[Elecraft] 4 Mhz oscillator

[Bob - AG5Q]

Hi Helmut,

Such a large change in the 4MHz osc might be due to a mechanical shock
causing the trimmer cap to jump a bit.
The tuning frequency won't be affected except when you cal the PLL or BFO
but it will affect your sidetone  frequency. If you use SPOT, it would make
a station appear to be at a different frequency when its beat matches the
sidetone.  Spectrogram can be used to check the frequency of your sidetone.

I haven't noticed more than about 20Hz drift in my K2 when operating at room
temp (QRP only), so I haven't even done the BFO mod yet.

73/ Bob - AG5Q



----- Original Message -----
From: "Helmut Usbeck" <vze2gmp4@verizon.net>
To: <elecraft@mailman.qth.net>
Sent: Saturday, December 28, 2002 11:34 PM
Subject: [Elecraft] 4 Mhz oscillator


> Greetings,
>
> Having my K2/100 [2698], (yes, I am one of the unsmart ones), for about 6
> months I figured I'd go though and check alignments and some nuts and
> bolts.
>
> -K100 Q1 and Q2 needed the usual 1/4 turn tightening.  No problem.
> -K100 bias was right where it was when I first set it.
>
> -Q7 mounting screw and nut very loose, Q8 nut came off somewhere along the
> line and fell off. Thermal Stress?  Anyone else have this problem?
> Replaced and tightened same said nuts and bolts.
>
> -Always noticed that my display reading of stations being received
> seemed 50 Hz high.  I figured that the 4Mhz oscillator needed a tweak.
> I originally aligned it by the frequency counter technique described in
> the K2 manual, page 57.  Upon checking it I found it to be right on and
> hadn't changed since I originally did it. So just for kicks I checked the
> 4 Mhz oscillator and found it sitting at 3.85 Mhz. That seems to explain I
> think my high display reading.  Problem I see is if I used a counter and
> did it by the book, how come the low 4Mhz reading?  Anyone used a counter
> and have this problem?
> -L30 needed a readjustment.  Was at 5.6 volts, adjusted to required 6.0
> volts.
>
> -Being that drift checking is all the rage nowadays, I checked mine, which
> has the BFO mod and PLL mod.
>
> -BFO, drifts downward 30 Hz in 20 minutes and stays put after that.
> -PLL, drifts downward 20 Hz in 15 minutes and then settles in.
>
> -Seems to be alot less than other people's K2's.  Must be something wrong
> with mine.
>
> -Didn't do any heat tests.  Don't seem to notice any drift while
> operating.
>
> Any comments welcomed.  Especially with calibration thing.
>
> Regards,
> Helm.  WB2ADT
>
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