[3830] TBDC K1LT Single Op HP

[webform at b4h.net]

                    Stew Perry Topband Challenge

Call: K1LT
Operator(s): K1LT
Station: K1LT

Class: Single Op HP
QTH: EM89ps
Operating Time (hrs): 14
Radios: SO2R

Summary:
Total:  QSOs = 667  Total Score = 1,937

Club: Mad River Radio Club

Comments:

I had a couple of extra days of from work around the Christmas
holiday, so I expended some effort to make my station effective for
SO2V: SO2R but with VFOs instead of whole radios except that I used my
KX3 (with no roofing filter) as the second receiver beyond the 3 or 6
or 10 receivers (depending on how you count) that I am already using.

The first step was to prepare a receive antenna that could drastically
reduce the signal from my own transmitter.  I built a box to combine
the output of 2 short verticals that are roughly in line with the
transmit vertical, about a 1000 feet away.  The box inverts one short
vertical output, delays the signal of one vertical or the other using
coax with the same amount of delay as the speed of light distance
between the verticals, and adds the two signals.  This is the standard
arrangement to make a pair of verticals into a switchable end-fire
array.  I added a 1000 ohm 10-turn pot in parallel to the "hottest"
vertical and a variable capacitor and inductor in parallel to the
other vertical.  Tweaking the capacitor and the pot allow fine tuning
of the amplitude and delay to nearly cancel my own transmitted signal.
With care, I could reduce a 40 db over signal to about S5.

The second step was to arrange to mute my transmitted signal so that I
could hear stuff on a separate receiver while transmitting without
having to perform any audio routing chores.  The proper way would be
to modify my new SO2R / audio routing box.  Instead I modified my beam
steering phased array SDR receiver antenna gadget to automatically
reduce the gain by a factor of 200000 when a sufficiently strong
signal is present.  This method was conceptually simple although I was
still tweaking the timing after I started operating.

Left over from the ARRL 160 contest is the arrangement in which the
"east" phased array puts 2 signals in my left ear while the
"west"
phased array puts 2 signals in my right ear.  The audio is each ear is
"phase locked" by virtue of a common local oscillator in the
receivers
feeding that ear.  But the local oscillator of the "east" array are
not locked to the oscillator of the "west" array.  So there is a
hetrodyne of a few hertz, which just makes the audio sound weird on
strong signals.  I spent some time trying to get the 2 SI570 VFO chips
to calibrate to exactly the same frequency, but about 5 hertz
difference remains, which causes a slow, annoying flutter.  I got rid
of the last 5 hertz by tweaking the software so that the slave
("west") receiver is offset by 5 Hz from the master
("east") receiver.
The remaining fractional hertz difference could easily be ignored.

I started the contest expecting a slow ramp up of activity, which is
handy because I can eat up some "off time" by taking a 30 minute
break
to make adjustments.  But activity started strong and only got
stronger.  I had to make the final adjustments while running.  One
adjustment was to make the automatic muting last an entire
transmission.  That took only about 10 software restarts.  The other
adjustment was to find a "noise free" power supply for the KX3. 
When
running on the same 12 volts that feeds the K3, there is thumping
because the power supply and wiring load response is too poor.  (Note
to self: rearrange power wiring so that accessories are attached to
the power supply independently of the transmitter.)  Various wall wart
supplies had too much hum.  Finally I noticed that the KX3 has
batteries which should last for receiving for some time.

Once these adjustments were complete, operation was reasonably
straight forward.  If there was a lull in the running, I could turn up
the audio from the KX3 and tune around to find a station not yet
worked.  Once tuned in on the KX3, I would tune the "VFO B" knob of
the K3 to the same frequency.  Then when it was time to pounce, bang
the down arrow key on Writelog, bang the F4 key, and complete the
"second VFO" QSO.  I forgot the keystrokes in Writelog that allow
one
to type a call to dupe check without interrupting the ongoing CQ.  But
the rate on the second radio (or VFO) was low enough that I could dupe
check between CQs.  Overall, I think I made about 30 QSOs this way.
This method doesn't improve rate so much as making sure that one works
everyone, since the number of accessible QSOs is somewhat limited.

I was surprised by the number of and signal strength of the South
American stations.  I think I worked more countries in South American
than in Europe.  Hopefully OA4TT uploads his log to LoTW so I can
confirm Peru on 160.  The call from PY5XH was a surprise since I
rarely work Brazil on 160.  The Caribbean stations were also numerous.
I did not work any Africa and I never heard a peep from V55V.  I think
ZS6EZ called me but I did not recognize his call at the time and we
did not complete the QSO.  VK3IO was my best DX.

Another note to self: a method to reconfigure the audio routing from
the phased array receivers to select one or the other array with each
of 2 beams routed to an ear.  Also discover why sometimes a strong
trace would be visible on the waterfall, but with very, very weak
audio.

Continuing the ongoing tracking of performance:

        raw     raw    points  cooked  cooked  points  cooked-raw
year   QSOs    score  per QSO   QSOs   score  per QSO     ratio

2005    491     2033    4.14    483     2439    5.05      1.22
2006    604     2224    3.68    didn't submit log in time
2007    691     3712    5.37    669     4293    6.42      1.19
2008    633     3328    5.26    617     3895    6.31      1.20
2009    761     4006    5.26    737     4871    6.61      1.26
2010    642     2477    3.86    623     2931    4.70      1.22
2011    656     2501    3.81    642     3169    4.94      1.27
2012    679     3214    4.73    667     3986    5.97      1.24
2013    723     3559    4.92    710     4525    6.37      1.30
2014    667     1937    2.90

Repeating from last year: the "points per QSO" number seems to be a
potentially useful figure of merit.  Also note that the "cooked"
score
is usually about 20% better than the raw score, because of the points
awarded for working low power stations.  Since that ratio is pretty
constant, then the "points per QSO" number looks like a concise
measure of "conditions".  2010 and 2011 were crappy years, 2007 -
2009
were very good years, and the rest must be "normal".  This year was
apparently a very bad year.

DX Worked: EI (2), G (3), HC, HI (2), KH6 (2), KP2 (2), KP4, OA, OK,
P4, PA, PY, SM, VK, and XE (2).  5 EU countries, 4 SA countries, 4 NA
countries (not counting K/VE), and 2 OC countries, a nice even spread
across the world, ha!

Equipment: K3, P3, KX3, Alpha 8410, Writelog in SO2V mode, 16 short
verticals comprising 3 phased arrays, 12 Beverages only used while
restarting the software, 65 foot "Tee" top vertical over 75 or so
125
foot radials.


Posted using 3830 Score Submittal Forms at: http://www.3830scores.com/