| Symptom: |
No RX/TX at all.
Display is OK. |
| Probable
Cause: |
Open R1 resistor on
reg. unit. |
| Cure: |
Replace R1 resistor
(4.7 ohm, 1/2 watt). |
|
|
| Symptom: |
Preamp inoperative or
intermittent. RX may be noisy. |
| Probable
Causes: |
1) Bad preamp RL1 relay
on RF unit. 2) Cracked solder on RF unit in preamp section. |
| Cure: |
Replace bad relay RL1
(FBR221D012). Carefully examine the preamp section of the RF unit
for bad joints and resolder as needed. |
|
|
| Symptom: |
Intermittent low RX
sensitivity. Actuating PTT temporarily restores RX or causes it to
drop out again. |
| Probable
Cause: |
Intermittent preamp
relay on RF unit, or intermittent T/R relay on filter unit. |
| Cure: |
Replace RL1 relay
(FBR221D012) on RF unit. If this doesn't help, replace RL1 relay
(SR-202) on filter unit. |
|
|
| Symptom: |
Unit jumps frequency
unexpectedly when turning VFO knob. Digital display does not track
with this jump. The frequency jump is consistent and happens at the
same place every time. Actual operating frequency does not match in
some parts of the bands. |
| Probable
Cause: |
LDO is out of
alignment. |
| Cure: |
Adjust R22 trimmer pot
on main unit for best performance. |
|
|
| Symptom: |
Frequency instability. |
| Probable
Cause: |
Dirty RIT/XIT pot and
switches. |
| Cure: |
Clean dirty RIT/XIT
pots and switches with Blue Shower solvent. |
|
|
| Symptom: |
Drastic change in audio
frequency response between USB and LSB., i.e. USB audio has too much
bass while LSB audio has too much treble. TX frequency response is
also poor. |
| Probable
Cause: |
Misadjustment of the
BFO or IF shift oscillator. |
| Cure: |
Realign BFO and IF
shift oscillator as per page 8-4 and 8-5 of the service manual. |
|
|
| Symptom: |
Intermittent TX output. |
| Probable
Cause: |
Cracked solder joints
at J3 connector on RF unit. |
| Cure: |
Resolder solder joints
at J3 connector. |
|
|
| Symptom: |
Distorted/raspy-sounding
SSB TX. Carrier power present in SSB modes. Complaints of RFI. Unit
tests fine on dummy load. |
| Probable
Causes: |
1.) Inadequate station
ground. 2) External power supply used with unit needs additional RF
decoupling. |
| Cure: |
Recheck station ground.
Improve if necessary. If a 3rd party power supply is being used with
radio, install additional decoupling capacitors across output
terminals. |
|
|
| Symptom: |
TX oscillations, or low
spurious output. |
| Probable
Causes: |
1) Bad Q5 transistor on
RF unit. 2) Bad electrolytic capacitors on PA unit. 3) Band switch
is misaligned. 4) Bad drivers or PA transistors. |
| Cure: |
Disconnect J2 connector
on the RF unit and see if the problem goes away. If it does, then Q5
transistor is most likely bad (replace it with a 2SC2878B). If
disconnecting J3 has no effect, examine the PA unit. Replace C18
and/or C23 capacitors if they appear swollen or overheated. Check
alignment of the front and rear band switch wafers. If none of the
above are causing the problem, then most likely the drivers or PA
final transistors are bad. |
| Remarks: |
If Q5 transistor on the
RF unit is a 2SC945, it should be replaced with a 2SC2878B. |
