90_8705
(pcb marking 34A8538).
Tables 3 and 4 provide information for identifying the system fre-
quency. The Crystal Letter Code, when used with the appropriate Shure
model number, identifies a specific operating frequency for both transmit-
ters and receivers. Note that, although a Crystal Letter Code always des-
ignates a specific frequency, it may be used with different Group Letters
on other products.
Table 3
T2 System Operating Frequencies for
FCC-Approved Models
Group Crystal Code Operating Freq. (MHz)
A V 169.445
A W 171.845
A CA 176.200
A CC 177.600
A CE 182.200
A CF 183.600
B CG 186.200
B CL 192.200
C CQ 202.200
C CV 208.200
Used with pcb assembly 90_8690
(pcb marking 34A8494).

Shure T2 Vocal Artist Microphone Transmitter
13 Service Procedures
25C1018 (CC)
Table 4
T2 System Operating Frequencies for ETSI-Approved Models
Group Crystal
Code Operating Freq. (MHz)
A AQ 173.800
B ZZ 174.500
B BB 175.000
B NB 175.000
B ND 176.600
B NE 177.600
C NH 182.000
C NK 183.600
C NL 184.600
C S 184.000
D NP 189.000
D NR 190.600
E NX 197.600
E NY 198.600
E NZ 200.350
E PU 201.650
F PB 203.000
F PD 204.600
H PP 217.000
H PR 218.600
H PS 219.600
K PV 232.825
K PX 233.125
K PY 234.625
K PZ 237.325
Used with pcb assembly 90_8705
(pcb marking 34A8538).
Changing the Frequency
The operating frequency of the T2 transmitter may be changed with-
in a specific Group by changing the crystal on the pc board. (For Group
information, see the preceding subsection). Check the transmitter for
proper operation before changing its operating frequency. After installing
the new crystal, perform the alignment procedures. Then run an opera-
tional test to ensure that the transmitter is functioning properly. Finally,
update the label to show the new frequency and letter identification code.

Shure T2 Vocal Artist Microphone Transmitter
14
Service Procedures 25C1018 (CC)
Note: To ensure proper operation, obtain the crystal from Shure and
verify that it operates within the frequency range of the pc board.
Since crystals are marked with the nominal oscillating frequency, not
with a letter code, you can use the following equation to determine
the frequency at which a transmitter will operate with a given crystal:
Carrier Frequency = (9 x nominal crystal freq. in MHz) –.09
FCC- and ETSI-Approved Models
To accommodate the different frequencies and requirements, Shure
supplies the T2 with different RF boards for FCC-approved models (used
in North America and other places) and ETSI-approved models (used in
Europe and other places). Although the RF alignment procedures are
similar for the two boards, there are some differences, especially in the
number of tuning stages and in the numbering of components and test
points. The audio-alignment procedures are the same for both versions
of the T2.
Note: Before the introduction of a distinct RF board for ETSI 300 922
requirements, all units shared the same RF and audio boards.
Drawings for Different Versions
At the back of this manual are diagrams of the circuit boards and
schematics for the original versions of the audio and RF boards as well
as for the current versions of the audio board, FCC-approved RF board,
and ETSI-approved RF board. Refer to the circuit-board diagrams for the
test points.
Alignment The RF and audio alignments are generally done together, as a
single, continuous procedure. Before beginning, do the setup described
in the following subsection, “Test Conditions.”Unless specified for FCC-
or ETSI-approved models, the alignment procedures apply to all models.
Test Conditions The following test conditions apply to all versions unless otherwise
specified:
SAn external 9-volt supply is connected to the battery terminals
(J101 and J102).
SThe Gain pot (R125) is set to its mid-range position.
SThe audio analyzer’s 400 Hz high-pass and 30 kHz low-pass
filters are pressed in.
FCC-Approved Units
1. Obtain a 50 Ω test cable for connecting the circuit boards to vari-
ous test equipment. (To construct this cable, see “50 Ω Test
Cable Assembly”in the Wireless Service Equipment manual.)

Shure T2 Vocal Artist Microphone Transmitter
15 Service Procedures
25C1018 (CC)
2. Tack-solder the cable to side1 of the RF circuit board as follows:
SCenter conductor to the 50 Ω solder pad, I210
SShielding to I2GN (on older versions, IGND)
ETSI-Approved Units
1. Obtain a 50 Ω coaxial test cable for connecting the circuit boards
to various test equipment. (To construct this cable, see “50 Ω
Test Cable Assembly”in the Wireless Service Equipment manu-
al.)
2. Tack-solder the cable to the bottom of the RF circuit board as fol-
lows:
SCenter conductor to the 50 Ω solder pad, TP6
SShielding to TP7 (ground)
High-Impedance Probe for TP5: When measuring test point 5,
fashion a high-impedance probe on the end of the test cable by connect-
ing a 50 Ωresistor between the center conductor and the shield, and a
0.5 pF capacitor to the end of the center conductor (see the following
illustration).
ÌÌ
50 Ω
0.5 pF
shield
Figure 4. High-Impedance Probe for ETSI-Approved Models
All Units
3. Carefully remove C240 (domestic units) or C242 (ETSI units) from
the RF board.
Note: This disconnects the battery antenna to allow accurate
conductive-power measurements.
Display Checks 1. Connect the 9 Vdc power supply to the audio board: the positive
lead to I140 (the positive battery terminal), and the negative lead
to I145 (ground).
2. Slide S101 (Power) to “On”(toward the board number), and
S102 (Mic) to “Off”(away from S101): the green LED should
glow. If it doesn’t, there is a circuit malfunction.
3. Reduce the power-supply voltage to 6 Vdc: the red LED should
glow.
4. Return the power supply voltage to 9 Vdc.

Shure T2 Vocal Artist Microphone Transmitter
16
Service Procedures 25C1018 (CC)
+
–
Ç
Ç
Ç
Ç
Ç
Ç
Ç
Ç
Ç
R130
U101
U102 J101
J102
–
+
R125
J101
J102
L209 R217 Y201 C217 C216
+9 V
+9 V
+5 V
+9 V
Audio Board (top)
Low battery
(red)
D101
Power
(green)
D103
Head Board (front view)
FCC-Approved Model RF Board (top)
+
–
Ç
Ç
Ç
Ç
Ç
J101
J102
Y201
ETSI-Approved Model RF Board (top)
L201 R201 C214 C222 C226
Gold-plated contacts
C216
Power
On/Off
S101
Mic
On/Off
S102
Audio In
(from audio board)
Gnd
Gnd Gnd
Audio Out
(to RF
board)
Audio In
(from cartridge)
ÇÇ
ÇÇ
ÇÇ
ÇÇ
+9 V
(to cartridge)
Audio In
(to audio board)
IGnd
I210
TP6
TP7
+
C107
TP5 (base of
Q202)
Figure 5. Major Components Referred to in the Alignment Procedures

Shure T2 Vocal Artist Microphone Transmitter
17 Service Procedures
25C1018 (CC)
RF Alignment: FCC-Approved Models
Do not apply modulation during the following RF alignment proce-
dures.
Note: If you cannot achieve any of the settings described in these
procedures, see “Bench Checks,”starting on page 23.
1. Make sure that the Mic switch (S102) is turned to ”Off.”
2. On the spectrum analyzer, set the center frequency to the fre-
quency of the T2. Then make the following settings:
SSpan: 1 MHz
SReference level: +20 dBm
SScale: 10 dB/div.
3. Connect the 50 Ωoutput cable to the spectrum analyzer.
A: Output Power (FCC-Approved Models)
1. With a yellow Toray non-conductive tuning tool, adjust C217 and
C216 for maximum (peak) output power on the spectrum analyz-
er. If the signal is very near the top of the screen, switch the
scale to 2 dB/div.
2. The output power should be 15 dBm, ±2 dBm (compensate for
cable losses in this calculation).
B: Frequency Adjustment (FCC-Approved Models))
1. Connect the 50 Ωoutput cable to the frequency counter through
the 20 dB attenuator. With a pink Toray driver, adjust L209 to set
the RF carrier frequency to the operating frequency
(±1 kHz—see Table 3 on page 12).
2. Reconnect the 50 Ω output cable to the spectrum analyzer. Con-
firm that the output power remains within specification. If not,
readjust C217 and C216 as described in the preceding “Output
Power”subsection.
C: Spurious Emissions (FCC-Approved Models)
1. Set the spectrum analyzer as follows:
SScale: 10 dB/div
SStart Frequency: 10 MHz
SStop Frequency:1 GHz
SReference level: 20 dBm
2. Check the level of spurious emissions: All must be at least
30 dB below the carrier level. If necessary, retune C217 and
C216.

Shure T2 Vocal Artist Microphone Transmitter
18
Service Procedures 25C1018 (CC)
D: Current Drain (FCC-Approved Models)
1. With a digital multimeter, measure the current drain of the trans-
mitter: it should be less than 35 mA. If it is too high, try detuning
C216, but make sure that the power and spurious response re-
main within specification.
2. Check for 9 Vdc (±0.35 Vdc) at +9 V on the head board (I133 on
the audio board).
RF Alignment: ETSI-Approved Models
Do not apply modulation during the RF alignment procedures.
Note: If you cannot achieve any of the settings described in these
procedures, see “Bench Checks,”starting on page 23.
1. Slide the Mic switch (S102) to the ”Off”position.
2. On the spectrum analyzer, set the center frequency to one-third
the frequency of the T2. Then make the following settings:
SSpan: 30 MHz
SReference level: +20 dBm
SScale: 10 dB/div.
3. Connect the high-impedance probe to the spectrum analyzer.
A: Output Power (ETSI-Approved Models)
1. Connect the high-impedance probe to TP5 (the base of Q202).
2. With a yellow Toray non-conductive screwdriver, adjust C214 for
maximum (peak) output power on the spectrum analyzer. For
better resolution while tuning, switch the scale to 2 dB/div and
adjust the reference level to the center of the screen.
3. Remove the high-impedance probe. Connect the standard 50 Ω
output cable to TP6 (before antenna-matching).
4. Plug the BNC end of the 50 Ωcable into the spectrum analyzer.
5. Set the center frequency to the frequency of the T2.
6. Adjust C216 and C222 for maximum (peak) output power on the
spectrum analyzer.
Note: C216 is not tuneable on earlier ETSI-approved units.
B: Frequency and Final Output Power (ETSI-Approved
Models)
1. Connect the 50 Ωoutput cable to the frequency counter. With a
pink Toray driver, adjust L201 to set the RF carrier frequency to
within ±1 kHz of the operating frequency (see Table 4, page 13).
2. Reconnect the 50 Ω output cable to the spectrum analyzer. Peak
C226 for maximum output power on the spectrum analyzer.
3. Confirm that the output power is 9.5 dBm (±2 dBm).

Shure T2 Vocal Artist Microphone Transmitter
19 Service Procedures
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C: Spurious Emissions (ETSI-Approved Models)
1. Set the spectrum analyzer as follows:
SScale: 10 dB/div
SStart Frequency: 10 MHz
SStop Frequency:1 GHz
SReference level: 20 dBm
2. Check the level of spurious emissions: All must be at least
44 dB below the carrier level. If necessary, retune C226.
D: Current Drain (ETSI-Approved Models)
1. With a digital multimeter, measure the current drain of the trans-
mitter: it should be less than 35 mA. If it is too high, try detuning
C226, but make sure that the power and spurious response re-
main within specification.
2. Check that 9 Vdc (±0.35 Vdc) is present at the head board +9 V
location (I133 on the audio board).
Audio Alignment (Both Models)
The audio boards on the FCC-approved and ETSI-approved models
are identical except for the pcb number printed on the board. (These
numbers differ because the boards are made as parts of larger assem-
blies for the two different models.)
The audio board has changed relatively little in the history of the T2.
Two examples of changes are the renumbering of the LEDs (the green
used to be D101, and the red, D102) and some slightly different designa-
tions (e.g., I1GN used to be IGND).
E: Setup
1. Disconnect the power supply from the T2.
2. Unsolder the test cable.
3. Replace C240 (domestic units) or C242 (ETSI units) on the RF
board.
4. Slide the board assembly, battery terminals first, into the test
handle: be sure to align the sides of the assembly with the han-
dle’s inner tracks. Alternatively, slide the assembly through the
test ring.
5. Screw the audio test head into the handle or ring. Connect a
BNC-to-BNC cable between the audio analyzer and the test
head.
6. Reconnect the 9 V power supply to the battery terminals of the
T2.
7. Place the Mic switch in the “On”position. Verify that the green
power LED (D103) lights steadily.