Frequency Measuring Test 2004The test format changed this year, and in my opinion not for the better. Instead of measuring a CW signal, transmitted in the CW part of the band, W1AW used SSB and transmitted an audio tone. They announced the carrier frequency ahead of time, and the exercise now involves some additional math to determine the audio tone, given the known carrier frequency.
I can see the learning advantage of this format, but it actually reduces the challenge a bit since we are bound by the accuracy of the announced carrier frequency. And, using the voice part of the 40M band means that there are many hetrodynes and other spurious signals to dig through in order to find the desired tone.
Propagation and interference didn't favor this year's FMT. We had good copy on 80M. On 40M, the signal wasn't strong and there was a huge amount of interference from a SW broadcast station. Like last year, we didn't hear a peep on 20M. Mike, WB8GXB, who operated from his own shack this year, reports hearing signals on all three bands, but he has a tribander at 90 feet, so his signal-catcher is a bit better than mine.
|Band||N8UR Measurement||ARRL Measurement||Error|
|80M||1 105.013||1 105.02||-0.007 Hz -- -1.75x10-9|
|40M||1 108.279||1 108.26||+0.019 Hz -- +2.6x10-9|
If you're interested, here's my ARRL Submission Letter (pdf).
The test setup this year was the same as last year -- an HP 3586C selective voltmeter served as receiver, with its tracking generator looped back to the input (via an attenuator and 2-way coupler) to provide the reference tone. The external frequency reference was an HP 5065A rubidium frequency standard that was monitored against GPS at the time and was within 5x10-13.
Here are a couple of screenshots of the signals as recorded by Baudline. The signal near 1850Hz is my local reference, and the signal ~25Hz lower is W1AW. The screenshots each show an average of the signal over about 3 minutes.
By contrast, here's a close-up of the 80M W1AW signal. No problem spotting the peak here!