Hi all, The KX3's standard VFO temperature compensation is adequate for nearly all operating modes. However, JT65 and some other narrowband digital modes can benefit from better tracking with temperature, especially on the highest bands.
I have a new revision of KX3 field-test firmware available that can meet this requirement. It includes a "custom" VFO temperature compensation feature that accurately matches the temperature/frequency curve to each individual radio. After performing the calibration procedure, long-term (key-down) VFO frequency change can be as low as about +/- 2 Hz on 20 meters. There's a catch, however: You'll need a very stable signal source that can provide an RF carrier on about 50.1 MHz, at a level of S8 to S9+20 dB. A temperature-stabilized or reference-locked signal generator is preferred, although a ham-band transceiver covering 6 meters can be used, assuming it can be keyed for 15 to 20 minutes at low power output without appreciable drift. (One tester successfully used a K3 as the signal source.) The procedure takes about half an hour to complete. I still consider it experimental, but if you're a serious JT65 operator and don't mind putting in the effort, I'll be happy to send you the new firmware and instructions. One other important note to those considering JT65 and other modes where key-down times can be very long: You may need to keep power output level down to 3 watts or lower. (Modes like CW and SSB have a far lower duty cycle and can be used at up to 12 watts.) The maximum sustainable JT65 power level can be determined by experimentation. 73, Wayne N6KR ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
