[Elecraft] XV222 Local Oscillator

[Matt Osborn]

On Fri, 24 Mar 2006 14:53:26 -0800, "Ron D'Eau Claire"
<rondec at easystreet.com> wrote:

>Matt asked:
>
>The local oscillator on the XV222 will not generate a sufficient signal
>level. The voltage measured at TP1 is 0.45VDC.
>
>When first tested, TP1 read 0VDC. Seeing posts about a balky oscillator
>being sensitive to L4A,  I adjusted the slug while watching at TP1.  Sure
>enough, as the slug was adjusted, TP1 rose from 0VDC to 4.5VDC and then
>started back toward 0VDC as I continued to turn the slug into L4A.
>
>I backed out the slug until TP1 read its maximum of 0.45VDC and then
>continued out until the voltage at TP1 returned to 0VDC.
>
>When oscillating, the frequency measures at 193.995, which is well within
>the accuracy of my frequency counter.
>
>I checked all components and voltages at Q1 & Q2, everything was correct.
>
>I'm sure there are some clues buried in the above observations, but I'm
>unable to sort them out.  Does anyone have any clue as to how I get the
>voltage at TP1 up over 1.0VDC?
>
>---------------------------
>
>Is the local oscillator transistor mounted up off the board with a Teflon
>spacer on one lead as shown in the assembly manual? 
>

Hi Ron,

Yes, Q1 is mounted 3/8" high with the teflon spacer.  I was thinking
that the crystal is OK because it oscillates at the correct frequency.

How critical is the MPS 918?  Could I substitute a 2N2222  in place of
Q1 just to check out the operation of Q2 (BFR96)?  Is that a sensible
thing to do?