Motorola Two Way Portable Radio Ht1000 Jt1000 Mt2000 Mts2000 Mtx Series 6881200c75 B Manual

							19
Each SERVICE screen provides the capability to increase or decrease 
the ‘softpot’ value with the keyboard UP/DOWN arrow keys 
respectively. A graphical scale is displayed indicating the minimum, 
maximum, and proposed value of the softpot, as shown in Figure 3.
Adjusting the softpot value sends information to the radio to increase 
(or decrease) a DC voltage in the corresponding circuit. For example, 
pressing the UP arrow key at the Reference Oscillator screen instructs 
the radio microprocessor to increases the voltage across a varactor in 
the reference oscillator to increase the frequency.
In ALL cases, the softpot value is just a relative number corresponding 
to a D/A (Digital-to-Analog) generated voltage in the radio. All 
standard measurement procedures and test equipment are similar to 
previous radios. 
Reference Oscillator 
AlignmentAdjustment of the reference oscillator is critical for proper radio 
operation. Improper adjustment will not only result in poor operation, 
but also a misaligned radio that will interfere with other users 
operating on adjacent channels. For this reason, the reference 
oscillator should be checked every time the radio is serviced or once a 
year, whichever comes first. The frequency counter used for this 
procedure must have a stability of 0.1 ppm (or better).
1. From the SERVICE menu, press F2 to select TRANSMITTER 
alignment.
2. Press F2 again to select the REFERENCE OSCILLATOR softpot.
3. Press F6 to key the radio. The screen will indicate that the radio is 
transmitting.
4. Measure the transmit frequency on your service monitor.
5. Use the UP/DOWN arrow keys to adjust the reference oscillator per 
the targets shown in Table 13.
MAEPF-22858-O
Min.
ValueMax.
Value
015
Figure 3  Softpot Concept
Perform the following procedures in the sequence indicated.
Table 13 Reference Oscillator Alignment
BAND TARGET
VHF 0 to 300 Hz
UHF 0 to 300 Hz
800/900 MHz 0 to 300 Hz 
						

							20
Front-End
Pre-Selector
(VHF/UHF only)NOTE:This procedure is only required for tuning the 
front-end filter varactors in the VHF and UHF 
models. The 800 and 900 MHz models utilize a 
stripline pre-selector. 
1. Set the Test Box (RTX4005B) meter selection switch to the “VOL” 
position, and connect a dc voltmeter capable of 1mV resolution 
on a 2V scale to the Test Box AC/DC meter port to monitor the 
Received Signal Strength Indicator (RSSI).
2. From the SERVICE menu, press F3 to select RECEIVER alignment.
3. Press F2 to select the FRONT END FILTER softpot. The screen will 
indicate the receive frequencies at which the filter is to be tuned.
4. Set the RF test generator to the first receive frequency +150 Hz. Set 
the RF level at the radio standard antenna port to 4.0 µVolts with 
no modulation.
5. Adjust the UP/DOWN arrow keys to obtain a peak voltage on the 
dc voltmeter.
6. Press F8 to program the softpot value. 
7. Repeat steps 4-6 for the remaining test frequencies.
8. Press F10 and F2 to return to the RECEIVER menu.
Rated Audio1. Set test box (RTX-4005B) meter selection switch to the “AUDIO 
PA” position and connect an ac voltmeter to the test box ac/dc 
meter port.
2. Press F3 to select the RATED AUDIO softpot. The screen will 
indicate the receive test frequency to be used.
3. Set the RF test generator to the receive test frequency, and set the 
RF level at the radio standard antenna port to 1 mV modulated 
with standard test modulation (see Table 14).
4. Adjust the UP/DOWN arrow keys to obtain rated audio (as close as 
possible to 3.74 Vrms) into a speaker (28 ohms) or equivalent 
resistive load.
5. Press F8 to program the softpot value. 
6. For HearClear-equipped radios, go to step 7; otherwise press F10 to 
return to the RECEIVER menu.
7. Now set the RF test generator to the receive test frequency, and set 
the RF level at the radio standard antenna port to 1 mV modulated 
with a 1kHz tone, 1.2kHz deviation.Table 14 Standard Test Modulation (1 kHz Tone)
Band Deviation
VHF/UHF/800 MHz 3.0 kHz
900 MHz 1.5 kHz 
						

							21
8. Select the Hear Clear RATED AUDIO softpot, and adjust the UP/
DOWN arrow keys to obtain rated audio (3.74 Vrms) into a speaker 
(28 ohms) or equivalent resistive load.
9. Press F8 to program the softpot value. 
10.Press F10 to return to the RECEIVER menu.
SquelchNOTE:Verify that audio output is set to rated audio 
(3.74 Vrms)
1. Select the 25kHZ squelch tuning menu. (note: 25 kHZ must be 
tuned before tuning either 12.5kHZ or 20kHZ squelch).
2. With no signal applied, decrease the softpot value until squelch 
opens. Set the RF test generator to the frequency plus the 
following offset; (VHF: +200HZ), (UHF: +200HZ), (800MHZ: 
+500HZ). Adjust the generator for 8 to 10 dB Sinad.
3. Increase the softpot until the squelch closes.     
4. Monitor for squelch chatter. If chatter is present, increase the 
softpot until no chatter is detected. Press F8 to program the softpot 
value. Press ENTER to select the next softpot adjustment.
5. Repeat step 2 through 4 for all test frequencies shown on the 
screen.
6. If you are using 25kHZ channel spacing, skip to step 8. Otherwise, 
go into the 12.5kHZ or 20kHZ squelch tuning menus.
7. Repeat steps 2 through 5.
8. Press F10, then F10 again to return to the service menu.
Tr a n s m i t t e r  P o w e rVHF and UHF radios require two power-level adjustments, a high-
power or rated-power adjustment, and a low-power adjustment. The 
low power adjustment is required since the radio may be used in a 
reduced power mode, or with a vehicular adapter.
NOTE:All power measurements are to be made at the 
antenna port.
1. From the SERVICE menu, press F2 to select TRANSMITTER 
alignment.
2. Press F3 to select the TRANSMIT POWER softpot. The screen will 
indicate the transmit test frequencies to be used.
3. Begin with the highest test frequency shown.
4. Press F6 to key the radio, and use the UP/DOWN arrow keys to 
adjust the transmit power per the value shown in Table 15.
5. Press F6 to dekey the radio, and then press F8 to program the 
value.
6. Repeat steps 4 and 5 for the remaining test frequencies.
7. Press F10, then F2 to return to the TRANSMIT menu. 
						

							22
Tr a n s m i t
Deviation Balance 
(Compensation)Compensation alignment balances the modulation sensitivity of the 
VCO and reference modulation (synthesizer low frequency port) lines. 
The compensation algorithm is critical to the operation of signalling 
schemes that have very low frequency components (e.g. DPL) and 
could result in distorted waveforms if improperly adjusted. 
NOTE:Disable all audio band filters on the service monitor.
NOTE:(Secure-Equipped Radios Only)
If a secure module is currently installed in the radio 
being aligned, refer to the appendix at the rear of this 
manual. Read section III, “Secure Alignment 
Procedure”, before performing the transmit deviation 
balance (compensation) procedure. 
1. Press F4 to select the TRANSMIT DEVIATION BALANCE softpot. 
The screen will indicate the transmit test frequencies to be used.
2. Begin with the lowest test frequency shown on the screen.
3. Set the Test Box (RTX4005B) meter selector switch to the “MX 
DISC” position, and inject an 80Hz tone at 100mVrms into the 
AC/DC MTR port. Keep the ac voltmeter in parallel to ensure the 
proper input signal level. 
4. Press F6 to key the radio, and measure deviation. Record this 
measurement. 
5. Change the input tone to 3 kHz, 100mVrms and use the UP/
DOWN arrow keys to adjust the deviation to within ±2% of the 
value recorded in step 4.
6. Change the input tone back to 80 Hz and measure the deviation.
7. Repeat steps 5 and 6 until the 3kHz tone deviation is within ±2% 
of the 80Hz tone deviation.
8. Press F6 to dekey the radio, and press F8 to program the softpot 
value. Press ENTER to move to next softpot value. Table 15 Transmit Power Setting
VHF UHF
Power Level Test Frequencies Power Level Test Frequencies
136 - 174MHz 177.975MHz 450 - 512MHz 512 - 520MHz
5 W5.2 - 5.4  4.2 - 4.44 W4.2 - 4.4 3.2 - 3.4
1 W1.2 - 1.4 1.2 - 1.41 W1.2 - 1.4 1.2 - 1.4
800 MHz 900 MHz
Power Level All Test Frequencies Power Level All Test Frequencies
3 W3.2 - 3.42.4 W (Typ.)
2.9 W (Max.)2.4 - 2.6 
						

							23
9. Repeat steps 3 through 8 for the remaining test frequencies.
10.Press F10 to return to the TRANSMIT menu.
NOTE:The step size change for step 5 is 
approximately 2.5% per softpot value. This 
adjustment should only be made to the 3kHz 
deviation. Do not adjust the 80Hz deviation.
Transmit Deviation 
Limit1. Press F5 to select the TRANSMIT DEVIATION LIMIT softpot. The 
screen will indicate the transmit test frequencies to be used.
2. Begin with the lowest test frequency shown on the screen.
3. With the meter selector switch (RTX4005B) set to MIC, inject a 
1kHz tone on the AUDIO IN terminal on the test set, 80mVrms as 
measured on the AC/DC MTR port.
4. Press F6 to key the radio, and use the UP/DOWN arrow keys to 
adjust the deviation per the values shown in Table 16.
5. Press F6 to dekey the radio, and press F8 to program the softpot 
value. Press ENTER to move to the next softpot value.
6. Repeat steps 3-5 for the remaining frequencies shown on the 
screen.
7. Press F10 to return to the TRANSMIT menu.
Transmit Deviation 
Limit ReferenceNOTE:This procedure is required for VHF, UHF, and 
800 MHz models with 20kHz channel spacing 
and VHF and UHF models with 12.5kHz 
channel spacing. This procedure is not 
required for 900MHz models.
1. Press F6 to select the TRANSMIT DEVIATION LIMIT REFERENCE 
softpot. 
2. With the meter selector switch (RTX4005B) set to MIC, inject a 
1kHz tone on the AUDIO IN terminal on the test set, 80mVrms as 
measured on the AC/DC MTR port.
3. Press F6 to key the radio, and use the UP/DOWN arrow keys to 
adjust the deviation per Table 17.Table 16  Transmit Deviation Limit
BAND Deviation (KHz)
VHF/UHF/800 MHz 4.30 - 4.60
900 MHz 2.20 - 2.30 
						

							24
4. Press F6 to dekey the radio, and press F8 to program the softpot 
value.
5. Press F10 to return to the TRANSMIT menu.
VCO Crossover 
FrequencyNOTE:This procedure is only required after the field 
repair of a VHF or UHF VCO. 
In order for a phase-locked-loop to tune very wide bandwidths, both 
negative and positive control voltages (Vcntl) are required. This 
procedure sets the crossover frequency at which the negative Vcntl 
(or –Vee) switches from zero to negative.
Transceiver Board 
Identification
VHF RadiosVHF transceiver board NUD7070 and NUD7085 (“C” and later) kits 
include new VCO varactors, and are factory aligned with a new 
transmit VCO crossover frequency of 164.850MHz.
Since the transmit crossover frequency has changed, whenever 
transmit VCO crossover alignment (an RSS function) is performed, 
circuit board identification will be important. The “C” kits can be 
identified by the circuit board number 5511Y02 or 5511Y32 visible on 
side 2 of the board, located along the circuit board edge just next to 
crystal filter FL1. All future VHF transceiver boards will be in the 
“5511Y” series. 
Anytime a controller board or transceiver board is replaced in a radio, 
it will be necessary to perform the RSS transmit VCO crossover 
alignment, and check the transmit VCO crossover frequency. The RSS 
s c r e e n  f o r  t h i s  a l i g n m e n t  w i l l  s h o w  a  “ c u r r e n t  v a l u e ”  b o x                   
with a frequency already assigned, placed inside the box. When 
performing transmit VCO crossover alignment, first check the 
transceiver circuit board number. In a VHF radio:
If the board number is any “5511Y” series number, other than 
5511Y01 or 5511Y31, the transmit VCO crossover frequency in the 
“current value” box should be 164.850MHz. If it is not, change it 
to 164.850MHz. 
If the board number is 5511Y01, 5511Y31 or any other number 
not in the 5511Y series, the transmit VCO crossover frequency in 
the “current value” box should be 161.50500MHz. If it is not, 
change it to 161.50500MHz.Table 17 Transmit Deviation Limit Reference
Channel Spacing Deviation (kHz)
20 KHz 3.40 - 3.60
12.5 KHz 2.20 - 2.30 
						

							25 VCO varactors (CR201, 202, and 203) in “C” and later kits are not 
interchangeable with VCO varactors in earlier kits; Motorola parts and 
part numbers are different. When replacing a VCO varactor, Identify 
the transceiver board and order replacement parts from the applicable 
parts list.
UHF, 403-470MHz RadiosUHF transceiver board (403 - 470MHz band split) NUE7231 and 
NUE7240 (“C” and later) kits include new VCO varactors, and are 
factory aligned with a new transmit VCO crossover frequency of 
449.500MHz.
Since the transmit crossover frequency has changed, whenever 
transmit VCO crossover alignment (an RSS function) is performed, 
UHF band split and circuit board identification will be important. 
UHF band split can positively be determined by checking the 
markings on the power amplifier shield. If the power amplifier 
shield marking is 25U04 or 85Y10, then the transceiver is a 403 - 
470MHz band split. If the power amplifier shield marking is 25U05 
or 85Y11, then the transceiver is a 450 - 520MHz band split. 
The “C” kits can be identified by the circuit board number 
4221J07 or 4221J37 visible on side 2 of the board, located along 
the circuit board edge just next to crystal filter FL1. All future UHF 
transceiver boards will be in the “4221J” series. 
Anytime a controller board or transceiver board is replaced in a radio, 
it will be necessary to perform the RSS transmit VCO crossover 
alignment, and check the transmit VCO crossover frequency. The RSS 
screen for this alignment will show a “current value” box                   
with a frequency already assigned, placed inside the box. When 
performing transmit VCO crossover alignment, determine the UHF 
transceiver band split, and then check the transceiver circuit board 
number. In a UHF radio (403 - 470MHz range):
If the board number is any “4221J” series number, other than 
4221J01 thru 4221J06 or 4221J36, the transmit VCO crossover 
frequency in the “current value” box should be 449.500MHz. If it 
is not, change it to 449.500MHz. 
If the board number is 4221J01 thru 4221J06, 4221J36, or any 
other number not in the 4221J series, the transmit VCO crossover 
frequency in the “current value” box should be 438.025MHz. If it 
is not, change it to 438.025MHz.
VCO varactors (CR201, 203, 207, 208, and 209) in “C” and later kits 
are not interchangeable with VCO varactors in earlier kits; Motorola 
parts and part numbers are different. When replacing a VCO varactor, 
identify the UHF transceiver band split and the transceiver circuit 
board number, and then order replacement parts from the applicable 
parts list.
UHF, 450-520MHz RadiosUHF transceiver board (450 - 520MHz band split) NUE7232 and 
NUE7241 (“C” and later) kits include new VCO varactors, and are 
factory aligned with a new transmit VCO crossover frequency of 
495.375MHz. 
						

							26Since the transmit crossover frequency has changed, whenever 
transmit VCO crossover alignment (an RSS function) is performed, 
UHF band split and circuit board identification will be important. 
UHF band split can positively be determined by the markings on 
the power amplifier shield. If the power amplifier shield marking 
is 25U04 or 85Y10, then the transceiver is a 403 - 470MHz band 
split. If the power amplifier shield marking is 25U05 or 85Y11, 
then the transceiver is a 450 - 520MHz band split. 
The “C” kits can be identified by the circuit board number 
4221J07 or 4221J37 visible on side 2 of the board, located along 
the circuit board edge just next to crystal filter FL1. All future UHF 
transceiver boards will be in the “4221J” series. 
Anytime a controller board or transceiver board is replaced in a radio, 
it will be necessary to perform the RSS transmit VCO crossover 
alignment, and check the transmit VCO crossover frequency. The RSS 
screen for this alignment will show a “current value” box                   
with a frequency already assigned, placed inside the box. When 
performing transmit VCO crossover alignment, determine the UHF 
transceiver band split, and then check the transceiver circuit board 
number. In a UHF radio (450 - 520MHz range):
If the board number is any “4221J” series number, other than 
4221J01 thru 4221J06 or 4221J36, the transmit VCO crossover 
frequency in the “current value” box should be 495.375MHz. If it 
is not, change it to 495.375MHz. 
If the board number is 5521Y03, the transmit VCO crossover 
frequency in the “current value” box should be 486.025MHz. If it 
is not, change it to 486.025MHz.
VCO varactors (CR201, 203, 207, 208, and 209) in “C” and later kits 
are not interchangeable with VCO varactors in earlier kits; Motorola 
parts and part numbers are different. When replacing a VCO varactor, 
identify the UHF transceiver band split and the transceiver circuit 
board number, and then order replacement parts from the applicable 
parts list.
TX VCO Crossover
Procedure1. From the SERVICE menu, press F2 to select TRANSMITTER 
alignment.
2. Press F7 to select the TRANSMIT VCO CROSSOVER softpot. The 
screen will indicate the transmit test frequency to be used.
3. Connect a dc voltmeter capable of 1mV resolution to test point 5 
(TP5), which is accessible through a hole in the bottom side VCO 
circuitry shield.
4. Beginning with the default softpot frequency of line 2, press F6 to 
key the transmitter, and adjust the UP/DOWN arrow keys until the 
voltage reading at TP5 is 3.0 ±0.1 volts. The frequency will 
increment in steps of 50kHz. 
5. Press F6 again to dekey the transmitter, and press F8 to program 
the softpot value.
6. Press F10 twice to return to the SERVICE menu. 
						

							27
RX VCO Crossover
Procedure1. From the SERVICE menu, press F3 to select RECEIVER alignment.
2. Press F5 to select the RECEIVE VCO CROSSOVER softpot. The 
screen will indicate the receive test frequency to be used.
3. Connect a dc voltmeter capable of 1mVolt resolution to test point 
5 (TP5), which is accessible through a hole in the bottom side VCO 
circuitry shield.
4. Beginning with the default softpot frequency of line 2, adjust the 
UP/DOWN arrow keys until the voltage reading at TP5 is
3.0 ±0.1volts.
5. Press F8 to program the softpot value.
6. Press F10 twice to return to the SERVICE menu.
Signalling DeviationTransmit deviation balance compensation and transmit deviation 
limit adjustments should be completed before signalling deviation is 
adjusted.
DTMF Tuning1. From the SERVICE menu, press F4 to select SIGNALLING 
alignment.
2. Press F2 to select the DTMF softpot.
3. Press F6 to key the radio on the test frequency. The screen will 
indicate that the radio is transmitting.
4. Measure the DTMF deviation on your service monitor.
5. Use the UP/DOWN arrow keys to adjust the DTMF deviation per 
Table 18.
6. Press F6 again to dekey the radio.
7. Press F8 to program the softpot value; press F10 to return to the 
SIGNALLING menu.
High Speed Signalling1. From the SERVICE menu, press F4 to select SIGNALLING 
alignment.
2. Press F3 to select the TRUNKING HIGH SPEED softpot.
3. Press F6 to key the radio on the test frequency. The screen will 
indicate that the radio is transmitting.
4. Measure the TRUNKING HIGH SPEED deviation on your service 
monitor.
5. Use the UP/DOWN arrow keys to adjust the TRUNKING HIGH 
SPEED deviation per Table 18. 
						

							28
6. Press F6 again to dekey the radio.
7. Press F8 to program the softpot value; press F10 to return to the 
SIGNALLING menu.
MDC 1200 1. From the SERVICE menu, press F4 to select SIGNALLING 
alignment.
2. Press F4 to select the MDC softpot.
3. Press F6 to key the radio on the test frequency. The screen will 
indicate that the radio is transmitting.
4. Measure the MDC deviation on your service monitor.
5. Use the UP/DOWN arrow keys to adjust the MDC deviation per 
Table 18.
6. Press F6 again to dekey the radio.
7. Press F8 to program the softpot value; press F10 twice to return to 
the SERVICE menu.
Alignment Procedure 
ConclusionThe radio alignment procedure is now complete; the radio may be 
disconnected and returned to service.Table 18 Signalling Deviation
Channel Spacing 
(kHz)DTMFHigh 
SpeedMDCSingle
To n e
25 / 30 3.05-3.45 2.5-3.5 3.40-3.75 3.0-4.0
20 (VHF/UHF) 2.44-2.76 2.0-2.8 2.6-3.0 2.4-3.2
20 (821-824, 866-869) 2.44-2.76 2.0-2.8 2.6-3.0 2.4-3.2
12.5 1.55-1.85 1.40-1.75 1.640-1.875 1.5-2.0