[Elecraft] [K2] No signal at TP1 during Alignment and Test Part 2

[Don Wilhelm]

Robert,

Those voltages say the VFO is oscillating, but the DC voltage at the 
gate of Q18 indicates that either your DMM is dragging the voltage to a 
low level, or the oscillation is weak.  If that is true, T5 is OK.

I would suggest that you build up the RF Probe - parts are supplied with 
your K2 kit.
Then go to Appendix E of the K2 manual and do the checks shown on pages 
10 and the first part of page 11.  If you have an oscilloscope with a 
10X probe, do the same checks but the peak to peak voltage should be 2.8 
times the expected RMS voltages.

As always with new kits, check the soldering.  Inadequate heat to flow 
the solder is a common source of failure to have circuits work 
correctly.  Also check the value of components in the VFO circuit. I 
have repaired K2s where the only problem is that the builder did not 
identify the correct capacitors.  For instance, C68 must be a 10pF 
capacitor.  There is a 1pF capacitor in the kit which is marked 1D and 
can at first glance be interpreted as "10".

73,
Don W3FPR

On 6/8/2017 10:20 PM, Robert Forster wrote:
> Hi Don and Group,
>
> I got a bit of time to troubleshoot this evening.
>
> I do have a good signal at TP3 so I am ignoring the PLL and U4.
>
> I did the DC measurements at Q18 and found some issues.
>
> the gate shows as a negative polarity but at -.001 volts
> Source is .08
> Drain is at 6.8
>
> This should lead me to suspect T5 correct?
> the soldering on the underside of the board for T5 looks ok (no ring 
> for these points but the topside of the board looks rough!  I used the 
> USB microscope and took some photos.
> Here: https://flic.kr/s/aHsm2aNdeG
>
>