Once we determined that the problem was probably particular to my unit, I ran the synthesizer calibration as Joe suggested - but to no improvement (wait, there's more - Joe was on the right track). So I called Dale Farmer who had me display the PLL voltages (tap "DISP" button and then turn VFO-B) which read "PLL 1*7.4" while I was tuned to the range in question - an indication of a PLL problem. Dale said that normal PLL voltages were in the 0.7 or 1.0 to 6.5 Volt range. He suggested that I rerun the synthesizer calibration with the tighter manufacturing tolerances (tap "8" as explained on page 61 of the manual). This fixed the problem, but running the calibration a second time brought the problem back. Clearly we were on the edge of some tolerance here. Oddly, the calibration routine never indicated any error message.
Here comes the fun part. Dale suggested that I "massage" the toroid on the synthesizer board. This consisted of removing the plastic bolt and ferrite cover (making sure not to drop the brittle ferrite) and then making sure the bifilar windings were properly spaced and that the third winding (gold wire with only three turns) was up against the bifilar windings. Dale indicated that this needed to be done to some of the boards in the production process. Having done that and after reassembling the toroid cover and rerunning the synthesizer calibration, the problem was reliably fixed. Thanks to Joe and all who responded. I know I learned something and I hope by writing this up, anyone else who has this problem can benefit. Bob, N7ZO -----Original Message----- From: Joe Planisky [mailto:[email protected]] Sent: Monday, October 11, 2010 4:13 AM To: Wright, Robert Cc: [email protected] Subject: Re: [Elecraft] [K3] Tuning problem from 1485 to 1585 kHz (AM broadcast) Hi Bob. Try rerunning the synthesizer calibration procedure as described in the "Calibration Procedures" section of the manual (page 49 in the D5 revision). 73 -- Joe KB8AP On Oct 10, 2010, at 9:38 PM, Wright, Robert wrote: > I was DXing the AM broadcast band tonight with my K3 when I noticed > that > the received frequency stopped moving as I tuned from 1485 to 1585 > kHz. > The dial frequency (VFO-A) continues to change but the received signal > does not change. This seems to happen in both AM and SSB modes. Has > anyone else noticed this or is this a problem unique to my K3? > ... > > > Bob, N7ZO ______________________________________________________________ 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
