[Elecraft] KX1 Serial #01872

[Don Wilhelm]

Justin,

The KX1 is relatively quiet, and the sensitivity of your headphones has 
a lot to do with how much the AF gain has to be advanced before you can 
hear the noise floor of the receiver.  The important factor is not how 
loud the noise floor is, but how far above the noise floor is the signal.

Since you have a calibrated signal generator, I suggest that you can 
easily observe the signal with Spectrogram (or other audio spectrum 
analyzer) if you connect the KX1 headphone output to a computer line-in 
jack - with the KX1, I usually expect to see a -120dBm signal well above 
the noise floor on any band - some bands will show an MDS better than 
-130dBm and other bands a bit worse.

How is the transmit power on 20 compared to 40 meters.  If the 20 meter 
output is significantly lower (below 3 watts), you may want to spread 
the turns of L2 a bit to raise the LFP cutoff frequency.  The receive 
signal will also be reduced if the LPF cutoff is set too low.

73,
Don W3FPR

Justin Burket wrote:
> I managed to get my unit built up and installed in a bout 8 hours or so. 
> Everything went very well by following the check list to the letter.  I
> caught myself installing a cap in the wrong position just once but some
> quick work with a bit of solder wick took care of that.
> 
> This is just a basic KX1 with no options yet.  Alignment and testing for
> 40 meters sounds great but 20 meters I have to take my AF volume quite
> high before I hear the noise.  I could copy stations on 20 meters last
> night just fine but had to crank the AF volume pot to about 3/4 volume
> before I heard the noise floor.  Is this normal?
> 
> I took the unit to work to use some of the nicer test gear to see if it
> was simply a lack of a good tweeker.  I put a sig gen on the input with a
> carrier set at 14.100mhz @ -100dbm and was able to hear the signal just
> fine with the AF pot cranked up around 3/4 of the way.  Tweeking on the
> 20A 20B cap's I was able to get things cranked up as high as they would
> go.
> 
> Does this sound like expected behavior with the large difference between
> apparent noise level between 20M and 40M?
> 
> Thanks and 73,
> Justin KL1RL
> 
> 
> 
> 
> 
> 
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