[Elecraft] KX1 receive problem

[Don Wilhelm]

Joe,

The first thing I can say is that you should check your soldering - it
sounds like the entire receive chain has lower than normal gain, and things
before the Mixer are likely OK since you can peak the tuned circuits.  Check
the DDS and BFO injection levels to the Product Detector and the Mixer -
they shoud be 200 mV peak to peak or greater if the mixers are to function
properly (70 mV or greater if measured with an RF Probe).

The first most likely problem is soldering - check each solder connection
carefully, even to the point of re-flowing every solder connection.  If the
solder looks like 'balls' on the component leads, there was not enough heat
provided to the solder pads.  It seems some builders fear applying too much
heat to the solder connections for fear of damaging components - the fact is
that modern components can withstand high soldering temperatures for short
times, and too low a soldering temperature WILL damage components because it
takes too long to make a good solder connection and the joint 'heat-soaks'
for an extended time.  If you cannot accomplish a good smooth solder flow in
2 to 3 seconds, your soldering temperature is too low.  Use a heat of 650 to
700 degrees F for good results.  A good solder joint has solder tapering out
to a thin edge on both the solder pad and the component lead - also be
careful of too much solder which can create solder bridges to adjacent
leads, this is a case where more is NOT better.

The other common problem is a misplaced component.  Did all the components
comae out 'right' when you were finished building, or did you have something
either left over or an incorrect value on your hands toward the end - either
of these things is an indicator that you have a wrong component somewhere.

Bottom line, check the soldering, then re-check the soldering, and when you
have finished that, check the soldering - that is the most common problem
encountered when something does not work properly.  Have someone else check
over your soldering if possible, often another pair of eyes can spot
something wrong that you have continuously overlooked.

Component placement ranks second among the problems encountered in kit
building, right up there with improperly stripped and tinned toroid leads,
although inproperly tinned toroid leads could be classified as soldering
failures if one wants to get 'picky'.


73,
Don W3FPR


> -----Original Message-----
>
> HI!  I am building my KX1, and have gotten to the receiver
> alignment stage.
> I am using an XG1 for my signal source on 40M and the 50uv S9 signal is
> audible and I can get a good peak on the 40m trimmer, but it
> isn't as strong
> as an S9 should be.  When the XG1 is in the 1uv position, I don't
> hear it at
> all.  On 20M, I used an antenna, and I couldn't hear anything at all, but
> barely heard the XG1's harmonic on 14.080 and was able to peak
> the trimmers,
> but signal was very low.   Any suggestions??
> 73, de KØNEB
> Joe
>