SB-037 TS-120S VOX operation pick-up time 7-10-79 High speed CW ops may inquire about partial loss of the first character when operating VOX-CW. The transceiver will operate up to about 20WPM before this is apparent. Improvement may be had by changing three components on the RF Unit X44-1260-01. R33 100K ohm, change to 150K ohm R52 33K ohm, change to 4.7K ohm C62 .022 uF, Change to 1 uF @ 50v Production later than serial # 940701 has this change. Please make these changes in your service manual. -=-=-=-=-=- SB-038 TS-120S Final Transistor Replacement 7-10-79 When ordering single replacement 2SC2290 Final transistors for the TS-120S, please specify the hfe rank, by color. When replacing pairs of finals, always select the same hfe randk for both transistors. Rank designation will be found printed on the transistor, directly under the transistor number. Rank: R 30-65 O 55-95 Y 85-150 Please return all defective 2SC2290 finals to the attention of the TRIO-KENWOOD service department, along with the warranty claim form. Please make these changes in your service manual. -=-=-=-=-=- SB-040 TS-120S Ant Input Transformer Replacement 7-12-79 Ts-120S transceivers subject to strong static fields or similar high current atmospheric discharges may suddenly exhibit low RX sensitivity on all bands. TX will be OK. You may suspect T1 on the RF unit X44-1260-01. When replacing or ordering T1, L43-0696-35, also check the value of C20. If it is 33pF, just replace and repeak the transformer. First production transceivers will have a 15pF cap for C20. When changing T1, also replace C20 with a 33pF capacitor, and repeak the circuit. Old part number: L34-0696-05 Antenna Coil New part number: L34-0696-35 Old Capacitor was 15pF, replace with New part number: CC45RH1H330J 33pf Please make these changes in your service manual. -=-=-=-=-=-=- SB-048 Hum in SSB TX, TS-120S and others 8-9-79 Some TS-120S users may complain of a hum during SSB operation, which may be caused by RF feedback. There may be various reasons for this complaint. 1. Bad feedline and antenna system ground. 2. Poor Mic hookup or shielding. 3. Vertical antenna with poor or no radial system. 4. For base operation with other than a PS-30 Power supply: Poor regulation and insufficient filtering in the supply. 5. Linear amplifier creating hi RF field near the operating position. 6. RF induced back into the power supply causing falsie protection (other than PS-30). 7. RF pickup by any cables to or from ancillary equipment. Prevention is the best cure. For those cases where all normal measures have been tried, try installing a .01uF bypass cap across the mic input jack between pins 1 and 4. Some AFSK operators may have similar RF feedback problems with TS-820S or TS-520S. Bypass the mic ground pin to the chassis, pin 3 to 4 and in extreme cases, install a ferrite bead on the Mic coax center conductor at the microphone connector. Please annotate your service manual. -=-=-=-=-=- SB-060 TS-120 Repair Notes 12-18-79 Symptom Repair No CW, No Audio Sidetone oscillator Q25 on AF GEN unit 2SC1815 Receiver Sens Down T1, L34--696-35 on RF unit Shorted Analog Dial Cal OFF Mechanical Adjustment Carrier in SSB RF unit D2 and D3 shorted see TKC Service Bulletin Loss of Digital Check P5/J5 on Carrier Unit Smoke at Final Unit Check for long eds of wire shorted to case inside final unit also burned L10 and L11, L40-1011-04 (100uH) SSB Audio bad IF shift control turned max CW Power on Meter Max The RF gain control was turned max CCW VFO freq drift Replace the TEMP comp CAP C17 TX Audio BAD Check the Carrier Point adjust and make sure final bias is set to 150 Ma PLL digital NG Check D15 PLL unit High IC in RX Check the Final transistors 15 Meters only The BCD rotary band switch has a broken wafer RX TX only 10M The BCD divider Q16, 74LS163 on PLL unit bad. Check the BCD inputs against the pin 2 frequency. 28.5 HF Osc Check ground screws and tighten at Relay Unit X41-1250 No CW Filter Solder short across pins 1-2 J29 IF Unit No RX After the CW filter was installed the pins were not cut off shorting the signal to ground. Analog dial off Perform VFO tracking adjustment at 50 and 450 TX out 40M only 40M 50W and 10M 10W bad finals No 15M Core on the VCO transformer for 15M broken 3.5 and 7 Band same Shorted trace at Band switch under IF unit Low RF out All bands, Q12 SN16913 on AF gen unit, 2SK19GR bad No TX all bands L25 open on the RF unit Small gree inductor No digital no TX Q12 mixer on the PLL unit bad No RX no digital Q26 mixer on PLL unit bad INtermitt SSB AUdio Pin 5 of J5 on AF GEN unit loose No key or TX D26 and Q24 2SA562 on AF gen unit bad No TX R8 220 ohm at key jack burned open. Make sure customer uses shielded line on CW KEY. 15M osc. On 15M band only with antenna HF oscillation when first speaking. Install Ferrite bead on base of first mic amp Q18 AF GEN UNIT. No TX Loss of AVB Voltage at RF unit. Check Q9 2SA473 on the filter unit, also check 6 volt Zener diode. -=-=-=-=-=-=-=- SB-816 TS-120S Band PAss Filter Change 2-7-80 For complaints of out of band interference, especially BCI, the BPF (Bandpass filter) terminating resistors may be changed for an improvement of approximately 10dB. On the RF unit X$$-1260-01 change R3,5,7,9,11 from 1.5K ohm to 470 ohm No adjustments are required. -=-=-=-=- SB-827 TS-120S VFO Stability 6-6-80 (Supercedes 7/9/79 bulletin) VFO drift characteristics may be improved by changing component values and location in the VFO. This change applies to serial numbers before 00100001. Note: DO NOT disturb lead dress or component placement while working inside the VFO. 1. Remove the VFO unit by four 3mm hex head bolts. 2. Withdraw out the front panel and unplug the leads. 3. Remove the VFO cover by 5 phillips head screws. 4. Remove C17, and C18 from the PCB. Thes may be cut flush to the board. 5. Reposition the Ground terminal for the Variabel Capacitor by heating the post and pushing it through to the opposite side of the PCB. 6. Install paralleled 10pF green and 18pF yellow caps from the bottom tank coil terminal (LH) to the modified Ground post. Position the caps near the coil, not the PCB. Make certain the ground lead doesn't touch the coil or coil mounting. 7. To reassemble, perform steps 3,2,1. Snug all VFO case screws. A later complaint of frequency jump would indicate a loose VFO shell. New Parts: 10pf CC45SG1H100J 18pf CC45RG1H180J Analog Dial Calibration: 1. Turn the main dial fully CCW. The red cursor should line up with the VFO mark on the sub-dial. If it does not, remove the main knob, loosen set screws and align the scale start point with the red cursor. 2. Turn the main knob to 50 kHz analog. Adjust the aluminum slip sub-dial to line up with any one of the larger black dial marks. 3. Note the digital error. If it is MORE than 2 kHz adjust the VFO trimmer cap TC1 (center under the seal tape) to exactly 50.0 on the digital readout. 4. Turn the main knob to 450 analog. If the digital error is less than 2 kHz it is in spec. If the digital error is greate proceed: For instance if the digital error is 14.454.0 (plus 4 kHz), multiply the error times 4 (16 kHz) and adjust the VFO trimmer cap to the desired frequency (14.450.0) less the error, or 14.434.0. Next adjust the VFO inductor L10 (front under the seal tape) back up to the desired frequency of 14.450.0. 5. If the error in step 4 was in the minus direction, reverse the direction of correction adjustment in step 4. 6. VFO linearity final check: The digital readout and analog dial should agree to within +/- kHz at every 100 kHz dial point. PORTED AND REALIGNED FROM PC TO AMIGA FORMAT BY BOB G0LBQ - N6XDI.