CHAPTER 5
.'
"'~
.~~
:ı.:}~
A/ignment Procedures
PRELlMINARY
Alignment of the SP-605H
should be performed by qualified technicians only. Warranty may be void if
technical
repair is attempted
by anyone that is not trained and famiHar with portable communications
equipmenL.
Alignment
of the SP-605H
can easily be accomplished
with standard test equipment.
However, the
equipment should be within calibration standards to assure accurate alignment of the radio equipmenL.
PHASE-LOCKED
LOOP (PLL)
Connect an oscilloscope
to TP101 and adjust L 118 for maximum
signal (in receive mode) at this poinL.
Once this is accomplished,
turn the core of the coil dow n one turn to broaden the adjustmenl.
(This
adjustment should be accomplished
on the lowest frequency that the unit is programmed
to operate.)
With the unit on the lowest programmed
receive frequency, connect a DC voltmeter to TP1 03 (top of R120)
and adjust L 114 for 1.28 VDC. Connect a wattmeter to the antenna jack. Then key the transmitter on the
lowest frequencyand
increase this voltage until the transmit power appears.
Connect an oscilloscope
to TP104 and adjust L 119 for 1.0 to 1.6 volts peak-to-peak
in the transmit mode.
After this adjustment, recheck the DC voltage at TP1 03 to assure that the voltage is less than 3.0 VDC in
the transmit mode. If the reading is greater, perform the above procedure for L 114 again.
Canneel a frequency counter to TP105 and adjust the following variable capacitors to obtain the proper
frequency
(+ /-
200 Hz) according to the following calculation:
RX
==
(Fo - 21.4)
X
.5
TX
==
Fo
X
.5
Where Fo
==
selected frequency
For frequencies in the lower 5 MHz receive band, adjust VC1 07 to obtain the proper frequency.
For frequencies in the upper 5 MHz receive band, adjust VC108 to obtain the proper frequency.
For frequencies in the upper 3 MHz transmit band, adjust VC1 06 to obtain the proper frequency.
RECEIVER ALlGNMENT
Local Oscillator -
Connect an RF voltmeter to the source of receiver mixer TR222. Adjust L 10 1 and
L102 for maximum leveJ. If an RF voltmeter is not available, L101 and L102 can be adjusted for best
SINAD while feeding a high level, on-channel signal to the receiver.
Receiver Front-End Alignment -
Input an on-channel signal into the receiver and adjust L201-L204
for best SINAD. (This adjustment should be startoo on the center frequency of the programmed channels.
After setting L201-L204,
the outside channels should be checked for proper specifications.
if outside the
specified limits, readjust L201-L204
for proper readings.)
IF/Detector
Alignment -
These circuits ~re normally factory tuned and should not be retuned unless
absolutely necessary. If retuning is required, adjust L205 and L2Ö6 for best SINAD.
,
'-
.'
,.
.
"-
.
Squelch Threshold
Adjustment
-Connect"asignal
generatar to the receiver and modulate the
selected frequency with a 1 kHz
tane,
set. for 3.3. kHz deviatian. Set the ouptut level of the generatar at
0.25,N.
Adjust the squelch control to maximum squelch pasition and adjust VR202 to open squelch. After
adjustment, remove the input signal to the receiver and rotate the squelch control to assure that the radio is
squelched within the first quarter turn of the control.
9
