Kenwood TS-850S/AT & TS-950S/AT Contest Helper!

By Eric A. Snyder N7DLV

The project described in this article was inspired by a fortuitous find in a local thrift store. While browsing the aisles, I spied a computer gaming joystick controller. What piqued my interest was it’s ergonomically sound form and the three push buttons on top that was in addition to the trigger. Additionally, the joystick was ambidextrous, in that it could fit either hand comfortably. Upon closer examination, I also noticed a gray ON/OFF slide switch. I came to realize, this would make an excellent hand held controller for my transceiver. The trigger would control the Push to Talk, and the three buttons on top would control the messages to be transmitted. The slide switch could be used to disable message transmission. Two shielded cables would go from the controller to the transceiver. The Hand Held PTT and Playback Controller can be constructed in an afternoon. It is simple to make, and the required parts can be found in a well stocked junk box. Any additional needed parts are readily available at your local electronics parts supplier.

The Kenwood TS-850S/AT and TS-950S/AT Amateur radio transceivers have as an option, a digital voice recorder and playback module. This module can be programmed with up to 3 voice messages, which are accessible remotely by using a resistor network and switches. Other Kenwood HF transceivers also have voice record and playback abilities. Unfortunately, I do not know of any that can remotely control these messages using a similar device. When I originally purchased my TS-850S/AT I also purchased the DRU-2 voice module. I also built a remote hand held controller to play back messages and allow for Push to Talk operation. This made contesting and Field Day operating very easy and convenient, especially when a headset is used. Though it served me adequately and never failed, it was uncomfortable to use. The TS-950S/AT transceiver uses the RM-1 to remotely access the messages. However, the RM-1 is cumbersome and does not offer PTT capability. Fortunately, the resistor values used for message playback on the TS-950S/AT are the same as those used on the TS-850S/AT. This controller should work just as well on both transceivers.

When operating Field Day, I use a Heil headset. My home built adapter cable connects the headset to the transceiver using a RCA jack for PTT control. Original equipment Heil adapters accept a 1/4" plug for PTT. I decided that the PTT line from the controller is to connect to the adapter. Alternatively, you can select one of the connections on the rear of the transceiver. Pin 3 and ground of the 7 pin Remote connector can be used, or you can use Pins 13 and 8 of the Accessory 2 connector. The playback select function is connected to the Accessory 3 terminal. Both transceivers use a 1/8” or 3.5mm stereo phone plug.


FIG. 1

Please refer to Fig 1 for the schematic diagram of the controller. Play-1 is enabled by selecting a 150 ohm resistor, Play-2, 270 ohms, and Play-3, 412 ohms (390+22ohms). Messages are played back by the use of three normally open, momentary closed contact switches. A single post, single throw slide switch opens the circuit, thus disabling message playback. The trigger controls the PTT.

FIG. 2

Please refer to Fig 2. The joystick I selected is a “tiny” brand, model JSK210 joystick controller. As can be seen in the image, it has 3 pushbutton switches, which is perfect for our use. These switches also have tactile feedback to give you a positive indication when they are selected. The ON/OFF switch can be used to disable these switches to prevent inadvertent playback of the voice messages. This joystick was purchased at a thrift store for less than $2.00 plus tax. If you can not find this particular joystick, consider an alternative. If you just need one playback control, select a joystick with just 1 switch on top. You or your children may have a suitable replacement somewhere around the house.

The first step is to remove the joystick handle from it’s base. Most joysticks can be easily disassembled and are put together with screws located on the bottom or handle. This is a fairly intuitive process and I will not go into detail here. After you remove the handle from the base you will have something that resembles that shown in Fig 3.

FIG. 3


The next step is to disassemble the handle. This will be required, since the controller will have be modified and additional parts added. Some handles are snapped together and can be difficult to take apart. Be sure to choose one that simply screws together.


FIG. 4

FIG. 5

Refer to Fig 4 and Fig 5. Once it has been taken apart, examine the parts. Be sure to note how the switches are arranged and look to see if there are any unusual circuits or parts. On the controller I chose, you can see a black shape in the middle of the switch circuit board. This is some sort of surface mounted IC chip that must be removed or isolated from the rest of the circuit. I chose to isolate it by cutting the associated traces. Upon closer examination, I was able to visualize how the circuit for this joystick controller was to be modified. All I had to do was isolate the IC chip, isolate the slide switch, reposition a wire, remove others, and install a short jumper as part of the construction process. Be sure to check the other side to make sure there are no unexpected parts.


FIG. 6

Refer to Fig 6. As can be seen for this joystick controller, I isolated the IC chip by taking a dremel brand tool and cut the traces connecting it to the rest of the circuit. I also isolated the slide switch by cutting additional traces. A yellow wire was repositioned and connected to the center lead of the slide switch. Finally, a short jumper wire will be connected as illustrated by the red line. This short jumper connects the common side of the center pushbutton switch to the common of the other pushbutton switches.


FIG. 7

Refer to Fig 7. At a convenient place near the base of the controller, cut a notch in each half to facilitate entry of the cable assembly.


FIG. 8

FIG. 9

Refer to Fig 8 and Fig 9. As per page 51 of the TS-850S/AT owner’s manual, voice channel 1 playback is controlled with a 150 ohm resistor, channel 2 with a 270 ohm resistor, and channel 3 with a 412 ohm resistor. Since 412 ohms is not a common value, a 390 ohm and a 22 ohm resistor are placed in series. Using a hot glue gun, glue the resistors to a convenient place inside the handle of the controller. Do not use RTV, because a corrosive gas is produced during the curing process. Connect one side of the three resistor values together. This will be connected to the Yellow wire later. Please note the black pushbutton switch above and to the left of the resistor network. This is the trigger switch. The cable connecting the PTT line will be soldered to this switch later during the construction process.

Decide if the controller is to be used by your right or left hand. If used by your left hand, solder the wire connecting the left side playback switch to the switch side of the 150 ohm resistor. Solder the wire connecting the center playback switch to the switch side of the 270 ohm resistor. Next, solder the wire connecting the right side playback switch to the switch side of the 390 + 22 ohm resistors. This way, your thumb will be able to select messages 1, 2, and 3 from left to right. If you will be using the controller in your right hand, just reverse the two outside switch connections. If you want, you can add additional circuitry that will allow left and right hand operation. I chose not to include this feature during the construction of this controller and will add it to future controllers.


FIG. 10

Refer to Fig 10. Next, we will construct the cable assembly that leads from the controller to the transceiver. I chose to use a 6ft. length of shielded stereo audio cable. Make sure the cable is shielded. You want to minimize the amount of RF intrusion. At one end of the cable, slide a piece of heat shrink tubing and place it approximately 2 feet along it’s length. Apply heat to the tubing to shrink it in place. This serves to prevent the cable from separating beyond this point. Next, “unzip” or separate a 2 ft. length of the cable up to the heat shrink tubing. Take one of the separated conductors and measure approximately 3 inches and cut it off at this point. Make a note of the color of the center conductor. Attach a RCA plug to the 3 inch section. The center of the RCA plug is soldered to the center conductor of the cable, The shield connection of the RCA plug is soldered to the shield of the cable. Attach a 1/8” or 3.5mm stereo plug to the end of the 2ft. section of the cable. The center conductor is soldered to the tip of the stereo plug. The shield of the cable is soldered to the shield of the plug, and the “ring” terminal is left unused.


FIG. 11


FIG. 12


FIG. 13


FIG. 14


FIG. 15

Refer to Fig 11, Fig 12, Fig 13, Fig 14 and Fig 15. Prepare the controller end of the cable as illustrated. Connect the shield of the cable for message playback to the common of the message playback switches. Connect the center conductor to the appropriate lead of the ON/OFF switch. I chose to solder the shield directly to the common side of the pushbutton switches. Connect the PTT line to the trigger switch. Route the cable through the notches cut earlier, and reassemble the controller.

This completes the construction of the Hand Held PTT and Voice Playback Controller and it is ready for testing. Connect an Ohm meter to the RCA jack. The meter must show an open. Press the trigger. The meter must show a short. Release the trigger and the meter must return to show open. Connect the Ohm meter to the Tip and shield connection of the 1/8” or 3.5mm phone plug. With the playback enable slide switch in the ON position, the meter must read open. Press the switch for message playback #1. You must get a reading of 150 Ohms, +- 5%. Release the pushbutton switch and the meter must read open. Press and release the switch for message playback #2. While the switch is pressed, the meter must read 270 Ohms, +- 5%. Press and release the switch for message playback #3. While the switch is pressed, the meter must read 412 Ohms, +- 5%. Turn the message playback slide switch to the OFF position. Press and release the message playback switches. The meter must read open. Return the slide switch to the ON position.

Connect the Hand Controller to your transceiver and confirm the proper operation of the controller. If any of the tests reveal a problem, it must be corrected prior to on the air operation.

Amateur radio operators are encouraged to construct this or a similar controller. All others please note that a patent is pending for this controller and all rights associated with it are reserved.



I hope this information has been helpful. If you have any questions, send me an E-Mail and I will try to answer them for you.


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Copyright © 2005, 2006 by Eric A. Snyder. All rights reserved.