[Elecraft] Questions about crystal replacement in K2 and SB board

[Don Brown]

Hi

The X5-X11 and the SSB crystals are all the same and a matched set. X3-X4
are different even though they are the same frequency. They are series mode
crystals while the others are parallel mode.

Some of the earlier reference oscillator crystals would not pull enough with
one crystal so 2 in parallel were used to de-Q each other so the varactors
could change the frequency enough. The newer crystals have been selected to
have enough range with only one crystal giving the benefit of much reduced
drift in the reference oscillator thus the VFO drift is reduced by more than
50%

The change of the BFO toroid reduces the BFO drift but two crystals are
required to get enough range in the BFO that is why X3 and X4 are in
parallel.

Don Brown
KD5NDB


----- Original Message -----
From: "Todd Gahagan" <tgahagan@imt.net>
To: <elecraft@mailman.qth.net>
Sent: Thursday, January 02, 2003 9:34 AM
Subject: [Elecraft] Questions about crystal replacement in K2 and SB board


> In the process of doing all the mods here (must be what its like to do
brain
> surgery on your own child) and have now reached the point where I need to
> swap out the crystals.  Guess I'll risk showing my ignorance but wanted to
> make sure that in the K2 this means replacing x5-x11 and not x3 and x4?
> Also, replace all the crystals on the SSB board.  From what I can tell it
> now looks like Elecraft recommends using two grounds for each crystal and
> grounding them near the base??
>
> One other question:  Why are we able to go to only one PLL crystal (X1)
> instead of the original 2?
>
> Thanks, Todd