KX1 Weak Audio on 20M

[Martin Gillen]

Hi, Mike.

You're right.  This is normal behaviour for the KX1.

The S meter is lower on 20m because it driven by an
audio derived AGC, and audio levels are lower on 20m
due to the design of the radio.
 
It does work though... with a 20-40 foot wire
vertically in a tree, in good solar conditions, around

6pm in the evening you should see the S meter pegged
to
max for quite a few of the stronger signals, but the
weak or medium ones will not cause any S meter
indication.

I find at other times or on my 10ft indoor RX antenna,

because signals are weaker, the S meter does not
usually show any LED segments for any signals on 20M.

Have you calibrated the S meter?  I have mine
calibrated so that background atmospheric noise on 40m
causes the first LED segment to flicker.  On 20m/30m
there is usually no LED segments lit when there is no
signal, and on 20m it takes a fairly strong signal to
light any segments.

My LED menu settings are:

  H 3
  L 75

For comparison.

Don't forget to perform the S meter calibration on
your "real" antenna not just with 10ft wire connected
in the shack ;)

The receiver sensitivity is fine though as you pointed
out.  I have had most of my contacts on 20m and even
to the Azores Island (8,500 km per watt!).

Using earbuds over standard earphones helps because
they limit the external noise due to the fact that
they
fit tightly into the ear canal.

Some people have suggested using earbuds with a
greater sensetivity rating.  I have Sony MDR-E848
earbuds which have a sensetivity of 108 dB/mW and
a pair or earphones (not earbuds) with a 117 dB/mW
rating.  I can hear no difference, I need to max out
the AF gain on 20m for both.

There is a behaviour of the KX1 which you will also
discover.  Very strong signals cause a weak "mirror
image" of the signal on the other side of the carrier
frequency.  I'll explain what I mean:

For a weak or moderate signal as you tune the radio
you will hear the signal start high in pitch and get
lower or start low in pitch and get higher depending
on the tuning direction.  Once the signal is either
too high or too low in frequency that it is outside
the
receiever's passband you will not hear the signal
again
if you continue tuning in that direction.

For a strong signal however if you tune in the
direction that the signal goes from high pitch to low
pitch, and continue tuning after the signal is no
longer audible you will hear the signal again but
much weaker, rising in pitch (while all the other
signals are lowering in pitch).

This is an indication of a very strong signal!

Martin.
VA3SIE/QRP/P.






       
       
               
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