http://elecraft.85.s1.nabble.com/More-data-on-my-K2-problem-tp7630818p7630834.html
Thanks a lot Don. You nailed everything. Now working fine. I have a
20MHz TCXO (1ppm) that I use to cal check my counter. I was also tuning
> Woodie,
> In addition to your 15 and 17 meter problem (see my prior email), I
> have the following questions.
>
> Is that the maximum or minimum frequency?
> A few K2s need additional range for the capacitors around the crystal.
> If the frequency is too high, it is easy to lower it with a parallel
> low value capacitor (try 10pF).
> If that drives it in the wrong direction, you will need to reduce the
> value of C21 - try 27pF and if that is not enough try 22pF.
>
> Be certain your frequency counter is truly accurate. I can do that
> measurement with my frequency counter, but it is accurate to 10exp-9.
> If you have any doubt about that counter accuracy, use the N6KR method
> when tuned to the highest frequency WWV signal that you can receive.
> Details on this method can be seen on my webpage www.w3fpr.com -
> article on K2 frequency calibration.
>
> 73,
> Don W3FPR
>
> On 5/18/2017 8:28 PM, woody wrote:
>> Took more measurements, Ref the K2 manual (Rev C) Pg 57, 58...
>> -----------------------------------------------------------------
>> _4 MHz Osc Cal_:
>> Setting C22 with well calibrated outboard counter, the counter at TP3
>> indicated 12,096.62. As close as C22 would adjust was a K2 display of
>> 12,095.89.
>>
>> _PLL Ref Osc Range Test_
>> Ref High Freq = 12.104.37
>> Ref Low Freq = 12.08237
>>
>> _VCO Test
>> Voltage readings_ (left end R30) Note (*) that in the table below the
>> band progression still has 15M and 18M progression *reversed* (see
>> earlier, below). Also note ZERO volts at 18000 !
>>
>> 3500 - 2.06 volts
>> 7000 - 2.98
>> 10000 - 5.13
>> 14000 - 4.27
>> * 21000 - 8.22
>> * 18000 - ZERO (0.02v)
>> 24.800 - 6.82
>> 28000 - 4.74
>>
>> Hope this is some help. Thanks again, Woody
>> ------------Earlier email is below----------------
>>
>> On 5/18/2017 20:18, woody wrote:
>> Hello,
>>
>> I have an elderly K2 (S/N 02600) that had been working well. After all
>> these years, it was about 200 Hz off frequency so I proceeded to do an
>> alignment. Got it pretty close, but the trim cap (C22) would not pull
>> quite on freq. Close enough maybe...
>>
>> Proceeded with band by band alignment / peaking. All bands peaked as
>> expected except 17M, (maybe 15M too).... No change when adjusting C32
>> & C34 for 17M.
>>
>> More symptoms:
>> * Stepping up the bands is normal until going from 20M to 17M. Then:
>> 17M and 15M are reversed from normal progression.
>> e.g: 160, 80, 40, 30, 20, _*15, 17*_, 12, 10
>> * System Rx noise is significantly reduced on 17 & 15.
>> * In CW mode, the Tx freq is OK on all but 15 & 17.
>>
>> The display reads as expected on 15 & 17 - as VFO is adjusted. But, my
>> freq counter indicates the actual Tx output freq is different and does
>> not change when the display freq is changed:
>> Example... For 17, the Display indicates 18.120, the output is on
>> 18.766+-. For 15, the display indicates 21.265, the output is
>> 21.434+-. It is also receiving on the (actual but wrong) Tx freqs.
>> Changing the VFO changes the display but does not change the actual TX
>> or Rx frequency which seems to always be the same.
>>
>> I am stumped!!! Can you offer any suggestions as to what might be
>> happening???
>>
>> Thanks,
>> Woody, KZ4AK (Formerly WB4QXE)
>>
>
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