Kenwood TS-700 General Modification: (Use at your own risk!) SUBJECT: Kenwood TS-700A Squelch Won't Close fix Kenwood TS-700A FM squelch won't close? Change Q15 on FM IF unit. It's probably leaky, which disallows build-up of DC charge based on noise detection by Q14, which causes Q16 to not be able to shut off FM audio with no signal quieting. The FM-IF unit is located right center, top of rig, and has the little ceramic filter on it and the socket for the optional tone unit. Q15 is a 2SC733(Y) which is no longer available. Use the NTE-289A, Digikey part number 526-NTE289A. Same pin out as the 2SC733(Y) (E-C-B). Maybe also change Q14, the squelch noise amp, same type transistor, for more effective amplification. SUBJECT: Converting the channel and band lights to LED in the TS-700A I recently obtained after many years a Kenwood TS-700A. The unit is in good shape and seems to work well thus far, however, the lights that illuminate the VFO dial, band selector and channel selector were burned out. The VFO is easy to reach, and the bulb is readily available, so I did not convert this to LED at this time, however, the channel and band lights are difficult to reach, so I decided to change them to LED so that I would not have to replace them again. It is a fairly straightforward operation, but the spaces are tight. After reviewing the service manual, I was able to identify 2 possible method to mount the replacement LED's. This is an overview of how I converted the lamps to LED's 1. I measured the voltage at the lamps, and found that is was just over 10 V. 2. From this, I estimated that the LED would drop 2V, leaving 8, and I wanted about 20 mA to the LED. 3. From this (actually, I had initially figured the lamps were driven from 12v) I computed that I needed about 500 ohms. I had a large collection of 1k ohm, -+ W resistors, so I paralleled 2 and placed them into the circuit. Had this been 12 volts, and with 2v drop, this leaves 10 V, and the 500 ohm resistor provides 20 mA. Since the supply is 10 volt, then the 2V LED drop leaves 8V for the resistors to drop. This provides about 16mA to the LED's. The brightness was fine for me, but you can adjust to your preference. The resistors will dissipate about 200 mW, so it might be wise to either use 2 -+ W in parallel like I did, or use a -?? W resistor. 1. Remove the top and bottom covers. Check for any other mods on the bottom of the VFO case. (Mine has what appears to be a CTCSS tone board installed, which short leads, which will cause an issue when you try to tilt the panel later.) 2. Remove the old lamps. 3. Slip some heat shrink tubing over the wires, and solder the resistors and LED's into place. 4. Carefully place everything, then power on the unit to confirm LED polarity. If an LED does not light, reverse the leads. 5. Mounting the LED's was a bit of trouble. The rubber mounts did not fit well, and the lamps were set a bit to the side of the switch position window, and it is a tight fit in that area behind the front panel. So, instead of using the original mounting holes, I noted that the metal mount had a channel that ended up almost exactly behind the dial windows I was trying to light. I initially placed the LED and the rubber mount for the bulb in this channel. Since the LED is a bit more directional, this would be a good place to mount the LED as it shines almost directly on the switch position window. Using either some silicone adhesive or hot glue, this could have completed the mod. 6. Using this, I would be able to have the LED's shine directly at the panel window so the light would show up a bit better. 7. However, I decided to go ahead and try to get the rubber mounts back into the original places. Once I tilted the front panel outward, I was able to accomplish this. 1. To open the front panel, 2. 2 screws must be removed from each side of the panel. My 700a had a ground screw under the red coaxes to the power button side of the VFO cage. Loosen and remove this screw. Do not loosen the flat blade screw at the bottom, it is a pivot. The front panel should now tilt open from the top. 8. Even thought it was tight, I was able to place the LED's and the rubber mount into this rail, thus illuminating the window for the band and channel switches. The green LED's seem to match the other green windows well, and I can read the switch position now. The LED had enough lead slack to allow pointing the LED at the switch position window. 9. When I get some more time, I plan to change the VFO, RIT, and ON AIR as well as the meter light to LED's. I will probably use 3 LED's to light the VFO dial. The green LED's match the TS-700A color scheme very well. With this, this radio will have NO incandescent lamps. SUBJECT: RSK-7 installation Kit for TS-700A/S This kit will add 600 KHz repeater offset in the 145 MHz band position of the TS-700A and TS-700S 2 meter all mode transceivers. This offset will be 600 KHz lower than the displayed (VFO) frequency. This is the same type of offset used in the 146 MHz band. SUBJECT: Solving the problem of the digital frequency readout of the TS-700s Sometimes the digital frequency readout is going off when turning the VFO. This is due to a bad contact on the variable capacitor. There is some sort of spring which makes the contact from rotor to the chassis. You can solve this problem without taking the VFO out of the transceiver. On top of the aluminum case of the VFO is a hole (abt. 8mm). You take a can of contact spray with the supplied straw. You melt the straw on the end to close it. Put in a small hole on the end with a needle on the side of the straw to make it spray sideward’s. Now you put the straw abt. 5-6 cm deep in the hole, in an angle of 45 degrees to the backside of the VFO. Now spray only shortly. Rotate the main dial of the VFO, and "voila" your display is functioning properly again. SUBJECT: Put CW on USB for the Kenwood TS-700A, S, SP The following paragraph is an excerpt from my letter to Kenwood (which received no response, as expected): "Why did you put the CW carrier on LSB in the TS-700? This design quirk is creates mass confusion and operating inconvenience for all your TS-700 customers. Picture the following: you are calling a weak distant station on CW, which means you are automatically transmitting and receiving in LSB mode... the called station answers, but on SSB. You will probably not even hear that response; in any case, the response will at best be unintelligible, since you are in LSB mode and the other station is in USB mode, which is the convention on all amateur bands above 14.0 MHz!" Readers, take heart! This design flaw is easily corrected in 30 minutes with a simple modification requiring only one additional switching diode which relieves the problem by putting CW on USB, producing an 750 Hz note in any other transceiver operating in USB mode which is tuned to the same frequency as the one which is doing the transmitting. Additionally, it does not affect compatibility with unmodified transceivers. Steps 1 - 5 below apply to the 700A CARRIER board, or the 700S/SP CARRIER-VOX board. 1. After sufficient warm-up of your frequency counter and the TS700x, record the frequency of the generated carrier in all modes by connecting the counter to the TP (Test Point) following the buffer Q2 (700S/SP = Q11). The following listed frequencies are from my TS700A and are provided as an example only: USB 10.698558 LSB 10.701525 CW-TX 10.700775 CW-TX 10.701525 Note: Make certain an open circuited key jack is inserted to prevent transmitting a carrier which could affect counter readings. 2. Interchange crystals 'X1' and 'X2'. Unsolder one end of C3 (700S/SP = C23) and ensure it does not short to adjacent components... it will be left permanently disconnected. 3. Interchange one end of L2 and L3 by lifting the wire from their respective terminals and installing crisscross jumpers. 4. Interchange the wires to the USB and LSB connection posts on the board... there are 2 wires on each post. 5. Adjust the oscillators to the relative frequencies shown, using the trimmers indicated. USB and LSB are to be adjusted to the original frequencies recorded in step 1, and CW-TX is to be adjusted to be 850 Hz higher than the USB frequency. CW-RX will be identical to USB and requires no adjustment. USB 10.698558 adjust TC3 LSB 10.701525 adjust TC1 CW-TX 10.699308 adjust TC2 CW-RX 10.698558 requires no adjustment 6. This completes the modification for the TS-700A Correcting the frequency readout on the 700S and 700SP: After sufficient warm-up of the transceiver, perform the following steps on the 700S/SP COUNTER board: a. Cut the PC trace at the USB post. Bridge a 1N914 (or equivalent) diode across the cut with the anode toward the post. This diode will be referred to as D4a. b. Disconnect the cathode end of D1 from its current position and reconnect it to the cathode end of the newly installed D4a. c. Place the transceiver in USB mode and note the dial reading. Switch to CW mode, place in the transmit condition (make certain than an open-circuited key jack is in place in the KEY jack) and adjust TC2 on the counter board for a reading 750 Hz higher than the USB reading just noted. Note: on some 700S/SP's, it may be necessary to disconnect one end of C16 and place a 10pF capacitor in series with TC2 to achieve your goal. Otherwise, settle for the same readout as that shown in USB mode. Some 'X2' crystals just won't pull quite far enough for +750 Hz. This completes the modification for the 700S/SP 7. Note: The absolute accuracy of the frequency counter used is not overly important ?????? Most important is the relation of the frequency measurements, therefore, the counter should be powered on, allowed to warm up sufficiently to eliminate drift and left on during this entire process. SUBJECT: Distorted mic signal for TR-7200G & TS-700 Service bulletin no. 23 (31-10-1977) Receiver 1. No squelch: Check C84 47uf on X55-1110-11. 2. Intermittent receive: Check for D14 touching to ground on X55-1110-11. 3. Both Q17, Q18 audio transistors burned up: Send for bulletin before replacing. 4. Poor receiver sensitivity: Check for proper output of Q10 10.245 MHz stage. If it is defective replace xtal. 5. No receiver audio noise: Check L23 discriminator coil. 6. No receiver: No C9 voltage at X55-1110-11. 7. Receiver sensitivity poor: Check D2 MI301. Transmitter 1. Distortion on audio TX: Bad Q8 TA7061 IC. 2. No TX HI: Check for shorting terminals at HI/Low switch. 3. No TX: Check for proper T9 voltage at X56-1190-11. 4. No TX: Collector voltage SB at X45-1080-00. Check Q9 2SA496Y. No TX: Check D1 MI301. SUBJECT: TS 700 CW QRG same as USB The TS 700 uses LSB when generating CW. This is quite annoying because when you would like to call a SSB station (which will always be using USB) you are unable to listen to this station while in CW-receive position. This happens quite often on 23/13 and 3 cm for which I use the TS 700 as exciter. A cumbersome switching is the result. This modification allows receiving in the USB mode of operation, while in CW. Steps to be taken: Remove the bottom cover; Locate the CAR VOX unit; Locate the wire warp pin USB (first pin, close to var. C); Locate L1, 1mH, green, which is connected to USB pin, Cut the L1 connection on the pin-side, leaving a wire as long as possible on L1; Connect a diode (1N4148) between the pin and L1, the cathode connected to L1; * Locate the wire wrap pin CWR (fourth pin, counting from var. C); Locate diode D10, close to pin CWR; Cut the cathode wire of D10, leaving as much wire on the diode as possible; Connect the cathode of D10 with the cathode of the added diode at the USB pin. The result is that CW is now received in the USB mode CW transmit is unchanged. The frequency read-out is incorrect, this will be adjusted later!! The CW transmit frequency must be shifted Locate var. C, TC 3, which is in the corner of the PC board. Connect 150 pf parallel to TC3, using its solder pins as connection points. Frequency adjustment (the simple way, not using measuring equipment):Take a second TRX Transmit CW in a dummy on 144.100. Receive the transmitted signal on the TS 700 and adjust for a audio tone of 900 Hz. Switch the second TRX to RX ; do NOT change the frequency; Key the TS 700 with CW and adjust TC3 to get the correct audio tone on the second TRX (400-900HZ, depending on its filter) Frequency readout * Locate the counter unit; the short end of the PC board has 4 var. C?????? On the PC board side of these C??????s locate a connector as far in the corner as possible. The second wire of this connector is a blue one. Cut the wire approx 4 cm away from the connector; put a crimp sleeve of 2 cm over one of the wire-end (do not crimp yet); insert a diode in the wire cut, the cathode facing the connector; locate D1, which is close to the middle of the connector; cut the cathode side of D1 , leaving as much wire on the diode as possible; connect the D1 cathode with the cathode of the inserted diode (blue wire); place the crimp sleeve over the blue wire diode + wire connection and crimp; Switch the TS 700 to FM; Adjust the frequency to 144.100.0; Switch to USB, the readout should be 144.098.5, if not adjust TC 4 on the counter unit (TC4 is mounted on the PC board side opposite the connector and stands a little bit to the middle). CW and USB readout should be the same in receive. Switch to CW transmit. The readout should be 144.099.4. If not adjust TC 2 (second var C from connector). Switch to LSB, the readout should be 144.101.5 if not adjust TC 1, closest to connector. (For proper adjustment refer to the service manual and use a frequency counter). Replace the bottom cover and enjoy SSB/CW or CW/SSB QSO??????. Without difficult switching procedures. SUBJECT: Replacement of 9V regulator IC MFC.4060 with improved MC1723CL-A X43-1250-00 PCB comes complete with mounting hardware and extended leaded leads for easy installation. Procedure: 1. Remove old IC MCF4060-A Q11. 2. Remove R27 1.5Kohm (Delete). Replace with wire jumper. 3. Remove and reinstall R28 1Kohm on foil side of PCB. 4. Mount PCB per illustrations (observe lead call-outs between X43-1250-00, new PCB, and old Q11 position (X43-1120-00). 5. Reset VR1 for 9.0V measured at power supply output terminal. 6. Reset VR2 for 21.0V measured at power supply output terminal. SUBJECT: TS-700A for Repeater operation in Europe Service bulletin no. 5 (June 11 1975) We have had several inquiries about repeater operation of the TS-700A in Europe. The 2 Meter band in Europe is 144 MHz to 146 MHz with repeater operation in the 145 MHz to 146 MHz range. The repeater offset is generally 600 KHz down from the output frequency. The repeater offset in the TS-700A occurs only in the 146 MHz and 147 MHz bands. By changing these to 144 MHz and 145 MHz, respectively, and changing the appropriate offset, the TS-700A can be used with European repeaters. The TS-700A uses varicap diodes to tune the HET unit, MIX unit and RX NB unit because of the 4 MHz coverage. These varicap diodes are used to resonate various stages, precluding the need to retune from band range to band range. The varicap diodes are biased by resistors that are selected by the Band and REPEATER switches. These bias resistors must be changed if the band frequency and/or offset crystals are changed. The table below shows the resistors and crystals that need to be changed to make the TS-700A useable with European repeaters. All resistors are 1/4 watt. HET UNIT Part No. 145-147 MHz 144-145 MHz X3 127.100 MHz 125.100 MHz X4 128.100 MHz 126.100 MHz X6 128.700 MHz 125.500 MHz R31 62 K 39 K R32 82 K 47 K R34 100K 39K BAND SWITCH UNIT Part No. 146-147 MHz 144-145 MHz R103 12 K 22 K R104 8.2 K 15 K R110 12 K 15 K R112 6.8 K Delete R113 6.8 K 18 K ADD -?? 138 K It is necessary to remove the front panel to make this modification. To do this, remove the top and bottom cabinet halves. Next, remove the FINAL tuning shaft by loosening the shaft coupling and pulling the knob and shaft out. Then, remove the six screws (3 on each side) holding the front panel. Remove the BAND and DRIVE knobs and the nuts holding these controls. Gently pull the front panel out until there is enough room to work on the BAND SWITCH unit. The 138 K resistor that is to be added consists of a 120 K resistor and an 18 K resistor in series. It is connected from pin 3 of the band switch to ground. Show below is a diagram of the BAND SWITCH unit. After installing the new resistors in the BAND SWITCH unit, reassemble the front panel, leaving out the FINAL tuning shaft. The procedure for replacing the resistors in the HET unit is to first remove the three screws holding the board and tilt it up towards the VFO. Plugs P-1 and P-2 may be removed if necessary. The resistors that need to be changed are located on the outside edge of the board. Replace the resistors and reinstall the board and connector. Install the crystals in the separate sockets (X3, X4, and X6). Replace the FINAL tuning shaft and align as per page 40 of the Service Manual. SUBJECT: 9600 and TS-700a I connected the 9600 baud input directly across R21 (33k ohm) on the Generator Unit Board via a 10 microfarad tantalum capacitor. The + of the tantalum is connected to the junction of C23,R21 and R22. The - of the tantalum goes to the conductor of the shielded cable, and the earth shield to the immediately adjacent earth terminal. I carefully scraped off the 'insulation' on the top of R21 (approx 5mm) and soldered the + of the tantalum to it. The 10 microfarads was basically for isolation. I originally intended to match the load as per James Millers article by modifying C34, however I just adjusted VR1 and because it works like a charm I have never bothered to attempt matching. I have also been meaning to run the JAS-1 via the varactor for Fuji-Oscar 20, but once again have not got around to it. With the launch of all the Digital Satellites, time just seems to fly, especially when we have daylight saving, as the first evening pass goes by between 11pm and 12 midnight. Just lately I have been going to bed at a respectable hour, hence the delay in answering. However this weekend Daylight Saving finishes, so UO_14 and AO_16 will be here 'an hour earlier, which will be just great. SUBJECT: Service notes on TS-700A Service bulletin no. 20 (18-10-1977) Power supply 1. 9 volts down: The MFC4060 Q11 and 2SA495 Q9 are bad. 2. No 21V: Replace Q3 (2SC733Y (X43=1120-00) Power Supply Unit. 3. Dial light is VERY bright: Replace shorted Q2 2SA671 on rear panel. 4. Intermittent +9 volt supply: The legs of Q12 2SD235 are too short at the PC board. The leads were pulled away from the board. Replace Q12. 5. Power supply intermittent when tapped: Check for short leads on pass transistors, pulled out of circuit board. 6. No RX - No TX: Check diode D6 Zener in power supply. -6V supply. If shorted, replace. 7. No 13.8 volts at power supply: The wire on bridge D1 is not soldered. 8. +9 volts is okay, but 21 volt or more than 16 volts: Q1 is bad in the power supply 2SC733Y. TRANSMITTER 1. No modulation: Replace bad diode D15 Varactor on X52-1080-21. 2. USB or LSB is too high frequency: Recheck alignment of carrier board according to TKC service Manual procedures. 3. No RF out AM CW SSB: Replace D13 on GEN unit X52-108021. 4. FM RX and TX different frequency: Readjust all HET unit frequencies. Also check VFO linearity and adjust TX frequency L3. 5. TX wrong frequency: Adjust L3 at X52-1080-21. 10.7 oscillators for final TX frequency. 6. No power out FM: Check for loose connection at L3, the 10.7 coil on GEN unit X52-1080-21. 7. No TX or RX: The fixed channel switch is in the wrong position. 8. Low power out only 8W. 21 volt supply down to 16V: The protection diode D7 in the power supply is shorted. 9. VFO drift: Q1 3SK22Y in VFO is bad. 10. No TX FM: D15 on X52-1080-21 GEN is bad. 11. Drive control does not peak: This is normal - leave at center 500 position. 12. No TX: TX B terminal touch to ground at X52-1080-21 GEN unit. 13. No TX FM: Check diode D16 on GEN unit. 14. Only 3 watts out: Bad Q2 2N5642 in final amplifier. 15. The RF meter doesn't Work, but TX output okay: Bad diode D1 on BPF, the 1N60 is open. 16. No TX: Bad Q3 in mixer unit (X48-1130-21) 3SK35 (BL). 17. No VFO output: Cold solder joint of R2, 100 ohm resistor inside VFO on circuit board. 18. Intermittent TX: Bad ALC pot on mixer board VR2 (X48-1130-21) 19. No TX 147 Simplex: Loose resistor not soldered on rear circuit board of band switch. Receiver 1. Spurious signals on receive; if the output level or VFO is too high or mixer Q3 on HET unit: SN76514 is bad. 2. IF the noise blanker does not work: Check Q6 2SK19GR on X55-1120-00. 3. There is no audio from receiver-no 21 volts: Q1 2SC733(Y) in 21 volt supply is bad. 4. FM receiver sensitivity is down 30 - 40 db: Check 10.245 xtal at TP-1 on FM IF unit. If oscillator level is down, replace crystal. 5. Receiver sensitivity is intermittent and TX intermittent: Check contacts RT relay. Replace if bent or miss-contact. 6. If you cannot adjust the center meter: Maker sure S meter start, VR4 is set at zero. If you cannot get enough adjustment with center meter, adjust VR1, replace Q4 (2SK19GR) on X55-1120-00. 7. No receive: Check for solder touch at 133 terminal on Het unit, if there is no 133 het output. 8. No RX or TX and no VFO light: Check diode D2, 1N60 located on VFO circuit board. 9. VFO drifts or moves with shock: Wire is not soldered VFO main coil L1. 10. No repeater operation: Check for wire that is touching at repeater switch. 11. No receive: Resistor R7 is touching Q1, 3SK41 on X55-1120-00 board. 12. No RX on 144, or any single band: Check HET xtal-realign the Het unit. 13. Center meter drifts for the 300000series and before: Send for the TKC bullent on Center Meter Drift. 14. VFO is intermittent when turned: There is loose tension on VFO rotor and Stator plate contact. Re-bend tension spring. 15. RX audio output distorted: Check Q4 on X49-1060-00. 16. No SSB or CW receive: Resistor R73 is touching to the can of T6 on X52-1080-21. 17. FM receive okay but SSB sensitivity is down: Check alignment of SSB IF transformers T4,5,6. 18. FM receiver is bad: Bad T1 on the X48-1140-20. Scratchy audio with internal speaker: Check for bad speaker. No 146 band: Replace bad Het Xtal on Het Board.