30
III. REFERENCE OSCILLATOR ADJUSTMENT
PROCEDURE
Adjustment of the reference oscillator is critical to
radios operating in the 896 MHz band (which has much
tighter channel spacing than the other land mobile
bands). Improper adjustment will not only result in poor
operation, but also, a misaligned radio will interfere with
other users operating on adjacent channels. For this
reason, the reference oscillator should be checked
every time the radio is serviced. The frequency counter
used for this procedure must have a stability of 0.1 ppm
or better.
NOTE
The radio internal circuitry must be at room tempera-
ture (25 ±3°C; 77 ±5°F) to properly center the
adjustment. Additionally, the radio should not be
heated from transmitting or operating at a loud audio
setting for a long period of time. Turn the radio off
and let the radio cool thoroughly to room temperature
before setting the reference oscillator.
1.
Connect the frequency counter and a
50-ohm load (or service monitor) to the antenna
connector.
2.
Connect dc power to the radio and switch radio
power on.
3.
At the PC’s “MAIN MENU” prompt, press F2 to
select “SERVICE.”
4.
At the “SERVICE” menu, press F2 to select “ALIGN-
MENT.”
5.
At the “ALIGNMENT” menu, press F5 to select the
Reference Oscillator adjustment screen.
6.
At the Reference Oscillator adjustment screen press
F6, “TOGGLE PTT,” to key the radio. Use the up or
down arrow keys to adjust the reference oscillator
frequency by selecting the relative value that yields
the frequency closest to 896.0125 MHz.
NOTE
When you press F6, "PTT TOGGLE,” you place the
radio into test mode 1 and cause the radio to transmit
on 896.0125 MHz. Do NOT use the microphone
PTT during this procedure. While this does cause the
radio to transmit on the test mode, it also corrupts the
alignment data.
7.
Press F6 to dekey the radio; press F8 to program
the value.
8.
This completes reference oscillator adjustment pro-
cedure. Press F10 as needed to return to the MAIN
MENU or to other SERVICE screens.
IV. TRANSMIT DEVIATION ALIGNMENT
PROCEDURE
NOTE
Compensation should not require any adjustments;
however, if for any reason such adjustments are
needed, adjust compensation per paragraphs V. and
VI. before you attempt to align deviation.
The transmit deviation should be checked any time
the radio is serviced and must be readjusted whenever
any compensation adjustments are made.
NOTE
This radio incorporates an interference-reducing fea-
ture that adaptively changes the deviation and power
based on the strength of the last-received signal.
Because of this, check the deviation in test modes,
which turn the feature off, before setting.
1.
Connect a modulation analyzer (or service monitor)
to the antenna connector, using minimum cable
length and as few adapters as possible. Apply a 1-
volt rms, 1- kHz tone to the microphone audio. Set
the modulation analyzer to read peak deviation.
2.
Connect dc power to the radio and switch radio
power on.
3.
At the PC’s “MAIN MENU” prompt, press F2 to
select “SERVICE.”
4.
At the “SERVICE” menu, press F2 to select “ALIGN-
MENT.”
5.
At the “ALIGNMENT” menu, press F3 to select the
TX Deviation screen.
6.
At the TX Deviation screen press F6, “TOGGLE
PTT,” to key the radio. (The programmer defaults to
the low-test mode.) Press the up or down arrow
keys to adjust the deviation to ±2.4 kHz, maximum.
Press F6 to dekey the radio.
7.
Press F3 to move to the next test mode. Press F6
to key the radio.
8.
Check the deviation and readjust as necessary.
Press F6 to dekey the radio.
9.
Press F4 to move to the last test mode and check
the deviation again, pressing F6 to key the radio;
readjust as necessary.
10. Press F8 to program the value.
11. This completes TX deviation adjustment. Press F10
as necessary to step back to the MAIN menu or to
other SERVICE screens.
Summary of Contents for Spectra
Page 6: ...v PERFORMANCE SPECIFICATIONS FOR SPECTRA PRIVACY PLUS TRUNKED CONVENTIONAL 900 MHz RADIO ...
Page 7: ...vi PERFORMANCE SPECIFICATIONS FOR SPECTRA SMARTNET TRUNKED CONVENTIONAL 900 MHz RADIO ...
Page 8: ...vii PERFORMANCE SPECIFICATIONS FOR SPECTRA 9000 RADIOS 900 MHz 30 WATTS ...
Page 25: ...1 GENERAL INFORMATION 1 ...
Page 73: ...53 INSERT GPW 7221 B Figure 22 Front Panel Diagnostics Key Closure Displays ...
Page 75: ...INSERT GXW 4278 O PICKUP FROM PW 4320 O 55 CONTROL STATION WIRING DIAGRAM ...
Page 79: ...PUSHBUTTON SPECTRA 900 MHz RADIO MECHANICAL EXPLODED VIEW 59 INSERT GXW 6225 B ...
Page 96: ...82 MECHANICAL EXPLODED VIEW PARTS LIST FOR SPECTRA 900 MHz RADIO ...