Re: [Elecraft] [K2] CAL FIL Temperature Sensitivity Question
Fixed! A year of looking at solder joints, and flowing a few, did not fix the problem. I recently ordered and replaced L33 and the two BFO crystals. The three parts fixed the problem! Replaced L33 so that I did not need to worry about breaking the fine wires when removing the old one. John KN5L On 07/24/2013 10:59 AM, John Oppenheimer wrote: > My K2 has a 100 Hz difference in CAL FIL frequencies between cold and > full warm up. __ 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 Message delivered to arch...@mail-archive.com
Re: [Elecraft] [K2] CAL FIL Temperature Sensitivity Question
Performed another test today, last night I aligned 200 Hz CW normal to 04913.08, First power up this afternoon 04913.21, after one hour warm up (no transmitting) 04913.10. John KN5L On 07/24/2013 12:39 PM, John Oppenheimer wrote: > Hi Don, > > My question is directed specifically at the CAL FIL BFO frequency being > 100 Hz different between cold and warm. As mentioned, because the BFO > frequency is off by 100 Hz, the 200 HZ filter is unusable because a > properly received pitch will place the signal on the filter skirt. > > This K2 serial number is above 7K > > The test is: Multi hour warm up, enter CAL FIL, measure and record a > filter BFO frequency. Next morning, cold start, perform same measurement > as above and compare the difference between the two BFO readings. > > John KN5L > __ > 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 > __ 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
Re: [Elecraft] [K2] CAL FIL Temperature Sensitivity Question
Hi Don, My question is directed specifically at the CAL FIL BFO frequency being 100 Hz different between cold and warm. As mentioned, because the BFO frequency is off by 100 Hz, the 200 HZ filter is unusable because a properly received pitch will place the signal on the filter skirt. This K2 serial number is above 7K The test is: Multi hour warm up, enter CAL FIL, measure and record a filter BFO frequency. Next morning, cold start, perform same measurement as above and compare the difference between the two BFO readings. John KN5L __ 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
Re: [Elecraft] [K2] CAL FIL Temperature Sensitivity Question
John, The specified stability for the K2 is less than a 100 Hz drift from a cold start at 25 degC, so your K2 is within the specification (granted it is just on the border). The drift will usually be worse for a K2 with the KPA100 installed than a basic K2 because there is more heat generated in the enclosure and less air volume present to disperse it in.. That is a 'cure' -- Is the serial number of your K2 less than 3446? That is when the PLL Temperature Stability change (Thermistor Mod) became available. If you have a K2 below SN 3000 that has been upgraded, than that mod was likely installed with the upgrade. Examine the K2 RF board toward the left side near the front - if there is a small board sitting vertically in the RP3 location, the mod has been installed. You may have to remove the KDSP2 option to see it. If your K2 does not have it, a kit to install that thermistor mod is available from Elecraft - PN E850138. If you do have that mod installed, the installation instructions for that mod have guidelines for advanced builders about altering the value of RA to achieve better drift compensation for your K2. You can download those instructions from http://www.elecraft.com/manual/PLL%20upgrade%20rev%20C.pdf. Note that the information about altering the RA value does not appear in the K2 manual, and is intended only for those advanced builders who have good capability for properly measuring the drift that results after changing RA. It may take some experimenting to find the right value for your K2.. 73, Don W3FPR On 7/24/2013 11:59 AM, John Oppenheimer wrote: My K2 has a 100 Hz difference in CAL FIL frequencies between cold and full warm up. The 100 Hz difference renders the 200 Hz BW unusable until the K2 warms up. Is this typical, or do I have a component with excessive temperature instability? John KN5L __ 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
