Rig Blaster Pro TS450S Control Interface, Rev -B

7 July 2004

RIGblaster Pro Rig Control Interface to the Kenwood TS-450S Transceiver
By Gene Hinkle, K5PA K5pa@arrl.net
This paper describes the rig control interface between the RIGblaster Pro (http://www.westmountainradio.com/index.html) and Kenwood TS-450S transceiver. This implementation makes minimal modification to the Pros hardware and basically affects a logic level conversion using transistors located inside a 1/8 stereo phone/jack assembly. The completed interface is used to control the TS-450S transceiver with the Writelog for

Background

Windows, Version 10.47, (http://www.writelog.com/) log & radio control program.
Technical Overview The rig control interface between the TS-450S expects the TTL Rx and Tx data lines to be inverted logic from the RIGblaster Pros implementation. Adding transistor level inverters in the TTL Rx and Tx data lines is all that is needed as far as the logic is concerned. There is one small problem with this method however. The Pros design has a 0.033 uF capacitor across the TTL control input line to ground to act as a filter. This is a good design
the Rig Blaster Pro level converter circuit has a 5 Meg Ohm resistor pull-up to +5VDC (Vcc) built into the IC itself. But with that 0.033 uF capacitor hanging off the input to ground, it cannot pull the logic level up to a logic one quick enough at the 4800 bps data rate of the control signal. The solution is to add a 330 Ohm, W resistor from the TTL receive input to +5VDC inside the Rig Blaster Pro. It does not hurt anything in normal operations, and acts as a pull- up to +5VDC supply when the externally mounted transistor inverters are being used (the two transistors are mounted in a small adapter cable that connects between the RIGblaster
methodology and works when TTL circuits are driving the input to the RIGblaster Pro. But, if a transistor pull-down inverter is driving it, a pull-up to +5VDC is needed. Normally, the level converting IC, DS14C232 (http://www.national.com/pf/DS/DS14C232.html ), in
Pro's control output jack and the DIN [ACC-1] connector on the TS-450S).
Cable Logic Inverter This implementation allows the use of another interface cable should another radio be used that does not require logic conversion. The cable, shown in Figure 1, is built from a stereo plug cable assembly (Radio Shack 42-2497, 1 ft., shielded cable cut into half, http://www.radioshack.com ) and a 3 conductor, stereo phone jack (Radio Shack 272-249, 1/8 phone jack). The inverting transistors are common NPN-type transistors (e.g., 2N2222, 2N3904, 2N4401, etc.) that were selected from a batch of transistor in Radio Shack part number 276-1617. Each base of the transistor has a resistor added in series to limit the current (I used values of 330 ohm, W).
Information may be protected by Non Disclosure Agreement. Copyright 2004. Provided for Non-Commercial Use Only. All other uses prohibited.

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In-line Cable Adapter Containing Transistor Logic Inverters

1/8 Stereo Phone Jack

1/8 Stereo Phone Plug Cable
Part of Cable Going to TS-450S DIN Connector
Figure 1. In-line Adapter Cable Containing Transistor Logic Inverters and Resistors Figure 2 shows the schematic layout for the logic level inverter cable.
330 Ohm, W NPN 2N2222 or equivalent RXD (Tip) TXD (Ring) NPN 2N2222 or equivalent 330 Ohm, W
1/8 Stereo Phone Plug Rig Blaster Pro CTL IN/OUT (R4)
Ring is wired to ring and tip to tip with logic level conversion in-between
Figure 2. Schematic of the In-line Inverter Cable

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TS-450S Interface Cable A cable is still necessary to connect from this inverter cable assembly to the TS-450S DIN connector. The cable is already shown correctly in the RIGblaster Pro documentation but is redrawn in Figure 3 for completeness. The cable is made from another 1/8 stereo phone cable cut to length (as needed) and then connected to a full sized, 6-pin, male pin, DIN type connector. This connector and cable were purchased from a local supply house. There is nothing special about the cable assembly; use good quality shielded cable and cut the assembly to the required length for your situation. In the previous photo shown, this cable is shown attached to the inverting cable adapter and has the label TS-450 CNTRL wrapped around the plug.

TXD 6 GND 1

RXD CTS 4 Loop Back 5 RTS TXD RXD
6-pin DIN Connector Viewed from the rear
Rig Blaster Pro CTL IN/OUT (R4)
Figure 3. Cable Assembly to Connect to the Kenwood TS-450S ACC-1 DIN Connector for Rig Control Pull-up Resistor Addition The last item needed is to add the pull-up resistor inside the RIGblaster Pro chassis. Figure 4 shows the location of the 330 Ohm, W pull up resistor. It attaches from one end of the R28 resistor to the +5VDC output regulator lead of U6. Static protection measures should be taken to prevent damage to the circuit boards electronics. Alternately, two small clip leads as shown in Figure 5 could be used to attach to the R28 resistor and +5VDC lead to avoid having to solder the connection. If you do solder, use only the amount of heat necessary to create a solid connection to avoid heat damage to the board or components. The use of this pull-up resistor is in parallel with a 5 meg-Ohm resistor internal to the level converting IC. It will have no affect on its operation when regular TTL circuits are used to interface to the RIGblaster Pro, thus it can be left installed for other radio interfacing as well.

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Add this 330 Ohm Resistor, W

Solder Solder

Note: The resistor added (upper most resistor whose image is just below the J18 silkscreen letters in the photo) attaches to the +5VDC regulator (U6) lead and to one end of R28.

Figure 4. Added Pull-up Resistor, 330 Ohm, Watt
Note: The resistor is shown exposed prior to the heat-shrink tubing being added. The clip leads attach to the two same points as shown in Figure 4 above.
Figure 5. Alternate Way of Adding the Pull-up Resistor to Avoid Soldering Inside the Unit
This completes the discussion of the TS-450S interface to the RIGblaster Pro. If you have any questions or comments, please contact me at k5pa@arrl.net. 7 July 2004, Rev-B

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