[Elecraft] K2 Ser 6160 lives but............

[Don Wilhelm]

Denis,

Your 12/10 meter problem will likely be found either in the Low Pass 
Filter or the Bandpass filter area.  Look for an improper component 
value or a bad solder connection.

Your audio problem (and sidetone) sound suspiciously like bad solder 
connections.  Check the Control Board over carefully (and don't forget 
the connectors on the RF Board that the control board and front panel 
plug into).  Nothing that was added after the 40 meter receive test 
would have changed the AF Gain or the sidetone operation.

Warning - My periodic soldering rant follows:
Be very critical of your own soldering because that is where most faults 
can be found.  Look for how the solder flowed out onto the edge of the 
solder pad - if the solder did not flow out to an almost invisible edge, 
either too much solder was applied, or the solder pad did not receive 
adequate heat during the construction.  Too much solder can hide a poor 
solder connection too, so if you have a large mound of solder on the 
pads, you are well advised to remove it with solder wick.  Only enough 
solder to fill the thru-plated holes is sufficient.

A few soldering guidelines: - use an iron temperature between 650 and 
750 degrees F (344 to 400 degrees C) - apply only the minimum amount of 
solder required, enough to fill the thru-plated holes, but if you desire 
to see a small fillet, use a very small extra amount. - watch for the 
solder to flow while you are working, it should flow out to a thin 
invisible edge on both the solder pad and the component lead when 
everything has reached an adequate temperature.  If the solder 
connection looks more like a ball (with a convex surface), you have too 
much solder already, remove some with solder wick.  A solder fillet will 
have a concave shape if everything was adequately heated.

73,
Don W3FPR


Denis Jackson wrote:
> alas it has a few problems.
>
> First one is that there is no tx on 12m/10m.  All other bands are fine so I guess I need to start signal tracing.
>
> Second one is a bit more unusual though.  The AF Gain control has stopped working - it does not alter the audio level at all.  This was working properly when the 40m only rx was tested earlier in construction.
>
> Third one is that the side-tone has become totally distorted - it's now just a "buzz".  Perhaps linked to the af gain issue as it too was OK at the 40m rx testing stage.
>
>