ARRL (and non-ARRL) Frequency Measuring Tests
April 2014 Frequency Measuring Test
The test transmission will be from a single station in Oklahoma using the call sign W100AW/5. The transmission format will be a single, unmodulated carrier. Measure the frequency of that carrier as accurately as possible.
The FMT will start on 20 meters near 14121 kHz at 10:30 PM EDT on April 9th (Wednesday evening) in North America. (That is 0230 UTC on April 10th, Thursday morning, in Europe.)
A special W100AW Frequency Measuring Test certificate will be available to stations submitting a measured frequency within ±10 Hz of any of the three transmitted frequencies.
Frequency Measuring Test Schedule
Start: Wednesday April 9th 2014 10:30 PM EDT (0230 UTC)
20 Meters near 14121 kHz
10:30 call up (3 min)
10:33 key down 2 min)
10:35 end announcement
40 Meters near 7055 kHz
10:45 call up (3 min)
10:48 key down (2 min)
10:50 end announcement
80 Meters near 3598 kHz
11:00 call up (3 min)
11:03 key down (2 min)
11:05 end announcement
Submit your measured frequencies using the data entry website provided by WA7BNM at www.b4h.net/fmt. Results will be published immediately following the data entry deadline, which is 10:30 PM EDT on Friday, April 11th (Saturday, April 12th at 0230 UTC)
More information on FMT measuring techniques can be found here on the K5CM website.
Other Frequency Measuring Tests links
- Midwest VHF/UHF Society Frequency Measuring Test: http://www.febo.com/time-freq/mvus-fmt/
- Connie, K5CM's FMT web page: http://www.k5cm.com/
FMT History & References
From the January, 1980 issue of QST:
ARRL Frequency Measuring Test, begins with a call-up at 0300 and 0600Z February 10 (10 P.M. EST February 9 and 1 A.M. EST February 10).
W1AW transmitters will be on the air simultaneously (on 20, 40 and 80 meters for the duration of the test but in order to correlate your readings with those of the umpire measurements should be made during the specified periods. Approximate frequencies and measuring periods for the early run are 14,075 kHz between 0307 and 0312Z, 7030 kHz between 0315 and 0320Z, and 3565 kHz between 0323 and 0328Z. For the late run, 14,100 kHz between 0607 and 0612Z, 7090 kHz between 0615 and 0620Z, and 3525 kHz between 0623 and 0628Z. Submit your averages for each period to be compared with the umpire, a professional frequency measuring laboratory. Indicate how many readings you took to for in your average. Your report must be received by February 21. W1AW will transmit official results in an ARRL bulletin beginning February 23.
Frequency Measuring Test
Frequency shifting occurred during the early 20-meter FMT on September 14, with stability attained near the end of the period. Late 20-meter signals suffered the fate of poor propagation and were not copied by the umpire. The umpire measured frequencies for the early run at 14,076.241, 7010.999 and 3550.415 kHz. The late run checked out at 7014.292 and 3560.422 kHz. A total of 80 entries were received, representing 825 individual measurements.
Sixty-six of the 80 who submitted entries measured within 100 Hz, an annual requirement of 100 "precise frequency measurement." They are listed as follows, with average error preceding their call signs: (0 Hz) W1JH W1PLJ W2AXT WA4AXA W41BU W4NTO WA5NOM W5ZTN WA6IQL WB7CRU W8CUJ W8OK W9LCK K0KV W0USL, (1) W1BGW W3BFF W3WD W5FMO ex-7HM W8NWU, (2) K2RG K7AW, (3) WA3RXE W6RQ (4) K1VYQ WA4CAW W1FDH W6CBX K7CC, (5) K6MZN, (7) W3FYX, (8) W8LX W9HPG, (10) W2AIQ, (11) K9AUB, (12) W4DRF AJ5P, (13) K5FSA, (15) W2ND W0GW, (16) W4HU WB9VUO, (17) W0SS VE3FCU, (20) W4PKD, (22) N0ST, (24) W6DLL N8AU, (25) W3KEK W9TGN, (28) VE2JN, (29) W3KCM, (37) KE8X, (44) WA7DUY W7SC, (49) WA3CFC, (51) W6SSB, (63) N6PE, (72) VF4ZX, (75) WA2MID WA6NQF, (77) W7SK, (82) W4UCL, (88) W9KEZ and (97) W8ZRL. All entries measuring over 100 Hz have been notified individually.
The equipment used here for the tests consisted of a Heath SB-300 receiver using a 400-cycle band-pass filter. The VFO, i-f and het osc. frequencies were brought out of the receiver and went to a mixer unit, which in turn went to a homemade 8-digit counter. The counter was checked against WWV to four points (W2AXT). I enjoy the FMTs and am looking forward to the next one. Keep up the good work (WA4AXA). I enjoy getting set up for the FMT nearly as much as the actual FMT itself (W4IBU). I "cheated" and borrowed an HP-3586 wave analyzer from work. It's really an FMTer's dream in that it is fully synthesized to 0.1 Hz resolution. It has a 20-Hz i-f filter and a built-in counter to measure the exact frequency of any signal in its band-pass (K0KV). My plans to use all homemade equipment for this test did not get accomplished. Perhaps by the next test, I will have the receiver working well enough to use (W3WD). Any interest in an article on "How To" for frequency measuring? (W0USL). [Sure! - W1CKK] I use the NBS "transfer oscillator" method, using a Heath IB-1100 counter with modified time base (K1VYQ). I enjoy participating in the FMT and hope they continue for years to come (W2ND). Thanks for this event. Sometimes I even come close (W4UCL).
W4NM measured 13 Hz average error for the May FMT instead of 72 Hz error as reported (sorry 'bout that).
November 15 (UTC) is the date set for the next FMT. Be sure to check the "Contest Corral" column in November QST for full details. Good luck! Jeannie DeMaw, W1CKK
From the August, 1970 issue of QST
Open to All!
THOSE Of you who have been following recent issues have realized that some basic changes in the quarterly FMTs were underway. For many years the procedures in the quarterly FMTs were essentially standard, to wit: Official Observers could participate in all four FMTs, while non-OOs were limited to participation in the two QST announced runs (held in February and September).
In recent months, W1AW has been transmitting the official readings approximately ten days following each of the tests. The object of this is to get word back fast to those anxious to know how accurately they measured the test signals. (Well in advance of the necessary paper work by Hq.!)
Considerable evidence exists that numerous listeners would like the opportunity to actively participate in the test, and have the accuracy of their measurements compared with others. Thus, effective with this FMT, we're attempting something different. Participants reporting their measurements prior to the W1AW transmission of results (about 10 days following the FMT), will be listed in QST. Results will be tabulated in order of average accuracy with a cutoff point at some still-to-be-determined percentage.
1. Do some listening an hour or so before the test, to get an idea of band conditions and consequently of which band or bands will be best for measurement purposes. 2. The FMT transmission will start with a general call (QST) at exactly 0130 GMT, September 12. 3.Transmissions for measurement, sent simultaneously on all frequencies, consist of 15-second key-down periods interspersed with W1AW identification. 4. The three periods for measurement will start at 0137 (80 meters), 0145 (40 meters) and 0153 (20 meters); for the "late" run, 0437, 0445 and 0453 respectively. Each period will last for five minutes, including a series of dits at the end of it and identification before the start of the next period. We suggest you make your measurements in that order to coincide as closely as possible with those of the umpire. The table herewith shows the approximate frequencies which will be used.
Sept. 12, 1970
First 5 min.
Second 5 min.
Third 5 min.
5. Your percentage error is calculated on all the measurements you submit, so we suggest that you omit any readings in doubt. Watch out for careless mistakes in arithmetic, typing and other simple operator errors which can throw your percentage off. Submit more than one reading on each transmission and, if possible, measure more than one frequency so we can strike an average.
No entry consisting of a single measurement will be eligible for QST listing of top results. Listing will be based on overall average accuracy, as compared with readings made by a professional lab. Never tried the FMT? An excellent introduction to the basic techniques can be found in the W2VMX article "Try the FMT", page 54 July 1968 QST.
Technical Editor, QST:
For weeks before the recent Frequency Measuring Tests I had brayed to my friends on the air about how I would make a concerted effort to place high on the FMT results list. I had built a separate mixer, fed by my Drake twins' oscillators and followed by all outboard t.r.f. amplifier. The amplifier gives out a signal on whatever frequency is being tuned, directly into my newly acquired Hewlett-Packard 5216A frequency counter. With no interpolations involved, nothing could go wrong, I asserted.
I was busy most of the day of the FMT preparing for the two runs that evening. The Tektronix 547/1A1 dual-trace scope was set up to afford envelope or sine presentations of the receiver's 50-kHz. i.f., as well as to monitor the counter's time base against WWV (from a second receiver), and to peak the signal going to the counter. It was disturbing to discover that receiver dial backlash and frequency drifting were a real problem at those last hours, when attempting to tune and maintain zero phase difference, so I haywired a multiturn vernier capacitor across the receiver p.t.o. With a large knob attached, I was able to "ride" a calibration marker quite well.
That evening, at the start of the first FMT run, I was "loaded for bear," so I thought. All equipment was properly warmed up; I had attempted to stabilize the house temperature all day and had just closed all windows to prevent drafts. I was skeptical about receiving W1AW on 80 meters while it was still daylight here on the west coast, but there it was, right on schedule. However, the received signal on the scope was all fuzzed up with noise, and was bouncing from a nearby c.w. QSO. Tightening the bandwidth and using rejection tuning helped somewhat, but I still could not discern zero frequency clearly, much less ride zero phase as I had practiced earlier with a nice clean calibration signal.
When key thumps informed me W1AW would now shift to 40 meters(1) I was horrified and thought aloud, "Wait! I'm not finished yet!" But I wheeled everything up to the next approximate frequency, and there was a beautiful, clean signal. But just as I was ready to take some readings, some clown came on with dashes in unison with W1AW, and nearly zero beat. The 20 meter run was received well, except that by then I was so spooked I may have booted that reading also.
The second FMT run at 0430 GMT that evening was also chaotic here at W6FP. I never heard W1AW on 80 meters, not one peep. I had a good crack at a 40-meter reading, but the 20-meter transmission was hopelessly covered by heavy, continuous RTTY. By the end of the second FMT run, I was crushed by the enormity of my failure.
I know I must improve my antennas in order to have more of a received signal to play with, especially on 80 meters.
This will give me a cleaner scope readout. And I must groom my receiver regularly, not just wait until total outages force me to service it. Periodic tube checks, performance tests, and realignments "by the book" were let go here to my detriment, I subsequently observed.
With a clean enough signal at the receiver i.f. output, perhaps I can phase-lock my b.f.o. I have tried mixing the received i.f. back to the signal frequency and counting this, with only marginal success. Perhaps with more work, this idea of measuring "regurgitated" received signals directly might be the answer - to use the receiver as a tunable window only. Thanks to the ARRL for the FMTs as a challenging program, and watch out for us next time! - Dick Carpenter, W6FP, 6634 Ampere Ave., North Hollywood, Calif. 91606.
W1AW does not shift frequency during the FMT. The entire transmission is sent by all transmitters simultaneously. However, the "umpire" measures the frequencies in the order indicated in advance announcements. Actually, the frequency seldom drifts more than a few cycles during the entire transmission period, so any significant differences will be noted only when precision measuring equipment is in use. - Editor