I'm trying to understand a bit more about temperature-related VFO drift in the K2. My K2 sits in the basement where it is currently seeing stable ambient temperatures around 67F. When using 10 MHz WWV as a reference, I see approximately 40 Hz of drift (10,000.03 to 9,999.99) over a 30 to 45 minute period from a cold start. I am not transmitting during this period, I assume this is just due to a slight heating (can't be much of a temperature change) of various resistors, capacitors, inductors, and varactors. This is clearly in-specification as it is much less than the 100 Hz that is specified in the manual. ;^) My K2 is serial number 4137, so it has had the Temperature-Compensated PLL Reference Upgrade from the start. The Temperature-Compensated PLL Reference Upgrade documentation says that you can check the VFO drift by transmitting for a while to raise the temperature of the radio 15 or 30 degrees F _AFTER_ you have allowed a warm-up period of 30 or more minutes. This appears to infer that there is a difference in the nature between warm-up drift and post warm-up drift. If so, can someone explain what that difference is? I haven't performed the formal post warm-up drift testing, but I plan to give it a try to see how stable the VFO is after warm-up. This raises another question... Will making any changes to resistor RA on the PLL thermistor board have any affect on the 40 Hz of warm-up drift (as opposed to the post warm-up drift), or is this something that can't really be addressed by the Temperature-Compensated PLL Reference circuit? Thanks, Michael N9BDF PS It was nice to see that resistor RA was placed at the top of the PLL thermistor board -- makes it much easier to fine tune the temperature compensation! :^) _______________________________________________ Elecraft mailing list Post to: [email protected] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft
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