kx1 20 meter oscillation

[Rick Dwight]

Stan,

   Before you conclude you have an oscillation on 20 meters, please make
sure you are actually correctly sampling the actual output of the kx1 from
the BNC antenna jack and not picking up stray signals radiated from the
interior of the kx1, especially if its cover is removed.  Sometimes the kx1
waveform as viewed on a oscilloscope or spectrum analyzer looks much better
if correctly sampled.  Put the cover on the kx1 and ground the case.  Run it
into a dummy load through a coax cable and a T connector.  One way to sample
the actual signal is to put a piece of insulated wire into the t connector
(no direct electrical connection) and run this short wire and a ground to a
variable or fixed pad and adjust the coupling and pad to provide a
reasonable signal into your monitor receiver (say something less than about
S9 + 20 db.  

    I have also coupled a small signal to an outdoor antenna through a T
connector, insulated wire & dummy load, then hooked my receiver to another
outdoor coax fed antenna.even if it is not a 20 meter antenna, possibly
through a pad and/or receiver attenuator, and have had a good (reasonable
level) signal to monitor.  There are also RF sample circuits and special
pads (possibly around 100dB ?)  which provide the attenuation to safely and
correctly sample the transmitter RF, which are probably not necessary unless
you want to set up an actual means of measuring levels.  

   Please be very careful not to couple too much signal into your K3.
Probably you will need only a small amount of capacitive coupling into the T
connector and can use a considerable amount of padding (try 20 to 40dB or
more).  Signal levels into a receiver of > +10 dBm could potentially damage
a receiver.  

   Rick  KL7CW   KX1 # 798    Palmer Alaska

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[Stan Gibbs, KR7C]

Rick,

Thanks for your words of caution. I understand the issues and have tried to be very careful not to overload my K3.  The KX1 signals on my P3 have been in the S9 region.  Typically, I was driving a dummy load with my KX1 while my K3 was sampling my dipoles outside, about 30 feet above my shack location.  I don't plan to chase this goose any more at this time, but I will try to run an experiment by taking my KX1 way out of the near field of my antennas and see if there is any change to the spectrum on the K3/P3.