WRTC 2010 Blog #2 Reprise

After our last-minute insertion into the roster of WRTC 2010 competitors, K6XX and I began a whirlwind of preparation. I gathered equipment from my mountain and valley ham shacks. Bob segregated competition gear from his vast inventory of personal and business equipment. (He is a consulting engineer at Elecraft.) We divided up the construction tasks: Bob would build the triplexer and station controller; I would build the audio control boxes and recording facility. We planned to meet at Bob's shack for WPX CW for the first trial run of our WRTC setup.

WRTC was not just a test of operating ability. The rules implied that significant station engineering and system integration be performed in order to maximize capabilities. Teams were tested on technical innovation as well.

The triplexer was pretty much as published in the June, 2010 issue of QST. A very simple design, this article left us all mumbling "Why didn't I think of that?" It is 1970s technology that the Russians have evidently been using for some time now. I predict that it will revolutionize Field Day in the US! It was perfect for WRTC, allowing us to operate any two of 10, 15 and 20 meters at the same time, sharing a tribander with a single feedline. It worked perfectly and almost every competitor had one or something like it. There is a Russian company selling a (very expensive) version. 

The primary purpose of Bob's controller (yellow box in the picture) was to inhibit a transmitter when the other transceiver was transmitting, thereby complying with the WRTC 2010 rule that only one rig can transmit at a time. It worked very well. The box also contained two WinKeyers and two SixPak controllers with decoders. We would have automatic antenna selection with manual override (which, in the event, we didn't use much at all). 

I built a pair of audio control boxes that gave us each a choice of My Audio, Other or Both. On "My Audio" we got full stereo from our own K3, letting us take advantage of audio effects digital signal processing. (No subreceivers were allowed, so that kind of stereo was irrelevant.) "Both" let us listen to the right-hand rig in our right ear and the left-hand rig in our left ear. This was invaluable when trying to interleave transmissions so we could really operate at the same time. The "Other" switch position should have been labeled "Bad Operating Practice, why aren't you making QSOs?" The boxes included a volume control for the opposite radio and an LED that indicated when the other rig was transmitting. These little boxes got quite a workout during the contest. 

The contest rules required that we make a single stereo recording of the audio from both radios throughout the contest and turn it over to our referee within 15 minutes after the contest. Although our logging software, TR for Windows, had a recording capability, we had not used it previously and were loathe to add the extra burden to our computers. Instead, we got a nifty external audio recorder that was originally intended for professional musicians. Basically an iPod with a Line In connector, this Olympus LS-10 recorder worked beautifully. Its 2GB internal memory was more than adequate to record the entire 24 hour contest, both rigs, to an MP3 file at 128K bps. This was its lowest fidelity but more than adequate for our purposes. We also used its monitor jack for the referee's headphone connection, completely isolating him from our own audio circuits.

The K3, by the way, was ideal for this complex audio environment. Its KIO3 rear panel includes separate jacks for Speakers, Phones and Line Out, so we needed no external circuit sharing. 

After our initial test run in WPX, we tweaked our devices and tested them again in the All Asian CW. Everything worked fine and what remained was a dual-mode trial. We did that in Field Day with an antenna environment representing the worst-case configuration that we might encounter at WRTC: We used a tribander on a 35' mast directly above the station with 80 and 40 meter dipoles right below it. In the event, our antenna was 50' away from the tent, so our RF environment would be better. We declared ourselves ready.