> Someone wrote: > Use any standard frequency transmission on any frequency ( the higher > the better).
I thought the higher frequencies were not as reliable for frequency reference due to propagation delays such as multiple hops via the ionosphere. I have seen professional calibration labs use WWVB 60 KHz for a reference. This low frequency signal normally is received via ground wave therefor has much less propagation delays. For many years I had reference to the primary frequency supply signal which the telephone network used for synchronization. I routinely calibrated my service monitor to this signal which was derived from an atomic clock synced with the NBS clock. After loosing access to this reference I built a large loop antenna and tuned it to the WWVB 60 KHz signal. Since I live about 1400 miles from this signal source I had to amplify it about 20 db to see a nice signal directly with an oscilloscope. By triggering the scope with this 60 KHz signal and displaying the test oscillator signal with the scope input the oscillator can be adjusted to synchronize with the 60 KHz reference by watching the sine wave crawl across the screen. When he displayed pattern stops moving it is on frequency. The same can be done with a dual trace scope. Reference signal on one channel with the oscillator to be test on another. Triggering can be off either channel. The displayed patterns will stay still when they are in sync. I recently calibrated an IFR-1200S with this method. I then checked it with a GPS frequency reference signal used for CDMA timing. It was dead on. Dexter, w4dex Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
