• While the manual shows 35 power-on front panel adjustments, there really are 36. Function number 35 is set from the factory to the OFF state. Well, what exactly is this unknown function? Well Bunkies, this enables the tranceiver to transmit on 27.500 through 28.000 mhz! Do yourself a favor, and set this option to ON for TX inhibit! DO NOT JEAPORDIZE YOUR LICENSE! Why in the world did the factory allow this??? Maybe they don't want the Chicken Banders butchering up the rigs....
• Tone control. The setup only allows Burst or Continuous modes, there is no way to turn it OFF, even though the manual indicates there is a way.
• Quick memory function. You MUST pass through either the VFO A or VFO B registers to program these.. You cannot go from standard memory to quick memory directly.
• My 850S came out of the box running low power (50 - 75w PEP), so I called the local ham radio dealer inquiring about service manual availability. Well they had them in stock, but at a price of $50.00! Unbelievable! Kenwood wants fifty dollars for (in the continuing Kenwood tradition) a terribly organized, incomplete, and horrible reading manual!!! Well, I dug into the schematics and opened up the the radio, here's a list of items that might be of interest to some:
  
  

    RF Board Controls
    -----------------
    VR  - RX BAL
    VR  - TX BIAS
    VR  - TX BAL
    VR  - TYP (50W output power adjust, used with S1 below)
    VR  - MIN (?????) /  internal antenna tuner
    VR  - TUN (Tune mode power adjust)
    VR  - VSF (THIS IS THE 100W POWER OUTPUT CONTROL)
    VR  - SWR Protect activation
    VR  - PWM (Forward power meter calibration)
    VR1  - RWM (Reflected power meter calibration)
    VR1  - AL0 (ALC meter zero)
    VR1  - ALM (ALC meter calibration)
    VR1  - CPM (Processor meter calibration)
    VR1  - ALG (ALC gain adjustment)
  
    S  - All Band Power Down Switch (Decreases power to 50 watts)
  
  
    IF Board Controls
    -----------------
    VR      -
    VR      -
    VR      -
    VR      - Beep volume
    VR      - Sidetone volume
    VR      - Processor adjust
    VR      - ?????
    VR8  & VR9  - ?????
    VR1      - ?????
    VR1      -
    VR12 & VR13 - S Meter adjust
    VR14 & VR15 - AGC adjust
    VR1      - Notch filter adjust
  

• PLEASE NOTE!
  Most of these controls are 1/8" pots, so if you intend to adjust them use a VERY SMALL non-metallic tool.
• My 850S also came out of the box with the RIT/XIT control not dis- playing 0.00 khz at fiducial (12 o'clock position) center. Behind the front panel in the upper right corner is the control for center adjust. It just needed a wee bit of tweaking... Along with this control on the circuit board are the master adjust- ments for the SSB slope tuning (High Cut and Low Cut).
• When both top and bottom covers are removed, on the left-hand side is the FM board. There are 3 (three) pots on the board. They are FM Wide (12khz) deviation, FM Narrow (6khz) deviation, and FM Mic gain.
• FM mode defaults to WIDE (12khz). This is WAY too wide for accessing any 10m repeater. Hit the 455khz filter button again for FM-N (narrow). This will set the IF to 6khz width, and you be able to work FM 10m stations. Note: The 8.83 filters are NOT selectable in FM mode.
• Memory scrolling via M CH./VFO CH. You can bypass all unused channels if you press the 1 mhz button. With the button active, only stored memory channels will be displayed as the knob is rotated.
• Tuneable memories. Out of the box, the radio is set up for non- tuneable memories. Just bring up setup function xx on the display, and set it to ON, and ALL memories can be tuned via the VFO. When use the M.CH/VFO CH. switch you will be returned to the original frequency & mode setting in the memory.
• It may or may not be obvious to some, but the radio is capable of cross-band and/or cross-mode operation. Just pump the required modes and frequencies into memory channels or VFOs, and you're off and running. Hope you have a very broadbanded antenna!
• CW message storage is lost when you power off the radio. I didn't order the DRU-2 option (yet), so I don't know whether these messages will be saved. You'd think that with everything else that is stored in RAM and backed up by battery, that Kenwood would have made pro- visions to keep recorded messages alive also. A modification????
• When adding additional filters, is is necessary to set the corresponding switch on. Under the hatch on top, is a 4 position dip switch. The manual shows a picture of it, but makes no mention of their settings. This switch is necessary to inform the micro- processor of the filters' absence or presence. ON is for presence, OFF is for absence. Below is the switch diagram:

     -----
     | = |  <-- YK-88C-1, YK-88CN-1, YK-88SN-1
     | = |  <-- YK-88CN-1, YK-88CN-1, YK-88SN-1
     | = |  <-- No Function
     | = |  <-- YG-455C-1 or YG-455CN-1
     -----
     O   O
     N   F
         F
  

• I received the DRU-2, voice recording unit this week, and installed it.Here's what I found:
• The unit comes witè a lithium battery for backing up the voice messages when tèe rig is powered off.
• The initial state of the DRU-2 is:
  
  Message 1 - 8 seconds
  Message 2 - 8 seconds
  Message 3 - 16 seconds
  
  You can halve the sampling rate via front panel setup control xx. This will effectively DOUBLE the time of of each message, however, the quality of voice repro- duction will suffer because of the lower sampling rate.
• On playback of the messages, the microphone IS NOT disabled, so be quiet when you're transmitting stored messages.
• Use the MONI function to hear what you've recorded and/or are transmitting, and tèe MIC gain control to keep the ALC in range, as the DRU-2 drives the radio much harder than the microphone input.
• The high boost function and speech processor are available to the DRU-2 during transmit.
• I also got the VS-2 voice unit. The voice is the same as the older VS-1 for the TS-440, and TS-940, but the unit is in a smaller package. It will speak the frequency in either English or Jápanese. There is a volume control pot on the bottom of the board whécè should be adjusted PRIOR to screwing down the VS-2. The output on my unit was very low, until I tweaked it up. Also there are jumpers on the board to speed up the voice playback... You'll need to consult the instruction page for the VS-1 for speeds, as there is nothing mentioned in the instructions for the VS-2.
• A note on output power of the rig. The radio uses 2SC2789's... These devices are rated as 100 watt devices Kenwood is running the finals VERY conservatively. When playing around with output, I had the rig dead-keying 175 watts, but backed it down to 100 watts, as I didn't want to blow up the rig, but I was äefinitely smiling as the Birds' meter swung with a 250 watt slug!
• The ROM chip on the digital board is socketed. Kenwood had problems witè early 440's and 940's with poor soldered connections. While it's a nice idea to allow removal and replacement of the ROM to add features/fix bugs, this might become a problem area in the future.
• Hidden function!!! If you turn on the radio while holding down the VOICE button, EVERY button on the radio will acknowledge its function via morse code! This is a terrific feature for sightless hams! I can't understand why it is not mentioned in the owners manual or marketing literature!

  00 - This is the ROM Cèecksum displayed as a 4-digit hexadecimal
       number  This cannot be changed.

  01 - Allow filter selection in transmit. Initially set OFF.

  02 - Antenna tuner power down.  Initially set to OFF.

  03 - Antenna tuner non-stop mode.  When set to on, the antenna
       tuner will not stop when the lowest VSWR is found.  Initially
       set to OFF.

  04 - Store mode, and filter settings prior to changing bands, or
       cèannels.  Initially set to ON.

  05 - Display -HELLO- on digitial display, anä send it in Morse
       code on power up.  Initially set OFF.

  06 - Turn full LCD display ON on power on.  Initially set OFF.

  07 - Turn Subtone ON or OFF.  Initiálly set ON.  Note tèat even
       when set off, the TONE indicator will be lit on the display.

  08 - Unknown. Initially set OFF.

1. remove the eleven screws that secure the bottom cover to the rig. the six ones on the sides and the five on the bottom cover itself.
2. remove the bottom cover. there are no wires attached to the cover. lift it right off. leave the top cover of the radio ON.
3. locate the RF BOARD. it's number is: X44-3120-00. this is the board where you plug the optional filters into. with the open radio in front of you, and the front of the radio facing you, the RF BOARD is the one on the left. (there are only two boards under the bottom cover)
4. locate the chrome like shield on the rear of the RF BOARD. it's made out of shiney steel. remove the four screws that hold this shield to the board.
5. remove the shield by lifting the front of it up while sliding it forwards, towards you. watch out for all the little wires and ribbon cables going to and from the RF BOARD.
6. look at the rear of the board and towards the left corner.(the radio is stil facing you upside down) notice two I/C's numbered IC1 and IC2. directly behind the I/C's are a bank of adjustable coils in metal cans. there are nine of these coils in a group. directly to the left of these coils are many green and red inductors which are standing up. they look like resistors but they're really small coils.
7. these inductors are part of the bandpass filtering for each of the bands on the radio. the capacitors and resistors that complete the bandpass filtering are on the other side of the board and are of the surface mount type. you are only concerned with the bandpass filter for the .5 to 1.6 band. notice the numbers for the inductors. find L8 and L9. they are right at the edge of the board in the left rear corner you will notice that .5 - 1.6 is stamped right next to L9. BINGO! you have found the part of the circuit that you will modify.
8. look at where the .5 - 1.6 is stamped on the board next to L9. you will see two bronze or gold solder points there directly next to the numbers .5 - 1.6 . there is nothing soldered at those two points. this is where you will solder a jumper wire between the bronze points. do NOT confuse it with the other two solder points with the line running in between them next to the phillips head screw!!! you want the two points that are spaced very close together that is right next to L9.
9. you will have to do the soldering on the OTHER SIDE OF THE BOARD. remove the nine phillips head screws that hold the RF BOARD to the chasis.
10. on the back of the radio, look for the switch stamped SW 1. it's right below the grounding post and has the two postions: INT and EXT. remove the two screws that hold the switch to the back of the rig. the switch is soldered to the RF BOARD and you wont be able to lift the board up until the screws are removed.
11. unplug enough cables from the board so you'll have enough room to lift the RF BOARD up to solder the jumper. there is no need to remove the board from the rig. slide it towards the front of the rig until the switch SW 1 clears the back of the rig and lift the left side of the board up and prop it up with a small block of wood.
12. locate the bronze solder points on the underside of the board. there will be a small amount of solder at these two points on the underside of the board.
13. bend a small jumper out of wire that fits the two bronze points on top of the RF BOARD. you will place the jumper on the top and solder on the underside of the board. with a pair of needle nosed pliers, place the jumper into the holes and simply heat up the existing solder on the underside until the jumper slips down farther into the holes.
    you'll notice the large amount of components on the underside versus the lack of components on the top of the board. be carefull when heating the solder on the two points. you don'y want to disturb the surface mounted parts or cause any excess solder to run onto them or the foil nearby.
14. you are now done. re-assemble in reverse order, plugging the wires back in carefully, making sure they don't get plugged into the wrong place. also, avoid pinching them when replacing covers.

____________________________________________________________________
l                                                                   l
l                                                                   l
l  X                        __________________                      l
l  4      L8                l                 l                     l
l  4      O  O  O  O  O  O  l   COIL BANK     l                     l
l          O  O  O  O  O  O l                 l                     l
l  3    .5 o    inductors  l_________________l                     l
l  1          O O O O O O                                         l
l  2   1.6 o               _______   _______                      l
l  0                      l ic1  l  l ic2  l                     l
l            l             --------  --------                     l
l  0    solder                                                    l
l  0    point    l                                                 l
l                l             RF BOARD                            l
l            solder                                                l
l            point    l                                             l
l                     l                                             l
l                    L9                                             l
l                                                                   l
l                                                                   l
l                                       this area for optional      l
l                                          plug in filters          l
l                                                                   l
l                                                                   l
l                                                                   l
l                                                                   l
l                                                                   l
l___________________________________________________________________l

                 FRONT OF RADIO

• Remove the IF-UNIT (you must solder on the rear side of the IF-UNIT). Be carefull to mark all the cables before you remove them!!!
• Remove R239 (330 kohm, close to VR5).
• Install a new resistor (330 kohm) from the output of VR5 to the junction R229, R230, R231 and C172 (rear side of the IF-UNIT, close to IC7).
• Adjust VR5 to maximum audio level.

Page 20:

2 Full break-in operation timing
--------------------------------
...signal enters pin 10 of the BW-SW module from the...
should be
...signal enters pin 10 of the BK-IN module from the...



Page 21:

Resistor R3 (10 kohm) in the BK-SW schematic does not exist.
(This is corrected in the schematic that's in the user's manual)


Page 23:

Key up
------
In line 8 and 10 capacitor C230 is mentioned 
-should be C231

1. Remove all knobs at the front of the radio.
2. Remove the front.
3. Remove the very small unit (E/6 page 57) that contains the phone jack itself.
4. Install a jumper between pin no. 1 and pin no. 2 on the CN8 connector.

1. Remove the original TRX-relay (K3 at the RF unit).
2. Remove the IF unit.
3. Locate the BK-SW unit (X59-3880-00).
   
   Cut between Q2's collector and pin 10 on the BK-SW unit.
   Feed Q2's collector to the "key-in" on the Titan linear.
   Feed pin 10 (where you cut) on the BK-SW unit to the "key-out" on the Titan linear.
4. Reinstall the IF-unit.

1. Set your meter on the radio to read ALC
2. PK232 OWNERS: if alsso using a VHF tranceiver, adjust the AFSK level for proper VHF operation as expalained in chapter 3 of the operating manual.If not adjust for proper SSB operation.
   
   DSP - 1232 / DSP - 2232 Owners: Adjust the appropriate AFSK level control for proper SSB operation as expalined in chapter 3 of the operating manual.
3. Place the TNC in calibrate mode and press K to key the radio.
4. Adjust VR-13 on the TS-450 or VR-18 on the TS-850 so that the meter "Just comes off the peg" as described in the section titled "SSB Tranciever Final Adjustments" (in the TNC operating manual).
5. Press Q to quit the CALIBRATE mode

1. Turn the unit upside down with the back of the TS-850 toward you.
   
   
2. Remove the bottom cover.
   
   
3. In this position the IF board is on your left.
   
   
4. Remove all the screws holding the IF board to the chassis.
   (put them in a jar or something for safe keeping).
   
   
5. Unplug enough of the cabling to allow you to tilt the board up so that you can access the bottom side of the board underneath S1 the "External/Internal" keying switch.
   
   
6. On the bottom side of the board directly underneath S1 you will see 6 solder pads arranged in two rows of three pads each.
   
   
7. The middle pad on S1 nearest the back of the radio should be GROUND, solder the braid of an approximately 9 inch piece of small audio style shielded cable to this point, being careful to dress the coax so as not to short to other circuitry.
   
   
8. The middle pad on S1 in the next row up of three pads is the keying line. Solder the center of the shielded cable to this point.
   
   
9. Route the other end of the shielded audio cable through the chassis in the vicinity of the DSP jacks above.
   
   
10. Carefully inspect all solder joints for shorts, etc. Replug the wire harnesses unplugged in step 5 above and reassemble the board to housing. Reassemble the bottom cover.
    
    
11. Turn the unit over and remove the top cover.
    
    
12. Find the DSP input board with the three RCA phono jacks on it at the rear of the unit.
    The two DSP jacks are on the right when facing the rear of the unit. There are two connectors on this board (a 2pin and a 4pin). Unplug the 4 pin connector. Obtain another 4 pin connector and connect as follows (or directly solder to the underside of the board as follows) If you only need one additional CW jack then ground is pin 2 (closer to center of the radio)connect the braid of your new key line to this pin. The input from the middle RCA phono plug is pin 1 connect the ceneter conductor to this pin. Like wise if you want two additional CW jacks then do as above plus add a short between pins 1 and 3. If you want a small RF choke or some ferrite beads on the center conductor of the audio cable may prevent keying problems in high RF field environments...
    
    
13. Close the unit up and switch S1 to INTERNAL keying. You should now be able to key the unit via the internal keyer (Via the standard key input jack) or with an external keyer or computer via the old DSP jacks, without having to switch S1.

1. Remove the top panel (you don't need to take off the bottom one).
   
   
2. Remove the plate which sits between the fan and the back of the radio. This covers the output filter PC board.
   
   
3. Unsolder the connections to the SO-239 output connector.
   
   
4. Remove the three cables from the PC board next to the SO-239. This includes two coax and one 3 conductor harness.
   
   
5. Remove the two screws holding in the PC board and remove it.
   
   
6. Locate the trace that goes from the relay's normally closed contact. You can use an ohm-meter to find it - probe from the wire that went to the SO-239. You will find a short trace on the back of the board which runs to a chip capacitor. Cut this trace and solder some very small coax to each side of the cut - connect ground to the nearby ground trace.
   Make the cables about 4 inches long.
   
   
7. Remove the antenna tuner. There are 2 screws in the back and front (you will need a magnetic screw-driver) and one on the side. You will need to carefully unplug two wire harnesses and one coax connector.
   
   
8. Drill two holes for phono jacks on the back of the radio. Be careful not to obstruct the screw hole for one of the screws in the back of the antenna tuner. The best place is between the RF output connector and the groundpost. Put them on top of each other and as close to the bump on the back panel as possible. I used a vacuum cleaner while drilling to make sure no metal chips went anywhere.
   
   
9. You will find a small hole under the SO-239 where you can feed the two coaxs through. Solder them to the phono jacks and reassemble everything. I put back to back diodes on the RX antennas input, but you may not want to do this. A better thing would be to add a relay to disconnect the RX antenna input when transmitting. I took care of that in project #2.
   
   
10. Obviously, you will need a jumper cable to make your receiver work again.

• 4 position rotary switch
• DPDT 12 VDC relay
• 1 K Ohm pot (optional)
• 12 phono jacks (or you can get by with 9)
• mini box for above and knobs.
• Clamp diode for relay coil if not included in relay

                    470 ohms
DB9 PIN 3 (TXD)  ----////------------ TS850 ACC 1 PIN 3 (RXD)
(DB25 PIN 2)                  |
                              |
                              |
                            ----  5 VOLT ZENER DIODE
                              / 
                             /  
                              |        
                              |
DB9 PIN 5 (GND)  ------------------------  TS850 ACC 1 PIN 1 (GND)
(DB25 PIN 7)

DB9 PIN 2 (RXD)  ------------------------  TS850 ACC 1 PIN 2 (TXD)
(DB25 PIN 3)

                                   -----  TS850 ACC 1 PIN 4 (CTS)
                                   |
                                   |
                                   |
                                   -----  TS850 ACC 1 PIN 5 (RTS)

1. Remove the little hatch on the top of the radio.
   
   
2. With the front of the radio facing you, find connector CN505. It is a five pin connector near the filter DIP switches. The white wire on the leftmost terminal carries the DRU audio output.
   
   
3. Cut the white wire and insert a 100K ohm micromini pot, shunted with a 220 pf capacitor. Adjust the pot until DRU playback level matches live microphone level.

 Wenn man von hinten auf den TS850 schaut, ist rechts eine komplette Leiste mit Steckern (ACC, diverse Cinch (ALC etc..)) usw. Oben sind zwei Reihen und unten ist noch eine dritte Reihe. (da ist auch  die Cinch IF-Out dabei, die original (lt. Manual) benutzt werden sollte. Mir persönlich hat das mit den 12 Volt nicht gefallen; das Risiko für Transverter und Nachsetzer bei Ausfall der 12 Volt war mir zu groß!

Genau dazwischen (oben 2 Reihen, unten 1 Reihe) ist rechts ein Platz von ca. 2cm hoch, 8cm Breit und 3 cm tief. da passen die benötigten 4 Cinchbuchsen (drvout, drv in, ant out, ant in) problemlos hin.

 Diese muß man für den normalen KW-Betrieb nur außen mit Cinch-Cinch-Koaxkabeln brücken. Da es sich um Kurzwelle (d.h. f < 30MHz) handelt, dürfte die auftretende Dämpfung vernachlässigbar sein.

Zudem gibt es dort in den Gehäusseverstrebungen IDEAL Platz zum Kabeldurchführen, als ob es von Kenwood dafür vorgesehen wäre und aus Marketinggründen zugunsten des TS950 gestorben wäre. So schauts jedenfalls für den Bastler aus. Oder der Platz wurder einfach präventiv für Stecker freigehalten... wer weiß...?

Vorgehensweise:

1. !!!!! OHNE GEWÄHR !!!!!
2. Boden und Deckel abnehmen.
3. von oben: Filterplatine (mitte) wegnehmen.
4. Gehäuserückseite abschrauben, PL-Buchse ablöten (evtl. sind hier mehr als zwei Hände hilfreich!)
5. Anzeichnen, bohren, auf genügend Abstand zwischen den Cinch-Buchsen und Gehäuseverstrebungen achten. (ca. 16 mm Lochabastand reicht, damit man sich die Finger nicht klemmt, beim Betrieb  hinterher wie z.B. Stecker ziehen...) Beschriften mit z.B. ANT out, IF in, DRV out, FINAL in (oder wie's beliebt).
6. Kabel auftrennen: von der IF-Platine (wenn das Gerät umgedreht wurde, vorne links) gehen ziemlich hinten an den Steckverbindungen nach hinten mitte unten zwei Kabel weg, CN1 und CN2 (weiss und Rot/Orange/Rostbraun). Die beiden Kabel sind im Bild zusätzlich mit einem gelben beschrifteten Klebeband gekennzeichnet.
7. Das eine führt direkt zur Antennenumschaltplatine, wo auch die PL- Buchse angelötet ist. Auftrennen, Verlängern und auf 2 der Cinchs legen. Das zweite führt direkt zur Final-Unit (unter der Filterplatine). Auftrennen und auf die Cinchs führen.
8. sind die Buchsen hinten RICHTIG beschriftet? und RICHTIG verbunden? Besser mehrfach prüfen, das Teil ist teuer! Ist die Beschriftung eindeutig?
9. Zusammenbauen. Dabei ALLE Steckverbinder wieder stecken. Mögliche Fallstricke sind vielleicht:
   • Verbindung Final-Unit-out -> Filter-Unit-in ? (muss gelöst werden, um die Filterunit auszubauen).
   • PL-Buchse wieder angelötet ?
   • Lautsprecher wieder angesteckt ?
10. Hinten brücken und als KW-TRX testen. Preselektor anstöpseln, testen. Transverter anstöpseln, testen.
11. !!!!! OHNE GEWAEHR !!!!!

Löcher:Kenwood-Aufkleber.

Leitungen: Ersetzen durch  originale Leitungen (gibts bestimmt für Geld bei Kenwood).

We have received several reports of distorted transmitter audio when using a TNC controller such as the AEA PK-232 or Kantronic KAM, etc. The symptom will generally disappear if the transceiver and TNC units are powered from different sources.

Cause:
The audio output level form the TNC is generally too high and causes overload of the microphone amplifier circuit. In previous models such as the TS-440S the incoming TNC audio was inserted after the microphone amplifier. With the TS-850S it is inserted before the microphone amplifier. Just moving the insertion point to the output of the circuit is satisfactory since the drive level for FM packet is higher then that required for SSB.

Procedure:

1. Add a 10 dB attenuator to the PKD line on the IF unit (X48-3080-XX). This will prevent overmodulation of the microphone input circuit.
   1. Change chip resistor R258 from 2.2 Kohm to 1 Kohm (RK73FB2A102J)
   2. Change chip resistor R260 from 220 to 330 ohms (RK73FB2A331J).
   
   
   
2. Add the following note to page 29 of the Instruction manual.
   
   
3. When adjusting for proper ALC levels with an AFSK RTTY terminal or Packet TNC terminal you should adjust VR-18 on the IF Unit for a reading similar to the one shown in the accompanying diagram.
   
   Note: The transceiver and RTTY or TNC terminal should use separate power supplies, in order to prevent RFI (Radio Frequency Interference).

Time required for this modification is ½ hour or less.



22-04-2000 TS-850S Low/no Receive sensitivity
Author: Kenwood Communication, inc.

Symptom:
Reports of low or no receive sensitivity accompanied by a lack of audio from the speaker during CW or SSB modes might be caused by improper RXB voltage levels. Normal RXB voltage is +8 Vdc during receive and 0 Vdc during transmit. If you find approximately + 2 Vdc during receive you might suspect a problem with a leaking diode, D31 on the RF unit (X44-3120-00).

Cause:
D31 is used as the transmit switching diode. Leakage of this diode id most probably caused by electrostatic surge or discharges from the antenna.

Parts required:
D31, MI204

Procedure: A temporary cure for units that have already been manufactured is to replace D31 with an MI204 diode. Future production radios will change D31 to an LFB01 diode and incorporate a change in the printed circuit foil pattern to allow addition of a series diode. D103 (LFB01).

Caution: This modification requires soldering equipment rated for CMOS type circuits. It also requires familiarity with surface mount soldering techniques. If you do not have the proper equipment or knowledge do not attempt this modification yourself. Seek qualified assistance.

Time required for this modification is 15 minutes or less.



23-04-2000 TS-850S No audio from VS-2
Author: Kenwood Communication, inc.

Symptom:
Several have reported a problem with the Voice Synthesizer Unit VS-2 not voicing the frequency reliably when the Voice button is depressed. This symptom is caused by a drop in the 5C voltage from 5 Vdc to approximately 4.5 Vdc when the VS-2 is connected. The following change will correct this symptom.

Parts required:

Qty   Description                Old part No.      New Part No    Circuit desc.
 1    47 µH Chip coil            L40-221-48        L40-4701-48    L501

Procedure:
Change L501 from 220 µH to 47 µH on the RF unit (X44-3120-00 C/4).

Caution: This modification requires soldering equipment rated for CMOS type circuits. It also requires familiarity with surface mount soldering techniques. If you do not have the proper equipment or knowledge do not attempt this modification yourself. Seek qualified assistance from your closest Kenwood Service Center (Long Beach, CA, or Virginia Beach, VA).

Time required for this modification is 30 minutes or less.



23-04-2000 TS-850S Mixer FET change
Author: Kenwood Communication, inc.

Symptom:
Several units were discovered during production by our QC department that experienced difficult when the transceiver was being adjusted for an S-1 reading on the S-meter.

Countermeasure:
Variations in the gain of the devices used for Q16 and Q17, the second mixers, on the RF unit (X44-3120-00) appear to cause of this symptom. We, therefore, recommend replacing these two transistors with 2SK520(K43) devices. These devices have lower IDSS (Drain breakdown current), and therefore provide a greater conversion gain. As a result the total gain of the circuit is increased.

Parts required:

Qty   Description              Old part No.   New Part No    Circuit Description
 2    Second Mixer FET         2SK520(K44)    2SK529(K43)    Q16, Q17

Time required for this modification is 60 minutes or less.



23-04-2000 TS-850S "Click noise" with NOTCH ON
Author: Kenwood Communication, inc.

Symptom:
When a strong signal of S-9 or greater is received at the antenna terminal with the NOTCH circuit ON a "clicking" noise might be noticed. This is caused by excessive response in the AGC loop circuit.

Countermeasure:
The changes detailed below will add additional delay to the AGC circuit and reduce or eliminate this tendency.

Parts required:

Qty   Description              Old part No.   New Part No.   Circuit Description
 1    22 Kohm chip resistor    RK73FB2A103J   RK73FB2A223J   R289
 1    0.47 µF capacitor        NA             CQ92M1H474K    NA

Caution: This modification requires soldering equipment rated for CMOS type circuits. It also requires familiarity with surface mount soldering techniques. If you do not have the proper equipment or knowledge do not attempt this modification yourself. Seek qualified assistance from your closest Kenwood Service Center (Long Beach, CA, or Virginia Beach, VA).

Time required for this modification is 60 minutes or less.