Modifications for the Kenwood TS-850
Observations of KC2CT
Having lived with Kenwood's TS-850S tranceiver for 5 days, here are some of my
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 - Beep volume
VR - Sidetone volume
VR - Processor adjust
VR - ?????
VR8 & VR9 - ?????
VR1 - ?????
VR12 & VR13 - S Meter adjust
VR14 & VR15 - AGC adjust
VR1 - Notch filter adjust
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
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
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
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
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
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!
TS-850S All band transmit
Kenwood markets this radio worldwide, and has made orovisions
to allow the radio to transmit between 1.625 mhz and 29.999 mhz.
I am providing this modification for INFORMATIONAL PURPOSES ONLY!
DO NOT TRANSMIT OUT OF BAND, THIS WILL JEAPORDIZE YOUR LICENSE,
AND HAVE THE FCC, AND/OR INTERNATIONÁL AUTHORITIES KNOCKING AT
The All-band transmit modificatéon requires the removal and re-
location of a diode on the the digital board which is located
behind the front panel. The US version of the radio has diode
D11 installed, and diode D9 removed. D11 must be removed, and
installed in the D9 position. This modification IS NOT for the
faint of heart, as it entails removing the front panel, and the
digital board. Note that the digitál board has solder holes thát
are through-soldered; that is, there are circuit traces on both
sides of the board, so make sure that ALL solder is removed from
the holes. This modification will also allow the antenna tuner
to tune anywhere the receiver is tuned. This modification should
ONLY be performed ây those familiar with soldering and de-soldering
techniques, and requires patience, and dexterity.
TS-850S Broadcast Band Sensitivity
BCB sensitivity REALLY suffers as a 24db attenuator is inserted
when band-switched. This attenuator circuit is very similiar to
the TS-430/440. Possible modification?
TS-850S Additional Front Panel Functions
Pressing SCAN + TX-M.CH will set the radio into its extended
function mode. These options can be scrolled via the M.CH/VFO CH.
switch. The following are the extended functions:
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.
Step by step instructions to disable the broadcast band attenuation for TS-850S
This mod greatly improves the sensitivity and likewise the reception on the AM broadcast band.
No noticable unwanted side effects have occured following this procedure.
I live within three miles of a 5,000 watt broadcast station on 1150 kc's
and am able to listen to stations on either side of that station. There
is some splatter but using the notch filter and the attenuation on the
front of the radio takes care of that for the most part. This is *NOT*
complicated and can be done in fifteen minutes. Only one caution here:
you WILL BE SOLDERING TWO POINTS ON A CIRCUIT BOARD THAT IS LOADED WITH
SURFACE MOUNTED COMPONENTS!!! There is little room to work on the board,
so be very careful with your iron! If you don't feel comfortable soldering,
get someone else to do it as you can cause a solder bridge and ruin your
radio without even trying. With that in mind, here goes:
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.
remove the bottom cover. there are no wires attached to the cover.
lift it right off. leave the top cover of the radio ON.
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)
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
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.
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.
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.
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
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
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.
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.
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.
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.
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 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 this area for optional l
l plug in filters l
FRONT OF RADIO
Sorry, that's the best art work I can do. The purpose of the jumper is to
bypass the two 150 ohm resistors that are in series after the bandpass
filter. The resistors add between 20 and 25 db attenuation to the AM
broadcast band. For some reason, Kenwood thinks that the receiver would
become overloaded by strong nearby broadcasting stations, which would
cause distortion. I simply don't find that to be the case. It's funny,
Kenwood already had those two points there on the board, but without the
jumper......it seems to me that they had anticipated the need to bypass
the attenuation in Europe or Asia. Thus, all export models going to the
states were missing that jumper. Who knows? I can't find any other reason
for the jumper points to be there.
Anyway, you'll notice an immediate increase of signal strength. You'll
hear stations that you never knew were there! As I said, if you are
bothered by strong stations in your area, try using the 6 and/or 12db
attenuation buttons on the front of the rig.
TS-850? ACC-2 audio problem
Following bulletin was sent to me by Dick, KB8DB:
KENWOOD/KAM SSB AUDIO PROBLEM
The problem is that some kenwood radios are being shipped with the rear
panel audio output very sensitive. We (kantronics) have had others report
the same problem, and the following response was prepared by our service
Some adjustments in the radio and in the kam may be necessary when using
Decrease the gain in the kenwood radio rear panel audio input circuit
(may be labeled vr18, check your radio manual).
Increase the afsk output from the kam (remove jumper k5 for maximum
Set the kam to transmit in rtty mode, and radio in ssb mode, adjust vr18
(or gain control in radio that controls rear panel audio input) for the
radio manufacturer's recommended output when using rtty.
Now, when using the front panel microphone, low-level noise on the rear
panel input will not be picked up or added to microphone audio. (unquote)
73 from Stan G4KSJ @ GB7BEN.#43.GBR.EU
Adjustable moni. on CW, TS-850S
If you'd like to be able to adjust the volume with your "MONI-knob" on the
frontpanel of your TS-850S when monitoring your transmission on CW read this!
Originally it's a fixed level controlled by VR5 internally.
This could be usefull when switching between the loudspeaker and the
When you're monitoring your CW with headphones at a pleasent level, and then
disconnect the headphones and monitoring with the loudspeaker the audio is
Now you're able to adjust your audio level in the CW mode with the "MONI-knob"
at the frontpanel of your transeiver.
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.
73 de Nate Bargmann
Packet: KA0RNY @ WF0A.#SCKS.KS.USA.NOAM
Valley Center, Kansas USA EM17hs
Visit my Linux + Ham Radio pages homepage.netspaceonline.com/~ka0rny/
TS-850 service manual, error corection
2 Full break-in operation timing
...signal enters pin 10 of the BW-SW module from the...
...signal enters pin 10 of the BK-IN module from the...
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)
In line 8 and 10 capacitor C230 is mentioned
-should be C231
TS-850S and speaker/headph
This is a very simple modification on the TS-850S to be able to hear the
receiving station through the loudspeaker and the headphones at the same
On ICOM rigs it does not require any modification at all as this is a
feature built-in from the factory.
On ICOM rigs if you push the connector halfway into the headphone jack
you have the sound in both the loudspeaker and the headphones, then if
you push the plug the whole way in, the sound is only in the headphones.
Unfortunally this is not the case on the TS-850S.
The headphone jack is a little different made on Kenwood rigs, so this
modification does not allow you this "halfway" feature described above.
But still you are able to have the sound comming from the loudspeaker and
the headphones at the same time.
This modification works on both mono and stereo headphones.
Remove all knobs at the front of the radio.
Remove the front.
Remove the very small unit (E/6 page 57) that contains the phone jack
Install a jumper between pin no. 1 and pin no. 2 on the CN8 connector.
TS-850 and Ten-Tec Titan 425 PA
If you're using the Kenwood TS-850S with the Ten-Tec Titan 425 linear PA
This explains how to modify the TS-850S' full QSK feature and avoiding
"hot switching" the relay in the amplifier when operating full QSK.
As you probably know the correct way to prevent "hot switching" is to feed
a signal to the Titan's "key-in" connector when you transmit. When the
linear's vacuum-relay is settled the Titan's "key-out" connector return that
information to the transceiver which then feed its output RF to the linear.
What's important here is that the transceiver DOES NOT feed any RF BEFORE
the vacuum-relay in the linear is settled!
(If you do, you have the problem called "hot switching")
This is how to overcome the "hot switching" problem:
Open the TS-850 and do the following:
Remove the original TRX-relay (K3 at the RF unit).
Remove the IF unit.
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.
Reinstall the IF-unit.
I connected the collector of Q2 to pin #4 on the REMOTE connector and pin #10
on the BK-SW unit to pin #2 on the REMOTE connector at the rear of the
transceiver where you originally connect the keying of an amplifier.
That's why you should remove the TRX-relay (K3) as described in point no. 1.
Pin 4 on the remote connector should now be connected to the "key-in" on the
Pin 2 on the remote connector should now be connected to the "key-out" on the
ONLY use shielded cables!!!
This modification works fine on my TS-850. I am able to operate full QSK at
the maximum speed on the built-in keyer unit without risking any damage to
the vacuum-relay in the Titan at full output power (1600W).
KAM-PLUS Problems!! with TS-450 & 850
A common problem when using a KAM-Plus multimode with the
Kenwood TS-850 or TS-450 occurs when the KAM-Plus is coupled to
the Accessory-2 socket on the back of the transceiver, producing
noticable distortion of the transmitted audio when using the
microphone in SSB mode..
The problem is easy to cure by disconnecting the Accessory-2
plug from the back of the tranceiver, but this meant moving the
transceiver around every time one wished to operate on SSB..
The problem is caused by the input sensitivity of the rear
Accessory-2 socket being set to high, so that it picks up very low
level noise from the KAM-Plus and associated computer wiring, this
mixes with the microphone signal, to produce the distortion.
The cure is to reduce the input sensitivity of the radio,
thus reducing the chance of distortion, also it goes without saying
that the output from the KAM-Plus must be increased to compensate
With both the TS-450 and TS-850, adjusting the input sensitivity
is straight forward and the transceiver manuals show you the appropriate
control and its location.. This is in both cases VR18 to be found on
the main board of the radio,(refer to manual) in practice I found that
it was best to adjust this control fully counterclockwise..
Then we need to adjust the output from the KAM-Plus by varying
potentiometer R28 and setting removable link (K9), this link is factory
set on one post only, (in the open position)!! this should be connected
shorting the two posts, thus putting the KAM-Plus into the high output
position, and then potentiometer R-28 is adjusted to give full power
out from your HF radio with very little ALC deflection, when the MIC
gain is in the normal operating position..
Then I am sure you will find that your problem is over, you can now
simply change from digital modes to SSB.. Remember if you have your
Beacon activated to turn it OFF or it could cause a few comments when
TS-450,TS-850 feedback,ACC-2 Conn
Hi if you are using the ACC-2 connector to interface with your multi-mode
controller, you may have had a problem with your transmitted audio signal
being distorted, to eliminate this see bellow.
This modification should not affect any of the other normal operations of the
Set your meter on the radio to read ALC
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.
Place the TNC in calibrate mode and press K to key the radio.
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).
Press Q to quit the CALIBRATE mode
Copy of service bulletin from AEA
Modification for External keying, while using the internal keyer
Author: N7EX (ex-N0DH), Dave Henderson
One of the minor draw backs to the TS-850 as a CW contest machine is the inability to use the internal keyer in conjunction with an external keying circuit such as a personal computer or auxiliary memory keyer. As designed you must manually throw a switch from internal to external keying to switch between one or the other. To make matters even more inconvenient this switch is on the back of the unit and is not readily accessible during normal operation.
Simply said this modification involves running a new keying line from the junction of S1 and D51 on the IF Board. For convenience this additional keying line can be wired to the DSP1 and/or DSP2 RCA phono jacks if you do not use the external DSP unit.
The modification to the unit to resolve this problem takes less than 30 minutes to accomplish and can be done without "permanently" modifying the unit which would detract from its future resale value. If you don't use the external DSP unit then the two RCA phono jacks marked DSP1 and DSP2 can be used as additional keying input jacks as will be outlined below. If you use the external DSP unit then the modification can still be accomplished by running the external keying line out on a "pigtail." I highly recommend the purchase of a service manual which will greatly improve your ability to indentify the circuit points involved in the modification.
Considering that the radio costs $1500 what's another $30 to keep from messing it up! By the way compared to the two TS-930's that I nursed through the 80's, this radio is a breeze to trouble shoot and repair which I have had to do twice through no fault of Kenwood (long stupid story ~8>).
From here you proceed at your own risk, if you fry the radio DON'T CALL ME. A precision low wattage solder pencil for doing surface mount soldering is recommended, If all you have is a 150 watt Weller solder gun then read no farther your better off taking the unit to an expert rather than "melt" the circuit traces.
I assume no risk for the accuracy or completeness of the enclosed information. All yee who enter here embrace all hope for you may likely have a better contest radio when you are done.
- Turn the unit upside down with the back of the TS-850 toward you.
- Remove the bottom cover.
- In this position the IF board is on your left.
- Remove all the screws holding the IF board to the chassis.
(put them in a jar or something for safe keeping).
- 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.
- On the bottom side of the board directly underneath S1 you will see 6 solder pads arranged in two rows of three pads each.
- 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.
- 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.
- Route the other end of the shielded audio cable through the chassis in the vicinity of the DSP jacks above.
- 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.
- Turn the unit over and remove the top cover.
- 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...
- 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.
TS-850 Separate Receive Antenna Modification
Author: Brian, WA3WJD
Make a short loop of white telfon cable with a male and female BNC connector.
Loop it out of the back of the rig so just enough of the coax sticks out so the BNCs can be joined with a barrel connector.
Locate the little header connector on the filter board in the TS-850 that is on the receiver side of the TS850 antenna relay. Pull that connector loose.
Spend a little time tracking down male and female header connectors that match what Kenwood uses. Install those on the ends of the white teflon coaxes sticking in the back of the radio.
For normal use, just connect the BNCs with a barrel connector and the rig is normal. For Beverage use, connect an extra antenna switch common and ant #1 to the BNC connectors, and put ur Beverages on the other positions.
TS-850 Separate RX antenna input mod
Author: N6TR - firstname.lastname@example.org
This is near the top of everyone's list when they are asked "What things bug you about the TS-850S." I initially overcame this deficiency by modifying my amplifier so I could connect a different receive antenna to the TR relay. However, I wanted to change things so there wasn't as much RF getting into the RX antenna due to close proximity to the amplifier's output. This became a problem when using the same receive antenna on a second radio (you knew two radio contest operating was going to work its way in here somehow).
Ville, OH2MM had provided me with instruction on how he modified his TS-850S to have a separate RX input and this inspired me to try it.
Here are some simple steps to hopefully inspire others:
It took me an unrushed two hours to do all this.
- Remove the top panel (you don't need to take off the bottom one).
- Remove the plate which sits between the fan and the back of the radio. This covers the output filter PC board.
- Unsolder the connections to the SO-239 output connector.
- Remove the three cables from the PC board next to the SO-239. This includes two coax and one 3 conductor harness.
- Remove the two screws holding in the PC board and remove it.
- 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.
- 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.
- 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.
- 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.
- Obviously, you will need a jumper cable to make your receiver work again.
The switch box
This box does two things: disconnects the receive antenna input when transmitting and allows selection of the transmitting antenna or one of three RX antennas when receiving. The pot can be used for RF attenuation if your rig doesn't have one.
- 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
The relay gets controlled by the PTT output from your rig that normally would go to your amplifier. Then one set of the contacts is used to key your amplifier. Don't forget to put a diode across the coil of your relay if there isn't one internally. Otherwise, you will have undesired arcing across the contacts of the relay in your radio.
The other set of contacts disconnect the output of the rotary swtich when transmitting. The rotary switch selects either the signal coming from the transmitting antenna (from the TR relay in your rig) or one of three receiving antennas. I use two phono jacks per RX antenna so I can feed them to other boxes for other radios. I also use two jacks for +12 volts so I can jumper power to another box.
You can build up one of these boxes in an hour or two. You can epoxy the relay to the mini box.
If you want the pot there to act as an attenuator, I just hook it up like you would a volume control: one end is ground, the other end goes to the output of the rotary switch and the wiper goes to the output. Use shielded cable as much as possible to avoid stray pickup.
Computer Interface for the TS-850, without using the IF-232 Level Converter
By N6TR and possibly others, with zener idea added by K6LL.
Note: This interface will work with "TR," contest logging software by N6TR.
Click here for links to TR and other contest logging software packages, including shareware.
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)
TS-850 Power Output Control
VR7 on the RF Board (bottom side of radio). 125 watts or so on cw is safe. Do not exceed
100 watts on SSB, since distortion will broaden the transmitted signal.
TS-850 Level Attenuator for DRU-2 playback audio
Author: K6LL - email@example.com
- Remove the little hatch on the top of the radio.
- 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.
- 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.
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