Two schematics are available giving a general overview of the transmit and receive audio setup and of the digital setup.
Each of the radios are connected to the computer for digital control and interaction with various programs. Designs for the computer interfaces for the Kenwood and Icom rigs were published by Wallace Blackburn, AA8DX in the February 1993 issue of QST on page 37. One interface is required for both Icom radios and one for the TS-690S.
The two interfaces are connected to a serial port switch box which allows me to use one serial port for rig control. The main disadvantage is that I can only control either the TS-690S or the Icom radios but not all 3 at one time. The trakbox, which is used for satellite operations is also connected to the serial port switch box in order to upload updated KEPs on an intermittent basis.
CAT control of the ICOM radios is via a local area network system using CSMA on a serial data bus. Up to 4 radios can be controlled at once. In order to connect the Icom satellite interface (CT-16), computer control line, and the Trakbox to the IC-275 / 475 radios a small switch box can be used to switch line control between each of the devices. The TS-690S is interfaced to the computer for remote control via the ACC1 serial port on the side of the rig.
I was interested in using the DSP-2232 with all my radios and I also wanted to solve the SSB distortion that occurs when a TNC is connected to the ACC2 port of the TS-690S.
To solve these problems, I bought a data transfer switch box from a computer supply shop. The box had two input ports and a total of 8 output ports. One input was a female 5 PIN DIN plug that could be switched to 4 separate female 5 pin DIN outputs. The other input was a DB9 plug arrangement that also switched to 4 separate DB9 output connectors. Since the 5 pin DIN is a standard connector on many TNCs, including the DSP-2232, I decided to use the 5 pin I/O on this switch box for connecting my PK-232MBX, and later, my DSP-2232 to my TS-690S.
I converted the PK-232MBX radio cable to a 5 PIN DIN configuration. I did this by cutting the cable in half. I terminated the cut ends of the shielded cable with male 5 pin DIN plugs. Plug them in to the proper input / output ports of the data switch box and you are away. Initially, I was just connecting one of the radio ports of the PK-232MBX to the TS-690S, so when I was using SSB, I just switched the box to an empty port. Similarly, when I wanted to use the TNC, I just switched the PK-232MBX in-line. This simple arrangement prevented the audio distortion that is common when a TNC is connected to the ACC2 port.
With some modifications, the DB9 I/O series in the data switch box was used to extend the receive audio capabilities of the TS-690S and allow me to place a W9GR audio DSP filter inline to the DSP-2232 when warranted for HF operations. Otherwise the audio was routed directly to the W9GR filter where it could be processed or the DSP filter bypassed as noted below.
When I connected Port 1 of the the DSP-2232 to the system I wanted to use it for HF, VHF, UHF and satellite purposes. As a result, I cabled the first output port of the digital switch box according to the information provided by W0SL for 9K6 satellite operation. The second port is cabled for 9k6 terrestrial packet operation with the IC-275. The third port is dedicated to HF operations and is cabled to the ACC2 port of the TS-690S with the W9GR audio DSP filter inline. The last port is wired as the same at the 3rd port except that the audio DSP filter is bypassed.
Port 2 of the DSP-2232 is used for 1200 PSK satellite operations as well as 1200 AFSK
terrestrial packet. In order to enable these operations on one port I had to make a small
switch box using a 6 pole 2 position switch for the output of this radio port. The switch
changes the RX audio and audio ground between the ACC1 port on the IC-475 (satellite 1200
PSK operation) to the ACC1 port of the IC-275
(1200 baud terrestrial operation).
Hand drawn schematics of the various connections are available if interested.
The setup centers on a Mackie
1202vlz Mixer which has 4 balanced microphone inputs and 8 balanced line inputs. The
mixer also has microphone preamps, equalization and numerous other capabilities. While
many amateur radio microphones are unbalanced, most professional microphones have balanced
outputs. I have two boom mounted microphones connected to the balanced inputs of the
mixer. One is a Electro Voice RE-20 which has a balanced output. The other is a
modified Kenwood MC-60 desk microphone refitted with a Heil HC-5 element that has an
unbalanced output and placed in a boom. Two other microphones ( a heil HC4 cartridge
mounted on a Kenwood headset & a DSP noise reduction electrec microphone headset
designed for computer use) may be connected either directly to the Mackie 1202 VLZ Mixer
or the Transmit Audio Switch Box via a small common receive/transmit
audio box setup just under the front edge of the operating table. This reduces the
number of wires related to headsets or headset-microphone combinations laying
on the table-top during station use in contests or for DXing etc. - that makes life much
easier!
An unbalanced line from the computer's sound card line output is also connected to a line level input of the mixer. This enables me to transmit analogue or digital data generated by the sound card. For example, in on air audio tests, I can digitally record a transmission and replay it back to the other operator. The setup also enables use of software that uses a sound card such as W95SSTV for SSTV digital operation.
The output includes 2 balanced XLR connections, as well as balanced 1/4 inch TRS jacks. I used one of the balanced XLR audio outputs of the Mackie. The cable is wired as a balanced to unbalanced shielded cable and runs to a transmit audio switch box. This switch box allows me to route audio from 2 sources to any one of my radios or the microphone input of the sound card in the computer. One of the input sources to this box is the Mackie mixer and the other input is received from the headset microphone input located in a transmit/recieve system box just under the font edge of the operating desk.
The Transmit Audio Switch Box is a modified computer data switch box that originally had two sets of I/O connectors each with one input and 4 outputs. The box provided a cheap source for a 5 or 9 pole, 4 position switch for control purposes. The DB9 series is not currently used. The other, a 5 Pin DIN series, is used for to switch the transmit audio between devices. This meant that I had 5 wires to work with from input to output. I had originally decided only to hard wire audio/audio ground and PTT/PTT ground. However, due to the availability of an additional wire in the system, I did install the step up/down function for the Icom radios. This feature is activated via two monetary push switches installed on the front of the switch box which grounds Pin 3 of the microphone input of the Icom radios to the PTT ground. Step up is activated by directly grounding Pin 3 by pressing the monetary switch once. The other switch grounds the pin via a 470 ohm resistor to allow for step down operation.
The input connector was changed to a 8 Pin female jack. A second 8 Pin Female jack was added as a second input. A DPDT switch placed on the side of the box toggles the audio/audio ground output pair between the two inputs. Only audio and audio ground were hardwired from the mackie and headset/boom microphone to the audio switch box. A separate mini-jack was installed in the back of the box for a foot activated PTT switch.
The 4 inputs: audio signal / audio ground; PTT/PTT ground were then wired to the input wires inside the box. The 5th wire was routed to a pair of monetary contact push switches for the step up / down function of the Icom radios. Grounding either monetary contact switch will result in a step up function in the TS-690S.
The output jacks for the radios were left in their 5 Pin DIN Pin jack format. The output to the computer is a mini stereo jack. Shielded cables were made that would interface the 5 pin DIN outputs with the 8 pin jacks on each radio. Non-audio lines were bypassed with 0.01 mf capacitors and audio lines were bypassed with 0.0033 mf capacitors for RFI protection. Ferrite beads were also placed on a number of connecting cables through-out the system as well.
NOTE:
The ICOM radios have a voltage on the audio input pin of the microphone jack. If you are using microphones other than Icom's a tantalum or electrolytic capacitor must be placed inline to prevent damage to the microphone. A 0.47 to 0.8 mf tantalum or electrolytic capacitor can be used to isolate this voltage from the microphone. Make sure the positive lead (+ve) of the polarized capacitor is placed such that it is on the radio side of the connection. I used 0.47 mf tantalum capacitors and placed them inside the switch box on the back of the 5 din plugs.
In order to maximize the capabilities in the station, and minimize the number of cables or wires on the desktop - or just lying around, I interconnected the audio outputs from each piece of equipment with a view to making arm chair copy a reality. Audio output from each of the radios and the computer is routed in a number of ways. The tip and ring segments of stereo jacks and plugs were used for audio and audio ground when wiring audio connections to isolate grounds and prevent RFI or audio interference. All audio output can be roted to a small receive/transmit audio box setup located just under the front left edge of the operating desk. The transmit section has been described above. The audio receive section of the box has a 6 position 2 pole switch that allows me to route audio from a number of sources to a headphone jack. This provides me with a convenient place to plug a headset in and just sit back and listen in to any audio source that is selected. Input is also received from the Kenwood TS-690s, each of the Icom radios and the computer sound card line out as described below.
TS-690S:
The audio from this radio first goes to the digital switch box used for the DSP-2232 as noted above in the digital switching system section of this page. The audio is then routed to the W9GR DSP audio filter that was described by Dave, W9GR in the September 1992 issue of QST on page 43. Depending on the switch position selected on that box I can switch the W9GR DSP filter in or out of line to the DSP-2232 for HF operations. There are 4 possible outputs from this DSP filter. Two are not currently used and one goes directly to the line input of the sound card in the computer. The remaining audio output is routed to a 5 inch speaker AND a common receive/transmit audio box that is located just under the front edge of the operating desk.
The audio outputs from each of these radios is routed to a "Dual Radio Speaker" as described by Neil, KL7JGS and Fred, KE7X in the November 1992 issue of QST on page 56. This setup allows one to chose to listen to either radio or both at the same time. I added a cable from the phono jack of the speaker that runs to the common receive/transmit audio box mentioned above to eliminate cables or wires running across the desktop.
This enables me to listen to either or both radios by plugging into the phono jack just to the left of the operating position and minimizes the number of wires running across the table top.Sound Card:
The audio line out from the sound card is routed to a RS audio switch box. I use this to route the output between the speakers, the line input on the Mackie for transmission purposes and the
common receive/transmit audio box so I can listen with a pair of headphones.Under construction and last modified 22 November 2002; © 1997, 2002 by David Seeler
