ARRL 160-Meter Contest
Call: K1LT
Operator(s): K1LT
Station: K1LT
Class: Single Op HP
QTH: Ohio EM89ps
Operating Time (hrs): 28
Summary:
Total: QSOs = 1417 Sections = 79 Countries = 23 Total Score = 309,570
Club: Mad River Radio Club
Comments:
During the Stew Perry TBDC Warmup I tried out the idea of feeding
multiple receivers to each ear using a wiring kludge. The idea
worked, although control was awkward because it was a kludge. So
before the CQ WW CW contest I built a more serious audio mixer that
could be controlled from a computer over a USB connection. The
intention was for the controlling computer to have a touch screen.
During the run-up to the CQ WW CW I made the audio mixer and switching
gadget into an SO2R controller, since to do so only requires a couple
of extra transistors and some more software. So the development of
the touch screen interface was delayed.
After the CQ WW CW was over, I got back to finishing the audio mixer
and switching gadget. Also, the day before the contest I realized I
had forgotten to arrange for the phased array receiving system
(antennas and receiver are thoroughly integrated) to deliver 4
channels instead of just two. So there was a mad scramble to rectify
this error. Making the software work consumed enough time that I
didn't get to test the audio mixing in real conditions. Its just
mixing to audio signals together, what could go wrong?
At the start of the contest, I had this collection of antennas,
receivers, and audio streams:
1. 4x2 phased array "east" delivering 2 steerable beams: one for
each
ear. Bearings from roughly 30 to 150 degrees are preferred,
although any direction is available.
2. 3x2 phased array "west" delivering 2 steerable beams: one for
each
ear. Bearings from roughly 210 to 360 degrees are preferred,
although any direction is available.
3. K3 and 12 Beverages, every 30 degrees in varying lengths, two at a
time, one for each ear.
Also at the start of the contest, I had an unresolved new noise from
the south west. This noise, which sounds like arcing cycles on for 20
seconds (taking 5 seconds to reach full strength) and then abruptly
goes off and stays quiet for 60 seconds. Then the cycle repeats.
This happens no-stop from dusk to dawn. Early in the season, the on
period was about 35 seconds, with about 60 seconds of off. I am not
able to hear this noise so far on my portable equipment. The 4x2
array hears the noise more prominently than the 3x2 array, so maybe
the noise is extremely close by. The noise raises the noise floor by
more than 20 db.
As the contest commenced, the received audio from strong stations
sounded very fluttery, somewhat like Aurora. My own transmitted
signal sounded the same way on the SDR receivers. Weaker signals
sounded normal, and each appeared in the appropriate ear as determined
by the beam steering. So in between making contacts at 120 per hour
for the first few hours, I though about why this distortion was
present and what to do about it.
One of the tutorials about setting up SO2R suggests that an operator is
ready to consider SO2R operation when they can watch TV while
contesting. Does debugging software while running stations count?
I'm sure I sounded like a lid trying to manipulate a code editor at
the same time as switching antennas around and pushing message buttons.
To make a long story slightly less long, the audio mixing as a strategy
was working but the sound was terribly distorted which interfered with
understanding strong signals, After a couple of hours I turned off
some channels and reverted to manual switching of 2 channels at a time.
Also, the 2 touch screens I tried were too slow to be usable. I
finally settled on just mousing around the logging screen.
Around 0510Z while trying to deploy the first attempt at fixing the
audio distortion, the power went off (with considerable blinking and
clacking). I sat there in the glow of the monitors (UPS on all the
computers) wondering whether this was going to be a 5 minute outage or
a 2 hour outage. The power cycled 3 times, with considerable
blinking, which is usually the sign of a failure rather than some
transient event. Also, when I took the headphones off, I could tell
that it was raining and the wind was blowing. Time to rig for
extended power outage!
In my household, when the power is off for more than 5 minutes, I have
to visit each computer and UPS and shut them down. If I leave them
running, the UPS battery runs down, the computer crashes and the UPS
battery dies an untimely death. Doing these shutdowns takes 10-15
minutes.
After the shutdown, I sat in the darkness wondering how the European
sunrise period was going. During the first 7 hours of the contest,
various Western Europe stations had called with reasonably decent
signals and I was hoping for a strong Eu sunrise period. The first Eu
DX came in at 2217Z which hasn't happened for a few years.
So, I plugged the SDR receiver into the spare battery and powered up
the SDR computer on the UPS for a quick listen. The best that I could
tell, the cycling noise was gone. Then I shut it down again, and went
for a nap. I spent a few minutes thinking about strategy as I quickly
fell asleep.
Around 0720Z the lights came on and that woke me up. Since I was very
groggy, I thought to myself screw it and slept some more. Around
0820Z is got up and started to power up all of the UPSes and computers
and reset my network. It took a few minutes to track down the rogue
DHCP server which tricked the other computers into failing to talk to
each other. Apparently, the upstairs wireless access point, which is
a retired router, can no longer remember its state across a long power
outage. By about 1000Z I was ready to operate again.
I operated until 1316Z and then slept some more. After the first
night with the missing Eu sunrise, I was missing EB, SJV, and WTX
along with the normal hard to find sections (AK, PR, NL, and NT). I
was also missing about 100 QSOs.
After sleeping, eating and showering, I felt like attacking the
distorted audio. I put a scope on 2 of the 4 SDR audio channels and
observed my own signal. The problem became clear after a moment: the
signals from the 2 SDR arrays differed by about 10 Hz. The distortion
was a heterodyne. I thought the two receivers were better calibrated
than that, but apparently not.
The solution was to change the audio routing so that each ear gets the
channels that originate from the same receiver. Then there is no
heterodyne, despite the slight frequency offset (my brain just hears 2
very close tones for the same strong signal).
So at the Saturday afternoon restart, this is the audio streaming
arrangement:
1. 4x2 phased array delivering 2 steerable beams to the left ear.
2. 3x2 phased array delivering 2 steerable beams to the right ear.
3. K3 and 12 Beverages, every 30 degrees in varying lengths, two at a
time, one for each ear.
This arrangement worked perfectly. Now I could call CQ and hear a
response from almost any direction without having to search through
multiple receivers and antennas looking for a signal. For some very
weak signals, I had to move the beams to find the best direction.
Much less fatiguing. I didn't use the Beverages at all the second
night.
During the second night, I normally grab a nap from about 0800Z to
1100Z or so. But since I napped the first night, I decided to operate
through the period. However, I think I dozed off several times while
the CQ machine was running, to be awakened by a loud caller. There are
several 8-10 minute gaps between contacts, which is not entirely
unreasonable for the second night. But if anyone noticed extreme
deafness, I was probably asleep at the key.
V31MA was the surprise multiplier. PJ2T called me twice. I've never
heard KH6LC so weak. He was my best DX.
Why does the ARRL 160 contest result in so many duplicate contacts?
The dupe rate in this contest is about 3% while every other contest is
1% or less.
Not much DX worked: CT, DL (10), EA (6), EA6, EI, F (4), G (11), GI,
GM, GW (3), HB, I (8), KH6 (2), KP2 (4), LY (2), OH, OK (4), ON, PA,
PJ2, S5 (3), SV, V3, XE (3), and YU.
Equipment: K3 with sub-RX, P3, Alpha 8410 with too much acoustic
noise, 4x2 phased array and SDR receivers, 3x2 phased array and SDR
receivers, beam steering and audio routing software, 6 2-wire
bi-directional Beverages, 65 foot "tee" vertical over 65-75
(depending
on breakage) 125-foot radials with a sagging top-hat wire.
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