19-07-1998

9600 and TS-700a

1st March 1991

I connected the 9600 baud input directly across R21 (33 kilohm) 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 dealy 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.

Trust the information is what you require. The 'old' TS-700a at this QTH is a very reliable and whats more one of my 'very sentimental' pieces of equipment. Do not think I could ever part with it. HI!!!!!

73 from "down under". de Colin VK5HI.

19-07-1998

Service notes on TS-700A

Author: Trio-Kenwood Communication, inc.
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. Intermittant +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 intermittant 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 onl 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 frequenc L3.
5. TX wrong frequency: Adjust L3 at X52-1080-21. 10.7 oscillator 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 poer 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. Intermittant 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. Spurrious 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 intermittant and TX intermittant: Check contacts RT relay. Replace if bent or miss-contact.
6. If you cannot adjust the center meter: Maker sure Smeter 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 ther 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 wit 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 xtals-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 intermittant when turned: There is loose tension on VFO rotor and Stator plate contact. Rebend tension spring.
15. RX audio output distorted: Chec 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 receive is bad: Bad T1 on the X48-1140-20.
19. Scratchy audio with internal speaker: Check for bad speaker.
20. No 146 band: Replace bad Het Xtal on Het Board.

12-02-2000

TS-700A for Repeater operation in Europe

Author: Trio-Kenwood Communication, inc.
Service bulletin no. 5 (June 11 1975)

We have had serveral inquirics about repeater operation of the TS-700A in Europe. The 2 Meter abnd 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

BAND SWITCH UNIT

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 chaft 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 anought room to work on the BAND SWITCH unit.
The 138 K resistor that is to e added consists of a 120 K resistor and a 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.

19-02-2000

Replacement of 9V regulator IC MFC.4060 with improved MC1723CL-A

Author: Trio-Kenwood Communication, inc.
Service bulletin no. 27 (28-12-1977)

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.

02-09-2000

TS 700 CW QRG same as USB

Author: Henk - PA0CIS - [email protected]


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 exiter.
A cumbersome switching is the result.

This modification allows to receive in the USB mode of operation, while in CW.

Steps to be taken :

• Remove the bottom cover
• Locate the CAR VOX unit
• Locate the wirewarp-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 kathode connected to L1
  
  
  
• Locate the wirewrap-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 counterunit
• The short end of the PC board has 4 var. C’s
• 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 crimpsleeve of 2 cm over one of the wire-end (do not crimp yet)
• insert a diode in the wirecut, 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 crimpsleeve 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 counterunit (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 receieve

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 servicemanual and use a frequency counter).

Replace the bottom cover and enjoy SSB/CW or CW/SSB QSO’s without difficult switching procedures.

20-04-2001

Distorted mic signal for TR-7200G & TS-700

Author: Trio-Kenwood Communication, inc.
Service bulletin no. 23 (31-10-1977)

Receiver

1. No squelch: Check C84 47uf on X55-1110-11.
2. Intermittant 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.
5. No TX: Check D1 MI301.

14-09-2001

Put CW on USB for the Kenwood TS-700A, S, SP

Author: Ron (W0PN/4) - [email protected]

W0PN/4
6/14/77, 4/3/96, 7/11/00, 9/10/01

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 warmup 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-rx   10.701525

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 criss-cross 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.

6.      6.      This completes the modification for the TS-700A

Correcting the frequency readout on the 700S and 700SP:

After sufficient warmup of the transceiver, perform the following steps on the 700S/SP COUNTER board:

1. 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.
2. Disconnect the cathode end of D1 from its current position and reconnect it to the cathode end of the newly installed D4a.
3. 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

This material is presented for your personal information only... no guarantees, warranties or other messy things are either expressed or implied. This modification has been installed by hundreds of VHFers worldwidewith no problems reported to date.

Ron Dunbar, W0PN/4 [email protected]
885 Proffit Road
Boone, NC 28607