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My SO2R setup

revised on 13 May 2002


In early 2000 Iíve decided to design and build an SO2R setup, which suits me the best. After some experimenting I ended up with the following setup:


The main SW I use for contesting is CT but Iíve also got SD from Paul EI5DI and in 2000 I bought Writelog, which I still have to learn to master. I use CT most of the time because after so many years Iíve really become used (or shall I say addicted?) to it and I managed to learn most of its tricks and nuances. Besides, as a potential candidate for RSI Iíd like to minimize mouse usage and this keeps my ham directory Windows-free as much as possible. Paul EI5DI gave me a copy of his SD software, which is the de facto standard for RSGBís popular IOTA contest and applies very intuitive solutions for the unassisted SO contester. I really like the way he implemented WAE in his SW.

However DOS has its own limitations and a few years back I wanted to make my feet wet with Writelog and the Windows-based software. The high number of supported contests enables me to learn the software in part-time or casual contesting and to hand out points on a casual manner more often. Seeing the amount of traffic on the Writelog email reflector and my experiences with Writelog so far didnít make me rely on it yet, but Iím confident within some years it will develop to a reliable and robust software.

The computer I use is a Compaq E500 Pentium III notebook running at 660 MHz and having Windows 98SE software. It has only 1 built-in COM-port, the other 2 are provided by an Argosy PCMCIA serial port extender, which hooks up as COM5 and COM6.

When I use CT I have to connect the logging PC to a second PC, which connects to the a local DX-cluster. It's done via a Xircom CE3 10/100 PCMCIA network adapter using K1TTT's NETTSR . The second PC isconnected to a TNC and a VHF radio. Handling the frequent link breaks and cluster breakdowns is easier on the separate PC and the second networked PC also keeps a copy of the log. With Writelog I can use the infrared port (COM3) of the notebook to connect to the internet via a Sony-Ericsson T68i the IR port and spare the second PC. This phone supports GPRS and enables me to connect to the Internet for long time on a very cost-efficient manner (byte-based billing).

The SO2R-box is designed and built by myself. It switches the headphones, the keyer, the microphone, the PTT. The box combines the keyer output with external paddle as well as the footswitch with the PTT signal of the PC.

It has a flip switch to activate the relay, which swaps the audio channels of the two radios when one of them is switched to transmit. When the pileups on the run radio gets too intense I temporarily disable the second radio.

The SO2R box also does audio mixing: With a 3 position switch I can select any of the 3 modes: active radio in both ears, one radio in each ear and non-active radio in both ears. When I use the two VFOís of the MP simultaneously, the switch is in the first position and the MP takes care of mixing. When I use the second radio, the second position is selected. The third (reverse) position is used when the S/N in the mixed position is not enough to get a good copy on the second radio and in this case I quickly turn the switch to get the call without changing the active radio (cq does not have to be interrupted).

Separating the PTT-controlled audio swap and the mixing function creates a tremendous flexibility, which enables of selecting the right combination for any operating situation.

Although I'm not very active (or even keen) in SSB contesting the voice keyer connections of the soundcard have also been implemented. The microphone is a Heil HC4 element mounted on flexible mike-boom attached to a Sony MDR-V600. The microphone is plugged in the notebook's mic input and the output is fed to the radio via an isolation transformer.

Both radios are from Yaesu: an FT1000MP and an FT990. The FT1000MP is the best radio I could afford and I use it for casual DXing and contesting. The FT990 was selected as second radio because:

        this radio combines simplicity and performance the best

        the connectors are the same as on the MP

        very well built and rugged


The MP has all CW filters (Yaesu) including the one in the 2nd VFO. This one will likely be replaced with an Inrad 400 Hz since its steeper skirts would better fit S&P. For SSB only the 2.4k filters are installed and Iím perfectly happy with them. The MPís mod options are maxed out. The PIN diodes have been upgraded, as well as the ALC and NB circuitries. I took W2VJNís idea of an intermittent IF amplifier and use a broadband HP measurement preamplifier in the MP. This preamp was designed to provide maximum linearity and has three selectable amplification levels. These are set to 6, 8 and 10 dB. This provides very handy flexibility without the need of entering into the hidden menus.

The FT990 has all filters installed.

The main radio has one amplifier connected, while the second radio has three via a 4-position Daiwa CS-401 switch (the 4th connection has a dummy load).

The benefits of this solution are:

        the two TX branches are completely isolated

        the tuning time is kept on minimal

        the system reliability increases, since the outage of one amplifier does not influence the system performance significantly

        the switching is done at low power (beneficial for the future automation)

        4 manually tuned amplifier is significantly cheaper than two auto-tuned ones (especially if home-made)


The Beverages (if built) are connected to a coax switch, where the appropriate direction can be selected, followed by a BC band filter and a two-position switch to select the Beverages to one of the radios.

This is the description of the SO2R setup how I have it implemented. It was first tested in the IOTA 2000 (#2 in SO24/Mixed) and WAE CW 2000 (#3 in SO) contests. In year 2001 my attempts in IOTA (#1 in SO24/Non-IOTA/Mixed) and WAE CW (#1 in SO) contests were more successful.

Major plans for the future:

        second amp (serial connected) for the run radio

        automate the amplifier selection for both radios

        design and build an radio controlled bandpass filters

SO contesting is the secondary option for me since I always referred team contesting. However there are some great contests like the Russian DX or the CQP offering lots of opportunities to improve my skills while competing in the SO class. SO2R seems to be the most competitive way of doing this thatís why I invested some time and effort to put this setup together. If you have any idea how to improve this setup further, please let me know. Your input would be gratefully appreciated.

Click here to get the schematics of the SO2R box

Click here to get the schematics of the FT-990 CAT controller

This setup has been developed based on ideas and/or publications of Tibi HA1DAE, Bill W4AN and Tree N6TR. TNX!!!