[Elecraft] [K2] VCO Not Oscillating

[Don Wilhelm]

Joseph,

Yes, leads 1 and 3 should be coming out of the top of the core, but the 
leads must look like the illustration on page 56 of the manual, the 
green wires must not cross over each other, but be wound between the red 
wires.

You can check with the internal counter probe or the RF Probe to see if 
the VCO is oscillating.  Make certain that the leads of T5 have been 
well stripped and tinned before inserting and soldering the leads.
If you look at the solder connections and see a ring around the toroid 
lead, it was not well tinned and soldered.  In other words, the 
connection should "look like a mountain, but not a volcano".

73,
Don W3FPR

On 4/28/2014 9:56 PM, Joseph Baxley via Elecraft wrote:
> Don,
>
> Thanks for the reply.  I should have mentioned that I checked the windings on T5.  Pins 1 and 3 should be coming out of the top of the core, no?  That's what I have.  I also used the yellow core for the transformer.
>
> Thanks,
> Joseph
> On Monday, April 28, 2014 8:43 PM, Don Wilhelm-4 [via Elecraft] <ml-node+s365791n7588092h87 at n2.nabble.com> wrote:
>   
> Joseph,
>
> The first thing to check is T5.  The direction of the windings is
> critical, and the leads must be in the proper holes as shown in the
> diagrams in the manual.  In other words, the sense (direction) of the
> green wire turns on T5 must be the same as the direction of the red wire
> winding.
>
> If that is correct, the VCO will oscillate, and things usually fall
> 'into line' after that once L30 is adjusted for the proper voltage at
> the left end of R30.
>
>