Although most can measure the frequency of WWV or CHU, and they are great to use for calibration and adjustment, they do little to improve one’s skill in measuring an unknown frequency on the Ham bands in a relatively short period of time. Beyond the technical skill to simply measure the frequency come the propagation effects that cause the signal to appear on a different frequency than it really is (Doppler effects). Learning to recognize these effects and understand the impact they have on the transmitted signal frequency is another acquired skill that can be developed with practice. For example: Some are exploring the possibility of monitoring WWV and CHU in hopes of gleaning what the propagation anomalies might be doing at any given time to affect the frequency of the FMT transmitting station. It is hoped these test will be an aid to both beginners and old timers alike in improving their ability to measure the frequency of off air signals....
Please join the FMT-nuts here
The next K5CM FMT Thursday evening May, 21st, 2015 9pm CDT (0200 utc)
Next ARRL sponsored FMT - November 2015
Most recent K5CM FMT results (May 21, 2015)
K5CM FMT results
Additional K5CM (impromptu) FMT's
Additional ARRL FMT Results
Entry form (Be sure to reload/refresh the form)
QSL and photos
Wide spaced FMT set ups
Dual Frequency Doppler test
FMT with only a Ham Transceiver
Spot light on, Previous spot light
Downloads and links
High accuracy AM broadcast stations
ARRL FMT Page
Additional ARRL FMT Results
VE2AZX WEB SITE go here for an excellent tutorial on Spectrum Lab
OKQP INFO and RESULTS
K5CM FMT transmitting equipment:
A HP Z3801 GPS frequency source clocks a HP-3336B. A 10 db transistor amp follows and drives a 12BY7 / pair 6146. Then to the final amplifier running 300 to 400 watts out. There are no mixers or any device in the chain of amplifiers that might impact the accuracy of the GPS frequency source. As a reality check, I periodically log the frequency source against WWV and other GPS referenced sources. I monitor each transmission with a completely separate receive system to look for any instability or short term drift. The separate system is not locked to the GPS transmitting system.
I typically see considerably less than 1 mHz difference at 10 Mhz when comparing two Z3801's or a Z3801 and a Tbolt, over a 10 second period.
160 - Vertical
80 - Cage Dipole (favors East, West, and North) or Dipole slopping down from 140' tower.
40 - Dipole hanging between two 80' towers (favors East, West)
30 - Dipole
20,17,15,12,10 - 4 element SteppIR
W6OQI FMT transmitting equipment:
My transmitting setup consists of a HP Z3801 clocking a HP 3336B which
drives a Johnson Viking I transmitter, the output of which is attenuated by a 6
dB attenuator, to then drive an Icom PW-1 amplifier to about 500 Watts. The
antenna is an inverted Vee which favors north and south from the Los Angeles
area. The QTH is actually La Canada, CA at 2000 foot elevation on the mountains
on the north side of the Los Angeles basin. The Rose Bowl in Pasadena is about
three miles to the east.
A little ARRL FMT history:
In the years prior to 1981 the ARRL used to transmit FMT’s. These test were truly a test. For example: The ARRL “Official Observers” had to pass this test at a certain level to be eligible for the highest level “OO” position. FMT’s were transmitted several times per year with more than one FMT on any given night (early run and late run). In 2002 the ARRL started transmitting one FMT each year. Many FMT'ers thought once a year and waiting several months to know the results was a bit frustrating. Some started transmitting signals in their local areas, but somehow this was just not the same as a real FMT.
Thanks to K6APW for help with the web entry form.
Thanks to Jeff, W3JW for his help in developing the two simultaneous frequency format.
Several have suggested formats consisting of two signals, including K6APW.
Also thanks to WA1ABI, W3CSW, W3JW, K6OQK, W6OQI, KM1P, WB9FIP, VE2IQ,VE2AZX, and K6YAZ for help with testing by supplying wave files, hardware, and other needed information.
I would like to thank Burt (K6OQK), Stuart (K6YAZ), and Marvin (W6OQI) for the help and advice on the HP-3336B.
Special thanks to Joe, KM1P for his help with testing and preparation for the first K5CM FMT.
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Copyright 2007 - 2013 by Connie Marshall