 | SSB, Distortion on transmit signal:
 | (1) C-116 leaky. |
| (2) 9 MC carrier oscillator not centered. |
| (3) Defective diode in balanced modulator. |
| (4) V-6 soft. |
|
| SSB Flat topping on transmit signal:
| (1) V-13 defective. |
| (2) C-116 shorted. |
| (3) V-8, V-9, V-10 soft. |
|
| AM, No carrier:
| (1) K-2 defective. |
|
| AM, No modulation:
| (1) V-14 |
|
| VOX Operation, relay cycles Anti-VOX control has no effect:
| (1) D-6 (2) V-19 (3) Anti VOX Pot corroded. |
|
| X-CW, Relay chatters, key up:
| (1) V-4 or V-6 leaky. |
|
| X-CW, Keys O.K. But relay drops out with no time delay, VOX control has no affect:
| (1) D-7 |
|
| Plate meter reads full scale, spurious oscillation on all bands (taking off). S-meter reads up scale 50 to 60/9 :
| (1) Receiver cathode line shorted to ground. |
|
| SSB, AM, Feedback in receiver when transmitting:
| (1) Adjust C-168 for null with unit is SSB mode, receiver and transmitter gain at 3 o’clock, VOX gain CCW, audio tone fed to mike amplifier stage. |
|
| SSB, AM, excessive RF feedback in receiver when transmitting:
| (1) Check grounding system |
| (2) SWR |
|
| Excessive carrier persists after adjustment of R-85 and C-127:
| (1) Defective D-l, D-2, D-3, or D-4 in balanced modulator. |
|
| SSB. Cannot set VOX but PTT functions normal , Relay will not close when switched to
X-CW:
| (1) D-5 |
|
| X-CW. Relay will not close. SSB, functions normal using PTT or
VOX:
| (1) V-2 |
| (2) Sidetone oscillator not running. |
|
| No relative output indication when unit is loaded:
| (1) D-9, check antenna VSWR. |
|
| SSB, Hum on transmit signal:
| (1) Check shield lead at mike cable. |
| (2) Check coaxial leads from mike amplifier stage to balanced modulator for loose ground shield. NOTE: Lead from C-139 to S2A, from S2A, to R-76. |
|
| SSB, Hum on transmit and received signal:
| (1) C-145 |
|
| X-CW, SSB, AM, decrease in transmitter output:
| (1) V-8, V-9, V-10. |
| (2) V -6 |
|
| SSB, decrease in transmitter output:
| (1) V-18 |
| (2) V-15 |
| (3) Switch to X-CW mode, advance transmitter gain to about 11 o’clock, peak T-14. |
|
| Low output SSB, AM , CW
| (1) Change V-8, V-9, V-10. Reneutralize. |
TR-4 RECEIVER
|
| Receiver. No indication on S-meter of signal strength or very low S-meter readings:
| (1) Turn receiver RF gain completely CCW, S-meter should read 50 to 60/9. If S-meter pointer does not move meter movement is probably open, If S-meter reads up scale but less than 50/9, change V-11. |
|
| S-meter zero, adjustment very erratic:
| (1) S-meter zero potentiometer (R-70) corroded. |
|
| S-meter reading up scale and cannot be zeroed:
| (1) C-135 shorted, V-17 drawing excessive current. |
|
| S-meter pointer pegs to right (60/9) and does not return to normal resting point:
| (1) Center contact on relay K-1 burned or pitted. Receiver cathode circuit open. |
|
| S-meter pegs to left, Receiver dead:
| (1) Transmitter cathode short |
| (2) Plate meter leads shorted going into meter housing. |
|
| Receiver, Only very strong signals audible, very low S-meter readings:
| (1) Antenna relay (K-1) contact corroded. |
| (2) Fuse lamp open. |
| (3) Receiver coaxial from relay (K-l) to T-9 shorted. |
| (4) Receiver coil at T-9 open. |
| (5) TCVR switch in RCVR position. |
|
| Low receiver sensitivity:
| (1) V-13 leaky, high residual AVC voltage |
| (2) V-11, V-12, V-7. |
| (3) T-11, T-12 not peaked. |
|
| Receiver, weak audio:
| (1) C-135 Open |
| (2) V-17 |
| (3) C-136 partial short. |
|
| Receiver, SSB, audio distortion:
| (1) V-2 cathode qrounded (2) 9Mc oscillator off frequency, adjust C-130 for same noise pitch on USB and LSB or use signal generator, couple 9 Mc signal to control grid of V-12, zero heat oscillator by adjusting C-130. If oscillator cannot be zeroed, change 9 MC crystal. |
|
| Receiver, relay closes when in receive mode:
| (1) C-142 partial short |
| (2) V-19. |
|
| SSB, X-CW, AM. No crystal oscillation. Output on 40, 15 , and 10 meter bands.
| (1) V-1 |
| (2) Tune L-1, L-2, and L-5 on appropriate bands for maximum negative voltage at
TP. |
|
| SSB, 40, 15, and 10 meter bands. Sudden shift in frequency of 50 Kc’s or more from 100 Kc crystal calibrator check points:
| (1) Crystal is spurious. Replace. |
|
| Receiver, excessive popping noise in receiver:
| (1) C-78 leaky. |
|
| Receiver dead, Resistors R-168 and R -71 burnt:
| (1) S-meter shorted (2) Meter leads pinched where going into meter housing. |
|
| Frequency jump or shift 1 or 2 Kc, both transmit and receive :
| (1) PTO cover loose |
| (2) Zener diode in PTO bad (check Zener voltage). |
| (3) K-2 has bad contacts.
|
|
