Heathkit SB-401 - Page 44

Page 119
POSSIBLE CAUSE
1, Defective crystal diodes,
2. Balanced modulator transformer improperly
installed,
38. Carrier Null control open or. shorted,
Level control not counterclockwise,
Gag Hearty nit
TRANSMITTER DIFFICULTY
Carrier Null does not
null properly,
Shorted coaxial cable from tube socket V5,
- Band switchincorrectly wired or positioned,
- Coils improperly wired,
No RF voltage at pin 1
2
3
4, Bandpass filter improperly installed,
5
6
2 of driver tube
socket (6CL6) V9,
- Heterodyne oscillator not functioning,
- Check voltages and wiring of tube sockets
V4 and V5.
7. Relay RL1 improperly wired.
8. Bias not removed from pin 1 of tube socket
V5.
9, Pin 2 foil of tube socket V5 shorted to
ground,
10, Cable to SB-301 not connected or FREQ
CONTROL switch not in LOCKED position,
1, Open choke, RFC4,
2. Open chokes, RFC5 and RFC6,
3, Check voltages and wiring of tube sockets
V9, V10, and Vi1,
4, Check wiring of Band switch,
5. Check wiring of coils.
6
7
No RF voltage at pin 5
of tube sockets V10 and V11,
.- Check wiring of relay RL1.
. Bias not removed from pin 2 of tube socket
v9,
8. 8,645 MHz trap improperly adjusted C303,
9, Cable to SB-301 not connected (Transceive
only).
Insufficient drive to finaltubes V10 and V11,
2, Check bypass capacitor wiring to driver
coils and Band switch,
3. Check wiring in final amplifier compart-
ment,
Neutralizing not possible,
No
RF
output,
Check
voltages
and
wiring
of
tube
sockets
V10
and
V11,
Resistor R17 open.
Feedthrough capacitor C67 not connected
to lug 2 of coil RFC9,
4, Check loading circuits,
5. Check wiring of Band switch,
6. Check antenna relay circuit (RL2).
7. Band switch incorrectly wired or positioned.