[Elecraft] K2 #7340 PreAmp Problem

[Don Wilhelm]

Ray,

Check every component in the Pre-Amp circuit, including the relay.

Do you have the leads of T6 well stripped and tinned?  If so, check to 
see that the leads are in the correct holes.
After that look critically at the solder pads for those components 
around the preamp circuit - look at the schematic sheet 2 to identify 
those components.  You should see the solder flow out to an almost 
invisible edge on both the solder pad and the component lead.  It has 
been said that the esolder connection should look like a mountain, but 
not a volcano - if there is a ring around the lead or you do not have 
concave solder fillets, not enough heat was applied to the connection.

73,
Don W3FPR

On 12/24/2012 3:51 PM, Ray Spreadbury wrote:
> Hi All
>
>   
>
> I have been building this K2 taking my time and I thought I was soldering
> carefully.
>
> All has gone well so far and I have got as far as the IF amplifier alignment
> having completed VFO linearization etc with no problems and all readings
> within spec. I followed the instructions for the IF alignment including
> putting the PreAmp on but I could not hear the internally generated signal
> at 7000kHz and there was only a very low audio output.
>
> With the PreAmp off (or even with the ATT on!) the audio is much louder and
> I can then hear that signal and so I adjusted the slug in L34 for best
> signal strength with low noise. I then carried out the 40 meter band pass
> filter alignment with no problem so I am about to start the next phase -
> Assembly, Part111.
>
>   
>
> Clearly there is something wrong with my PreAmp on 40 meters however. Does
> anyone have any ideas of what I should look at or check?
>
>   
>