[Elecraft] K2 Tuning 'glitches' every 5 Khz

[Brendan Minish]

Sorry about the delay in getting back with my results

I have measured the PLL reference oscillator tuning range on the internal 
counter

it goes from 12091.08 Khz to 12100.64 Khz

during normal dial tuning we go from 12095.02 to 12100.08

there is no 'gaps' in the tuning range and other than the glitch when 
crossing 5 Khz boundaries there are no other problems at the boundary 
points such as pitch jumps etc.

Could I simply be hearing the PLL regaining lock following the PLL 
reference oscillator change ?

the glitch is always audible when a signal is present, even when there is 
just one weak signal (rig connected to a sig gen @ -120 Dbm )

do I learn to live with this as it's not really a big deal or should I try 
with the other PLL xtal I have from the mod?


73
Brendan EI6IZ


At 13:20 23/02/2003 -0800, Ron D'Eau Claire wrote:
>How's the tuning range of the PLL Reference Oscillator?
>
>The PLL Reference Oscillator is a VXO whose frequency is "pulled" over 5
>kHz to provide the continuous tuning in between the 5 kHz steps of the
>Phase Locked Loop.
>
>I thought it was interesting that the Stability Mod kit instructions did
>NOT include a check of the PLL Reference oscillator after you pull the
>two crystals originally used out and install the single new crystal. Two
>crystals were originally used to be sure there was adequate tuning
>range. The "stability" mod replaces them with one crystal that SHOULD
>have adequate tuning range, but I noticed that there was no actual test
>of this range in the instructions. Apparently, someone thought that it
>was not needed, but it sounds as if yours does not have adequate tuning
>range and so it is "jumping" near the end of its range.
>
>Instructions for checking the PLL Reference oscillator tuning - and for
>making adjustments to get the range right - are in your original
>assembly manual under "Alignment and Test - Part II" That's on Page 57
>of my (Rev C) version of the manual. You want to do "PLL Reference
>Oscillator Range Test" and "VCO Alignment". Note: SKIP the 4 MHz
>oscillator alignment unless you are unhappy with your dial calibration.
>It won't affect the PLL Reference Oscillator operation.
>
>There's more hints under "Troubleshooting" section 030, in Appendix E -
>Troubleshooting (on Page 3 of the appendix in my Rev C version of the
>book).
>
>It's possible that you have a "bad" crystal that doesn't have adequate
>tuning range. Contact Elecraft if the tests you run according to the
>above instructions do not provide you with  the frequency range needed.
>
>Ron AC7AC
>K2 # 1289
>
>-----Original Message-----
>My K2 has little glitches every 5 Khz, these are not terrible by any
>means
>but are irritating when tuning around.
>
>I suspect that these are only present since I carried out the stability
>mods
>
>I have rerun CAL VFO but this has not gotten rid of the glitches any
>ideas on how to get rid of the glitches ? 73 Brendan EI6IZ (K2/100 1642
>)