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?
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