A simple approach to SO2R
From Contesting
By Jack Schuster, W1WEF, republished by permission
It's not that I never tried S02R before. I've spent countless hours cutting half an inch at a time off good quality coax, making stubs with deep nulls. I once bought a five-band Dunestar bandpass filter. I had two Yaesu FT 1000D transceivers sitting side by side for a few years waiting to be used in an S02R setup. In 1997 I actually did operate with two radios, but my station wasn't conducive to using the second radio because I still had irritating CW "buzz saw" QRM between the radios. Nevertheless, I gained a handful of extra Qs on the second radio and had my best CW Sweepstakes score ever.
Despite my efforts to lick the interference between radios well enough to feel comfortable using S02R, I concluded it was impossible to do it with three TH6s stacked on one tower. Sweepstakes was always the one contest where I would try to make it work, especially on the slow, boring Sunday.
A New Idea
SSCW 05 was going to be different. I had a new idea! I started thinking about my plan in May. After visiting Chris, W4/G4BUE, in Florida in January last winter while driving through his town in the RV, I decided I should have a Hustler vertical like the one that Chris used for his second radio. No matter what I wanted it for, it was such a well-built antenna at such a reasonable price that I had to have one. I bought and used a Hustler 6BTV similar to G4BUE's at my summer house with the idea that I could easily take it down and bring it on next winter's RV trip. What I would also do is put it up for a second radio in SS.
By using a separate multiband antenna, I wouldn't have to do any antenna switching on the second radio. I would locate it as far away as I could from my other antennas to minimize QRM between radios. Being vertically polarized would help in minimizing interference with the first radio since it would be on horizontally polarized antennas.
Although I am fortunate to have a lot that allows me to locate the Hustler vertical over 300 feet away from my single tower, I didn't have as much coax left on the spool as I thought. As a result, the Hustler was planted only 100 feet away from the tower. Being only 32 feet high, it was still a good distance from the lowest TH6 at 58 feet.
I put down only two ground radials per band, just as I had this summer. Since I figured I'd only be using the second radio when the rate really slowed (most likely on Sunday), I figured I didn't need 1500W on both rigs and set up a little FL-2100B amplifier to run at 500W on the Kenwood 930S. Finally, it was time to check QRM between the Yaesu FT-1000D and the 930S. First I ran 1500W on the main radio and tuned all the bands with the 930. Unless I was close to the first harmonic, it was amazingly quiet. I tried all band combinations and it was the quietest setup I ever had. I next did the same thing with the 930 and amp, and it too was excellent! The only time I had severe QRM was when I ran 1500W on the main radio to my 4 Squares on 80 meters. With the 4Square's vertical polarization, and with two of its verticals being closer to the Hustler than the tower, it wasn't doable. But my 80-meter dipole was quiet when used along with the Hustler, so I decided I could live with the dipole.
My hunch that a vertical on one radio and horizontal antennas on the other radio with no stubs or filters was correct. This was going to play!
I spent the next day building a switch box that let me listen to the left radio (1000D) in my left ear, the 930 in my right ear, or either radio in both ears. A toggle switch selected which radio was keyed. It was simple enough to use and I was ready to roll ...or so I thought.
The True Test I started SS on 20 meters, figuring t could CQ there for at least a few hours at a pretty good rate. It didn't happen. Where was everybody? After a few Qs I decided to scan the bands from the bottom up, working everyone I heard, knowing there were no dupes to worry about in these first few hours. The rate picked up, but it was nowhere near what I had hoped for, looking at Randy, K5ZD's, winning rate sheet from last year.
After a couple of hours, I decided it was slow enough to use the second radio, much earlier than I thought I would. I found big signals easily on the 930, and had no trouble working them with 500 W. I'd go back to the main radio, work some there and find another on the 930. This might be fun!
Then I realized a mistake I had made - a big mistake. What a dummy! I was so used to operating one radio with computer control and automatic frequency logging, I had forgotten to change bands in the logging program for the 930. Although the 1000D was interfaced for computer control of band changes, the older 930 was not. I thought I remembered who I worked on the second radio, and edited the contacts, but I found I would keep forgetting, or worse yet, I changed the band for the second radio, went back to the first with the second radio band still in the computer, and worked a bunch of guys before realizing it! After doing this about five times I knew it was all over. There was no way I could figure out the correct bands, and I thought I would be penalized severely. Five hours into Sweepstakes, very disappointed, I threw in the towel. The penalties would be so great that it wasn't worth a serious effort.
Lessons Learned
Sunday, I decided to get on for some casual operating during the day, without using the second radio. Since the log was so busted, I decided to try the PacketCluster since I had never used it in a contest. I decided to go for a sweep and send in a checklog. To avoid confusion, I continued to send a "B" precedence for the rest of the operating time. I never did get the Sweep, missing NL, but getting a sweep this way would have meant little to me anyway.
What did I learn? I learned that I can set up two radios with almost no interference between them, with no filters or stubs. I also learned that there's no way I'll ever do it again without computer control that will select the radio from the keyboard and log the right frequency!
