G'day,
Time flies, I didn't realise it was so long since this was posted.
Regards,
Mike VP8NO
----- Original Message -----
From: "KEN BROWN" <
[hidden email]>
To: <
[hidden email]>
| From: "John, KI6WX" <
[hidden email]>
| Date: Sun, 24 Aug 2003 20:51:50 -0700
| Subject: [Elecraft] 4 MHz Oscillator Mod for Easier Adjustment
| The reflector traffic seems to indicate that some folks are having
| trouble
| setting their 4 MHz oscillator to the desired frequency. I added the
| following changes to my K2 4 MHz oscillator about 2 years ago to
improve
| both its settability and its frequency stability. The mod increases the
| bandspread of C22 and significantly reduces the drift in the oscillator.
| The drift reduction will only effect the K2 frequency accuracy if you do
| a
| CAL PLL at a different temperature than when you first set the 4 MHz
| oscillator frequency. I haven't tested this change on any other K2 so I
| don't know if it will work for all 4 MHz Xtals.
|
| The change requires two 10pF N750 capacitors. Replace C21 with one of
| the
| 10pF capacitors. Solder the other 10pF capacitor across X2, the 4 MHz
| Xtal.
| With this change, the correct frequency is obtained with C22 in about
the
| middle of its range. If you don't need the frequency stability
| improvement,
| you can use 10pF NPO capacitors.
|
| If this change doesn't work in your K2, it can easily be backed out by
| removing both capacitors and re-installing the original C21.
|
| -John
| KI6WX
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