ARRL contest 2000

This page shows two screen dumps from the ARRL contest 2000.
The dumps are taken directly with the computer connected to
the antenna so data collecting is disabled during key down.
(Dumps taken from the DAT recordings show nothing during
transmit because the tx signal is not muted)

On these screen dumps the usefullness of a PIN diode switch
is demonstrated although, of course two PIN switches would
have been better to retain sensitivity at the polarisation
not used by the tx.

The antenna used is a 2SA13X, a cross yagi with 13 elements
on 8.35 meter boom length providing a gain figure of 14.5 dBd.

The first image was captured at about 0305UT on november
18 2000.

The curser is placed at 10.1kHz on the audio scale.
The center frequency is 144.030kHz, the DSP program
controls a direct digital synthetiser via the parallel port.
The curser is at 144029052 Hz. (The DDS is controlled by
a quite good reference oscillator)

The screen covers nearly 8 minutes and shows my contact with
RA4AOR 0300 to 0306UT.
The signals from RA4AOR and my own echoes are visible below
the cursor.

At 13.2kHz audio 4U1ITU is visible with two stations calling
about 1.5kHz up (one of them out of sequence).

The horisontal structure at the bottom is my tx in tune mode
when moving away from 4U1ITU who I worked immediately before.

The first screen is typical for operation on a single 2SA13X
at high elevation. The strongest spur is about 20dB above
the noise but there are not many spurs.



As a contrast to the nice looking image above, the screen below
is dumped with the moon about 5 degrees above horizon.
There is computer interference from my neighbours but UA4AAV
and 7K3LGC are easily copied around 6kHz audio at less than
1 dB degraded S/N.

The curser at 18.2 audio (144.037233) is locked at SM3PWM
who arrives at nearly vertical polarisation. I have here
called him with vertical polarisation to arrive as
a horisontal wave at his location.
My own echo is weak because it arrives as a horisontal wave
at my location also.
The ground wave of SM3PWM is visible about 200Hz below the
moon echo.