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[3830] TBDC K1LT Single Op HP

To: 3830@contesting.com, vkean@k1lt.com, mrrc@groups.io
Subject: [3830] TBDC K1LT Single Op HP
From: webform@b4h.net
Reply-to: vkean@k1lt.com, mrrc@groups.io
Date: Sun, 31 Dec 2023 21:02:49 +0000
List-post: <mailto:3830@contesting.com>
                    Stew Perry Topband Challenge - Dec 30

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

Class: Single Op HP
QTH: EM89ps Ohio
Operating Time (hrs): 13.1
OpMode: SO2R

Summary:
Total:  QSOs = 604  Total Score = 1,775

Club: Mad River Radio Club

Comments:

As usual I took most of my vacation time in December and worked on
projects.  Instead of working exclusively on the new phased array
receiving system, I added some other projects as well.

I built a couple of "Ethernet coax relays" to augment my
semi-automated antenna switching.  I designed a small circuit board to
connect a DPDT relay as close to some SO239s as possible and hacked my
existing Ethernet to relay controller to drive the relay.  The result
is a box with SPDT coax switching remotely controlled via Ethernet.
The coax side has a better than 1.05:1 SWR through 6 meters.

I also converted my remote 2-pole 14-position Beverage antenna switch
from touch tone audio over the feedlines to Ethernet to get rid of the
clunky keypads at my operating position and to make some extra
automation possible.  Unfortunately critters destroyed the Ethernet
cable I put in conduit years ago for this purpose before I had a
chance to use it.  Currently, there is a 180-foot run of CAT5E laying
on the grass awaiting critter or lawn mower death.

During the ARRL 160 test, I observed that the Beverages seemed to be
hearing better than my phased array.  In my ARRL 160 3830 post I then
expressed surprise but I had forgotten that the receivers in the old
phased array receiving system are not particularly sensitive and I was
observing that fact.  The insensitive receivers were one of the
motivations for developing the new system.

So I worked some more on the new and improved phased array receiving
system, which is considerably more sensitive, but has other issues.  I
added some newly developed hardware that minimizes the cabling between
the receivers and the controller and doubles the number of possible
receivers.  The main issue at the moment is that the software seems
to lose synchronization with the serial data stream which causes the I
and Q channels to swap which severely degrades performance.  I don't
yet fully understand this issue but it seems to be related to having 4
simultaneous receivers (after beam-forming 16 receivers in the FPGA).
Long story short: it ain't ready yet.

Since the old phased arrays seem deaf (not like this is a new thing)
and since I had a new and improved Beverage switch, I decided to
operate using the Beverages exclusively.  Since poking keys on a
keyboard seems to be my preferred human-machine interface, I obtained
a "numeric keypad" to command the Beverage switch.  I had planned to
use a Raspberry Pi computer to do the controlling, but the software
and the Pi had some disagreement so I used my laptop instead.
Ultimately I need to integrate another screen into my station
somewhere.  Already there are 3 or 4 screens, not counting the P3s.

After some field work on the warm days, I had all the Beverages
working simultaneously for the first time in many years, although the
north Beverage seemed to go partially deaf the day before the test.

As I have been using the phased array receiving system on 160 almost
exclusively for more than a decade, I was concerned about the return
of the old terror of hunting through 12 Beverages trying to make a
caller audible.  However, that situation seemed to occur only a couple
of times.  Most of the time, I would hear something and usually poke
the correct key on the first or second try.  It was helpful that I was
already listening to 2 directions at a time using the sub-receiver in
the K3.

Since my in-band receiving setup has evolved to consume the output of
a Beverage, I had to keep the sub-receiver Beverage always west since
this antenna connected to both radios (and the transmit nulling
circuit) via a magic-tee splitter.  Turns out that west is not a bad
direction to use for in-band hunting.  Previously I used a northeast
Beverage which was great for the first few hours but then couldn't
hear anything new.

One annoyance with in-band (full duplex) receiving is that the
amplifier has a two-level bias scheme that changes the tube bias
between keying elements (words, actually).  This means there is a
broadband click that evades the transmit signal nulling.  This noise
was particularly loud at the start but it gradually diminished of the
course of the test.

Propagation probably helped the Beverage experiment.  Before my nap at
0900Z, everything from the west was particularly good copy while
everything beyond one hop to the east seemed to be particularly weak.
Worst propagation ever, from my perspective.  But no static at all,
FM.

Worked a very weak KH6ZM about 30 minutes before his sunrise.  I had a
hard time peaking his signal until I recognized the "KH6" portion.
When searching through receive antennas, one might not notice the
better choice if one listens for only a fraction of a second.

Europe was in and out constantly, mostly out.  MM0ZBH was the first Eu
at 2227Z, just after sunset.  It took a couple of iterations to
compile all those dahs followed by dits.  The other Europeans:

    2309 LY4A         called me - rapid QSB, many iterations
    2330 DR5X         called me - quick QSO
    2359 YL3FT        called me - several tries
    0004 G3BJ         called me
    0011 YL7X         called me - rapid QSB
    0238 OK3C         I called him on top of N0AX
    0248 S53M         called me - rapid QSB
    0309 OM2XW        called me - rapid QSB
    0334 IT9BLB       called me - good QSB peak
    0407 CT9ABO       called me - remarkably weak
    0427 G4FAL        I called him - very weak
    0552 G4IRN        I called him - struggle
    0603 HA8A         called me - disappeared quickly

N0AX and OK3C were both CQing on the same frequency.  OK3C was
remarkably loud and stable for the circumstances but neither was
hearing the other.  Someone on the east coast worked OK3C through the
QRM so I called OK3C using his call a couple of times hoping N0AX
would recognize the situation.  Ward obliged.  Thanks!  Nevertheless,
I hate it when someone does that to me, so I apologize for the
intrusion and the hypocrisy.

KL7SB was remarkably easy to hear and work at 0645Z.

XE1FAS called twice but never transmitted an exchange.

Simultaneous calls from FY5KE, another caller, and an off frequency
QRL caused some momentary stress but sorted itself nicely.  Whew!

New record for SA QSOs in a TBDC: PJ2T, FY5KE, PY5XH, and CX6VM.
Hearing south has always been a weakness here.  Do the Beverages make
hearing the south better?  Sometimes I think the phased arrays are too
directional.  CX6VM was my best DX.  All of the South Americans were
easy to copy.

I napped for about 2 hours at 0900Z and returned about 100 minutes
before sunrise.  I worked 36 more stations including 1 6-pointer and 1
5-pointer but no DX.

Here is the annual propagation and participation "trends" table:

        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    655     2474    3.77      1.28
2015    620     1934    3.12    614     2440    3.97      1.27
2016    759     3381    4.45    742     4204    5.66      1.27
2017    transmit feedline disaster - quit with only 101 QSOs
2018    785     3587    4.57    764     4238    5.55      1.18
2019    828     4947    5.97    809     5846    7.23      1.21
2020    882     3661    4.15    866     4455    5.14      1.24
2021    676     2574    3.96    661     3130    4.74      1.22
2022    657     2252    3.43    643     2649    4.12      1.18
2023    604     1775    2.94

Note: the raw numbers are before log checking while the cooked numbers
are after log checking.  The cooked numbers exclude busted QSOs and
include the per-QSO multiplier for low power and QRP contacts.  The
points per QSO metric seems to be a good indicator of goodness of
propagation whereas the QSO count seems to track participation.

DX worked: 8P, CT3, CX, DL, FY, G (3), GM, HA, KH6 (2), KL, KP2 (2),
KP4, LY, OK, OM, PJ2, PY, S5, TI, XE, YL (2), and ZF for a total of 22
entities.  No Asian entity, so no install worked all continents.

Equipment: Elecraft K3S, P3, K3, P3, Alpha 8410, homebrew SO2R stuff,
too many computers, 60-foot "tee" vertical over 70 125-foot radials,
6
2-wire Beverages of varying lengths (12 directions), 2x4 broadside
end-fire array of short verticals and SDR receivers for beam steering
to the east, 2x3 broadside end-fire array of short verticals and SDR
receivers for beam steering to the west, and 2x2 broadside end-fire
array of short verticals to the north or south (not used).


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