Michael, N9BDF, wrote: 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. ;^)...
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? ------------------------------------------------- Yes, the additional heating caused by the RF power amplifier running (especially if you have a K2/100) causes additional drift. Also, even with the mods installed, there is a little drift in the BFO and PLL reference oscillators and they tend to drift such that their errors add on the higher frequency bands and cancel on the lower frequency bands. My K2 (S/N 1289) showed a drift on 15 meters (where the drift of the oscillators add to make it worst-case) of up to 240 Hz from a cold start before the mods. After the mods, I see about 50 Hz drift from a cold start for about 15 minutes or so. Then, worst case, I see up to 50 Hz additional drift if I really "hammer" the K2 at 100 watts out for a long-winded CW transmission (20 minutes or so). That's on 15 meters. On the lower bands, the drift is very close to zero, thanks to the canceling effect of the BFO and PLL reference oscillator. I believe my Reference Oscillator mod is typical. It is a "breadboard" version built out of discrete components mounted on the bottom of the main board that was used in testing the design for the production version of the circuit. It worked FB, so I never bothered to replace it with the "production" mod. Ron AC7AC _______________________________________________ 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 Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
