Elecraft P3 High-Performance Panadapter Manual - Manual (Page 20)

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right edges of the display, in terms of their offset
from the center. Usually, the VFO A frequency is
at the center of the P3 display unless you have
offset it with the P3's
C E N T E R
control. The
display can be re-centered at any time by holding
the
C E N T E R
key while already in center-frequency
mode, which can be accomplished by holding the
C E N T E R
control twice.
In fixed-tune mode the frequencies on the P3
display stay fixed as you tune VFO A. The VFO A
cursor moves across the screen instead of always
being at the same position, as it is in tracking mode.
You can toggle between fixed-tune and tracking
modes via MENU:FixTrack. Fixed-tune mode is
only available with the K3 transceiver.
The three frequency labels at the top of the screen
have different meanings than they do in tracking
mode. The one at the center is always the VFO A
frequency, even when it is not at the center of the
display. The labels at the top left and right are the
actual RF frequencies that correspond to the left and
right edges of the display, rather than the frequency
offsets from the center.
If you tune VFO A past the left or right edge of the
screen, one of four things can happen depending on
the MENU:FixMode selection. If the mode is set to
"Full" then the center frequency jumps up or down
one full screen width whenever you tune past an
edge so as to keep the VFO A cursor on the screen.
If the mode is "Half", the center frequency jumps
one-half screen width. In "Slide" mode, it moves
the minimum amount necessary to keep the cursor
on the screen. In "Static" mode, the center
frequency is truly fixed; the VFO A cursor is
allowed to disappear off-screen. In both tracking
and fixed-tune modes, whenever either the VFO A
or VFO B cursor is tuned off-screen, a small arrow
at the bottom left or right of the display points in
the direction of the missing cursor. The arrow color
matches the cursor color.
When you switch between tracking and fixed-tune
mode, the span stays the same. The center
frequency also stays the same when switching from
tracking to fixed-tune mode, but defaults to the
VFO A frequency when going from fixed-tune to
tracking mode. In either mode, the center
frequency and span can be adjusted using the
C E N T E R
and
S P AN
keys (unless the
C E N T E R
key has been disabled for tracking mode with
MENU:CenterEn).
The selection of fixed-tune or tracking mode is
global, that is, it is the same on all bands and it is
remembered when cycling power. In fixed-tune
mode, the center frequency and span are stored in
non-volatile memory per band. When changing
bands or when turning on power, the last values
used on that band are remembered, unless that
would put the VFO A cursor off-screen, in which
case the display is re-centered on VFO A. The only
exception is Static mode, where the only way to
change the center frequency or span while fixed-
tune mode is in effect is to adjust the
C E N T E R
or
S P AN
keys.
Typical Spectra
Below is a typical screen shot of the 40 meter band
during the day. At the center is a weak CW signal
that was inaudible on the K3 transceiver during
fades. It is hard to see on the spectrum display at the
top but is clearly visible on the waterfall. Just to the
right of that is a strong interfering carrier. At the far
right is another steady carrier and just to the left of
that is a spurious emission, probably from a
switching power supply, that is wavering back and
forth in frequency. A panadapter is a powerful tool
for tracking down interference.
This is another example of interference, this time
from a LAN router. The QRM includes both
wideband noise as well as discrete carriers and is
constantly heaving and writhing as the processor in
the router executes different portions of its software
routines.