Guys, I'm curious what is the max front panel temp you're seeing after a period of operating with significant transmit time? Also what is the room temp at this value.
The reason I ask has to do with the K3 Master Oscillator calibration procedure and later drift. A detailed set of measurements with a stock K3 indicates a good correlation of drift with front panel temperature. With the standard oscillator, measurements indicate that the K3 drifts about -1.2 Hz/C (.12ppm/C) degree at 10 MHz. Here a Rb 10MHz secondary frequency standard was used as well as a counter to measure how the audio tone changes vs time. This allows sub Hz changes to be observed. Normally one does the calibration receive only. In that case with an ambient temp of 24C here, the front panel temp rises 34 C after 90 minutes. I normally calibrate after such a warmup. If the front panel temp rises another 10C after periods of transmit, the frequency could be off by about -12 Hz at 10 MHz (-60 Hz at 50 MHz). Sure that's not a lot. But it says, perhaps one shouldn't knock themselves off trying to be super accurate with the calibration. There will be another couple or perhaps as much another 10 Hz (1ppm) error due to transmiter heat buildup. The actual amount can probably never be predicted. It is clear to me if one "needs" more accuracy, the high precision oscillator option and/or locking to an external reference would be needed. I'd love to look at the high stability oscillator drift as well. However, satisfying that curiosity for $100 isn't going to happen. Perhaps someone out there with the high stability oscillator could repeat the above measurements and report the results. 73 de Brian/K3KO ----- No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1388 / Virus Database: 1516/3733 - Release Date: 06/29/11 ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
