Philips PRM80 Series - VHF Receiver Front End Alignment

4.5.5 VHF Receiver Front End Alignment
Step
No
Result
Measured by
Result
Measured at
Adjust
Result Notes
1
Switch on power
and select
channel 3.
Highest freq.
channel.
2
Antenna
socket SK403
RF sig. gen.
output.
50uV pd., and
freq. of ch. 3.
Modulate generator
with 1 kHz at 60% of
max. dev.
3
DVM,
dc voltage
range.
TP403 R557 16.0 +/- 0.5V
Sets tracking gain
adjustment.
4
CRO,
5mV ac per div.
10uSec per div.
1 0x probe.
PIN 2 of
Tuning cores
U401
FL401.
Max level
of FL400 and
Sets tuning of filters.
an CRO.
5 Select ch. 1 Lowest freq. channel.
6
RF sig. gen.
output.
Freq. of
channel l
7
CRO,
5mV per div.
l0uSec per div.
10x probe.
PIN 2 of
U401.
R554
Max level
on CRO.
Sets tracking offset
adjustment.
8 Select ch. 3
Highest freq.
channel.
g
Antenna
socket SK402
RF sig. gen.
output.
Freq. of
channel 3
10
CRO,
5mV per div.
10uSec per div.
1 0x probe
PIN 2 of
U401
R557
Max level
on CRO.
Slight re-adjustment
may be necessary
11
RF sig. gen.
output.
1 mV pd.
12
AF level
meter.
Speaker
output at
S K202
Volume
control.
300mW in
4ohm.
13
AF level
meter.
Speaker
output at
SK202.
L404
Max AF
level.
Re-adjust volume
for 300mW output
when L404 is peaked
14
Distortion
Meter
Speaker
output at
SK202.
L404 Less than 3%.
Slight re-adjustment
of L404 may be
necessary
Section 4 Page 7